IAEA-TECDOC-755
Assessing the radiological impact of past nuclear activities and events
Part of the IAEA/CEC Co-ordinated Research Programme on the Validation of Environmental Model Predictions (VAMP)
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ASSESSIN RADIOLOGICAE GTH L IMPACF TO PAST NUCLEAR ACTIVITIE EVENTD SAN S IAEA, VIENNA, 1994 IAEA-TECDOC-755 ISSN 1011-4289 PrinteIAEe th AustriAn y i d b a July 1994 FOREWORD
Followin Chernobye gth recommendatioe lth accidenn o d an Internationae t th f o n l Nuclear Safety Advisory Group (INSAG Summars it n )i y ReporPost-Accidene th n o t t Review Meetine th n go Chernobyl Accident (Safety Series No. 75-INSAG-l, IAEA, Vienna, 1986), the IAEA established a Co-ordinated Research Programm "Thn eo e Validatio Model f nTransfee o th r sfo f Radionuclide o r s in Terrestrial, Urban and Aquatic Environments and the Acquisition of Data for that Purpose". The programm e informatioth e e environmentae seekus th o n t so n l behaviou f radionuclideo r s which became available as a result of the measurement programmes instituted in the former Soviet Union and in many European countries after April 1986 for the purpose of testing the reliability of assessment models. Such models find applicatio assessinn ni radiologicae gth l impac l partal f f so o t the nuclear fuel cycle. They are used at the planning and design stage to predict the radiological impact of planned nuclear facilities, in assessing the possible consequences of accidents involving release radioactivf so e materia environmene th o t l establishinn i d an t g criteriimplementatioe th r afo n of countermeasures operationae th n I . l phase the usee yar d together wit resulte hth environmentaf so l monitoring to demonstrate compliance with regulatory requirements regarding release limitation.
The programme, which has the short title "Validation of Environmental Model Predictions" (VAMP), was started in 1988; it is jointly sponsored by the Division of Nuclear Fuel Cycle and Waste Management and the Division of Nuclear Safety and is also supported by the Commission of Europeae th n Communities.
At the VAMP Research Co-ordination meeting in July 1993 a special one-day plenary session topie hels th cn dwa o "Recen ongoind an t g environmental impact assessment studies" collectioe Th . n paperf o s presente sessioe th n di rathe s ni r unique, reflectin availabilite gth informatiow ne f yo n from environmente th formef so r weapons test sites worldwid als d currene eoan th t concer evaluato nt e eth radiological impac eventf o t s surroundin earle gth y day nucleaf so r weapons productio testingd nan . Papers in the session also addressed the reconstruction of radiation doses received in the early phase e releaseoth f s from Chernoby assessmend an l e impacth f f marino o tt e dumpin f radioactivo g e wastes. This repor compilatioa s ti paperf no s presented durin Jule gth y 1993 Special Plenary Session.
Other reports issued under the VAMP programme are:
Modelling of Resuspension, Seasonality and Losses during Food Processing. First Report of VAMe th P Terrestrial Working Group, IAEA-TECDOC-647 (1992).
Modellin Depositioe gth Airbornf no e Radionuclides int Urbae oth n Environment. First Report of the VAMP Urban Working Group, IAEA-TECDOC-760 (1994). EDITORIAL NOTE
In preparing this document for press, staff of the IAEA have made up the pages from the original manuscripts submittedas authors.the viewsby The expressed necessarilynot do reflect those of the governments of the nominating Member States or of the nominating organizations. The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does implyintentionnot any infringeto proprietary rights, should construednor be it an as endorsement recommendationor partthe IAEA. ofon the The authors responsibleare havingfor obtained necessarythe permission IAEAthe to for reproduce, translate or use material from sources already protected by copyrights. CONTENTS
INTRODUCTION ...... 7 .
ASSESSMENTS IN THE VICINITY OF NUCLEAR WEAPONS TEST SITES
A dose assessment for a US nuclear test site — Bikini Atoll ...... 11 W.L. Robison, K.T. Bogen, C.L. Conrado Feature evaluation a f so radiatioe th f no n doses received populatioe th y b n after atmospheric nuclear testing at the Semipalatinsk test site ...... 25 V. Logachev Dose assessment studie t formesa r nuclear weapons test site Australin si a ...... 3 3 . G.A. Williams Assessmen potentiaf o t l Maraling dosee tesu th tt sEm a site d saan ...... 1 5 . S.M. Haywood, J.G. Smith
ASSESSMENTS IN THE VICINITY OF NUCLEAR WEAPONS PRODUCTION FACILITIES
Environmental modeling for the Hanford environmental dose reconstruction project ...... 63 B.A. Napier, D.B. Shipler, W.T. Farris, J.C. Simpson, CM. Heeb, J.V. Ramsdell, Jr., T.A. Ikenberry, W.H. Walters, M.D. Freshley Dose reconstruction studie t selectea s d nuclear weapon A ...... s facilitieUS e th n i s 9 7 . C.W. Miller, J.M. Smith, L.S. Denham
POST-CHERNOBYL DOSE ASSESSMENT STUDIES
Thyroid dose reconstruction in the aftermath of the Chernobyl release ...... 89 LA. Likhtarev, G.M. Gul'ko, I.A. Kairo, B.C. Sobolev Dose assessment and reconstruction in the areas of Russia contaminated after the Chernobyl accident ...... 105 /./. Kryshev, K.P. Makhon'ko, T.G. Sazykina CEC/CIS joint programm consequencee th n eo Chernobye th f so l accident ...... 5 11 . G.N. Kelly, CedlleL. A short note on recent USA/CIS collaborative studies on impact assessment ...... 125 W.L. Templeton
ASSESSMENT IN THE VICINITY OF DUMPED RADIOACTIVE WASTE
The International Arctic Seas Assessment Project (IASAP) ...... 129 K.-L. Sjoeblom, G.S. Linsley INTRODUCTION
The VAMP plenary session held in July 1993 was intended to bring together some of the scientists currently involved in studies aimed at assessing the radiological impact of past events concerned with weapons production and testing and with other events, some accidental and others deliberate, which have resulte contaminatioe th n di environmente th f no recenn I . t years thers eha been an increase in studies of this type. There are several reasons for this. Firstly, there is an increased awareness among the members of the public who have been potentially affected by the past releases or by the resulting contaminated environments. This has resulted in political pressure being brough beao t r tinvestigation fo r e potentiath e carrief b o t o t ls dou healt h impacts. Secondly, information on the detailed nature of the events, many of which were formerly secret, has only become common knowledg recenn ei t year resula dramatia s f sa o t c improvemen internationan i t l relations. Finally, there is interest, in some situations, in obtaining radiological data from these events for use in epidemiological studies. The interest from the standpoint of the VAMP study is in whicthe eus s bee hha n mad mathematicaf eo l model assessmene th n si efforte tth studien o i t s d san have such models validated and so to demonstrate that the associated results are reliable.
e studieTh s presente thin di s categorisee reporb n ca t followss da : Environments of weapons testing sites. Environments of weapons production facilities. Environments affected by fallout from nuclear accidents. Environments affected by radioactive waste disposal activities.
firse Inth t category four papers cover nuclear weapon (PacifiA s tesUS te c site th Island f o s s test formee sites)th f o ,r USSR (Maralinga/Emu)(SemipalatinskK U e th f o e secon d th an )n I d. category two papers discuss the ongoing studies in the environments of weapons facilities in the USA. Studies of radiological impact assessment in environments affected by the Chernobyl release are reported in four papers. Finally a study aimed at evaluating the potential impact of the dumping of high level radioactive Arctiwaste th n ei c Sea reporteds si .
The objectives of the studies vary although most have the common element of radiological assessmen meany b t f mathematicaso l modelling objectivee Th listee . b followss n da ca s :
To evaluate the risks to health in the exposed population; To provide radiation dose estimates in the exposed population for use in epidemiological studies; To evaluate the risks posed by the environmental contamination as an input to decisions on remedial actions.
e studiet falTh no l neatlo sd y intabove oth e categories; some have more thaobjectivee non . The studies in the vicinity of the Maralinga/Emu and Pacific Islands test sites were primarily intended to assist in decisions on remediation or on the acceptability or otherwise of land areas for habitation. assessmente Th s relate Semipalatinse th o dt k test site Hanfore th , d othee facilit nucleath S d U r yan r weapons facilitie beine ar s g conducte orden di evaluato rt locae risth e elth o k t populations e th n I . sitesS risU case e th som,f k eo th estimate f usee o b helo dy t psma establish whether compensation affecteo t d person justifieds si assessmene Th . t study concerned wit waste hth e dumpe Arctie th n di c Seas is intended to evaluate the possible future risks to various population groups but it also aims to determine whethe t remediano r o r l measure justifiee wastee b th n r technican ca sfo so d l grounds. Three of the Chernobyl studies are directed towards the retrospective evaluation of thyroid radiation doses in the early period after the accident occurred when comparatively few relevant measurements were made. In some cases the work is being conducted as an input to long term epidemiological studies papero Tw . s describe programmes aime understandint da ecologe gth radionuclidef yo e th n si environment f Chernobylo s ; measure remediatioe assiso t sth n i t f contaminateno d area e alsar so paperse th discussef o .e on n di Most of the studies involve some kind of retrospective analysis using modelling techniques. In most of the cases considered, few data were collected at the time of the event(s), either because potentiae th l health problems wer t properleno y appreciate time th et da and/o r because dosimetric techniques were inadequate Chernobye case th f th eo n I . l accident, ther usualls ewa y insufficient time and resources to carry out proper surveys of affected populations. In many of the studies, it is importan e dosth er estimatefo t e validateb o t stherefored an d , wherever possible a variet, f o y independent techniques for dose assessment have been employed.
Some of the studies are still in progress and may take several years to complete. In addition, other studies are going on in various parts of the world which were not reported at the VAMP session expectee studiew b y Ne . sma begio dt access na formeo st r military sites becomes possible. Thus, a complete picture of the world's major contaminated sites and of the associated impact on human populations may not be available for many years.
Next page(s) left blank ASSESSMENT VICINITE TH N SI F YO NUCLEAR WEAPONS TEST SITES A DOSE ASSESSMENT FOR A US NUCLEAR TEST SIT E- BIKINI ATOLL
W.L. ROBISON, K.T. BOGEN, C.L. CONRADO Lawrence Livermore National Laboratory, Livermore, California, United State f Americso a
Abstract
Marcn O , 1954h1 nucleaa , r weapon test, code-named BRAVO, conducte t Bikinda i e Atolth n i l northern Marshall Islands contaminated the major residence island. There has been a continuing effort since 1977 to refine dose assessments for resettlement options at Bikini Atoll. Here we provide a radiological dose assessment for the main residence island, Bikini, using extensive radionuclide concentration data derived from analysi f fooso d crops, ground water, cistern water, othefisd han r marine species, animals, airsoid l,an collecte t Bikinda i Islan continuinr pars ou d a f o t g researcd han monitoring program that bega uniqu1975e n i Th . e compositio coraf no l soil greatly alter relative sth e contribution of cesium-137 (l37Cs) and strontium-90 (90Sr) to the total estimated dose relative to expectations based on North American and European soils. Cesium-137 produces 96% of the estimated dos returninr efo g residents, mostly through uptake fro soie terrestriamo th t l l food crop alst sbu o from external gamma exposure. The doses are calculated assuming a resettlement date of 1996. The estimated maximum annual effective dose is 4.4 mSv y1 when imported foods, which are now an establishe ddiete paravailableth e f ,ar o t 30-e ,Th .50- 70-d an ,y integral effective cSv0 dose1 4 1 ,e sar cSv, and 16 cSv, respectively. An analysis of interindividual variability in 0- to 30-y expected integral dose indicate Bikinf o s tha% i 95 tresident s would have expected doses withi abovnfacto4 a 3. d f eo ran 4.8 below the population-average value. A corresponding uncertainty analysis showed that after about 5 y of residence, the 95% confidence limits on population-average dose would be ±35% of its expected value. We have evaluated various countermeasures to reduce 137Cs in food crops. Treatment with potaséium reduce uptake sth 137f eo Cs into food crops thereford ,an ingestioe eth n dose leso ,t s tha% n10 of pretreatment levels and has essentially no negative environmental consequencs.
1. INTRODUCTION Bikini Atoll was one of the two sites in the northern Marshall Islands that was used by the United States as testing grounds for the nuclear weapons program. Twenty-three nuclear tests were conducted from 1946 to 1958. The BRAVO test, on March 1, 1954, had an explosive yield that greatly exceeded expectations, wit resule hth t that heavy fallou s experiencewa t t Bikinda i Islan atolld dan s easf o t Bikini Atoll. The Bikini people, since their initial relocation to Rongerik Island in 1946, have had a continuing desire to return to their homeland. In 1969 a general cleanup of debris and buildings as well plantine th s a coconutf go , breadfruit, Pandanus, papaya banand an , a trees bega t Bikinna i Atoll. After preliminara y surve 197n yi 0 Bikini families moved bac Bikino kt i Island. A radiological survey was conducted in 1975, but few samples of locally grown food crops were available to confidently establish the radionuclide concentrations on Bikini Island to reliably estimate
dosee th ; predictions preliminar e baseth n do y data indicated that when food crops mature bode dth y
resultinburdeCd san 137 f no g doses would exceed federal guidelines 1978n I . , whe coconute nth s started producing fruits, whole body counting revealed thaCs t137 bod y burdens in the people on Bikini were well above the U.S. recommended level. Consequently, in August 1978 Trust Territory officials arrived at Bikini Islan relocated dan people dth Kilo et i Island. A preliminary dose assessmen Bikinf to i Islan earlien a 1982 n di d ran ,dos e assessmen Enewetaf to k Atoll, indicated that the most significant potential exposure pathway to the contaminated atolls was
terrestriae th l foo estimatee th d . f Nearlchaio 2] , % dn[1 y95 effectiv e dos t Bikinea i Island results
137 137 froCsm;137 90% of the total dose froCsm arises from ingestionC os fin terrestrial foods, with the remainder coming from external gamma exposure have W .e develope extensivn da e data bas !r 37efo Cs , 9 °Sr,plutonium-239+240 (239+240p americium-24d u/an ) 1concentratio) (24Am 1 e atolth ln n i ecosyste m through the sampling of soil, vegetation, animal, ground water, cistern water and marine species in an effor refino t t e dose assessment resettlemenr sfo t option t Bikinsa i Atoll thin I . s repor presene w t e th t most recent dose estimates, uncertainty in the estimates, and countermeasures designed to reduce the dos peoplo et e resettling Bikini Island.
11 2. EXPOSURE PATHWAYS
The radiological dose to inhabitants at the atoll occurs from both external and internal exposure. Eac thesf ho categorieo etw brokee b n sca n down further intfollowine oth g exposure pathways) (1 : External Exposure: natural background radiation; nuclear test-related radiation, (2) Internal Exposure: natural background radiation; nuclear test-related radiation — radionuclides in terrestrial foods, marine foods, drinking wate radionuclided ran s inhaled. externae Th l natural background radiatio northere th n ni n Marshalr lo Islanl h- R du Atoll5 3. s si 0.22 mSv y-1 [3] due to cosmic radiation; the external background dose due to terrestrial radiation is very Marshale th n i w l Islandslo internae Th . l equivalen naturar fo 1 ty ldos v occurrin abous ei mS 2 2. t g radionuclides suc Potassium-4s ha 0 (4°K), Polonium-210 (2lopo), andLead-210 (2iOpb) that result from consumptio locaf no imported an l d foods naturae Th . l background t include dos no dose e s ei th n sdi presented in the paper unless specifically stated.
DAT. 3 A BASES 3.1 External Exposusre Measurements externae Th l exposure rate t Bikinsa i Atoll were measure EG&y d b aeria e pars th G a f lo t survey conducte e 197th 8n di Northern Marshall Islands Radiological Survey (NMIRS) [4]e averagTh . e exposure rat Bikinn eo i Islan measures da EG&y db 197Gn i abous 8wa |i1 Rr3 h-i198n I 198d . 6an 8 additional external gamma measurements were mad 137f eo cobalt-6 Cd san 0 (SOCo) insid outsidd ean e house othed san r buildings around an , village dth e area; crushed coral placed aroun buildinge dth s provides sheildin addition gi buildingse th o nt . Measurement t Bikina s i Island indicate thae th t average exposure inside the houses is about 2.1 uR h-l while in the immediate area around the houses it is 11 |jRh-i.
External2 3. Beta-Particle Exposure unshieldee Th d beta contributio externae th o nt l dos estimates ewa t Enewetada k Atol 198n i l 0 [5]. More recent studies at Bikini Atoll using new, thinner thermoluminescent dosimeters (TLDs) indicate that the dose over open ground at 1-cm height is about three times that of 1-m height [6]. Thus, the unshielded beta dos t 1-cea mBikinn o i Island coul equae r slightldb o o t l y greater tha externae nth l gamma dose. However significana eyesr e ,fo th ,y uppeda r te o parrth m f bodyt8 o gonadd 0. t ,an a e sar more in height above the ground surface. The walls and floors of the houses and the crushed coral customaril t arounypu d village houseth d es an are a absorb bet e mosth a f radiationo t additionn I . y an , clothing, shoes, zories, Pandanus mats, or other coverings also greatly reduce exposure to beta radiation.
Airborne3 3. Radionuclide Concentrations Airborne concentrations of 239+240 pu and 241 Am are estimated from data development in resuspension experiments conducted at Enewetak Atoll in 1977, Bikini Atoll in 1978, and Rongelap Atoll in 1991. We briefly describ resuspensioe eth n methodology here; more foun e detaib Shinn n di ca l t al.[7]ne . Four simultaneous experiments were conducted characterizatioa ) :(1 normae th f no l (background) suspended aerosols and the contributions of sea spray off the windward beach leeward across the island, (2) a stud f resuspensioyo radionuclidef no s fro mfiela d purposely laid bar bulldozery eb worst-casa s sa e condition studa ) f resuspensio(3 ,y o f radioactivno e particle vehiculay sb food a ran t ) traffic(4 d an , study of personal inhalation exposure using small air samplers carried by volunteers during daily routines "normale Th . "backgroundr "o " mass loading (the mas solif so d materia r unipe l t volum airf eo ) measured by gravimetric methods for the atolls is approximately 55 ug nv3. The data from the Bikini experiments indicate that 34 ug nr3 of this total is due to sea salt that is present across the entire island resula s a oceanf o t , reefwind an , d actions mase Th s. loadin terrestriao t e gdu l origin , thereforesis , abou ji1 g2 t highes e nr3Th . t terrestrial mass loadin 3 immediatelnr g g|i observe6 13 ys aftedwa r bulldozing. Concentration 239+240pf so u were determine collecter dfo d aerosol normar fo ) s(1 l ground coved ran conditions in coconut groves, (2) for high-activity conditions, i.e., areas being cleared by bulldozers and being tilled, and (3) for stabilized bare soil, i.e., cleared areas after a few days' weathering. The plutonium concentration in the collected aerosols changes with respect to the plutonium concentration in surface soieacr fo lthesf ho e situations have W .e define enhancemenn da t facto r239+240p e (EFth s )a u concentration in the collected soil-aerosol mass divided by the 239+240pu surface-soil (0- to 5-cm) normale th concentrationr fo ) ,lesf open-aio <1 sF F thaE (E e n1 r Th .condition apparentls si resule yth t of selective particle resuspensio whicn ni resuspendee hth d particles hav ea differen t plutonium
12 concentration than is observed in the total 0- to 5-cm soil sample. Similarly, the enhancement factor of high-resuspensior fo 3 n conditions results fro increasee mth d resuspensio f particlno e sizes witha higher plutonium concentration than observed in the total 0- to 5-cm soil sample. We have developed additional personal-enhancement factors (PEF) from personal air-sampler data. These data represent the enhancement that occurs around individuals due to their daily activities. The total enhancement factor used to estimate the amount of suspended plutonium is the EF multiplied by the PEF. Consequently, the total enhancement factor (TEF) used for normal resuspension condition (0.8 5 high-resuspensior 1. fo 2s 1.9i x d )an n condition (3.9 2. 10.92) x s i . To calculate inhalation exposure, we assume that a person spends l h d"1 in high-resuspension conditions 1 unded- h r3 norma2 , l resuspensiony conditionda breathina r s pe ha 3 d m gsan 3 rat2 f eo (1.2 m3 under high-resuspension conditions and 21.8 m3 under normal-resuspension conditions). The radionuclide concentrations in surface soil (0- to 5-cm) for Bikini Island complete the information necessary for calculation of plutonium and americium intake through inhalation.
3.4 Radionuclides in Marine Foods, Soil, and Terrestrial Food The average concentrations of Cs, ^r, 239+240pu ancj 241 Am in marine foods and terrestrial foods are listed in Table 1. Most of the dat 137 a for the marine foods is a result of work conducted by Noshkin et al. [8]. The data for the terrestrial foods are part of our continuing program where samples have been collected and analyzed from 1975 through 1989 on Bikini Island [9]. The number of samples analyzed for drinking coconut meat, drinking coconut juice, copra meat, copra juice, Pandanus, breadfruit, papaya, squash, banan , respectively animald 36 aan d 797e an smediaar 9 e 3 , , 732Th . 53 n, , 18893 , , 17741 , 66 , 3 90 concentratio lf n?Cso , Sr, 239+240pu anc soin ji 24l m profile1A listee soie sar Tabln di lTh dat . e2 s ai also part of our continuing program.
3.5 Radionuclides in Drinking Water The major source of water used in cooking and for drinking is rainwater collected from roofs of houses and other buildings that is stored in cisterns. If extreme drought conditions occur, then the freshest groundwater availabl s usedei groundwatee th ; contaminates i r d with radionuclides fro soie mth l column. The concentrations of radionuclides in both cistern water and groundwater are listed in Table 1. For the dose estimates, we use an intake of l L d-1 of drinking water. We assume for the dose assessment that cistern yeae wastethad th an rf t o availabl s groundwateri year% e th 60 f r .o efo % uses 40 ri r dfo Soda and fruit drinks are frequently available and account for some of the daily fluid intake. The total daily drinking fluid intake from all these sources is between 2 and 2.5 L d-1.
Diet6 3. radiologicae Th l dose will scale directly wit totae hth l intak 137f eo Cs, whic s proportionahi o t l the quantity of locally grown foods that are consumed. Therefore, a reasonable estimate of the average daily consumption rat eacf eo h food ite messentials i laboratoryr Ou . othersd an , concern i , t with local government authorities, wit e legath h l representative e peopleth f d wito san ,h Peace Corps representatives anthropologistd an , s have endeavore establiso dt documend han t pertinent trends, cultural influences and economic realities. The diet model we use for estimating the intake of local plus imported foods is presented in Table 1. The basis of this diet model was the survey of the Ujelang community in 1978 by the Micronesian Legal Services Corporation (MLSC) staff and the Marshallese school teacher on Ujelang [10].
4. DOSE METHODOLOGY External1 4. Exposure
4.1.1 Gamma Radiation The external exposure calculation gammr sfo a radiatio basee n ar measurement n do s mad Bikinn eo i Island in 1978 and 1988 that are decay corrected to 1996. The following arbitrary distribution of time uses develoo dwa t average pth e external exposure: • Nine h d-1 are spent in the house where the exposure rate is 2.1 uR h-1. • Six h d-i around the house and village area where the exposure rate is assumed to be 11 uR h-1 (weighted average of outside house and general village sites). • Seven h d-1 in the interior region of the island where the average exposure is 31 uR h-1 [4]. • Two h d-i on the beach or lagoon where the exposure is 0.1 jjR h-1, based on EG&G data [4].
13 TABL . EDIE1 T MODE ADULTR LFO S GREATER THA YEARS8 N1 : BIKINI ISLAND, LOCAL FOOD COMPONENT WHEN IMPORTED FOODS ARE AVAILABLE.
Specific Activity in 1996, in (Bq g-i wet wt.) Local Food Grams d'l kcal £-1 kcal d'1 137Cs 90Sr 239+24u 0P 24lAm Reef Fish 24.2 1.40 33.83 1O 4 x 1 3. 4.9 x 10-5 1.3x106 1O 5 x 5 6 Tuna 13.9 1.40 1939 4.8x103 5.7x10- 610-x 9 61. 13 x 1O6 Mahi Mahi 3.56 1.10 3.92 4.8 x 10-3 5. 71Ox * 1.9 x 10-6 13 x 1O6 Marine Crabs 1.68 0.90 1.51 1.5 x 1O3 9.6 x5 10-1O 5x 6 3. 2.6 x 1O5 Lobster 3.88 0.90 3.49 15xlO3 9.6 x 10-5 3.6 x 1O5 2.6 x 1O5 Clams 4.56 0.80 3.65 4 4.10 9x 93 x 1O 10-5x 3 48. 4 1O x 6 4. Trochus 0.10 0.80 0.08 4 4.10 9x 93 x 10-5 83 x4 101O 4x 6 4. Tradacna Muscle 1.67 1.28 2.14 4 4.10 9x 5 9.1O 3x 8.3 x 104 4.6 x 104 Jedrul 3.08 0.80 2.46 4.9 x 104 9.3 x 1O5 8.3x104 4.6 x 1O4 Coconut Crabs 3.13 0.70 2.19 2.7x100 3.8 x 1O1 2.6 x 104 4 1.10 9x Land Crabs 0.00 0.70 0.00 2.7x100 1 3.1O 8x 2.6x104 10 4x 9 1. Octopus 4.51 1.00 3 4.511O x 0 2. 4. 910-x 5 1.3x105 65 x 1O6 Turtle 4.34 0.89 3.86 3.0 x 104 4.9 x 1O-5 1.3x105 65x10-6 • Chicken Muscle 8.36 1.70 14.21 10-x 0 17. 1.6x10-3 7.7 x 10-6 6.0 x 10-6 Chicken Liver 4.50 1.64 7.38 7.0x10 110-x 6 31. 7.7 x 10-6 6.0 x 1O6 Chicken Gizzard 1.66 1.48 2.46 7.0x101 1.6 x 1O3 7.7 x6 1O1O 6x 0 6. Pork Muscle 5.67 4.50 25.50 10 2 x 5 7. 1.6 x 1O 10-3x 7 67. 6 1O x 0 6. Pork Kidney NR 1.40 0.00 010 x 0 7. 3 6.1O 6x 3.5 x 1O5 1.2 x 1O5 Pork liver 2.60 2.41 6.27 3.9 x 100 3.1 x 1O3 1.2x104 5.2xlO5 . Pork Heart 0.31 1.95 0.60 4.5x100 1.6x10- 310-x 9 65. 1.8xlO5 Bird Muscle 2.71 1.70 4.61 2.7xlO3 25x104 1.3xlO5 6.5 x 1O6 Bird Eggs 1.54 1.50 2.31 4 7.10 2x 10-x 8 43. 13xlO5 65 x 1O6 Chicken Eggs 7.25 1.63 11.81 21O x 0 7. 3 1O x 6 1. 7.7x10-6 6.0 x 1O6 Turtle Eggs 9.36 1.50 14.04 4 3.10 0x 5 4.1O 9x 1.3x106 1O 5x 5 6 Pandanus Fruit 8.66 0.60 5.20 010 x 5 4. 1.0 x 1O1 3.2 x 10-6 3.8 x 106 Pandanus Nuts 0.50 2.66 1.33 4.5 x 100 1.0 x 10-1 3.2 x 10-6 3.8 x 1O6 Breadfruit 27.2 1.30 35.31 1O 1 x 1 4. 7. 1^4x 2 1.8x10-6 1.2 x 1O6 Coconut Juice 99.1 0.11 10.90 1.2x100 4.9 x 104 1.0x10-6 1O 6x 5 8. Coconut Milk 51.9 3.46 179.44 5.7x100 3. 410-x 3 1.9x10-6 1.1x106 Tuba/Jerkero 0.00 0.50 0.00 5.7x100 3.4 x 10-3 1.9x106 1.1 x 1O6 Drinking Coco Meat 31.7 1.02 32.30 10 3x 1 3- 3 1O x 3 6 10-x 7 62. 3.6 x 1O6 Copra Meat 12.2 4.14 50.30 5.7x100 3. 410-x 3 1.9xlO6 1.1 x 1O6 Sprout. Coco 7.79 0.80 6.23 5.7x100 3.4 x 10-3 1.9x10^ 1.1 x 10-6 Marsh. Cake 11.7 3.36 39.18 5.7 x 100 3.4 x 10-3 1.9x10-6 1.1 x 1O6 Papaya 6.59 0.39 2.57 0 2.10 4x 5.2 x 1O 10-2x 65 2 3.6 x 1O7 Spuash NR 0.47 0.00 1.3x102 1O 0 x 3 7. 2.2 x 1O5 3.0 x 1O6 Pumpkin 1.24 0.30 037 1.3x100 73 x5 10-1O 2x 2 2. 3.0 x 1O6 Banana 0.02 0.88 0.02 1.9xlOi 2 5.1O 2x 2.5 x 10-6 3.6 x 107 Arrowroot 3.39 3.46 13.60 5.8x102 73 x5 1O1O 2x 2 2. 3.0 x 1O6 Citrus 0.10 0.49 0.05 13xlOi 2 5.1O 2x 2.5 x 10-6 3.6 x 1O7 Rainwater 313 0.00 5 0.001O x 6 4. 1.6xlO7 1O 5x 3 3 3. 710x » Wellwater 207 0.00 3 0.001O x 8 4. 3 1O x 3 1. 6.1 x 1O7 4.4 x 1O7 Malolo 199 0.00 5 0.001O x 6 4. 1.6 x 10-5 33 x 1O7 3.7 x 1O8 Coffee/Tea 228 0.00 5 0.001O x 6 4. 1.6 x7 10-1O 5x 3 3 3.7 x 1O8 Soila 0.10 0.00 0.00 2.8 x 100 2.2 x 10° 4.0 x 1O1 2.8 x 1O1 Total Local 1322 547 Bq g-i dry wt.
Although the selection of this particular time distribution is arbitrary, general discussions with Marshallese peopl observationd ean s whil have ew e island e beeth n i s mak selectioe eth n reasonable. The resultant contribution averag137e f so th C o st e equivalent dose fro myear'a s occupanc variouf yo s island areas describe above th n dei scenario are: inside houses, 0.015 mSv; elsewher housine th n ei g and village area, 0.056 mSv; island interior, 0.35 mSv; beaches and lagoon, 55 nSv. The total average external dose attributable to such occupancy in 1996 on Bikini Island is about 0.42 mSv y1. Natural external background is about 0.22 mSv jr1.
14 TABLE 2. THE MEDIAN CONCENTRATION IN Bq g-' DRY WEIGHT OF l3?Cs, «Çr, 239+240Pu AND 24lAm IN SOIL AT BIKINI ISLAND.
Soil depth, cm No. of No. of No. of No. of Samples l37Csa Samples 90Sra Samples 239+240pua Samples 24iAma 0-5 242 2.3(2.2) 98 1.5(2.3) 96 0.26(0.44) 220 0.21(0.28) 5-10 241 1.2(1.8) 98 1.7(2.3) 97 0.26(0.46) 213 0.17(0.27) 10-15 238 0.62(1.2) 98 1.6(2.3) 97 0.19(0.42) 190 0.093(0.24) 15-25 233 0.23(1.2) 97 0.91(1.7) 91 0.074(0.25) 139 0.037(0.19) 25-40 231 0.095(0.85) 89 0.58(1.8) 87 0.014(0.32) 111 0.019(0.15) 178 0.023(0.43 1 3 0.34(1.8) ) 30 0.0069(0.20) 43 0.013(0.19)
0-40_____227 0.74(0.86) 89 1.3(1.4)____85 0.18(0.22) 104 0.12(0.13) a Decay correcte 1996o dt . Numbe parenthesen ri standare th s si d deviation.
4.1.2 Beta Radiation It is impossible to predict precisely what the beta dose to the skin will be, but it is clear that the "shallow bot o doset he bet"du a particle externad san l gamma exposure wil onle b l y slightly greater than the dose estimated for external gamma whole-body exposure. This higher "shallow dose" will occur primaril mose th to yt expose d bodye partth f so , usuall armse yth , lower legs skifeete d n,an Th . is a much less sensitive organ to radiation than other parts of the body; consequently, the beta contributio totae th lo nt effectiv e dos extremels ei y small.
4.2 Internal Exposure
4.2.1 Cesium-137 The conversion from the intake of 137Cs to the equivalent dose for the adult is based upon the ICRP methods describe ICRn di P Publication [11,12]1 6 , s56 , whic basee har Leggett'n do s model [13]e Th . biological half-lif 137f o eC determines si functioa s da masf no s (i.e. method,e ageth y )b s describen di Leggett [13]. In a separate report we estimated the comparative doses between adults and children [14]. The results indicate that the estimated integral effective dose for adults due to ingestion of J37Cs and 90Sr can be used as a conservative estimate for intake beginning at any other age. In this report we calculate only the doses to adults.
4.2.2 Strontium-90 e modeTh l develope y Leggetdb t al.[15e t e structurs basei th ] n o d functio an e f bono n e compartment generalls sa y outline ICRe th Pn di model [11] bone .assumeTh s e i composee b o dt a f do structural component associated with bone volume, which include compace sth t cortical bone larg,a e portio cancelloue th f no s (trabecular) metabolibonea d an , c component associated with bone surfaces. We wilt discusno l s further detail thesf so e models t refe readee originae bu , th rth o t r l articled san their associated references for additional discussion and clarification [15, 16]. Doses listed in this paper are calculated from the Leggett model.
4.2.3 Transuranic Radionuclides (239+240pu an(j 241 Am ) We calculated the equivalent dose from ingestion of transuranic radionuclides (239+240pu aruj 241 fan) by ICRP methods [17,18] amoune Th . ingestef to d plutoniu mamericiur o m crossine t walth gu o t le gth blood is assumed to be 1 x 1Q-3 for Pu and Am in vegetation, and 1(H [19] and lf>3 for the fraction of Pu respectively, Am d an reachinm , ingesteA r fractioassumebloode o s e i gth u soilth a % f P dvi f O ,.45 no d livee th ro t [17,18] % biologicae 45 bonliveo n t i Th d r . o y erfo an g 0 o 2 bont n l i d half-lify ean 0 5 s i e both elements [17]. The quality factor is 20 for the alpha particles from 239Pu, 240Pu, and 241 Am. The equivalent dose from inhalatio transuranie th r nfo c radionuclide intake bases si th n deo determined from the assumptions discussed in the section on Airborne, Respirable Radionuclide Concentrations of this pape ICRd ran P dose methodology [17,11] 239+240pe Th . u anc| 241 Aconsideree mar d classW particles, and the quality factor is 20. Other parameters are as described in the ICRP method previously discusse ingestioe th r dfo transuranif no c radionuclides activity-mediae Th . n aerodynamic diameter (AMAD) is assumed to be 1 urn.
15 4.3 Body Weights and Biological Half-Life of Cesium-137 Data from Brookhaven National Laboratory (BNL) have been summarize determino dt bode eth y weights of the Marshallese people [20, 21, 22, 23, 24]. The average adult male body weight is 72 kg for Utirikr average fo havth e Enewetak r g s fo W Bikinik a . e g e 9 g usek 6 k mal 1 0 d d7 ,7 e,an body weight r dosinou e calculations average Th . e biological half-liflong-tere th r fo e m compartmen ir 37fo tC n si adults is listed as 110 d in ICRP [11] and NCRP [25]. This is consistent with data obtained by BNL on e half-timth long-tere th f o e m compartmen Marshallesn i t e [26, distributioe 27]Th . f biologicano l half-life in 23 Marshallese adult males is lognormal with a median of 115 d, a mean of 119 d, and a range of 76-178 d. We used the 110 d half-life because it is based on a much larger sample population difference th half-lifd d 5 an 11 e e betwee observeth d Marshalles3 an 2 nt i n di e male minimals si .
5. COUNTERMEASURES — MITIGATION OF FOOD-CHAIN DOSE All remedial actions were evaluated agains e criterith t f reducino a e estimategth d average maximum annual effective dose to less than the world-wide average background effective dose of e integrath d an l 30-v 2.ymS 4 effective dos leso t e s tha e federath n l guidelinA f 0.0 . o e 5Sv countermeasure is not recommended to the communities for consideration if it cannot lead to doses below these criteria. Moreover, we strived for a countermeasure that would reduce the average maximum annual effective dos abouo et mSvt1 . Countermeasures evaluate reduco dt dose eth e from 137Cs through e terrestriath l food chain include salt water irrigation (leaching), zeolite d mineraan s l clay soil amendments, repeated cropping, soil removal (excavation), and potassium (K) treatment. All but the last two options have been discarded as either less effective or difficult to implement or both. Experiments at Eneu Island at Bikini Atoll using potassium-rich fertilizers (16N-16P-16K) or KC1 show reductioa n greater concentratioe tha th fol0 n1 n di 137f no C coconun si t mea fluidd 137e tan Cth ; s concentration foodn si s grown without potassium-rich fertilizer rangt weightwe 1 e frog- , q mB 3 0.21. 4o t while the 137Cs concentrations in foods grown using potassium-rich fertilizer are less than 0.074 Bq g-1 [28]. We began a similar experiment on Bikini Island where the 137Cs concentrations in soil, coconut, breadfruit othed an , r local food time0 aboue 1 sar o st highe8 t r tha t Enena u Island resulte Th . thaf so t experiment through August 1988 show tha have tw e reduce 137e dCth s concentratio coconun i t mead tan fluid from a range of 5.6 to 11 Bq g-1 wet weight to aboutO.55 to 0.74 Bq g-1 wet weight; in those trees wher initiae eth t weightl concentratiowe potassiu1 e g- th , q B 7 betweems 3. no treatmenwa t 9 n1. s ha t reduce 137e dCth s concentratio lesno t s than [28]l 0.3g- q .7B f soio l m oveOc e wholf 0 th rcourse4 o t e 0 islan3 , excavatiop dto alse th o f wilno l reduce effectively the potential dose, both external and internal. This option, however, would entail significant environmental soif costo lwels m a , c higs a l0 4 h o dollat 0 3 rp costremovae to e Th . th f o l would carry e removawitth t hi f essentiall o lorganie th f o cl yal material—materia l thas takeha t n centuries to develop and that contains most all of the nutrients needed for plant growth and provides water-retention capacity of the coral soil. Moreover, this would obviously require removing all the mature coconut, breadfruit, Pandanus, lime othed ,an r trees that supply food, windbreak shadd ,an t ea the island and take years to mature. This option would thus necessitate a very long-term commitment to rebuild the soil and revegetate the island. Such a commitment would, in turn, seem to suggest a continuous infusio efforf no expertised an t availabilite th , whicf yo seew h mdoeno t assuredsno e W . hav t addresseeno e mattee disposa dth th e ver f th o ryf o llarg e quantit f removeyo d d soian l vegetation, but recent experiences at other locations indicate that this would present a formidable proble botmf o h acceptanc costd ean .
6. UNCERTAINTY AND INTERINDIVIDUAL VARIABILITY IN ESTIMATED BIKINI DOSES Doses estimate describes da Section di basee ar distributen n4 do d quantities reflecting either uncertainty (i.e., lac knowledgf ko e concerning "the true" value r interindividualo ) variability (which hereafter wil e referreb l simplo t d s "variability"a y , i.e., heterogeneit n valueyi s pertainino gt different people), or both; consequently, predicted dose will necessarily reflect both of these characteristics as well. To characterize such uncertainty and interindividual variability it is necessary to systematically distinguish these attributes as each or both may pertain to each input variat , 32]e 31 [29 ., Below,30 , dose potentiao st l Bikini resident recalculatee sar d usin ggeneraa l method allowing characterization of integrated uncertainty and variability in predicted dose as a functio distributef no d input variâtes l assume,al tha e uncorrelatede b ar t o dt uncertainte Th . d yan variabilit thin yi s doss modeleewa d solel functioa s ya uncertaintf no variabilitd yan predicten yi d
16 dose due to ingested 137Cs, since this is clearly the dominant exposure route (see Results). In this approximation, the complex, multicompartment physiological model used above to calculate internal adult dosfunctioa s ea f ingesteo n replaces wa muca d ] y 137db 13 h C , simplers33 [11, , single- compartment model in order to facilitate the Monte Carlo evaluations:
e-toi at any time tir 0 < f,- < f, (1 )
qij '(«) = -U + K/ß) (ji(u) for any time u,tt aK/B)+ q{ j(u)FBRij= e-^i) (3 ^~ " timy fo , an £,-<«re u , ) (4 D,(t= D(f ) D+ ) ta (*s ) + ctyGi u )d ; 1=1 «; wher D-d e man D(t)x(f) were takedeterministie b o nt c approximation f adulso t external-gammd aan Am+Pu inhalation doses, respectively, and where c is a constant. Variability in the fraction, F, of ingested 137Cs input to the dominant biological compartment was assume uniformle b do t y distributed betwee uncertain na n lower bound ranging betweed an 0.8d 9n an 0.71 an upper bound of 1. Thus, uncertainty in F was assumed to be uniformly distributed within ± 5% of an assumed expected valuvariabilitd an 0.9f eo , assumes (JFf yo wa ) uniformle b o dt y distributed between 0.8 and 1, where angle brackets « )) denote mathematical expectation only with respect to uncertainty n overbaa d an r denotes expectation only with respec o interindividuat t l variability. These assumptions approximately characteriz e empiricath e e valulobtaine F th dat 7 f n 1 o eo a r dfo individuals reported by Schwartz and Dunning [34]. Interindividual variability in the biological half-time of the dominant slow compartment, H, was modele lognormalls da y distributed dat e baseth a n pertainindo Marshalles3 2 o gt e males indicatinga geometria d an d mediac5 standar11 f no d deviation (SDpresene th f 1.2r go )3 Fo t analysis[10]. , however tha d assumes based, an tH wa r SD d t ,i fo 0 1.3,g= 2d respectively 11 tha= tH ICRe th Pn ,o [35 ] reference mean value (used earlier) and on data reviewed by Schwartz and Dunning [34] indicating slightly greater variability associated wite parameteth h r amon 3 individual5 g s from whom measurements were available. A geometric mean (GM) value of H (105.9 d) consistent with the values selected for H and SDg was obtained using the method of moments. Uncertainty pertaining to H was represented by the independent factor ß assumed to be uniformly distributed (between 0.9 and 1.107), such that the true value of H pertaining to any specific individual was taken to lie within 10% of the expected_ value for that individual. population-average Th e valu f expecteeo d annual intake totaf , o (R),l 137Cs activit LLNe th n Lyi model die hypotheticar fo t l Bikini resident f 196o 6 s sa (assuming import availablee sar takes )wa o nt referenca r fo 1 y ekg-q 1adult, B 12.x 1 5 , analysi e base36 th e b n d o food-consumption-surve f so y datr afo 34 adult Ujelang females discussed above. Interindividual variabilit correspondinn yi g expected daily intakes, (Rjy) was modeled using the empirical distribution of average daily uptakes in Bq kg-1 calculated from the food-survey data for these same 34 adult Ujelang females, which was here multiplicatively scaled to have the expected daily population average value of 12.1 Bq Kg-1 d-1. Uncertaint randoo t e ydu m dietary sampling associated with daily 137C sgivey intakan nr fo e individual about that individual's mean daily level (presumed constan eacr fo th individuals wa ) estimated unde assumptione rth s stated above that food import available sar thad ean t local foodf so typ randomle ear j independentld yan y sample timey d n r yea spe r from among Bikini sources, using 17 TABL . EDIE3 T MODEL: BIKINI ISLAND (ADULT YRS)8 1 S> . l37Cs Intake IA Intake: 137Cs Activity Imports Available Local Foods Mean SD/Mean Mean SD/Mean Local Food (ed-i) (Bqe-i) (%) (Bqd-l) (%) Coconut Milk 51.9 5.7 65 Meat 31.7 3.1 73 Copra Meat 12.2 5.7 65 Juice 99.1 1.2 78 Total 194.9 3.0 73 590 73 Pork Heart 0.31 4.5 110 Muscle 5.67 7.5 64 Liver 2.6 3.9 91 Total 8.58 6.3 74 54 74 Chicken Muscle 8.36 0.70 64 Liver 4.5 0.70 91 Gizzard 1.66 0.70 91 Total 14.52 0.70 75 10 75 Breadfruit 27.2 0.41 56 11 56 Pandanus 9.16 4.5 86 41 86 Sprouting Coconut 7.79 5.7 65 45 65 Papaya 6.59 2.4 134 16 134 Arrowroot 3.93 0.058 41 0.22 41 Pumpkin 1.24 1.3 118 1.6 118 Marsh. Cake 11.7 5.7 65 67 65 Coconut Crabs 3.13 2.7 41 8.4 41 Subtotal 289 2.9 844 %f Totao l 22 99 LLNL-model-diet assumptions discussed previously along with the information summarized in Table 3 about predicted amount measured san d inter-sample variabilitC differenn si 137 f yo t food items locao t l purpose Bikinith r f thiFo e.o s analysis activitiee th , s associated wit iteme hth s liste thin di s table— which accoun -99r tfo %totaf Co s l137 intak e associated with local foods—were scale correspono dt o dt an assumption that these items comprise 100% of the local-food diet. Each corresponding coefficient of variation, ft.- = RESULT. 7 S estimatee Th d maximum annua integrad an l l effective dos peoplr efo e resettling Bikini Islane dar calculated usin r diegou t model average th , e radionuclide concentration foodsn i s average th , e biological removal rate depositiond san radionuclidee th r sfo organn wholse i th r seo e bodyth d an , average external dose rates. Doses are presented for two cases: imported foods available (IA), and 18 0• A BML wholtbotfy m«»urtm*nti O LLNL modtl dl»t 70 • N*ldu A dl*t • Nuldu B dl«t SO - , i c SO 40 30 20 lr 10 A O 0 15 30 46 60 76 90 Tirrw, month* sine« 1977 Figure 1. A comparison of body burden estimates from environmental data and models with direct whole-body measurements for residents of Rongelap Island. imported foods unavailable (IUA). The doses listed under the case "IUA" are calculated assuming no imported food available ar s thad ean t only local food consumee ar s d ove entire th r e lifetime th f eo people's residence on Bikini Island. As noted in the Data Base Section on Diet, our observations lead us to conclude tha lattee tth r cas unrealistis ei c ove extendey ran d perio tim f dhighlo d ean y conservative. Nevertheless, it is presented here so that the reader may apply different assumptions, or the results of future observations develod ,an apportionen pa d dos ehave estimatew , emoder assumeIA ou r n I lfo . d diee th tf wilo madimportee f tha% lb o tp 60 e u fro% dm food40 localld san y grown foods. The average maximum annual effective dose estimated for residents on Bikini Island is 4.4 mSv . The 30-, 50- and 70-y integral effective dose for residents of Bikini Island, for IA, are listed in Table 41. The dose presentee sar pathway db radionuclidd yan contributioe th o es eacf no h pathwa nuclidd yan e caevaluatede nb 70-d an 30-ye - integraTh 50 , . l effective cSv6 cSv0 dose1 1 cSv 4 ,1 d ,e sar ,an respectively; the same doses for the local foods only diet (IUA) are 20 cSv, 27 cSv, and 32 cSv. The relative contribution of each of the exposure pathways is presented in Table 5. The dose from e terrestriath l food-chain pathway e totaaccountth lf o r estimate aboufo % s 90 t d 30-y integral effective dose; 137Cs account f thi o abour sprocedursfo y % dose 90 96 td An abour S . an fo r, 2% te that would either block the uptake of 137Cs into food crops and/or eliminate it from the soil column would substantially reduc potentiae eth l exposur people th f eo e livin Bikinn go i Island externae Th . l gamma exposure is next in significance and contributes about 9% of the 30-y integral effective dose. e analysiBaseth n do f uncertaint so Intel-individuad yan l variabilit predicten yi d s dosewa t i , calculated thaexpectee th t d valu f 30-eo y integral population-average dose, (D(30) cSv8 d 9. s an ,i ) that the chance that 19 TABLE 4. THE 30-, 50- AND 70-Y INTEGRAL EFFECTIVE DOSE FOR BIKINI ISLAND RESIDENTS WHEN IMPORTED FOODS ARE AVAILABLE (IA). ______Integral effective dose, cSv______30 y______50y______70 y 5 1. 3 1. 1 .9 External Internal Ingestion 137CS 8.9 12 14 90Sr 0.1 0.15 0.18 239+240 Pu 0.011 0.028 0.051 24iAm 0.0067 0.016 0.028 Inhalation 239+24u 0p 0.013 0.032 0.058 241 Am 0.0079 0.019 0.032 Tola l 10 14 16 The total dose may vary in the second decimal place due to rounding. a TABLE 5. THE 30-, 50-, AND 70-Y INTEGRAL EFFECTIVE DOSE FOR THE VARIOUS EXPOSURE PATHWAYS. Effective intecral eauivalent dose, cSv Exposure pathway 30 y 50y 70 y Terrestrial food 9 12 15 External gamma 0.91 1.3 1.5 Marine food 0.0049 0.0098 0.017 Cistern and ground water 0.016 0.023 0.027 Inhalation 0.021 0.051 0.09 Total3 10 14 16 a The total dose may vary in the second decimal place due to rounding. of tim Bikinf eo aftey 5 i ~ residencer whicy ,b h time residual uncertaint derives yi d solely, froB , mF characterizes i d an . B d confidency db an e limits equa 8. VALIDATION OF ENVIRONMENTALLY DERIVED DOSE ASSESSMENT We assessed the "environmental data/model" approach by comparing our estimates of the body burden (i.e., dose peopln )i e residin Rongelan go p Atoll usin environmentar gou l data modele th , d san methods outlined in this paper, and three diet models with the actual whole-body measurements conducted by BNL [37]. Figure 1 shows that the LLNL diet model predicts very closely the results of the whole-body measurements over an eight-year period. Two other proposed diet models lead to estimated body burden excesn i r sthosf fa so e observe whole-body db y measurements. Results from Utirik Atoll are similar in that the LLNL diet model predicts actual observation while the other two proposed diets once again significantly exceed the observations. The estimated effective dose from Pu based on the concentrations in food, soil and air are very similar to those calculated by BNL based on the analysis of Pu in urine of the Rongelap people [38]. Thes vero etw y independent method excellenn i e sar t agreemen magnitude th n doso te th ef e o fro e mth transuranic radionuclides as shown in Table 6. The estimated average committed effective dose for 50-y residence from Pu based on environmental data and models is 0.4 mSv (0.14 mSv 50-y integral effective dose). The value of 0.40 mSv committed effective dose from urine analyses is based on the detection analyticae limith f to l method use detectior urinedn fo i media e u urine P Th .th f nf o n e o ni valuu P r efo all the people analyzed is below this detection limit value. The people have been living on Rongelap Island for about 28 y subsequent to the fallout from BRAVO where the Pu concentration in the surface soil is about 0.11 Bq g-i. Consequently, both methods indicate that the effective committed dose from Pu at Rongelap Island is below 0.40 mSv for residence between 30 and 50 y. 20 35 - (a) Upper 95% conf. lim. f30 S25 •g 20 I15 x" Population-average | 10 • ' expected dose 5 5 5 10 15 20 25 30 Cumulative exposure time (y) Figure 2a. Confidence limits reflecting interindividual variability in the expected value (with respect uncertainty)o t , {D(f)) cumulativf o , e dos tim y ehypotheticao b t et l adult Bikini residents beginninn gi 1966. 35 ^30 - (b) I» o tn o§20 T3 Population-average 15 expected dose D) | 10 Upper 95% conf. lim. _„.... -~J_U < 5 --"^^" ' Lowe conf% .r95 lim.: 0 5 2 0 2 5 1 0 1 5 30 Cumulative exposure time (y) Figure 2b. Confidence limits reflecting uncertainty in the corresponding population-average dose D(t). 9. DISCUSSION 1 Comparison9. f Estimatedo Doses Adoptedo t Guidelines Backgroundo t d an Doses To place the magnitude of the estimated doses in perspective, we have compared them to current background dose and guidelines adopted by several federal agencies. We acknowledge, and even emphasize, that there is a legitimate question as to which, if any, of the current guidelines are applicable to Rongelap, Enewetak and Bikini Atolls in the Marshall Islands, where the islands are already contaminate peopld dan e wis returo ht livd t "home.nean a " Nevertheless, such guidance does provid ereferenca e poin radiatior tfo n doses that leavera o dt y minimal risk mand ,an y provide useful insight for those who must decide on future actions. The National Council on Radiation Protection and Measurements [39] and the International Commission on Radiological Protection [11] have recently recommended an average annual effective dose of 1 mSv y to the general public for continuous exposure resulting from operating nuclear industries. The maximu1 m annual effective dose for Bikini Island in 1996, using average values for parameters in the dose model, is 4.4 mSv y when imported foods are available. The 30-y integral effective dose for Bikini Island is 0.1 Sv whic1 h is about twice the federal guideline for the 30-y integral effective dose of 0.05 Sv for the general population. Additional perspective can be obtained by comparing these estimated doses for Bikini Island with natural background source Unitee th n si d States average Th . e annual effective dose from natural background source Unitee th breakdowe n sth i d ; Statey v sourcabouy s sni b mS s 3 tei give NCRn i P [40] world-wide Th . e average backgroun1 d effectiv1 wity v h somemS 4 dos2. e s eareai s over 10 mSv y [41]. The average maximum annual rate at Bikini Island without countermeasures is about4mSvy11. applicatioe surface th Th subsequene o t th e K soi d f no an l t dissolutio transpord nan t int rooe oth t zone during period rainfalf so vers i l y effectiv reducinn ei concentratioe gth C edibln si 137 f no e foodsf I . a reasonable agricultural program is implemented that includes periodic use of fertilizer, the dose from 21 AVERAGE TABLTH . E6 E COMMITTED EFFECTIV RONGELAT EA DOSm A ED FROP AN u MP ISLAN mSvDN I . Method Environmental (LLNL) Urine Analysis (BMP Source______Committed effective dose______Committed effective dose______ Pu 0.41» (0.14)b 0.40C Am______0.37 (0.10)______No esdmate______significano Tw a t figure shoo st w slight differenc. e betweeAm d an u nP b Valu parenthesen ei 50-e th y s s i integra l effective dose. c Based on the detection limit; actual dose is below this number. Cs 137 throug fooe hth d chain wil greatle b l y reduced growte th productivitd d han an , somf yo e plants food an d crops wil enhancede b l . This salutary plan, coupled wit soie hth l remova additiod an l f no crushed housine corath n villagi ld gan e areas, could reduc average eth e maximum annual dose from estimatee th d integray an 0 d3 v abouo lmS t effectiv8 v 0. tabou mS 4 e4. t dosabouo t v e tfrocS 0 m1 137 137 1.8 cSv. The Cs, ^r, 239+240pu anxj 241 Am are still in the soil although the Cs uptake into foods is greatly reduced. Work performed unde auspicee th rU.Se th f . so Departmen f Energo t t Lawrencya e Livermore National Laboratory under contract W-7405-Eng-48. REFERENCES [1J ROBISON, W.L., W.A. PHILLIPS, M.E. MOUNT, B.R. CLEGG, C.L. CONRADO (1980), Reassessment of the Potential Radiological Doses for Residents Resettling Enewetak Atoll, Lawrence Livermore National Laboratory, Livermore UCRL-53066, ÇA , . [2.] ROBISON, W.L., M.E. MOUNT, W.A. PHILLIPS, M.L. STUART, S.E. THOMPSON, C.L. CONRADO A.CD AN , . STOKER (1982) n UpdatedA , Radiological Dose Assessment f Bikinio d an Eneu Islands t Bikinia Atoll, Lawrence Livermore National Laboratory, Livermore , UCRLÇA , - 53225. ] GUDIKSEN3. [ , P.H., T.R. CRITES W.LD AN ,. ROBISON (1976), External Dose Estimated Futurer fo Bikini Atoll Inhabitants, Lawrence Livermore National Laboratory, Livermore, ÇA, UCRL-51879 Rev. 1. J TIPTON[4 , W.J. R.AD ,AN . MEIBAUM (1981) n AerialA , Radiological Photographicd an Surveyf o Eleven Atolls and Two Islands within the Northern Marshall Islands, EG&G, Las Vegas, NV, EGG-1183-1758. [5.] CRASH, K.W., P.H. GUDIKSEN, AND W. L. ROBISON (1982), "ß- and y- Comparative Dose Estimates on Enewetak Atoll," Health Phys. 42, 559-564. [6.] SHINGLETON, K.L., J.L. GATE, M.G. TRENT W.LD AN ,. ROBISON (1987), Bikini Atoll Ionizing Radiation Survey, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-53798. ] SHINN[7. , J.H., D.N. HOMAN W.LD AN , . ROBISON (1989), Resuspension Studies t Bikinia Atoll, Lawrence Livermore National Laboratory, Livermore UCID-1853, CA , 8 Rev. 1 . ] NOSHKESI[8. , V.E., K.M. WONG, R.J. EAGLE, T.A. JOKELA, J.A. BRUNK (1988), Radionuclide Concentrations in Fish and Invertebrates from Bikini Atoll, Lawrence Livermore National Laboratory, Livermore UCRL-53846, ,CA . [9.] ROBISON, W.L. (1993), Radiological Dose Assessment and Countermeasures at Bikini Atoll, (unpublished data). 22 [10.] ROBISON, W.L. (1983), "Radiological Dose Assessment f Atolle Northero s th n i s n Marshall Islands," in Proceedings. Nineteenth Annual Meeting of the National Council on Radiation Protection and Measurements: Environmental Radioactivity, No. 5, National Council on Radiation Protection and Measurements, Bethesda, MD, pp. 40-82. [11.] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (1990), Age-Dependent Doses to Members of the Public from Intake of Radionuclides: Part 1, Pergamon Press, New York, Pub. 56. [12.] INTERNATIONAL COMMISSIO RADIOLOGICAN NO L PROTECTION (1991b), Annual Limits of Intake of Radionuclides y Workersb 1990e Basedth n o Recommendations, Pergamon Pressw Ne , York, Pub. 61. [13.] LEGGETT, R.W. (1986), "Predictin Retentioe gth f Cesiuno mIndividuals,n i " Health Phys., 50 747-759. [14.] ROBISON, W.L. D W.A,AN . PHILLIPS (1989), Estimates e Radiologicalth f o Dose from Ingestion f I37 o 90d C SInfants,o san t r Children, Marshalle Adultsd th an n i Islands, Lawrence Livermore National Laboratory, Livermore, ÇA, UCRL-53917. [15.] LEGGETT, R.W., K.F. ECKERMAN L.RD . AN ,WILLIAM S (1982), "Strontium-9 Bonen 0i CasA : e Study in Age-Dependent Dosimetric Modeling," Health Phys. 43, 307-322. [16.] CRISTY, M.R. . LEGGETTW , , D.E. DUNNING, K.FJR.D AN ,. ECKERMAN (1984), Age- Dependent Dose-Conversion Factors for Selected Bone-Seeking Radionuclides, Nuclear Regulatory Commission, NUREG/CR-3535, ORNL/TM-8929. [17.] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (1986), The Metabolism of Plutonium and Related Compounds, Pergamon Press, Oxford, Pub. 48. [18.] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (1988), Limits for Intakes of Radionuclides Workers:y b Addendum,n A Pergamon Press Yorkw ,Ne , Pub , Par30 . t4 [19.] HARRISON, J.D., G.P.L. NAYLOR, AND J.W. STATHER (1989), Gastrointestiral Absorption of Plutonium Americiumand Ratsin Guinea-Pigs and after Ingestion Dustsof fromFormerthe Nuclear Weapons Test Site t Marolinja:a Implications r Humanfo Exposure, National Radiation Protection Board, Chilton, Didcot, Oxon, NRPB-M196. [20.] CONARD, R.A., ET AL.Ü959), Medical Survey of Rongelap People, March 1958, Four Years After Exposure Fallout,o t Brookhaven National Laboratory, Upton , BNL-534NY , . [21.] CONARD, R.A., ET AL. (1960), Medical Survey of Rongelap People Five and Six Years After Exposure Fallout,o t Brookhaven National Laboratory, Upton , BNL-609NY , . [22.] CONARD, R.A., ET AL. (1963), Medical Survey of Rongelap People Eight Years After Exposure to Fallout, Brookhaven National Laboratory, Upton, NY, BNL-780. [23.] CONARD ,. (1975)R.A.AL T A Twenty-Year,,E Review f Medicalo Findings Marshallesea n i Population Accidentally Exposed o Radioactivet Fallout, Brookhaven National Laboratory, Upton, NY, BNL-50424. [24.] MILTENBERGER, R.P. . GREENHOUSE,N . LESSAR E . CUA F , D AN , D (1980), Working Draft Dietary Radioactivity Intake from Bioassay Data A Model Applied to Cesium-137 Intake by Bikini Island Residents, Brookhaven National Laboratory, personal communication. [25.] NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS (1977), Cesium-137 fromEnvironmente th Man:o t Metabolism Dose,d an National Counci n Radiatioo l n Protection and Measurements, Washington, DC, NCRP-52. 23 /60 [26.] MILTENBERGER LESSARD. E , R. ,N.A D . AN , GREENHOUSE (1981), ' C™7çd oan s Long Term Biological Removal," Health Phys. , 615-62340 . [27.] MILTENBERGER . LESSARE D AN D, R. (1987), , Brookhaven National Laboratory, Upton, NY , "Body Burden and Dose Assessment for Bikini Island Residents 1969-1980." private communication. [28.] ROBISON, W.L., AND E.L. STONE (1991) "The Effect of K on the Uptake of "7Cs in Food Crops Grown on Coral Soils: Coconut at Bikini Atoll," Lawrence Livermore National Laboratory, Livermore , UCRL-JC-97903ÇA , , submitte publicatior dfo Healtho nt Physics. [29.] BOGEN, K.T., AND R.C. SPEAR (1987), "Integrating Uncertainty and Interindividual Variability in Environmental Risk Assessment," Risk Analysis 7, 427-436. [30.] INTERNATIONAL ATOMIC ENERGY COMMISSION (IAEA) (1989), Evaluatinge th Reliability of Predictions Made Using Environmental Transfer Models, Safety Series 100. IAEA, Vienna. [31.] BOGEN, K.T. (1991), Uncertainty Environmentaln i Health Risk Assessment. Garland Publishing Co., New York. [32.] NATIONAL RESEARCH COUNCIL (NRC). COMMITTE N RISO E K ASSESSMENF TO HAZARDOU POLLUTANTR SAI S (1993), Science Judgmentd an Riskn i Assessment. National Academy of Sciences Press, Washington, DC (in press). [33.] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (1991a), 1990 Recommendations Internationale th f o Commission Radiologicaln o Protection , Pergamo n Press, Yorkw Ne ,. Pub60 . [34.] SCHWARTZ, G., AND D.E. DUNNING, JR. (1982), "Imprecision in estimates of dose from ingested 137Cs due to variability in human biological characteristics." Health Physics 43,631-645. [35.] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (1979), Limits for Intakes of Radionuclide by Workers, Pergamon Press, New York, Pub. 30, Part 1 and Supl. [36.] BOGEN, K.T. (1993), "Practical methods for quantitative treatment of uncertainty and interindividual variability" (submitted). [37.] LESSARD, E.T., R. MILTENBERGER (1979), Personal communications, Brookhaven National Laboratory, Upton, NY. (1992)N [38.SU ], Personal communication, Brookhaven National Laboratory, Upton. ,NY [39.] NATIONAL COUNCI RADIATION LO N PROTECTIO MEASUREMENTD NAN S (1987b), Recommendations Limitsn o r Exposurefo Ionizingo t Radiation, National Counci n Radiatioo l n Protection and Measurements, Washington, DC, NCRP-91. [40.] NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS (1987a), Exposure to the Population in the U.S. and Canada from Natural Background Radiation, National Counci Radiation o l n Protectio Measurementsd nan , Washington , NCRP-94,DC . [42.] UNITED NATIONS SCIENTIFIC COMMITTEE ON THE EFFECTS OF ATOMIC RADIATION (1988), Sources, Effects and Risks of Ionizing Radiation, 1988 Report to the General Assembly with annexes, United Nations Yorkw ,Ne , United Nations sales publication E.77.IX.1. 24 FEATURES OF AN EVALUATION OF THE RADIATION DOSES RECEIVEE TH Y DB POPULATION AFTER ATMOSPHERIC NUCLEAR TESTING AT THE SEMIPALATEVSK TEST SITE V. LOGACHEV Biophysics Institute, Moscow, Russian Federation Abstract Durin perioe gth atmospherif do c nuclear weapons testinformee th n gi r USSR between 1949 196 d explosion1 an tota2a 21 f o l s were carried out t includinno , undeg3 r northerwatee th t ra n test islane th sit f Novayn do eo r explosioa ai Zemly 1 d aan n durin Totse gth k military exercisess i t I . known that the most significant radioactive contamination of an area, with relatively high local radiation grounde levelth n so produces i , surfaca y db e nuclear explosion formee th n I . r USSl Ral surface th e nuclear tests whicf o , h there wer , were25 e conducte Semipalatinse th t da k (southern) test site. Hence assessmenn a , impace th f thesf o to t e nuclea populatiohealtre e testth th f n ho so n living in that region is of considerable scientific and practical importance. However, since insufficient data radiatioe th n o n situation were collected durin testine gth g period particularls i t i , y importano t w no t develop methods for the retrospective evaluation of the individual and collective doses to the population using different starting concepts magnitude datth e n Th a.o thesf eo e doses will servs ea a basis for tackling the problems of rehabilitating the population, mitigating the consequences of radiation effects, and compiling a register of exposed individuals and their direct descendants with viea assessinwo t g more accuratel rise f immediatyth ko latd ean consequences repore th n n I a .t attemp bees ha t n mad describo et e featuree somth retrospectivf a e o f o s e evaluatio radiatioe th f no n doses received by the population, using material from archives supplemented by what is known about lawe th s governin formatioe gth f radioactivno e plumes from nuclear explosions. 1. DETAILRADIATIOE TH F SO N PROTECTION ARRANGEMENT DISTRICTE TH N SI S ADJOININ SEMIPALATINSE GTH K TEST SITE histore th n nucleaf I yo r testin Semipalatinse th t ga k site, three explosion singlee b y t dsou ma as marking the main stages of activity. On 29 August 1949 the first test of a nuclear device based on a fission chain reaction took place, and on 12 August 1953 the first thermonuclear device was tested. Both these explosions were carrie t usindou g metal gantries approximatel highm 0 y3 . Lastlyn o , 22 November 1955, came the air explosion of a hydrogen bomb, dropped from an aircraft [1, 2]. In the intervals between these explosions and afterwards, further nuclear explosions were carried out for purpose th f solvineo numbega f scientifio r practicad can l problems. e wholTh e perio f nucleado r e dividetestinb n gca d into three parts, characterize theiy db r different radiation protection arrangements firste th ,n I .practicall radiatioo yn n protection measures were taken; in the second, measures were taken to prevent over-exposure of the population (temporary evacuation) thirde th n i ,; strict limitations were impose testingn do . Owing to the lack of radiation protection experience, the first nuclear test on 29 August 1949 was conducted without any regard for the consequences of radiation effects on the population. The results of an evaluation of those consequences will be examined below. In the interval between the first atomic (1949) and the first thermonuclear (1953) tests, two nuclear explosions were carried out in 1951 — a surface explosion on 24 September and an air explosion on 14 October [3]. The greatest radioactive fallout came from the surface explosion, which cast a radioactive trace south-east of the test area at the site in a thinly populated area. However, in the territory of two settlements the doses prior to total decay of the radioactive substances exceeded 25 showinp Ma e locatiogth f traceo n f radioactivo s e contamination beyon e boundanedth e restricteth f so de areth f o a Semipalatmsk test site which caused maximum radiation exposure of the population in the areas adjacent to the site The map shows the dates of the explosions and the position of isolines with the external gamma ray dose values m roentgens for open areas prio completo rt e decaradioactive th f yo e substance sequivalen000s 0 i uni e (scal' 00 'P )tTh 4 roentgeea 1 o t t n 26 10 cGy. It should be noted that owing to the lack of knowledge concerning the nature of contamination in a local radioactive trace and the sparse observation network for meteorological and aerological conditions, the measures taken to mitigate the radiation doses did not produce the desired effect. The most significant radiation protection measures were taken in the preparation and execution of the first thermonuclear explosion on 12 August 1953. The authorities in charge of testing decided evacuato t safo et e inhabitant e areath l sal settlementf so s locate sectoe th n di r wher radioactive eth e trac expectes ewa formo dt , i.e. withifro m centre tese k m th th 0 n radiut a f areae12 o f so , where eth radiatio ngroune dosth n eo d might excee cGy 0 evacuatee d20 Th . d inhabitants were concentraten di nine settlement distanca t sa 200-25f eo fro m centrexplosioe 0e k m th th . f eo 4] , n[1 A radiation survey was conducted at the settlements before any inhabitants were moved back e villagreture th Th o f . Abant o e in i (Karaaul e provincth n i ) f Semipalatinso e s startekwa n do Augus1 2 completed an t nexe (thy dth eda t tent afte y explosion)e hda th r , whe gamme nth dosy ara e 0.0s ratewa 3 cGy/h e inhabitantTh . s were remove village th o f Sarzhads t surroundineo it d an l g settlement Augus7 2 n o s t (the sixteent afte y explosion)e hda th r . Some time after their reture nth inhabitants of the worst contaminated settlements were examined by army medical officers, who found cases of radiation sickness. It should be noted that after every nuclear test, including the first explosion on 29 August 1949, official radiatioe th f o s n safety service fro tese mth t site used carair-borned -an measuring equipment to determin gamme eth dosy ara e are e rateth a n si aroun tese t settlementsdth a t sitd ean ; they also measured the content of radioactive substances in food and items of the external environment. In the first years of nuclear testing the main criterion for assuring radiation protection of the public was the maximum permissible dose from external exposure which in the early 1950s, was set at a single dose of 50 cGy (tentatively this may be taken to mean in one year), but was reduced to 25 cGy in the mid-1950s [2]. At the beginning of 1957 the "maximum permissible dose from external exposure over a year" was taken as 15.7 cGy (0.3 cGy per week) [5]. As might be expected, the value for "permissible dose" decreased as knowledge about the biological effects of radiation was accumulated, and by the 1961-1962 series of explosions the value was 2 cGy per year. At present the "maximum permissible dose" for a limited section of the population (category B) equals 0.5 cSv per year [6]. In orde proteco rt populatioe th t n living nea boundariee rth tese th t f sitso e area followine th , g additional limitations were imposed on the last series of atmospheric nuclear tests, completed at the en f 196do 2 [2]: . 1 Radiation levelboundare th exclusiot e sa th f yo ntese areth t f sitao e calculate houro tw r s dfo afte explosioe th r n excee o wert t cGy/1 eno d0. h (th egroune dosth n eo d prio totao t r l decay of the radioactive substances being 1 cGy). It was permissible to carry out one or two explosion t radiatiosa n levels three times higher, provided singla ther s ewa trac givea n ei n direction. 3 1 2. The height set for air explosions, h/J3 q, had to be greater than 15 m/t,' where h is the height explosioe oexplosio e fth yiele th th f ds o i metre n i q tonnes n i d san . Provided that condition met s tese wa th t, coul conductee db d regardles f wino s d direction s lona , thers ga e wero en settlements lying along the trajectory taken by the cloud. charge size th surfacf r eTh o e fo onl d e. explosioe 3 explosionan yon , kt uniteI 5 ns 0. wito sdwa t h permitteds wa t k whicr 2 equivalenT fo ,weathee o t hth TN p a u f ro t conditione b o t d sha perfect. 27 4. Testing was forbidden if the average wind speed in the 0-5 km layer was less than 3 m/s and precipitatioy if an ther s ewa n . withikm 0 nradiua 10 f so Durin perioe gth atmospherif do c nuclear weapons testin maie gth n data use evaluatinr dfo e gth radiation situatio providind nan g radiation protectio publie th r cnfo wer dose eth e rate valuer fo s gamma radiation recorded afte explosion a r air-borny nb e and lessea o ,t r extent, car-borne gamma surveys. Whe e gammth n y dosra a e rates significantly exceede e backgrounth d d level, aerial reconnaissance was most frequently used, covering an area extending up to 600 km from the test site. The radiation levels measured at flight altitude were reduced to a height of l m from the earth's surfac thed ean n recalculate commoa r dfo n time, usually three hours afte explosione th r , usine gth Way-Wigner formula. e earlth yn I year f testino s g there were practicall dato n yconcentrationn f o ao r ai e th n i s radioactive substances and their individual biologically dangerous radionuclides at the time of formation of the plume. Contamination of soil, vegetation, foodstuffs, water and other items of the external environmen s analysedwa t rulea s a , onl r totayfo l radioactivity content. Identificatiof no iodine-131, strontium-90, caesium-137 and other radionuclides in various items commenced only in secone th periode halth f atmospherif o fdo c nuclear testing orden I . evaluato rt extene eth whico t h atmospheric nuclear weapons testing affected the health of the population, therefore, it is very importan develoo t t p method r retrospectivelfo s y reconstructin dosee gth s from external exposure receive populatioe th y varioue db th n ni s region formee th f so rthyroi e dosee USSth th o d st dRan glan othed dan r vital human organs wels a ,methods a l r calculatinsfo g effective doses. 2. PRINCIPAL METHODS FOR RECONSTRUCTING THE RADIOLOGICAL SITUATION AND RADIATION POPULATIO E DOSETH O ST N Since information on the conditions under which the nuclear tests were carried out, on the scale of the radioactive contamination of the environment and on the radiation doses to the population remained virtually unpublished until recently and inaccessible even to a wide group of experts, the public, including the scientific community, formed a subjective opinion about the radiation conditions outside the testing site, the nature of the radioecological situation and the effect of the nuclear tests on the health of the population. As a rule, the dangers from local radioactive contamination are exaggerated. Experience gained from studyin consequencee gth f radiatioso n factors associated with nuclear weapons tests suggest thamaie th t n method r reconstructinfo s g radiation dose evaluatind an s e gth radiation situatio currentle nar followss ya : 1. The first step in reconstructing the radiation doses to the public is to obtain archived material with results of radiation parameter measurements and other data on the nuclear tests contained in scientific reports. Archival records provid mose eth t accurat determininf o y ewa positioe gth n of local traces and their axes, but do not give a complete picture of the internal exposure of the population (thyroid gland and other critical organs). In order to evaluate the internal exposures and, in particular, the dose to the thyroid gland it is necessary to introduce certain assumptions abou quantitative tth e characteristic factore th f so s which cannot alway provede sb correct. This lead errorcalculationo e st th more)d n si an factory 3 . s(b 2- f o s methoe Th mathematicaf do . 2 l modellin radioactive th f go e contamination resulting fro mnucleaa r explosion starts with the formation of the source of radioactive contaminants, which develops in a non-stationary high-temperature field. Then the distribution of radioactive particles of different sizes is calculated taking into account gravitational deposition and diffusion processes. initiae Th calculatione l th dat r afo s includ explosioe yiel e th energe eth f th do d ynan released 28 f fissioo e fusiod us nan resule a n th s reactiona f o t chargee th n heighexplosione se i th th , f o t , the nature of the soil at the epicentre, and also the wind direction and speed at different heighe altitudeth o t t p reachetim e sclouu e th t stabilizes th ei y dy b d b . maie Th n error makinn si g predictions using this method stem essentially fro impossibilite mth y takinf o g into account factors relatin spatio-temporae th o gt l variabilit wine th f dyo current field during the formation of the radioactive contamination traces and to the falling of atmospheric precipitation [7-11]; . 3 Reconstructio radiatioe th f no n situation analysibasen a n do soif othed so an l r environmental sample determino t s e concentrationth e then i s f long-livemo d radionuclide i.e— s. fission products from nuclear explosives. The analysis involves determining the activity of alpha, beta and gamma emitters using radiometric methods and the proportion of the activity accounted for by artificial radionuclides using gamma spectrometric and radiochemical methods. To reconstruct the doses to the population from data on the concentrations of caesium-137, strontium-9 r plutonium-23o 0 plutonium-24d an 9 e muson 0 t hav modea e l describine th g dynamics of trace formation. The main difficulties here are associated with the correct selection of semi-empirical constants and the evaluation of the contribution of global fallout to the contamination of environmental items [12]. . 4 Measuremen radiatiof o t n doses fro toote mth h ename exposef o l d persons, ceramic othed san r material whicn si h dosimetric informatio preserveds ni . Other method r reconstructinfo s radiatioe gth n situatio appliee b n s wellnca da ; howevern i , practic uncommos i t ei emploo nt y jusmethoe on t mord— e often combinatioa tha t nno s ni chosen. 3. RADIATION SITUATION AROUND THE SEMIPALATINSK TESTING SITE During the period of nuclear testing 467 explosions were carried out at the Semipalatinsk site, of whic wer9 h9 e high-altitud airundergroun3 d surfac5 2 e,34 an d ean d explosions (the beinlase ton g on 19 October 1989). The total yield of the nuclear explosions carried out in the atmosphere wamégatonne3 s6. equivalentT sTN f strontium-9,o wit i f caesium-13o h i MC 0.1 1 MC 80. 0d 7an being released into the atmosphere [1]. y analysinB d processinan g e availablth g e archiva e degrel th dat f n radioactivo o ea e contamination of the locality, it is possible to reconstruct the location of local traces and the possible radiation e populatiodoseth o t s n differeni n t regione countrth f o s y throughou e perioth t f o d atmospheric nuclear testing. The diagram reproducing part of the map of the former USSR shows traces cas nucleay b t r explosions ove aren ra a wher externae eth l gamma exposure populatioe th f so n could have exceede radiatioe d Th 5-1 . teste 0R preservee tim e nth sar th f dos eo t a ee unitdus n i s here. The map also shows the dates of the nuclear explosions and the position of the isolines with the dose completo st e radioactive decath f yo e substance roentgenn si approximationn a s s(a e b y ma t i , taken that l R = 0.8 cGy) [13-17]. Let us examine the radiation consequences of the first nuclear test on 29 August 1949, the plum f whiceo h forme tracda e ove Altae th r y territory. Some data suggest that ove perioe th r f do atmospheric testing the radioactive clouds from 22 nuclear explosions [3] may have spread in the directio e Altath f yo n territory; accordin o othet g r dat e clouda th s truthi f wa o se from 56 explosions [2]. However, not all of these explosions could have caused exposure of the territory's population above the permissible limits. Analysis of the data on the radiation situation after the nuclear explosions in different years shows that the first nuclear weapons test in 1949 made a major contribution (not less than 65%) to the exposure of the population in the region. The zones with the trace from this explosion delimited by various exposure values have been plotted using data from 29 Table I Radiation dose inhabitanto st f somso e settlement Altae th yn si territory situated alon radioactive gth e trace fro firse mth t nuclear test on 29 August 1949 External gamm dosy ara e Radiatione dosth o et Settlement cGy thyroid gland, cGy Children Adults Topolnoye 49 28OO 700 Naumovka 52 3000 750 Lokot 28 1600 400 Kurya 6 380 95 Petropavlovskoye 0.6 40 10 Biysk 0.3 20 5 Solton 0.3 20 5 air-borne and car-borne radiation surveys carried out by workers from the test site between 5 and 14 September 1949 weeko tw ,o s t i.e afte e explosione .on th r . e resul retrospectiva Th f o t e reconstructio radiatioe th f no n dose inhabitanto t s f variouo s s settlements in the Altay territory situated close to the trace axis are given in Table I. In assessing the external exposures, radiation shielding by buildings and the typical daily routine populatioe th f so n were taken into account thyroie dosee th Th .o st d gland give Tabln ni eI were calculated separatel r childrefo y e adulth nr t fo agepopulationyear7 d 0- d an s , wite th h assumption thamaie th t n rout iodinr efo e radionuclide enteo s t huma e rth n bod througs yi mile hth k chain. It is known that the impact of radiation on the health of the population is determined by the effective dose, whic calculates hi d taking into account both externa internad lan l exposures. Tests have shown that the effective dose is approximately twice the external gamma ray exposure. In evaluating delayed radiation effects, the main attention is given to the risk of malignant tumour development e probabilitth , f whico y h e collectivdepende valuth th f o en o s e dose commitment. Table II presents a forecast of radiation-induced cancers, based on the recommendations of the International Commission on Radiological Protection (ICRP) [18]. cleas Ii t r fro date m th Tabln a i thaI eincreasI e th tmortalite th n ei y rat mosr efo t districtn si Altae th y territor r cenarouns r pe less o tywa e .d on Result s from earlier researc evaluato ht e eth influence of radiation factors on the health of the population have shown that the year-to-year fluctuatio spontaneoue th n ni s mortality rate from cancepurelo t e yrdu randoo t p mu e causeb y sma 37% within a single administrative district [19]. Such fluctuations in the indices make it difficult to conduct epidemiological studies of the state of health of the population. Studie long-tere th f so m radiation effects have established thacollective th t e radiation doso et populatioe th territore th f no y from natural radiation source medicad san l procedures ove pase th r t 40 years was more than ten times greater than the dose received from nuclear weapons tests at the Semipalatinsk site. It is thus difficult at the present time to link any increase in the morbidity and mortality rates from malignant tumours to the impact of local radioactive fallout from nuclear test explosions. At the same time it should be recognized that the nuclear weapon tests have caused some damag healt populatione e searce th th th f o r linkeht o o h s fo sd betweean , n radiatione doseth d san stat publif eo c health should continue. 30 Table II Expected long-term effects in the form of malignant tumours of all localizations due to exposure of the population mose inth t contaminated Altaareae th f yso territory District Population, Collective Increased mortality Spontaneous Increase thousands external due to cancer, ex- mortality rate over exposure, eluding cancerleukaemio t e du , a spontaneous man'Sv and cancer of the No. of deaths rate, thyroid gland, over % 70 years, f deatho . No s 1. Uglovskoye 4.5 2210 110 630 [17.5] [* ] 2. Rubtsovsk 133.5 3 108 155 18700 [0.8] 3. Lokot 30.5 1 786 90 4240 [2.1] 4. Zmeinogorsk 16.8 710 36 2 350 [ 1.5] 5. Kurya 16.2 590 30 2270 1 [ .3] 6. Krasnoshchekovo 27.5 246 13 3850 [0.3] 7. Ust-Kalmanka 17.6 131 7 2 460 [0.3] 8. Pospelikha 27.0 314 16 3780 [0.4] 9. Petropavlovskoye 34.4 132 7 4820 [0.1] 10. Shipunovo 33.9 115 6 4750 10.1] 38. Zarinsk 42.4 145 7 5940 [0.11 Altay territory 937.2 11 000 550 131 000 [0.4] ] * Translator's note: These figures were supplie translatoe th y b d the s a r y were illegible th n ei original text provided. CONCLUSIONS The report demonstrates the possible application of one of the main methodological approaches, namel f archivyo e thaus et e basematerialth retrospective n dth o r fo s e evaluatio f individuano d an l collective radiation doses receive populatioe th y db regioa f no n nea Semipalatinse rth k test site. This method can reconstruct with maximum reliability the basic parameters of a radiation situation which was observed several decades ago during the period when atmospheric nuclear tests were conducted. As other method determininf so g radiation dose alse sar o available theis i t i ,r combine thae dus t will be most effective in reconstructing the radiation situation of past years and assessing its influence state th healtf populatioe eo n th o f ho varioun i s regions. 31 REFERENCES [I] DUBASOV, Yu.V., MATUSHCHENKO, A.M., FILONOV, N.P., et al., The Semipalatinsk testing site: evaluating the radiological consequences... Information Bulletin of the Public Information Centre (Central Scientific Research Institute for Information and Technical and Economic Research in the Field of Atomic Science and Technology — TsNIIatominform, 1993, Spetsvypusk, 22-34. [2] BYALYKH, V.N., D'YACHENKO, V.l., ISAEV, N.V. t al.e , , Nucleae r th test t a s Semipalatinsk site. Repor Apri7 2 t l 199 conferenca t 3a Altae th n yei territory. II , ] [3 LOBOREV, V.M., SUDAKOV, V.V., SHCHEBRIN, M.D. t al.,e , Evaluatio f levelno f o s radioactive contaminatio e Altath n yi n territory resulting from nuclear explosione th t a s Semipalatinsk test site. Report of the Aerohydrodynamics Association, Moscow, 1992. [4] KOBZEV, A.F., STEPANOV, Yu.S., TURAPIN, S.L., et al., Results of astudy of the impact of radioactive fallout on environmental items and the state of health of the population of the East-Kazakhstan, Semipalatinsk, Karaganda and Pavlodar provinces of the Kazakh S.S.R. (Results fro wore joinma th f ko t scientific team fro Biophysice mth s Institut tese th t site)d ean , Report fro librare Biophysicme th th f yo s Institut Russiae th f eo n Federation Ministr Healthf yo , Moscow, 1958. ] [5 Protection measure radiatior sfo n workers. Edite Profy db . Zhdanov, Moscow, Medgiz, 1958. ] [6 Radiation safety standards NRB-76/8 basid 7an c health regulation r worsfo k with radioactive substances and other sources of ionizing radiation OSP-72/87. USSR Ministry of Health, third edition, revised and supplemented, Moscow, Ehnergoatomizdat, 1988. [7] LOBOREV, V.M., SUDAKOV, V.V., SHCHERBIN, M.D., et al., Assessment of the radiation situatio RSFSe th n ni R resulting from atmospheri underground can d test f nucleaso r weapons and their medical and biological impact. Report of the Aerohydrodynamics Association, Moscow, 1991. ] [8 PETROV, V.N., Report USSe th f Rso Academ Sciencesf yo , 196286 ,, 1 146. . ,No [9] ANDERSON, A.D., J. Meteorology, 18, No. 4, 431, 1961. [10] KELLOGG, W.W. . MeteorologyJ , , No.I14 , , 1957I , . [II] Meteorology and atomic energy, Translated from English, edited by N.L. Byzovoj and A.B. Makhon'ko, Leningrad, State Scientific and Technical Hydrometeorological Publishing House, 1971. [12] BOJKO, V.A., D'YACHENKO, V.l., VIL'DANOV, S.Z., et al., Radiation impact of nuclear tests carried out at the Semipalatinsk test site on the health of the population in the Altay territory. Report of the Kurchatov Scientific Institute, 1992. [13] STEPANOV, Yu.S., Radioactive fallout in the areas adjoining UP-2. Report of the Biophysics Institute of the USSR Ministry of Health, Moscow, 1961. [14] STEPANOV, Yu.S., YATSENKO, V.N., MARTISHENYA, E.P. al.t ,e , External gammy ara doses in areas adjoining the territory of the restricted zone of military unit 52605. Report on scientific research work, library of the Biophysics Institute of the RF Ministry of Health, Moscow, 1984. [15] LOGACHEV, V.A., STEPANOV, Yu.S., MIKHALIKHINA, L.A., KHOKHLOV, V.F., Analysis of data from biomédical research and from an evaluation of the health of critical groups of the population of the Altay territory and the Altay Republic, living in districts affecte radiationy db . Information Bulleti Publie th f no c Information Centre (TsNIIatominform) 1993, Spetsvypusk, 3-22. [16] LOGACHEV, V.A., STEPANOV, Yu.S., MIKHALIKHINA, L.A., Traces from nuclear tests conducte t Semipalatinsda Altake casth yn i t territor neighbourinn i d yan g province press)n s(i , Collection "Atoms - unclassified material: points of view", 2nd ed. [17] DUBASOV, Yu.V., KRIVOKHATSKIJ, A.S., FILIPPOVSKIJ, V.l., et al., Assessment of the radioecological situation in the Altay territory of the Russian Federation. Report on scientific research e "V.Gworth y kb . Khlopin" Radium Institute . PetersburgSt , , 1992. [18] Recommendation Internationae th f o s l Commissio Radiologican o n l Protection (Publ. 60), Radiological Protection, 1991, vll, No. 3. [19] LOGACHEV, V.A., MIKHALIKHINA, L.A., TsVIRBUT, A.I. al.t ,e , Influenc f radiatioeo n and non-radiation environmental factors on the health of the population of the Mogilev province following the accident at the Chernobyl nuclear power plant. Med. radiology, 1993, No. 2, 19-24. 32 DOSE ASSESSMENT STUDIES AT FORMER NUCLEAR WEAPONS TEST SITES IN AUSTRALIA G.A. WILLIAMS Australian Radiation Laboratory, Yallambie, Victoria, Australia Abstract Field and laboratory measurements are described and data presented which enabl dosa e e assessmen e inhalatioth r fo t f artificiano l radionuclidet a s Maralinga and Emu, the sites of United Kingdom atomic weapons tests between 1953 and 1963. Dose assessments for the inhalation of artificial radionuclide e l presentear remaininsal r fo dg contaminated areat a s Maralinga and Emu. In the case of Aborigines, these doses are estimated assuming inhalable dust loading mg/m1 5 mg/m r adult1. r f fo o ^sfo ^d an s childre d infantsan n . Particle ji5 sizm e s takeAMADb i e o t n. Plutonium d americiuan e e takerepresenteb ar mo t n y solubilitb d y r majoClasfo rY s trial sites and 25% Class W and 75% Class Y for all minor trial sites. For other radionuclides, where no data are available, the most conservative dose intake conversion factor values are used. All calculations of dose assume 100% occupancy. The results indicate that doses to children are higher than dose adulto t s d infantssan . consequenca Thi s i s childref eo n being subjecte higheo t d r dust concentrations than adults becaus f theio e r play activitie d becausan s f generallo e y higher dose intake conversion factor values than adults, which more than offset their smaller breathing rates. Thus children form the critical group. With the exception of one site which is contaminated with uranium, at all other sites it is only the inhalatio plutoniuf no americiud man m that contributes significantle th o t y dose, and of these ""Pu is the largest contributor. Therefore, having regard to the long half lives of the radionuclides concerned, the inhalation problems highlighted by this dose assessment will not diminish significantly within any reasonable period of time and hence management strategies mus e developetb o deat d l with them. 1. BACKGROUND TO THE STUDY 1.1 Major Trials The United Kingdom conducted a programme of nuclear weapons development trials at Maralinga and Emu in South Australia, and at the Monte Bello Islands in Western Australia, between 1952 and 1963. In all, 12 major nuclear trials involving atomic explosions were performe e threth et a d locations. The smallest of these were two trials at Maralinga, each of abou e kilotoon t n largese Monte yieldth th d et a tan ,Bell o Islandf o s swa 56 kiloton. All were atmospheric tests, and devices were generally explodem towers 1 3 e site Th n thes.f do o s e major trial o longesn r present any significant health risk, because all the radioactivity released in the explosions was either widely dispersed (i.e. worldwide) at the time, or has decayed sufficiently by now.[1,2] 1.2 Minor Trials The UK also conducted several hundred 'minor trials' at Maralinga over the years 1955 to 1963. These minor trials were essentially developmental experiments designe o investigatt d e performanceth e variouf o s s components o nucleafa r device, separatel combinationn i d yan almosd ,an involvel tal d radioactive materials with conventional high explosives d dispersean , d radioactivity to the local environment. 33 TO EMU LEGEND MAJOR TRIAL SITE DOBO MINOR TRIAL SITE PLUME CONTOUR (241Am 1 kBq/m2) MARALINGA VILLAGE Maralinge FigurTh . 1 e a area showing majo minod ran r test site maid san n features. The Australian Radiation Laboratory (ARL) has surveyed the minor trial site n mani t Maralinga s yd an case d e Emusite] an th as[2 , s have been adequatel e radioactivth y r cleaneo , eup d materials used werf o e sufficiently short half-lives tha o tlongen thee rar y detectablee Th . sites with significant remaining contamination are all at Maralinga; they are show Figurn detailed ni an 1 e d below. Tad je- Tadje was the site of a one kiloton nuclear detonation in 1957. Because naturdevice th th f f eo o tested, n arethera s ai e extending from the ground zero for about 1000 m in a NNE direction which is contaminated with plutonium (and associated americium wels ) a soms a l e small pelletf o s cobalt-60. The cobalt-60 is of sufficiently short half-life (5.3 years) for it to present little potential hazard in the long-term, but the half- lif plutonium-23f o e s suci 9 h (24,100 years) that this small area nortf o h 34 the Tadje ground zero must be considered a potential hazard well into the future. Kuli- Over 7000 kg of uranium was explosively dispersed at Kuli, as well as berylliumf o g 6k 5 .uraniu e th Muc berylliud f ho an m s collectemwa e th t a d e trialsth tim f o e. Some berylliu s repatriate mwa K followin U e th e o t th dg e uraniutrialsth e d s th presumei m an ,e n burie b o a larg o t n t di dpi e northern side of the Kuli site. However, pieces of uranium metal and uranium oxides are quite plentiful close to the firing pad in the centre of e sit d furtheth e eastan e occasionath Th o .t r l small piec berylliuf o e m metal can also be found. Wewak- Burning d explosivan s e dispersal f berylliumo s , uraniud an m plutonium occurred at Wewak in trials code-named 'Vixen A' . The two plutonium burnings (involving a total of 405 g plutonium, of which 395 g was returned to the UK in 1959) took place at the VK33 site which was subsequently treated by 'ploughing'. Four explosive dispersals of a total f plutoniuo o fg abou0 m57 t took plac t sitea e s VK60 d VK60Can A . Surrounding these site fragmente ar s metaf so l contaminated with plutonium. TM100 and TM101- Explosive dispersals of plutonium (about 600 g at each site) took plac bott a ef thes o h e locations plutoniuf o . g Som0 50 em from n 1979i . K U s returne e wa TherTM10a higth 1s o hi et d concentratiof o n plutonium-contaminated fragment d smallean s r friable particles e closth o t e firing sites. Taranaki- Taranake sit t th Maralinga e s i i a whic s mosi h t extensively contaminated with plutonium d thereforan , e represent e greatesth s t remaining potential hazard to health. It was the site of the final major atomic detonation at Maralinga in October 1957. This was a balloon-borne test of 27 kiloton yield at 300 m, which left very little contamination. Betwee e are th e ground 1963ne anortth an ,th 196jus f 0do ho t zer s wa o used for 12 'one-point safety trials' (code-named 'Vixen B') in which about 22 kg of plutonium was explosively dispersed in a sector extending from the west, through north, to north-east of the site. As well as plutonium, uranium-23 berylliud an 5 m were also disperse thesn i d e trials. The plutonium contamination at Taranaki occurs mainly in three forms[3,4]- as a fine dust, as small sub-millimetre particles, and as surface contaminatio n largeo n r fragments n thesI . e one-point safety trials, jets of molten plutonium were eth projected m an into e 100airt 0th , o p u d contamination was dispersed by wind in narrow 'plumes'. The main plumes e westextenth ,o t dnorth-west , nort d north-easan h Taranakif o t e mosTh . t extensive of these is the north-west plume which can be detected up to 100 km from the firing pads at Taranaki. In a clean-up in 1967 ('Operation Brumby') e surfacth , e centrae th soi n i ll are t Taranaka a s treatewa i y b d mixing to reduce average contamination levels, and plume areas were 'ploughed' . Beyond the ploughed area the plutonium contamination tends to e surfaceth e firinn th bo e . f go padm Withi 0 s 50 nther e manar ey thousands of contaminated fragments large enough to attract attention as potential souvenirs. The range of types of fragments includes wire, rusty steel plate, lead, piecea gre f yo w sdensity lo meta f o l , bitumed an n yellow bakélite. 1.3 Previous Studies During the period that the Maralinga and Emu Ranges were in use, various radiation survey d clean-uan s p operations were performed.[5] Once th e decision was taken to close the Maralinga Range, a final clean-up of all sites was undertaken by the UK in Operation Brumby in 1967, and a final 35 report on the state of the Maralinga and Emu ranges (the 'Pearce Report'[6] s presente wa )e Australia th o t d n Government e goalTh f o .s Operation Brumby were to reduce the level of contamination and to perform such other operation s woula s d meet requirement e Atomi th t dow se y scb n Weapons Test Safety Committee (AWTSC e Australian th behalo ) f o f n Government. Essentially these requirement s a thei d r ha sbasi e th s Recommendations of the International Commission on Radiological Protection (ICRP), Publication 9 for maximum permissible gamma dose rates,[7] and Publicatio maximue th r mfo 2 npermissibl e concentratio plutonium-23f no n i 9 the atmosphere r continuoufo , s exposur memberf public.[8e o th f o s ] Major surveys of the whole of the Maralinga and Emu areas were conducted by ARL in May and November 1984 and February 1985, and a report was presented to the Royal Commission into British Nuclear Tests in Australia.[2] Subsequently, surveys have bee o ndetermint conducteL e AR th ey b d distributio f plutonium-contaminateo n d fragment e Taranakth t a s i site,[3] the definition of levels of plutonium contamination on the ring and outer road systems surroundin Taranake th g i site,[9 e geologth ] hydrogeologd an y y Maralinge oth f a area,[10 d level]an plutoniuf so m contamination beyone th d boundarie e testh t f o rangs Maralingn i e a Tjarutja (Aboriginal) lands.[11] Other work that ARL has performed in association with these surveys has bee e determinatioth n f isotopio n c ratio f actinideo s e nucleas th use n i dr trials (both majo d minoran r t Maralinga ) d Emu,[12,13an ae th d an ] determinatio e propertieth f o n f o plutonium-contaminates d particles resulting from the Vixen B trials at Maralinga.[13,14] This latter study include e measurementth s f o isotopis c ratio r actinidee fo sth n i s individual plumes at the Taranaki site. During these studies t becami , e clear tha a numbet f e aspecto rth f o s residual radioactivity differed substantially froe officiath m K recorU l d (1968 Pearce Report[6] e finath lf e rang o )th stat ef o e afte e 196th r 7 clean-upn Operatioi K U e ,nth carrieBrumbyy b t ou d. Field data acquired since 1984, together with other careful studie f recentlo s y declassified reports,[15] have indicated thainformatioe th t n provide Britise th y o db t h the AWTSC following the clean-up of Maralinga in 1967 is deficient in a numbe f areaso r n particularI . , plutonium levels e greateb ten p o u t d y rb ta 0 factooveo1 rf o rthos ee Pearcth give e n i th en Reportd an ] ,[6 contaminatio s muci n h more extensive n aeriaA . l radiological survey conducte n 198i d 7 supports these findings.[16 e PearcTh ] e Report also make mentioo hundredsn e th f no f thousand so f fragmentso f debrio s s highly contaminated with plutonium. Man f thes o ypotentialle ar e y 'souvenirable' and could lead to a totally unacceptable health risk either on or off site. K modellinU e inhalatioe th Th f o g n pathwae Pearcth n ei y Report, basen o d ICRP Publicatio s alswa o] deficien[8 - , n2 20 o t n tha i tx t ignore i tsi e th d fold enhancement of plutonium concentrations found in the inhalable fraction in the present study. Finally, there remains strong doubt, based on data in other reports, [17] about the accuracy of the estimate in the plutoniuf Pearco g k e2 2 Reporm e n shalloendei th tp f u do tha w0 2 tburia l pits at Taranaki. In fact, it would seem more likely that most of the plutoniu s dispersemwa n aerosoa s a d l over very wid e w levelarealo f t o sa contamination. A realisation that the inhalation pathway would present one of the most significant potential health hazards arising from residual contaminatiof no the Maralinga and Emu areas led to the current studies presented in detail elsewhere,[18-21] and summarised in this report. The work was performed under a contract defined by the Technical Assessment Group (TAG[22]) set up by the Government of Australia following the report of the Royal Commission 36 into British Nuclear Test Australian i s e studTh .y include a surves f o y ambient concentration f o radionuclides d dusan n i sair t , artificial resuspension studies e characterisatioth , e contaminatioth f o ne th n i n Maraling soilsu dosa Em d ed an ,assessmen an a e inhalatioth r fo t n pathway. 1.4 Maralinga Aborigines The traditional occupants of the Maralinga lands are the Maralinga Tjarutja (Pitjantjatjara) Aboriginal people. Currently the Maralinga Tjarutja lands cover some 80,00, wit m a pooh k 0 f somo l e 2000 Aborigine o havwh s e traditional obligation o partt sf theso s e landse areTh a. thas i t presently e formee Aboriginedenieth th o o t rt d atomie du s c weapons tests comprises 3,200 km ^. e Maraling Recentlyth f o 0 a, 20 peopl betweed an e0 6 n have establishe a semi-traditionad l lifestyl k ValleyOa t a em ,k som0 10 e north-wes Maralinge th f o t a range. 2. DESCRIPTION OF THE ASSESSMENT 2.1 Ambient Concentrations of Radionuclides in Air at Maralinga and Emu Ambient concentration f radionuclideo r e ai toxith n i cd s an chemicas l beryllium were botf monitore o w volum he lo higus d ey an hb dsampler s over several years during calm condition d durinan s g dust storms e datr Th fo .a the contaminated sites indicate that airborne concentration f plutoniuo s m e tim th w mosare lo f eo t(<1 0 Bq/m^).[18,19] Annual average ambient activity concentrations of plutonium at the most heavily contaminated sampling sites wer. 10"" ca em abov^ 1 heighBq/a e1. t a mgrounf to d level. The highest concentrations measured were ca. 2 x 10~^ Bq/nr averaged over a few days. The results indicate that the radiological risk due to naturally resuspended dust is dominated by a rare event, viz. the occasional dust storm that resuspends considerable activity. 2.2 Artificial Resuspension Studies Artificial resuspension studie ranga n soilf o so e s from Taranak majod ian r trial sites wera mechanica ef o performe e us l y dust-raisinb d g apparatus.[18,20 A cascad] e impacto s use o analyswa rt d e airborne dusn i t term f mas2d o s^A an sm activitie r particlfo s e sizes less tha //m7 n s .A well e surfacth , e soil froe siteth m s studie s characterisewa d e th n i d laborator y meanb y f sievino s d microparticlan g e classificatione Th . activity median aerodynamic diameter (AMAD) was determined as ca. 6 /im for resuspended soil from several sites at Taranaki, and decreased to 4.8 pm followin a delag f severao y l minute alloo t sr settlin fo w g between raising and sampling the dust. Plutonium and americium activities were found to be enhanced in the inhalable fraction (taken to be <7 jum aerodynamic diameter) over their e totavalueth n li s soil e d value'enhancementh an , f o s t factor' (defined as the ratio of activity per unit mass of the inhalable fraction to that of the total soil) were similar in resuspended dust and surface soil samples.[18,20] Observed enhancement factors ranged from 3.7 to 32.5 for Taranaki soils with an average value of ca. 6 appearing reasonable for general application in outer (plume) areas. Closer in to the more heavily contaminated areas, higher values were observed. Values close to unity were measured for the enhancement factor at the major trial sites. Some experiments were performed where uncontaminated duss raisewa t y b d activities such as walking and driving over dusty ground.[18] The highest inhalable dust loading observed was 13 mg/nr for travelling in the open 37 tray section of a vehicle following another vehicle on a dirt track. In the absence fronth tf o e vehicle e inhalablth , e dust 8 rng/mloadin0. s 3.gwa Walking on dusty ground in a confined space gave an inhalable dust loading of 8 mg/nr. 2.3 Characterisatio f Contaminatioo n Maralingn i nu Soil Em sd an a A range of Maralinga and Emu soils were characterised by means of sieving and microparticle classification, yielding d mas^41an s ^ activity distributions with respect to size.[18,20] Mass distributions all the way througe inhalablth o t h e fractio e essentiallar n y simila a rang r f o efo r soils froMaralinge th mk Valle Oa d yaan areas l soil e Al characterise.ar s d as sandy, with the greatest mass generally associated with the 250-500 fj,m fraction. The amount in the fraction centred on 5 pm (optical size) was generall e rangth en i y0.5-1.0% . Thus thes t econsidere no soil e ar s d particularly dusty. The activity distribution of plutonium and americium is quite different froe masth ms distribution d mucan , h more variable. Average enhancement factors for plutonium and americium activity distributions were determined (see below). Depth profile analyse r undisturbefo s d area t Taranaka s i indicated that most (74% on average) of the americium (and hence plutonium) activity is found in the top 10 mm of soil. [18,20] For all samples analysed, between s wa f soil o t I n .nu f 0 plutoniuo 2 p % to 99 e d m8 th an 5activit n i s wa y clear tha e plutoniut th muc f o h m contaminatio t bota n h majo d minoan r r trial sites was present as discrete sub-millimetre particles. This non- uniform distribution of isolable particulate material, of ^41^ activities >0.1 Bq, extends at least 100 km from the firing sites at Taranaki. 4 Inhalatio2. n Dose Assessmen Maralingr tfo Emud aan t 2.4.1 Model of Respiratory System The model of the respiratory system used in this assessment is that described in IGRP Publication 30.[23] This compartment model provides a mathematical approximatio e passagth o f t inhaleno e d materials througe th h human respiratory system, but model compartments do not correspond with specific physiological processes w lunne g A mode. beins i l g developey b d the ICRP which more closely reflect e physiologth s e respiratorth f o y y tract, but is yet to be internationally adopted and is not considered furthe thin i r s work. 2.4.2 Input AssessmentData, Scopethe and of e currenth n I t work e effectivth , e dose committee th r eacfo f do h radionuclides present is computed by use of the formula: effective dos ——;——= e ^volumx e inhale dosdx e intake conversion factor volume with ——î——— being computed from: volume ° ——::——activit•* -dusy= t ,concentratio —————x r ai *-n i n. ... activity volume mass tReproduced from the journal Health Physics [21] with permission from the Health Physics Society. 38 The effective dose per unit intake, or dose intake conversion factor, is dependent on both particle size of the airborne material and its chemical form (i.e. ICRP solubility class). 2.4.3 Dust Concentrations Ther e threar e e main component e dusth t o t exposurs e Pitjantjatjarth f o e a Aboriginal people ) ambien(1 : t dust that woul presene absence db th n f i teo people, (2) dust raised by human activity, and (3) dust resuspended by wind froe disturbeth m campe de availabl th areaar .f ) o (1 Dat en o afro m these studies,[18,19 t thibu ] s componen s considerei t minoa e b r o contributot d r to the total dust inhaled by the Aboriginal people. Quantitative data on the other components of the dust environment are sparse. The Oak Valley Aboriginal people have been studied extensively by Palmer and Brad o notywh e that their lifestyl vera s yi e dusty one.[24] However, data on the dust concentrations to which these people are exposed are limited to the results of one field study at an atypical camp site.[25] e limitationTh f thio s s stud e well-documentear y s authory b it d y b dan s Palme d Brady.[26an r e lac Th f direc]o k t dat s resulteaha n attempti d o t s simulate some Aboriginal dust-raising activities.[18,27,28] While these data are inadequate, they are in fact all which are available. Consideration of Aboriginal daily activity profiles by TAG has led to agreed value f averago s e inhalable dust concentration e orde1 th f o rf o s mg/nmg/nr5 r adultr childre1. fo Pfo ^d an sd infants nan . These valuee sar adopted in this assessment for all members of the Aboriginal community who n i futur y e currentlema th livn i e y restricted areasf I dust. concentrations other than these are believed appropriate, new doses can be obtained readily from those presented belo y lineawb r scaling. 2.4.4 Particle Size The artificial dust-raising experiments[18,20] indicate that there are two main fractions to the particle-size distribution of radioactive material, with AMADs of 5-8 jum and >11 ^m. The relative proportions of these two fractions vary with the amount of time allowed for the larger particles to settle. The field measurements of dust loadings for Aboriginal activities were conducted with size fraction cutoffs excluding the >11 ^m fraction. The 1 and 1.5 mg/m^ dust concentrations used in this assessment are assumed to have an AMAD of 5 jum. 2.4.5 Chemical Class Radionuclidesf o Animal studie o determint s e translocatioth e n rate f plutoniuo s d an m americium following intake have been conducted by the National Radiological Protection Board (NRPB n Englani ) d using material from Maralingaf o e On . these studies involve e translocatioth d f plutoniuo n d americiuan m m following inhalation or instillation into the lung using four samples from the minor trial site Taranakif o s , TM10 TM10d 0an 1 (two samples )[29. ] The studies of Stradling et al.[29] resulted in translocation rates: Clas TM10> sW 0Taranak> iClas> TM101> Y s . The translocation rate f americiuo s d plutoniuan m m were very similar. Stradling suggested that the worst case, which corresponds to the highest translocation rate, might be considered to be represented by 25% Class W % Clas75 . sY Thid an s prescriptio minol al uses r n wa fo dtria l sitest A . major trial sites, where the plutonium was high-fired, Class Y was assumed. 39 ICRP suggest that all chemical forms of americium should be considered to be inhalation Class W.[30] In the current case where Am has arisen from the transmutatio f ^^Po n situn u i e ^-^A th , m occupie plutoniua s m lattice sitd behavean e s like plutoniu e humath nn i mbody . NRPB animal data support this judgement , [29] as does evidence from in vitro solubility studies in the laboratory [18] and from the stability of plutonium/ americium ratios in the soil. The ICRP classification, which refers to direct intake f americiumo thus i , s inappropriat n thii e s instance. For other radionuclides wher o datn e available ar a e mosth ,t conservative dose intake conversion factor values were usedr uraniuFo . m radioisotopes, s assumedClaswa Y s , whic s appropriati h highle th r y fo einsolubl e oxides mose th ts i conservativ UC> d U^Od an 2an g e lung clas r uraniumfo s . 2.4.6 Calculation Effectivef o DoseUnitr Pe Intake Dat n chemicao a l clas d dosan se intake conversion factor values, together with the sources of the data, are tabulated elsewhere for the radionuclides considere n thii d s assessment ,218 .[1 ] Unfortunately, these data wert no e available fro singla m e source. Data were obtained from ICRP sources where possible (i.e. ICRP Publications 30 and 56). [23, 31] This information had e b supplementeto d with data from NRPB that follo e samth we basic philosoph s ICRa y P Publicatio r infantfo 0 d childrenn3 san . However, there ar dato Clasr en afo samericiumY . l indicational s A e thae americiuar sth t t Maralinga m a behaves t leasa , t approximately, liks associateit e d plutonium shoult i , e classifiedb a s a d similar Class W/Clas Y smixture . Accordingly, dose intake conversion factor value ^^Ar fo s m Clas wersY e derived from plutonium data, adjusting for the difference in alpha decay energy released and for the shorter half 241e Amth lif .f o e 2.4.7 Activity Concentrations Surfaceand Densities In order to perform dose assessments at the chosen locations, activity concentratio d activitan n y surface density e drawb dat o at n havd ha e together fro numbea m f sourcesro . Firstly, the aerial survey[16] is the source of much of the data on Am, 13/ 60 r areao £ sanco C jawa y majofroe th mr trial sites. Ground surveys, by use of soil sampling techniques, have given concentrations of radionuclides in the more contaminated areas. [2] 2.4.8 Activity per Unit Mass of Resuspendable Material Particle-sizing studies on contaminated Maralinga soils and the artificial dust- raising experiment s [18 , 20] showed that fine particle sizes usually had a greater activit r unipe yt mas e bulsth k thad a sitesoi di nt a l. Enhancement factors were determined for a selection of representative sites, to enable conversion of bulk soil activity concentrations to activity concentrations in resuspended inhalable material. The data available indicate that the enhancement factor is roughly constant for any given a rangtria r f particlo efo l e size fractions. However, enhancement factors, give varn Tabln ca ni y , widelI e y between trial sites. 2.4.9 Activity Ratios Some significant radionuclides presen t Maralinga u wertt Em no e d an a readily measurabl y eitheeb r aerial ground-baser o - d surveys (e.g. isotopes of plutonium and 90Sr) . Activities of these 'hidden' radionuclides have 40 Table I. Input Parameters for Dose Assessment Site 239 Pu/241Am 240pu/24lAm 2!41pu/241Am 90Sr/l37Cs Enhancement factor Taranaki Central 7.0 1 12.2 20 plumW e 8.0 1.2 13.4 6 NW plume 6.8 1.0 12.6 6 N plume 8 1 12.2 6 NE plume 9 1.2 11.6 0.52 6 TM sites TM100 20 1.9 11.5 4 TM101 7.6 1.2 12.1 4 Wewak VK33 23 1.0 10.6 10 VK60A/60C 20 1.4 11.8 4 Kuli Kuli - - - 6 Maior trials Totem I 40 4.6 7.1 0.18 1 Tote plumI m e 40 4.6 7.1 0.10 2 Totem II 50 5.7 6.9 0.18 1 Totem II plume 50 5.7 6.9 0.10 2 One Tree 30 3.5 8.6 0.24 1 One Tree plume 30 3.5 8.6 0.24 2 Breakaway 30 3.5 8.6 0.48 1 Tadje 40 5.7 9.0 0.61 1 Tadje 500 m NNE 40 5.7 9.0 0.61 0.3 Biak 40 4.6 9.0 0.26 1 been estimated from laboratory measurements of activity ratios or from calculation e ratioth f so s base n productioo d n date d decaan s y parameters, combined witfiele th h d measurement ^^-Amf so ^"cd an s activities. Values of appropriate activity ratios are given for various sites in Table I. The values for 239Pu/241Am (major and minor trial sites) and 240Pu/241Am activity ratios (minor trial sites) come from laboratory measurements using high-resolution gamma-ray spectrometry.[12-14] Details of methods used to determine other activity ratios are given elsewhere.[18,21] e activitth s A y ratio e timar se dependen a greate o t t r lesseo r r extent depending on the half lives of the radionuclides concerned, a date must be fixe whict a d perforo t h dose th me calculations e datTh .e whic s chosehwa n in this case is mid 1987, that of the aerial radiological survey. All calculated activit d 1987 mi d empirica yan ,r fo ratio e n Tablli ar s I e activity ratios are from within 18 months of this date. 41 2.4.10 Depth Distribution e availablTh e source -term data come from measurement f surfaco s e activity densities and measurements of activity concentrations in soil. These data are related by the depth distribution of radionuclides and soil density. Measurements of these parameters are presented elsewhere . [18 , 20] These show tha undisturben i t f o m m 0 d1 p areasto e ,e activitth th mosn i f to s i y most samples, and at least 85% is in the top 20 mm. e followinth r Fo g calculations s assumei t i , d tha n undisturbei t d areas, all the activity is uniformly dispersed in a layer 10 mm thick. Use of this depth distribution means tha dusta t loadin mg/nl f go r correspondo t s enhancemenn a r fo resuspensioa m r tpe facto 0 unityf 1 no r x facto 6 . f ro n plougheI d areae deptth o whics, t h h activit s beeha y n mixe s greatei d r and it is more appropriate to use surface activity concentration (Bq/kg) than surface activity density (Bq/m^) data for the following reasons: 1) soil belodeptm m unlikels 0 i hw1 resuspendede b o t y attenuatio) 2 d ,an f no gamma rays frof soi o s mquit i lm belom ee 0 importan1 wth sever r fo e t radionuclide Am. The surface activity densities of Am have had to be corrected for V gamm ke y fro ra aattenuatio0 m6 e ^^Amth f .o n This correctios i n dependent on the known or assumed depth distribution. If all the americium (and hence plutonium s uniformli ) y distribute a laye m n m f soii do r0 1 l thick e attenuatioth , s 25%i n . Changee assumeth o t sd depth distribution will affect both airborne contamination concentrations and the correction r attenuationfo . These effect e discussear s d elsewher] 21 , 8 [1 e. 2.4.11 Breathing Rates Breathing rates for adults, children and infants are taken from Haywood.[32] These rates are 8400 nrvyear for adults, 5500 m^/year for children and 1400 m^/year for infants. These data are for the British population. Data for Pitjantjatjara people are unavailable but are unlikel diffeo t y r substantially. 3. RESULTS Committed effective dose estimates from inhalatio r long-terfo n m inhabitants in the contaminated areas are presented in Table II . Detailed breakdowns of dose components are presented elsewhere . [18] For the contamination at Maralinga, inhalation has been shown to be by far the most important pathway. [33] For all sites except Kuli which is contaminated with uranium, the dose due to inhalation is dominated by ^39pu with minor contributions from other actinides. Fission and activation products are no longer significant hazardinhalatioe th r fo s n pathway. e resultTh s indicate that dose childreo t s highee nar r than dose adulto t s s and infants. This is a consequence of children being subjected to higher dust concentrations through their play activities, and because of generally higher dose intake conversion factor childrenr fo s , which more than offset their lower breathing rates. Thus children form the critical group. Froe dosth me estimates presented, certain areas have inhalation dose rates that are too high to be acceptable under all but the most rigorously controlled circumstances. These includ centrae th e l are Taranakit a t A . the other extreme, while plutonium is detectable on the ground way beyond the limit of detection of the aerial survey, for any realistic occupancy factor the corresponding inhalation dose is much less than 1 mSv per year. 42 Table II. Estimated Committed Effective Doses from Inhalation for Full-Time Aboriginal Residents in Contaminated Areas at Maralinga and Emu Site mSv/year Adults Children Infants Taranaki Central area [241A Bg/gm3 ] 273.0 306.2 124.5 W plum A contou e; r [241 kBq/m4 Am1. 2] 3.4 3.8 1.5 plumW N A contou e; r [241 kBq/m4 Am1. 2] 2.9 3.3 1.3 N plume; A contour [241Am 1.4 kBq/m2] 3.3 3.7 1.5 NE plume; A contour [241Am 1.4 kBq/rn2] 3.7 4.2 1.7 Uewak VK60A.60C; centre [241Am 30 kBq/m2] 105.1 118.0 48.2 VK60A.60C ;contouA r [241 kBq/m0 Am1. 2] 3.5 3.9 1.6 VK33; B contour [241Am 3.0 kBq/m2] 29.3 32.9 13.4 TM s Lees TM100; C contour [241Am 10 kBq/m2] 35.8 40.2 16.4 TM100 ;contouA r [241Am 1.0 kBq/m2] 3.6 4.0 1.6 TM101; C contour [241Am 10 kBq/m2] 15.5 17.4 7.1 TM101; A contour [241 kBq/m0 Am1. 2] 1.5 1.7 0.7 Kuli D contour (0.02 km2) [ 238kBq/m0 U15 2] 11.2 16.9 11.2 contouA r [238 kBq/m7 U1 2] 1.3 1.9 1.3 Major Trial Sitest Ground Zero Totem I (Emu) 4.0 5.2 2.4 Ground Zero ToteI I m (Emu) 16.4 21.4 9.9 Ground Zero Breakaway 1.2 1.6 0.7 Ground Zero Biak 5.6 7.2 3.3 Ground ZerTree oOn e 2.6 3.4 1.6 Ground Zero Tadje 42.0 54.6 25.3 Tadjf o are u P E eaNN [241Am 3.5 Bg/g] 14.4 18.8 8.7 Tote 137I m C sconA . [137Cs 0.6 kBq/m2] 0.2 0.2 0.1 Totem I 241Ara A con. [24iAm 2.0 kBq/m2] 4.1 5.4 2.5 Totem II 137Cs A con. [137 kBq/m6 Cs0. 2] 0.5 0.6 0.3 Totem II 241Am A con. [241Am 2.0 kBq/m2] 5.1 6.7 3.1 D contour d A,B,an C s refe o contaminatiot r n contours describee th y b d aerial survey of Maralinga and Emu.[16] t Contamination source term major fo s r trial sites come from réf.[2]. Having regard to the long half lives of the radionuclides concerned, the inhalation problems highlighte y thib d s dose assessment wilt diminisno l h significantly withi y reasonablan n e perio f timd o hencd an e e management strategies must be developed to deal with such problems. 43 An implication of some of the higher dose estimates in Table II is that extreme care y mus rehabilitatioe an b taket n i ne sitesth s a f ,o n rehabilitation work itsel y raisma f e high level f duso s t posina g significant hazar woro dt k crews. 3.1 Aboriginal Healt Lifestyld han e There are several lifestyle aspects and related health issues which might considerably alter doses received by residents of an Aboriginal community livin n contaminatei g ds notei areas t dI .thae Aborigine th t k Oa t a s Valle e commonlar y y mouth-breathers, mane heavar y y smokers d uppean , r respiratory tract infection endemic.[24e sar ] Mouth-breathers ten havo t d e lower deposition in the N-P region of the respiratory tract, which can affect dose intake conversion factors. Smoking further complicatee th s matter, but generally seems to have a small effect on regional deposition while substantially altering mechanical clearance capability. Endemic respiratory tract infections also complicate the situation, probably causing change n regionai s l depositio d clearancan n e capability. These infection y als ma e srelateb o o higt d h dust exposure d possiblan sa e ar y hige th caush r incidencfo e moutf o e h breathing. Other factors which may affect dose intake conversion factors are the general health and dietary deficiencies of the population. The dose conversion factors used in this assessment have been computed from a model designed for essentially healthy workers. The people living at Oak Valley do not generally fit this description. Unfortunately, while these factors are obviously importan n assessini t g doses that migh e receiveb t n a y b d Aboriginal residen a contaminate n i t d area, o littldatn r ao e exiso t t quantify their importance. Assessing these factors probably requirea s further specialised study. 3.2 Sources of Uncertainty e dosTh e estimates presente e dependenar d mann o t y factors, som whicf o e h are not well known. All of the estimated doses depend linearly on breathing rates, activity data, dust concentrations, and dose intake conversion factors. Breathing rates are reasonably well known. Activity concentrations on the ground are fairly well known, but activity in the air is not mann .I y cases, enhancement factors have been assumed base n onlo d y a few experimental determinations. These must be considered quite uncertain. Average dust concentrations have large uncertainty becaus a lac f f o ko e experimental data, but the assumed values are believed to be conservative. All dose intake conversion factor values have considerable inherent uncertainty, and further uncertainty because of the unknown impact of Aboriginal healt d lifestylan h e issues discusse 5 pm f o e d us above e Th . AMAD may also be inappropriate at sites not sampled. However, dose conversion t verfactorno ye sensitivar s o particlt e o thies sizsd an e paramete unlikels i r causo t y e much error. 3.3 Uncertainty Analysis In order to develop some understanding of the range of uncertainty in the estimated doses a particula, re effectiv casth - e e dosr •"'Pfo e u inhaled by a 10 year old child living for one year at a level of 1.4 kBq/m^ of ^•"-Am (the limi detectiof to aeriae th f nlo survey) alon norte th g h plume- was treated in detail. Each of the four parameters: dust loading, 2-^Pu/24^Am activity ratio e enhancementh , t facto r resuspendefo r d inhalable dust d breathinan , g rate s assignewa , a distributiod n function 44 wit a specifieh d media d rangan n e d (10t90tan h percentiles)e Th . uncertainty analysis,[18,21] without taking into accoun e rangth tf o e uncertaintie e ICRP-baseth n i s d dose intake conversion factors, indicated the assessed doses in Table II are likely to be within a factor of three (10td 90tan h percentiles bese th t f )estimateo dosef o s . Iranga f uncertaintf o e factoa f o yf thre o r s include i eestimate th n i d e of dose factors, the median value for the same case is unchanged (2.9 mSv), but with 10th and 90th percentiles becoming 0.6 and 12.8 mSv respectively. Thus, under these assumptions, there is one chance in ten that the true s greatee i n chanctha on te t i tn d dosi er an s les i ethav s3 mS n1 tha 6 0. n 6 eithe4. . a facto tha- re medianca , th sidv is f t o r f mS o e . 4 Occupanc3. y Factors e doseTh s compute r permanend fo abov e ar e t e residencth e sitr on fo e t a e inhalation exposure pathway only. Palmer and Brady[24] indicate that the Oak Valley people move camp every 7 to 10 days after the resources of the area around the camp are depleted. They then tend to move along roads to a new site usually one or two kilometres distant where they establish a new cam pe road th nex .o t Considerin k VallegOa thae yth t communit fairls i y y mobile, it is unlikely that total occupancy of contaminated areas would exceed practicn 10%I . l doseal e s reported mus e scaletb d dow whatevey nb r is reasonabla assume e b o t d e occupanc ye contaminate factoth r fo r d areas. 3.5 Casual Visitors A casual visito unlikels Maralingo i t r u Em remaio t yr o a n contaminatei n d area r morfo se than e yead l/50tprobablth an r f o h y woul e exposeb d o t d lower dust concentrations than a member of an Aboriginal community. It is assumed that the visitor does not engage in dust raising activities and consequently is only exposed to ambient sources of resuspended dust. The greatest hazar visitoa o t d r would aris thaf i e t person were present during a dust storm (and unable to shelter in a vehicle or move out of the area while conditions were unpleasant). Calculations for two of the most hazardous sites[18,21] indicate that there o iinhalation s n hazar r casuafo d l visitor o evet e moss th nt contaminated sites at Maralinga and Emu, so long as dust-raising activities are avoided. For such visitors, the greatest hazard occurs during a dust storm. Severe dust storms were estimate o delivet d n effectiva r 6 /iSr 3 pe v . e ca dos f o e stora perso o t m n present throughou e completth t e stor t eithea m r central Taranaki or near Tadje ground zero. Hence properly informed casual visitors making intermittent forays to the area, for example tourists, geological prospector t d engagsurveyorsno an s n duso i d e to ,raisinwh r o g soil disturbance activities are very unlikely to receive an effective dose by inhalation of 1 mSv. 3.6 Implications of Revised Tissue Weighting Factors The ICR n Publicatioi P f revise0 recommendo 6 n e us d e tissuth s e weighting factors.[34] The use of these revised weighting factors will affect dose intake conversion factors, and in particular for plutonium the reduction in the weighting factor for bone surfaces from 3 to 1% will cause a decrease in dose per unit intake. The potential magnitude of this effect on the doses presented in Table II, which are based on the old tissue weighting factors, can be estimated. Stradling et al.[29] have shown that for Maralinga plutonium represented by 25% Class W and 75% Class Y, doses based on the revised weighting factors would be lower by ca. 35%. For Class Y plutonium, dose srevisee baseth n do d weighting factors woul e lowedb r than 45 thos y n ca..b Tabli e I w I ICRe 25%ne Pe .lunTh g model, when adopted internationally, will further affect dose intake conversion factors. 4. THE FUTURE e futurTh f Maraling o ew reache no s a criticadha a l stage n thae i , th t Australia K governmentU d an n s have just this month (June, 1993) reached in-principle agreement on a settlement of Australia's claims regarding residual contamination of the test sites. The forthcoming clean-u Maralingf o p classicaa s i a l intervention situation as defined in ICRP Publication 60.[34] The philosophy guiding such a clean-u n existina f o p g contaminated sits beeha e n enunciatee th y b d TAG,[22 d essentiallan ] y involves decisions about wha s reasonablei t , having regar o economit d d sociaan c l factors e ICRTh P. recommends against the use of dose limits for deciding on the need for, or scope of, intervention.[34] Rather G havTA ,e forme a judgemend t base n weighino d g the benefits of a clean-up (e.g. doses averted by the public, ability to re-use land) against the detriment in clean-up (e.g. doses to workers, ecological cost, financial cost).[22] The judgement of TAG, based on the current ICRP lifetime risk factor for developing a fatal cancer of 5 x 10~^ Sv"~ , [34] was that the contamination contour corresponding to an annual committed dose of 5 mSv, assuming full-time occupancy, is the border-line between acceptabilit d unacceptabilitan y f risko y . Thi s basei s d upon knowledge of the present life style of the semi-traditional Aborigines and their life expectancy. The Maralinga Aboriginal people have indicated a general acceptance of the conclusionG report.[35TA e th f o s] Thewele ar yl aware thatresulta s a , , e contaminateth som f o e d area e considerear s d dangerou r continuoufo s s traditional occupation by them. The dilemma faced by the Maralinga people is what for f clean-uo m n adequatelca p y deal with this d thevere an ,ar y y concerned about the gross environmental damage that the removal of too much top soil from large areas woul woult di causs da - einvolv e removath e f o l every tree and blade of grass from an area of verdant bush land, with potential for subsequent erosion problems. The decision of the traditional Aboriginal owner s beeha s n tha t preparetno e the o ar solvt ye d on e environmental problem by creating another.[35] They thus reluctantly accept the fencing off of some 480 km^ of their traditional lands as being unsuitable for permanent occupation. The aim of the Australian Government is to deal with the most serious long- term radiological problems at Maralinga and Emu, and for this purpose a sum of A$101M will be available for a rehabilitation programme over six years. e clean-uTh p will involve in-situ vitrificatio f pito n s containing plutonium-contaminated wastes, the removal and burial on site of most of the area ploughed in Operation Brumby including all contaminated fragments, and fencing an area of ca. 480 km^ of which 120 km^ is contaminated at greate dosv mS r e 5 thacontoure th n . This fenced area would only presenta significant radiological hazar usee permanenr b dfo do t wer t i e t occupancy Aboriginey b s livin gsemi-traditionaa l lifestyle. REFERENCES [1] COOPER, M.B., LOKAN, K.H., WILLIAMS, G.A. and TOUSSAINT, L. 'The Radiological Monte Statuth ef o sBell o Islands y 1983'Ma ; , Aust. Rad. Lab. Repor ARL/TR062. tNo , October 1983. 46 [2] LOKAN, K.H. (ed.) 'Residual Radioactive Contamination at Maralinga and Emu, 1985', Aust. Rad. Lab. Repor ARL/TR070. tNo , April 1985. [3] BURNS, P.A., COOPER, M.B., DUGGLEBY, J.C., MIKA, J.F d WILLIAMS.an , G.A. 'Plutonium-Contaminated Fragments at the Taranaki Site at Maralinga', Aust. Rad. Lab. Report No. ARL/TR075, July 1986. [4] WILLIAMS, G.A., BURNS, P.A. and COOPER, M.B. 'Plutonium Contamination at Maralinga', Chemistry in Australia, 5>4, 122-125 (1987). [5] SYMONDS, J.L. 'A History of British Atomic Tests in Australia', Australian Government Publishing Service, Canberra (1985). ] PEARCE[6 . 'FinaN , l Repor Residuan o t l Radioactive Contaminatioe th f o n Maraling u Site'Em e ,a th AWR Rangd Ean e Repor . 0-16/68No t , Aldermaston, January 1968. [7] ICRP 'Recommendation e Internationath f o s l Commissio n Radiologicao n l Protection (1965)', ICRP Publication 9 (1966) (Pergamon Press: Oxford). [8] ICRP 'Report of Committee II on Permissible Dose for Internal Radiation (1959)', ICRP Publicatio (1959n2 ) (Pergamon Press: London). [9] BURNS, P.A., COOPER, M.B., WILLIAMS, G.A. and LOKAN, K.H. 'Radioactive Contamination at Maralinga', in 'Radiation Protection Practice', IRPA 7 (Pergamon Press: Sydney), 3^, 1374-1377 (1988). [10] JAMES, J.M. and WILLIAMS, G.A. 'Tietkens Plain Karst - Maralinga', Aust. Rad. Lab. Repor ARL/TR081. tNo , September 1988. [11] JOHNSTON, P.N., LOKAN, K.H., RICHARDSON, C.K d WILLIAMS.an , G.A. 'Plutonium Contaminatio Maralingé th n i n a Tjarutja Lands' Rad. t s .,Au Lab. Repor ARL/TR085. tNo , August 1989. [12] JOHNSTON, P.N., BURNS, P.A., COOPER, M.B. and WILLIAMS, G.A. 'Isotopic Ratios of Actinides Used in British Nuclear Trials at Maralinga and Emu', Aust. Rad. Lab. Repor ARL/TR080. tNo , October 1988. [13] BURNS, P.A., COOPER, M.B., JOHNSTON, P.N. MARTIN, L.J. and WILLIAMS, G.A. 'Determinatio e Ratioth 23 f 2^Pf o d ^°Pso n an 241u o r t uA fo m Nuclear Weapons Test Site n Australia'i s , Health Physics, submitted (1993). [14] BURNS, P.A., COOPER, M.B., JOHNSTON, P.N. and WILLIAMS, G.A. 'Properties of Plutonium-Contaminated Particles Resulting from British Vixe B nTrial t Maralinga'a s , Aust. Rad. Lab. Repor . ARL/TR086No t , December 1990. [15] MORONEY, J.R., personal communication. Aerian [16'A ] l Radiological Surve Maralingf yo d Emuaan , South Australia', EG&G Energy Measurements Report No. AMO-8807, Nevada, October 1988. [17] For example, McLEAN, J. 'NS Group Report', in 'Operation Vixen Bl', AWRE Repor T4/61. tNo , Aldermaston, August 1961. [18] WILLIAMS, G.A. (ed.) 'Inhalation Hazard Assessmen t Maralinga t d an a Emu', Aust. Rad. Lab. Report No. ARL/TR087, May 1990. 47 [19] JOHNSTON, P.N., WILLIAMS, G.A., BURNS, P.A. and COOPER, M.B. 'Plutonium Resuspensio d Airbornan n e Dust Loadinge Deserth n i ts Environmen Maralingaf to , South Australia' Environ. ,J . Radioactivity, 20, 117-131 (1993). [20] COOPER, M.B., BURNS, P.A., TRACY, B.L., WILKS, M.J. and WILLIAMS, G.A. Characterisation of Plutonium Contamination at the former Nuclear Weapons Testing Range at Maralinga in South Australia', J. Radioanal. Nucl. Chem., in press (1993). [21] JOHNSTON, P.N., LOKAN, K.H d WILLIAMS.an , G.A. 'Inhalation Doser fo s Aboriginal People Reoccupying former Nuclear Weapons Testing Rangen i s South Australia', Health Physics, 63, 631-640 (1992). [22] CHURCH, B.W., DAVY, D.R., DEVERELL , LOKAND. , , K.H d SMITH.an . H , 'Rehabilitation of Former Nuclear Test Sites in Australia', report by the Technical Assessment Group, Australian Government Publishing Service, Canberra (1990). [23] ICRP 'Limit r Intakefo s f Radionuclideo s y b Workers's , ICRP Publication 30, Part 1, Annals of the ICRP, 2, No. 3/4 (1979) (Pergamon Press: Oxford). [24] PALMERd BRADYan . . 'Th,K M e Died Lifestylan t Aboriginef o e e th n i s Maralinga Region, South Australia', Repor r Maralingfo t a Tjarutjs a a part of the Maralinga Rehabilitation Studies, Research Programme No. 1: Anthropology. Australian Institut f Aboriginao e l Studies, Canberra, October 1988. [25] PEARCE, M.W. and PEGLER, J. 'Maralinga Rehabilitation Study Dust Monitoring Programme 1989', ANSTO Technical Report, December 1989. [26] PALMER, K. and BRADY, M. 'Dust Monitoring and Daily Activity: A Report on a Field Trip November 1989', Report for Maralinga Tjarutja as part e Maralingth f o a Rehabilitation Studies, Research Programm: 1 . No e Anthropology. Australian Institute of Aboriginal Studies, Canberra, December 1989. [27] GILES, M.S., PALMER BRADYd an . ,K M.A. 'Dose Commitment Estimaten i s n Aboriginaa l Communit A Proble - y n Rapidli m y Changing Social Values', in 'Radiation Protection in Nuclear Energy' (IAEA: Vienna), 1, 173-179 (1988). [28] GILES, M.S., TWINING, J.R., WILLIAMS, A.R., JEFFREE, R.A. and DOMEL, R.U. 'Final e TechnicaReporth o t t l Assessmene tth Grou r fo p Maralinga Rehabilitation Project. Study No. 2 (Radioecology)', ANSTO Technical Report, April 1990. [29] STRADLING, G.N., STATHER, J.W., GRAY, S.A., MOODY, J.C., ELLENDER, M., Pearce, M.J. and Collier, G.G. 'Radiological Implications of Inhaled 239pu and 241^ in Dusts at the Former Nuclear Test Site in Maralinga', Health Physics, 631, 641-650 (1992). [30] ICRP 'Individual Monitorin r Intakefo g f Radionuclideo s y Workersb s : Design and Interpretation', ICRP Publication 54, Annals of the ICRP, 19_, No. 1-3 (1988) (Pergamon Press: Oxford). [31] ICRP 'Age-Dependent Dose o Membere Publit sth f o cs from Intakf o e Radionuclides: Par, ICR1' tP Publicatio e ICRPAnnal, , th 56 n 20 ,f o s No (19892 . ) (Pergamon Press: Oxford). 48 [32] HAYWOOD, S.M. 'Revised Generalised Derived Limits for Radioisotopes of Strontium, Iodine, Caesium, Plutonium, Americiu d Curium'an m , Report NRPB-GS8, National Radiological Protection Board, Chilton, UK (1987). [33] HAYWOOD, S.U d SMITHan . , J.G. 'Assessmen f Potentiao t le Doseth t a s Maraling Tesu Em t d Sites'aan , Health Physics 624-63, 63 , 0 (1992). [34] ICRP '1990 Recommendations of the International Commission on Radiological Protection', ICRP Publicatio Annale ICRP, nth , 60 21 ,f so (19913 No1- . ) (Pergamon Press: Oxford). [35] BARTON, A., personal communication. Next page(s) left blank 49 ASSESSMEN POTENTIAF TO L DOSET SA MARALINGE TESTH U TEM SITED AAN S S.M. HAYWOOD, J.G. SMITH National Radiological Protection Board, Chilton, Didcot, United Kingdom Abstract An assessment has been undertaken of potential doses to future aboriginal inhabitants of the Maralinga and Emu areas of South Australia, where nuclear weapons tests in the 1950s 1960d an s have resulte residuan di l radioactive contamination. Radioactive materia thio t se du l programm test f eotheo d san r experiment stils si l detectable several ten kilometref so s from some of the test sites, and continued occupancy by individuals following an Aboriginal lifestyle could give rise to annual effective dose equivalents of several millisieverts within contours enclosing areas of several hundred square kilometres. The most significant dose pathways are calculated to be the inhalation of resuspended activity and ingestion of soil by infants. An analysis of the effects of uncertainties in the dose calculation has indicated the uncertainty distribution on predicted doses from the inhalation pathway. 1. INTRODUCTION Between 1953 and 1963, the United Kingdom Ministry of Supply conducted a programme of nine nuclear weapon tests and other experimental explosions at Maralinga and Emu in South Australia (see Figs 1 and 2). The two earliest tests were at Emu and the seven later ones at Maralinga. Althoug "minow fe ha r trials", involving dispersa radioactivf lo e material were also conducte Emut da , the bulk of the other experiments, amounting to several hundred in all, were conducted at Maralinga. These experiments, which varied considerabl typn sizeyd i an e , involved chemical explosived an s resulted in the localised dispersal of radioactive material. The radioactive material was mostly short- lived isotopes, but in a small number of cases, long-lived radioactive plutonium and uranium were involved. As a consequence of these tests and explosions, residual activity is still present in the area today. The significant activity remaining includes isotopes of caesium, plutonium, americium, cobalt, strontium and uranium, in some areas at concentrations which are sufficiently great to justify restrictions on access to parts of the areas. The plutonium contamination in the area has been considered to be of greatest concern. o assesT radiologicae th s l significanc e activitth f o e y remainin t Maralingga Emud an a a , Technical Assessment AustraliaGrou e 198n i th p y 6pu b t (TAGnse s Government)wa responsn i , e to recommendations made by an Australian Royal Commission. Under its continuing obligation to provide GovernmenadviceK U e th , t agree participato dt undertako t d an e e e TAGstudieth r .fo s Hence, a programme of work began in 1987, involving research organisations in Australia, the UK and USAe th .wore undertakes Parth f kwa o t Nationae th t na l Radiological Protection Board (NRPB), including bioavailability studies, radiochemical analysis and an assessment of potential doses. The bioavailability studie d radiochemicaan s l analysi f o environmentas l sample e describear s d elsewhere^1'2'3'4!. The key points of an assessment of potential doses in the areas containing residual activity are described here; the dose assessment undertaken at NRPB has been described more fully[5l This paper outlines the methods adopted for the assessment, together with the main results and conclusions. 2. MATERIALS AND METHODS 2.1 Assessment principles assessmene th f provido o t s m ai wa te e informatioTh e radiatioth n o n n e locadoseth o lst aboriginal population likel resulo yt t fro residuae mth l activit Maralinge areasu th d n yi Em an , d aan to assist decisions on the necessity for decontamination or continued restrictions on access. The test 51 Darwin Brisbane Sydney Perth • /Canberra FIG . Geographica1 . l locatio Maralingf sitesnu o Em . d aan Are f residuaao l contamination EŒB Railway Great Australian Bight 0 km 200 FIG . Locatio2 . f Maralingtesnu o t Em sit d Southeren i aan n Australia. 52 TABL . ENUCLIDE1 S CONSIDERE ASSESSMENTE TH DN I . Average emission energy Half-life Gamma Nuclidc (years) Alpha (MeV) Beta (keV) (MeV) 90Sr 29.1 . 196 - 137Cs 30.0 - 187 - 60Co 5.3 - 96.5 2.5 i33Ba 10.7 - 53.8 0.4 152Eu 13.3 - 136 1.1 154Eu 8.8 - 288 1.2 155Eu 5.0 - 62.6 - 241Am 432 5.6 51.9 - 238Pu 87.7 5.6 10.6 - 239Pu 24,100 5.2 6.7 - 240Pu 6,550 5.2 10.6 - 241Pu 14.4 - 5.2 234U 244,500 4.8 13.2 - 235U 7 108 4.5 48 0.15 238U 4 108 4.3 10 - areas are semi-desert and are at present uninhabited. A community at Oak Valley, 150 km north of Maralinga, usually amounting to some 100 individuals, but which can at times increase to 300 or more, is the most likely source from which future occupation of the area could be resumed. They are part of the larger Tjarutja tribe, who are regarded as the "traditional owners" of the area and amount in all to about 1,500 to 2,000 individuals. Doses calculated in the assessment are therefore potential doses, in the event of the return of these people to the Maralinga or Emu areas. Observations and results obtained from the other studies in the Maralinga Rehabilitation Programme were used in the assessment, which was limited to consideration of the consequences of existing surface contamination. e consequencTh removae th f eo f activito l y fro maree th pit a n si tha t were use buriar dfo f activo l e t consideredwastno s ewa . Doses were calculated for an aboriginal population with a semi-traditional lifestyle. It may be assumed that, with the exception of particular activities such as souvenir hunting of contaminated fragments, the doses to other population groups would be less. The aim of the assessment was to establish realistic average doses to individuals in this population rather than doses to a critical subgroup. There will therefore definitiony b , individuale b , populatioe th n i s woulo nwh d receive larger doses wels a ,individual s a l woulo swh d receive smaller doses. Doses were calculated assuming 1 year's exposure or, for the intake pathways, 1 year's intake. They were calculated for four representative age groups: adults (20 y), children (10 y), infants (1 y) and infants in the first year of life (with a representative age of 3 months). The nuclides considered in the study are listed in Table 1. 2.2 Pathways of exposure followine Th g exposure pathways were considere assessmente th n di : (a) inhalation of material suspended from the ground, (b) ingestion of foodstuffs and associated soil, (c) external gamma dose from the ground, 53 (d) beta dose from the ground and from material on skin and clothing, (e) contamination of sores and wounds. Potential exposures resulting from prolonged proximit handlinr o , yto , contaminategof d items were not included in the assessment because of the lack of information on the likelihood and duration of such exposures. 2.3 Methods of calculation e principlTh e adopte e assessmens possiblth a r utiliso n t di fa e informatio s s th ea e wa t n provided by the various experimental and measurement programs in the TAG studies. The assessment method is summarised below for the most significant pathways. It was apparent at the start of the assessment that the inhalation pathway was of considerable importance because of the plutonium and americium nuclides present in the area, the dusty nature of environmene th aboriginae th d tan l lifestyle, which produce higsa h degre man-madf eo e resuspension. intake individuaTh n dusf a e o y b t l will depend upo daile nth y activities undertake varioue th n e i sag groups. Activity profiles, and associated airborne dust loadings (in mg of dust per m of air), were assumed for the three age groups, based on data obtained in the study programs (Table 2)3 . The annual average airborne dust loadings obtained were then calculatioe useth n di inhalatiof no n dose modeo st l amoune th materiaf to l resuspended average Th . e dust loading sassessmene useth n di 3 tm werg m e1 childrer fo 3 infantsd m nvaluan e g youngehighee s fom Th th .r e5 wa r adultgroupe 1. rfo ag rd san s largely becaus time th ef eo spen dustn i t y play. A study designe asseso dt behavioue th s f actinideo r s ( d PuAman ) associated with inhaled dusts^-'indicated doses per unit intake239 appropriat241 e for various Maralinga dusts. These values wer eassessmente useth n di r otheFo . r nuclides, dose r unispe t activit f inhaleyo d material were calculated using current dosimetric and metabolic models^. Both effective and organ doses were considered s recognisewa t I . d that metabolic, healt d behaviouraan h l difference havy n ma a es influenc dosee th unir n spe o e t intake appropriat aboriginae th r efo l population; these would include factors suc respirators ha y tract infection higa d h san incidenc smokinf eo moutd gan h breathinge Th . effect of these factors was considered further in the uncertainty analysis (described below). For the ingestion pathway, use was made of measurements made for TAG by the Australian Nuclear Scienc Technologd an e y Organisation f activit^o localln yi y hunted animals (kangaroo, rabbit, witchetty grubs, lizard, goannan locai d l an )vegetatio n (quandong, mistletoe, solanum). Combining these measurements with measurements of activity levels in soil from the area in which the food was obtained gave transfer factors for the principle locally derived foods and the most important nuclides, which were then used in the assessment. Some of the transfer factors used in the assessment are shown in Table 3. The transfer factor approach could not be used to estimate doses from ingestio f kangarono o meat becaus large th ef eo distance s covere kangarooe th y db ; instead measured range f activitieso kangaron si o mea organd an t s wer ecalculationse useth n di . e consumptioTh n rate f foowated o s an d re assessmen useth n di t were obtained fron ma anthropological study^ majorite aboriginae Th l th f yo westerf o w l dieno n s footi d broughe th o t n ti local township largt ,bu e quantitie somf so e locally obtained food consumede sar . Kangaro rabbid oan t remain staple parts of the diet. For some foodstuffs the rates obtained in the anthropological study could be conservative, as they imply a high calorie intake. This may be due to an underestimate of wastage, particularl e cas th f meat.e intak eo n yi Th e rate se assessmen useth n di showe ar t n ni Table 4. One of the most significant potential sources of ingested activity is the soil or dust that is associated with food, as virtually all food - whether of local origin or purchased - has some dust contene tim th f consumptio o ee methody b th t o t f preparatioo e s e e du nnatur th th f d o e an n environment totaA . ls estimate soiwa ly intake regio da grad1 th r basef n mei npe o faecan do l samples of non-aboriginals during field trips. This must be regarded as a low estimate of soil ingestio aboriginaly nb s under camp conditions absence th n I bettef . eo r informatio soina l intakf eo bees 1ha 0 n y gramassumeda r assessmene groupse sth pe ag n di l al . r Thifo t consideres si a e b o dt conservative value, likely to be more pessimistic for the 3 month infant age group than for the other age groups. A study of the behaviour of ingested actinides in Maralinga dusts[3] indicated a fractional gut uptake (f^) value of l 10" for plutonium nuclides and this value was used in the assessment. A value 5 54 TABLE 2. AVERAGE ACTIVITY PROFILES FOR ADULTS, CHILDREN AND INFANTS 1 15 Adult (male) Hour r weekspe a Sleeping 79.5 Sitting, talking, playing cards 35 Eating 21 Gambling coin game 4.5 3 1 Hunting, driving 4 Cooking, butchering Vehicle repairs 7 4 At Watson (township) Child (typically 10 years old) Hours per week Sleeping 87.5 Playing 52.5 Eating 8 Hunting/digging 8 8 Travellin vehiclen gi s (rear) 4 At Watson (township) Infant (1 year old) Hours per week Sleeping 100 Playing, or being played with 44 Eating 8 Near parents hunting/digging 8 4 Travellin vehiclen gi s (rear) At Watson (township) 4 Totaa l hours equal 168. of 1 10" was considered more appropriate for americium nuclides in dusts, as these seem to be more transportabl4 e in the body[9l For nuclides of both elements, values of fj 10 times greater than these values were considered appropriat r infante firsefo th t n i syea f lifeo r . Thi s consistensi t wite hth general approach adopted by a Task Group of the Nuclear Energy Agency^101 and by a Task Group 3 of ICRp. For the ingestion of biologically incorporated material, an f x value of l 10" was applied for both plutonium and americium, and this was increased to 1 10~2 for infants in the first year of life. r nuclideFo f elemento s s other than plutoniu d americiumman , assumptions weree madth f o e appropriate fl value and these are discussed in more detail in Reference 5. Doses were then calculated using current dosimetric and metabolic models[6l Estimating doses from wounds posed particular problem assessmente th n si , because th f eo lacfrequence f th datk o n ao f woundyamoune o th d f soisan t o l tha subsequentls i t y retainee th n di wound. Data indicate a very high occurrence of cuts and scratches, with a high percentage being classifie dirtys a d . Also higa , h percentag f woundeo s become infected. Body sore knowe sar o nt be very common, particularly on children's scalps, and puncture wounds on the feet are frequent. To estimate doses from wounds, assumptions were made of the amount of dust or soil that would be initially deposited in sores or wounds each year. Data from a study designed to measure 55 TABL . ETRANSFE3 R FACTORS FROM SOI FOODO LT 151. Transfer factor*1 1 fresg" hq (ratiy B weighdr f 1 oo g" tq fooB o t d weight soil in top 25 mm) Foodstuff Pu Am Cs Rabbit 2 1(T3 2 1(T3 2 10"2 Turkey 2 10'3 2 IG'3 2 10'2 Lizard 2 lO'3 3 lO'3 1 10'2 Plants 8 1 "These are the transfer factors assumed in the assessment, based on data give Referencn i . e7 TABL . EANNUA4 L INTAKE ABORIGINALR SFO S ASSUME ASSESSMENTDN I 151. Intake rates' y"g 1( 1) Intake Adults Children Infants Infants material (20 y) (10 y) dy) months3 ( ) SoU 3 3.710 3.7 103 3 3.710 3.7 103 Kangaroo 2.0 106 1.3 10s 8.0 104 - Rabbit 1.3 104 3 8.610 5.2 103 - Turkey 3.5 103 2.3 103 1.4 103 - Lizard 3.4 102 2.3 102 2 1.410 - Plants 2 2.710 1.8 102 1.2 102 - Witchetty 1.6 103 1.1 103 6.4 102 - Water ( the clearance of plutonium and americium isotopes from subcutaneous deposits^ were then used to calculate resulting doses. Accoun alss owa t breakdowe taketh f no f activitno soin yi l with particle size, which varies from one contaminated area to another. External beta and gamma doses were calculated in the assessment using current external exposure models[12>13]. Uncertainty is inevitably introduced by modelling external doses, due to the uncertainty associated with factors such as variations in activity distribution with soil depth, the amount of dust present on the body surface and on clothing and the amount of shielding provided by clothing and hair. For this reason, direct measurements should be the primary indication of the significanc f theso e e pathways e assessmenth d an ,s intende wa t provido dt e onl indication ya f no relative th e significanc pathwae th f eo comparison yi otheo nt r route exposuref so comparisoA . f no modelling results with dose measurements made in the Maralinga area was undertaken and those were founconsistente b o dt , allowin uncertaintiee th r gfo calculatione th n si . 56 TABLE 5. EFFECTIVE DOSE EQUIVALENTS IN SEVERAL REGIONSf5J. Annual effective dose Principal Principal Zone (mSv) pathway nuclide Taranaki North plume, Am contour 3 month old infant 241 4 Soil ingestion 239Pu and inhalation 10 year old child " 5 Inhalation 239,"Pu Taranaki Northwest plume, 241Am 4 contour Inhalation 239Pu 10 year old child Kuli 238 contouUD r 10 year old child 25 Inhalation and 234U and external 238U gamma Kuli 238U A contour 10 year old child Inhalation and 234U and external 238'U gamma Area northeast of One Tree at 2.0 kBq m2 mont3 infand hol t Soil ingestion 239Pu and inhalation TM100 241Am A contour 10 year old child 5 Inhalation 23i9' Pu Emu, Tote 241, mII A mcontouA r 3 month old infant 15 Soil ingestion 239Pu 10 year old child 9 Inhalation 239Pu Emu, Totem I, 137Cs A contour 10 year old child 0.5 Inhalation and 239Pu ingestion Inner Taranaki 10 year old child 470 Inhalation 23>9' Pu Emu, centre of Totem II 0 8 mont3 infand hol t Sou ingestion 239Pu 10 year old child 31 Inhalation 239Pu 3. RESULT ASSESSMENE TH F SO T A number of regions with different degrees and types of contamination were selected and the effective dose equivalent from 1 year's continuous occupancy in each area was calculated. This regional breakdow f dosnimportans o ewa t becaus pattere eth f contaminationo aree th vers ai n i y non-uniform for the key radionuclides, as a result of the various different tests undertaken at different times (see Figure 3). The patterns of contamination still show distinct plume lines, indicating that there has been very little movement of activity since the explosions. There has also been little downward movemen f activit o tsoie th l n columnyi r mosFo . t nuclides majorite activitth e , th f yo y centimetresw fe p to e th . n i s i mose Th t significant contaminatio Maralinge areau th s resulte n nEm i sha d aan d froe mth various conventionally triggered explosion r 'minoso r trials' largese th ; t suc Taranake hth ares awa i 57 137 Cs >0.3 kBq rn-2 241 Am>1.4kB- qm 238 U>17kBqm-2 FIG. 3. Patterns of 137Cs, 2"1Am and 238U contamination at Maralinga. region at Maralinga, covering several hundred square kilometres. An aerial survey, undertaken as part e Maralingoth f a Rehabilitation Programme s defineha , d contour f surfaco s e activit botn yi e hth Maraling areasu thesd Em an , d e contouraan s were use determino dt regione eth s consideree th n di assessment. Representative contamination level varioun si s zones have been derive Australiae th y db n 1 Radiation Laboratory^ an14 d these levels were used in the assessment to define the contamination in each of the areas considered. resulte assessmene th Th f so t demonstrat verea y wide doserange th n esi expecte resulo dt t from continuous (100%) occupancy in the various regions considered. Examples of doses in several regions are shown in Table 5. Of these areas, the largest are those defined by the 241Am A contours at Taranaki. These plume line tene skilometref ar s o manlengtn n si i d yh an place s several kilometres 137 A m24l contour A u Em widee s enclosTh . aren squar ea w f onl ao fe ya e kilometresCs e th t bu , A contour enclose biggesa r are f 10-2ao TM10e 0 Th km contou. 02 A r enclose aren sa f severa ao l square kilometres. The Kuli A contour is only about 1 km 2 in area. The doses shown in Table 5 are for the most limiting age group which is usually children or infants. The annual effective dose equivalent ranges from 0.5 mSv to about 500 mSv from continual occupancy in the areas considered. As would be expected, the highest doses would result from occupancy in the small regions immediately surrounding the test sites, but continual occupancy is extremely unlikely in these small areas. At the limit of aerial detection of the Taranaki minor trial plumes - the largest contaminated area sdose- predictee sar considerable b o dt y lower annua(abouv mS 5 tl effective dose equivalent a t the outermost contour, from continual occupancy). In such areas, occupancy for a significant proportion of the year is more likely, although the nomadic lifestyle of the aboriginals must be remembered othen I . r regions, beyon limite dth detectiof so aeriae th f nlo survey whic bees hha n used to define the regions considered in the assessment, doses are predicted to be lower. 58 The main radionuclide contributing to dose is 239Pu, although isotopes of uranium are significant in certain areas. The pathways making the largest contribution to dose were shown to be inhalation of resuspended activity (for which the largest doses were predicted to be received by 10 yea childrend rol ) and somn i , e areas, ingestio f soi ninfantso y b l . Ingestio f foono d (excluding the contribution to dose from associated soil) and external dose pathways were not in general significant contributor doseo st . Another significant pathway is the intake of activity into wounds. The results of the assessment indicate tha t wouli t t contributno d e significantl e averagth o t y e averagn dosa o et e individual, but there is the possibility of significant doses being received from contamination of some wounds, should a very active particle enter the wound and be retained. The probability of such an event occurring is difficult to assess. The results of the dose assessment are one input to determining the extent of decontamination or access restriction areae r thith Fo s.n si reason usefua , l quantit relationshie th s yi p between unit levels of surface activity and of individual dose, and in addition to the regional results described above, result alse sar o presente Referencn di whice5 h indicat ratioe eth s between surface activitd yan dose. 4. DISCUSSION OF UNCERTAINTIES Considerable data have been provide Maralinge th y db a Rehabilitation Programm t therebu e remain a number of limitations which lead to uncertainties in the predicted doses. The dose estimates described above are considered to be best estimates of dose to typical members of an aboriginal community livinMaralinge areasu th thest n gi Em bu , d e aestimatean uncertaie sar n becaus laca f keo of knowledge about the input data used in the assessment. As an example of the effects of uncertainty predictee th n o d doses uncertaintn a , y calculatio performes n wa calculatioe th n do f dosno e froe mth inhalation pathway. This calculation is described in more detail in Reference 5. In the analysis, the uncertainty on the estimation of the annual effective dose equivalent to a 10 year old child with 100% occupancy within the North Taranaki plume contour was investigated. Only the dose from the inhalation of Pu was considered, as this is the major contributor. The uncertainty associated wit bese hth t estimat inpue f eacth eo f t239ho parameter s characterisedswa n i , e 10tterm th 90td hf an o sh percentile e distributione shapth th f d o e e an inpus Th .t parameter uncertainties were then propagated throug dose hth e calculation meany b , modifief so d Monte Carlo samplin gcalculatione methodrun0 th f 10 so d san . resulte Th chancn s te indicate n i ee tha effective on th dta e dose equivalent from inhalatiof no Norte th P n uhi Taranaki plum mors ei e than about five times greater tha bese nth t estimated an , 239a one in ten chance that the dose is more than about five times less than the best estimate. In this particular dose calculation uncertaintiee th , s associated wit 239e hPth u dos unir epe t inhaled intakd ean the average dust loading for a 10 year old were the most important contributors to the uncertainty on the dose estimate. Similar ranges on inhalation doses may be expected in other areas, and the predicted doses from other pathways will also have significant uncertainty associated with them. This uncertainty should be borne in mind when interpreting the results of the assessment. . 5 CONCLUSIONS broae Th d conclusions fro assessmene mth followss a e ar t . (1) Within the area defined by the aerial survey, the potential annual effective dose equivalents resulting from permanent occupancy range from a few mSv at the defined vern i yv S smal 5 plumesedgee 0. th l o f t area so p u , s immediately surroundin tese gth t sites. inhalatioe Th ) resuspendef n(2 o d activit mose th s yti significant exposure pathway, wite hth ingestio f soio ny infant b l s also potentially significant e wounTh . d pathwas i y potentiall f considerablyo e significanc probabilit w t witlo ebu h a f occurrenceyo . 59 (3) The main nuclide contributing to potential dose is Pu, although in small areas radionuclide f uraniuso alse mar o significant. 239 (4) The uncertainty associated with the dose estimates should be borne in mind. REFERENCES [I] STRADLING, G.N., STATHER, J.W., GRAY, S.A., MOODY, J.C., COLLIER, G.G., ELLENDER, M., PEARCE, M. Biokinetics of Plutonium-239 and Americium-241 in the Rat after the Pulmonary Deposition of Contaminated Dust from Soil Samples Obtained from the Former Nuclear Weapons Test Site at Maralinga: Implications for Human Exposure. Chilton, NRPB-M197 (1989). [2] HARRISON, J.D., HODGSON, A., HAINES, J.W., STATHER, J.W. Biokinetics of Plutonium-239 and Americium-241 in the Rat after Subcutaneous Deposition of Contaminated Particles from the Former Nuclear Weapons Test Site at Maralinga: Implications for Human Exposure. Chilton, NRPB-M198 (1989). ] [3 HARRISON, J.D., NAYLOR, G.P.L., STATHER, J.W. Gastrointestinal Absorptio f Plutoniuno m and Americiu Ratmn Guinea-pigi d an s s after Ingestio f Dustno s fro Formee mth r Nuclear Weapons Test Sit t Maralingaea : Implication Humar sfo n Exposure. Chilton, NRPB-M196 (1989). [4] POPPLEWELL, D.S. Maralinga Rehabilitation Project Study 5: Radiochemical Analysis. Chilton, NRPB-M199 (1989). ] [5 HAYWOOD, S.M., SMITH J.G. Assessmen radiologicae th f o t l impac f residuao t l radioactive contamination in the Maralinga and Emu areas. Chilton, NRPB-R237; London, HMSO (1990). [6] NATIONAL RADIOLOGICAL PROTECTION BOARD. Committed doses to selected organs and committed effective doses from intakes of radionuclides. Chilton, NRPB-GS7; London, HMSO (1987). [7] GILES, M.S., TWINING, J.R., WILLIAMS, A.R., JEFFREE, R.A., DOMEL, R.U. Final report to e Technicath l Assessment e MaralingGrouth r fo p a Rehabilitation Project, 2 Stud o N y (Radioecology). Lucas Heights, NSW., ANSTO (1990). [8] PALMER , BRADYdiee lifestyld K. ,Th an t . f aborigineM eo , Maralinge th n si a region, South Australia. Report prepared for Maralinga Tjarutja as part of the Maralinga Rehabilitation Studies, Research Programm (Anthropology)1 o eN ; Australian Institut Aboriginaf eo l Studies, (1988). [9] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION. The Metabolism of Pu and Related Elements. Oxford: Pergamon Press, ICRP Publicatio . Annn48 . ICRP, 16(2/3) (1986). [10] NUCLEAR ENERGY AGENCY. Committee on Radiation Protection and Public Health, NEA OECD, Gastrointestinal Absorption of Selected Radionuclides - A Report by an NEA Expert Group. Paris(1988)A NE , . [II] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION. Age-dependent Doses to Member Publie th f so c from Intak Radionuclidesf eo : Par . Oxford1 t : Pergamon Press, ICRP Publication 56. Ann. ICRP, 20 (2) (1989). [12] LINSLEY, G.S. al Derive t .e d emergency referenc ee introductioth level r fo s f o n countermeasures in the early to intermediate phases of emergencies involving the release of radioactive materials to atmosphere. Chilton, NRPB-DL10; London, HMSO, (1986). [13] COMMISSIO EUROPEAE TH F NO N COMMUNITIES. Methodolog evaluatinr yfo e radiologicagth l consequences of radioactive effluents released in normal operations. Luxembourg, CEC, V/3865/79, (1979). [14] WILLIAMS, G.A. (editor). Inhalation hazard assessment at Maralinga and Emu. Yallambie, Victoria; Australian Radiation Laboratory, ARL/TR087, (1989). [15] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION. Report of the Task Group on Reference Man. ICRP Publicatio (1975)3 n2 . Next page(s) left blank 0 6 ASSESSMENTS IN THE VICINITY OF NUCLEAR WEAPONS PRODUCTION FACILITIES ENVIRONMENTAL MODELING FOR THE HANFOKD ENVIRONMENTAL DOSE RECONSTRUCTION PROJECT B.A. NAPIER, D.B. SHIPLER, W.T. FARRIS, J.C. SIMPSON, C.M. HEEB, J.V. RAMSDELL, Jr., T.A. IKENBERRY, W.H. WALTERS, M.D. FRESHLEY Battelle Pacific Northwest Laboratories, Richland, Washington, United State f Americso a Abstract Hanfore Th d Environmental Dose Reconstruction (HEDR) Projec s establishewa t 198n di 7o t evaluat release eth f radioactiveo e material from Hanfordose th ed receivedan individualy db e th n si surrounding loca regionad lan l population projece Th . stochastif o t t usese sa c source-term, transport, environmental-accumulation d dosan ,e models thae intimatelar t y linked, allowing transfef o r information in such a way that spatial, temporal, and distributional characteristics of the data are preserved projece Th . t released initial estimate 199n si r representativ0fo e individuals largese Th . t doses resulting from Hanford operations occurred in the mid-1940s. The most important radionuclide was iodine-131 releasee atmosphereth e moso t dth td significanan , t exposure pathwas wa y consumption of milk produced by cows on pasture downwind of Hanford. Detailed doses for specific individuals wil e calculateb l d withi e nexnth t year. Uncertainty analyse beine ar s g conducter dfo essentiall l dosal y e predictions d sensitivitan , y analyse e beinar s g performe l modelsal n o d . Ambitious plan laivalidatiosare dfor majothe nrof models HEDThe . R Projec cooperatinis t g with the Hanford Thyroid Disease Study, which is performing a pilot study to determine if sufficient information can be gathered to complete a full scale dose-response epidemiological investigation. 1. INTRODUCTION In 1943, the United States Army Corps of Engineers selected an area of nearly 1000 km , in semi arid southeastern Washington State, for producing plutonium and other nuclear materials supporting the United States' effort e Manhatta(knowth s a n n Project . ThiII n Worls i ) r areaWa d , callee th d Hanford Site, was used for uranium fuel preparation, nuclear reactor operations, fuel reprocessing, plutonium recovery, and waste management operations. Nine nuclear e reactorproductioth r fo sf plutoniuo n m were eventually constructed. Reactor operations bega 1944n ni lase ;th t production coln i dreactot standbpu s rwa 1987n i y . Additional support facilities were constructe e 1940 th d 1950s an n si d ; som f theso e e facilities continuo t e operate. Hanford Site operations develope changed defense an dth s a de needs of the United States and the understanding of nuclear energy changed. As knowledge of the harmful effects of radiation increased, concerns were raised about the impact of Hanford operations on the surrounding population. Furthermore e continuin,th g declassificatio f historicao n l Hanford documents mad publie eth c more possibilite awarth f eo f healto y h effect residento st s of the area surrounding the Hanford Site. The Hanford Environmental Dose Reconstruction (HEDR) Project was established in 1987 to evaluate the release radioactivf o e material from dosHanfore th ed receive an dsurroundine th y b d g loca d regionaan l l population. Battelle, Pacific Northwest Laboratoriee sar conductin e HEDth gR Project unde directioe th r n independena f o n t Technical Steering Panel (TSP) composed of knowledgeable individuals who are not associated witU.Se th h . Departmen f Energyto . Initial phases of the HEDR Project demonstrated the feasibility of dose estimation [1,2]. However, analysis of the initial dose estimates, based on available datd modelsan a , revealed several weaknesse e approacth n i s h used r modelinfo g [3,4] e resul Th s .bee ha ta substantian l advancemene th n i t 63 state of the art for environmental dosimetry. The project now uses a set of source-term, transport, environmental-accumulâtion, and dose models that are intimately linked, allowing transfer of information in such a way that spatial, temporal, and distributional characteristics of the data are preserved. These models are • source-term models that generate estimates of hourly radionuclide monthld releasan r ai ye e releasrateth o st e rate surfaco st e water • transport models that trace radionuclide movemen depositiod an t n ove atmospherin a r c domai rivea f 120,00d o n ran m domaik m 0k 0 45 n long • environmental pathway models that trace movementh e f o t radionuclides through the soil and vegetation to foodstuffs, and in aquatic biota, and from them through food distribution channels • dose models that allow individuals to move through the environment, with dose calculations base thein do r lifestyl d individuaean l food- consumption habits. 2. SOURCE TERMS HEDe Th R Project relie estimaten o s f radionuclidso ed releasean r ai o st water to start the calculation of radiation dose to individuals. 2.1. Atmospheric Source Terms Scoping studies indicated that the primary radionuclide of interest from the atmospheric pathwa s iodine-13wa y 1 [5,6]. Calculatin e releasth g f o e iodine-131 require e integratioth s f muco n h inpu d manan ty intermediate calculations e projecTh . t relie n originao d l records generated durine th g time period under study. These were supplemented with other reportd an s summaries. Wherever possible, multiple sources were use arrivo dt valuest ea . A knowledg e physicath f o e l processes, monitoring techniques usedd an , completenes f recordo s s allowe e uncertaintth d e estimateb o t yr eacfo dh valuee projecTh . t generated estimate e iodine-13th f o s 1 releasen a n o s hourly basis. e creatioTh f iodine-13o n e reactorth n i s 1calculate swa d from reactor power records. The production of this isotope is directly related to power level, whic s recorde i he reacto th n i dr daily logse calculationTh . s were based on the daily power records and took into account the day-by-day changes in the amount of iodine-131 present in the fuel. Whee irradiateth n d fue s dischargei l d froe reactorsth m , iodine-131 decays wit 8-dan a h y half-life decae th ; y time, know coolings a n s inferrewa , d from records showing when fuel was discharged from the reactor and when it may have entered the dissolving process. Dissolvin e separation th e fue n th gi l s planta two-ste s swa p process. First, the aluminum cladding was dissolved with a caustic solution of sodium hydroxide; the e fues dissolveth nwa l d with nitric acide iodine-13Th . s wa 1 released during this dissolving ste wels a ps durin a l g subsequent processing steps. Detailed plant records on the dissolution of batches of fuel were correlated with reactor discharge record o determinst e amounth e f iodineo t - 131 present during dissolving e fractioTh . f iodino n e released directlo t y the stack, as well as during subsequent processing, was taken into account. The estimated amount of iodine-131 released to the atmosphere between f 194 o summarizes i 7d en e th monty d194b d Tabln an i 4h [7]I e estimatee .Th d total releas r thifo e s perio s 2.5xl0i d q (685,001B 6 0 Ci). Because th f o e wealt originaf ho l documentatio redundand nan t sources, ther higa s ehi degree of confidence that the actual values fall within the computed ranges. The source term release model (STRM) [7] provides the HEDR computational system with estimates of the hourly releases to the atmosphere. Uncertainties 64 TABLE I. MEAN ESTIMATED MONTHLY IODINE-131 RELEASES FROM HANFORD SEPARATIONS PLANTS, 1944-1947 (Ci/Month) Month 1944 1945 1946 1947 January 1221 11753 6158 February 2126 7399 3835 March 2082 7952 5617 April 28746 11680 4853 May 74482 13820 3989 June 46466 4609 1652 July 47036 5558 2297 August 72090 8642 1249 September 88682 7670 1206 October 92066 4819 472 November 37752 5525 261 December 2139 62340 7398 261 TOTAL 2139555089 96284 31848 e actuaith n l amounts release e addressear d d f througMonto e eus h Carlo simulations, each of which represents an alternative release history that is consistent with existing knowledge. Together, these alternative release histories represen e rang th tf release o e s that could have occurrede On . hundred separate realizations of the complete hourly release history will be prepared with this source term code. 2.2. Surface-Water Source Terms The Columbia River, which passes through the Hanford Site, served as the source of cooling water for the original plutonium production reactors. The river water was drawn directly through the reactor core and returned to the river afte a rshor t retention time. Radionuclide compositio d activitan n y level in the discharged cooling water varied considerably as a result of several factors [8], includin numbee th g reactorf ro theid san r power levels, seasonal changee parenth n w i trives ra element e r th wate n i s r (i.e.e th , elements activate s thea d y passed throug e reactoth h r core), chemicals used in water treatment, corrosion rates of piping and fuel element cladding, occasional purging of radioactive film from reactor components, and the length f timo e effluen s retainetwa basinn i d s before discharge. Another factos rwa radionuclide releases from episodic fuel element ruptures e widTh e. variation thesn i s e factors, together wite hydrographith h e variablee th f o s Columbi am construction Riveda d an r , produce complea d x combinatio f riveo n r wate d reactoan r r effluent durin e year th gf reacto o s r operation. Scoping studies have indicated tha radionuclidee tth greatesf so t interes HEDe th R o tt Project are zinc-65, phosphorus-32, sodium-24, neptunium-239, and arsenic-76 [9], Chromium-51 emissions, althoug f significanco t no h o doset ee alsar , o being reconstructed to serve in the model-validation process. A figure fro repora m y Hald Jermab t an l n [10], reproduce s Figura d , 1 e e yearth sr fo 1955 through 1959 indicate e magnitud th se tota th lf o e non- volatile beta release rates. Releases of up to 10 Bq/d (30,000 Ci/d) were routin r lonfo e g periods. 65 1955 1959 FIGURE 1. Monthly Average Total Beta Activity Release Rates into the Columbia River for the Years 1955 through 1959 (Ci/day) The source term river release model (STRRM) [7] provides the HEDR computational system with estimates of the monthly releases to the Columbia River. Uncertainties in the actual amounts released are addressed through use f Monto e Carlo simulations, eac f whico h h represent n alternativsa e release history that is consistent with existing knowledge. Together, these alternative release histories represen range tth releasef eo s that could have occurred e hundreOn . d separate realization complete th f o s e monthly release history will be prepared with this source term code. 2.3. Ground-Water Source Terms Inventorie f solid-wasto s e disposa d liquid-wastan l e dischargee th o t s ground are summarized in Hanford Site documents provided by the various Hanford Site operating contractors [11] e amoun.Th detaif to l reported about the numbers of specific radionuclides in the waste stream and when discharges occurred increased with timee inventorieTh . f radionuclideo s s disposen i d the greatest amounts in the ground at the Hanford Site are listed in Table II. e inventorieTh f o radionuclides e decayear s o t 198d 9e (listeth s a d inventories present during 1989, taking into account inventory reductions because of radioactive decav). The total volume of solid waste in the ground is approximately 625,000 m . Inventories of radionuclides in liquid wastes discharge groundo dt , decaye 1989o dt alse ,ar o------liste------Tabl-n i d. II e e totaTh - l volum f o liquide s dischargee Hanfore th grounth t a o dt d Sits i e approximately 1,680,000,000 m3. 66 TABL . II E TOTAL RADIONUCLIDE INVENTORIES DISPOSE E O GROUNT TH D T A D HANFORD SITE AS OF 1989 (Ci) Radionuclide From Solid Wastes From Liquid Wastes Tritium 266,800 423,300 Strontium-90 2,030,600 40,500 Cesium-137 2,541,200 195,000 Technetium-99 960 Iodine-129 9 Carbon-14 6,300 220 Uranium 560 200 Americium-241 1,100 3,800 Plutonium 27,500 13,600 Total 4,875,100 678,000 . ENVIRONMENTA3 L TRANSPORT MODELING environmentae Th l transport model linkee sar d directl outpute th o t yf so the source term model. Each is designed to continue the stochastic simulation begun at the source term level. 3.1. Atmospheric Transport e modeTh l develope e HEDth R r atmospherifo d c transport calculations i s called the Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) [12]. The RATCHET computer code is a Lagrangian-trajectory, Gaussian-puff dispersion model. Sequences of Gaussian puffs are used to represent plumes released from ground-leve d elevatean l d sources. Time- integrated air concentrations and surface depositions are calculated at nodes modee ith n l domai y summinb n contributione th g s from puff thes sa y move past the nodes. Movement, diffusion depositiod an , f materia o ne puff th e n ar si l controlled by wind, stability, precipitation, and mixing-layer depth fields that vary in both time and space. The model domain, illustrated in Figure 2, extends about 490 km (306 mi) from north to south, and 395 km (246 mi) from east to west. Geographically, the area covered extends from central Oregon State to northern Washington State e Cascad d froe cresth an , th m f o te Mountain e easterth o t sn bordef o r northern Idaho State e areaTh . , which includes essentiall regioe th f no l al y known as the Columbia Basin, is bounded on all sides by mountains or other highlands. Atmospheric transport, diffusion, and deposition calculations are based on observed meteorological data. Date availablar a r aboufo e5 reportin2 t g station r neamodeo e n rth i s l domain. RATCHET prepare se entir fieldth r efo s domai y interpolatinb n e observationth g s froe stationth m a gridde o t s d coordinate system. The model is capable of treating four types of material--noble gases, nonreactive gases, participates, and reactive gases. Iodine is treated as a special typ materialf partitionee eo b y ma t ;i d into reactive gas, nonreactive gas, and particulate components. RATCHET treats uncertainty in three ways: through modification of point inputs, through direct input of distributions, and through functional relationships with these inputs. Uncertainties in wind direction, wind speed, 67 FIGURE 2. Location of the Hanford Site and the Atmospheric Transport Modeling Domain (Hanfor dars di k area near center, stippled area Native sar e American Indian reservations) atmospheric stability class, Monin-Obukov length, precipitation rate, and mixing-layer height are treated explicitly within the code. Uncertainties in surface-roughness length, source terms, and partitioning among physical and chemical forms are treated explicitly in the model input. The explicit treatment of uncertainty in the variables and parameters listed above leads o implicit t treatmen f uncertainto t n othei y r model relationship y usinb s g these variables and parameters. 3.2. Columbia River Transport modee Th l user analysifo d transporf so radionuclidef to Columbie th n i s a River is called CHARIMA [13]. The CHARIMA code is a commercial surface-water hydrolog d sedimenan y t transport model t useI .s daily river dischargd an e water surface elevation data to predict dilution and travel time to downstream locations. The model is basically one-dimensional, but the HEDR Project is adding empirical correction r laterasfo l dispersio somt a n e locations neae rth reactor outfalls. The river source term release mode uses i lo prepar t d 0 realization10 e s of the monthly Hanford Site releases. The project is currently using the CHARIMA modedeterministia n i l c sense (ther variatioo n s transpore ei th n i n t parameters), and preparing 100 realizations of the downstream concentrations f radionuclideo waten i s r accountin e uncertaintgth onl r e sourcfo yth n i ye term. 3.3. Terrestrial Environmental Transport The environmental accumulation model provides, and is called, Dynamic Estimates of Concentrations and Accumulated Radionuclides in Terrestrial 68 AtmospheriI c Deposition Data Parameter Value Selection Biomass Soid an l Animal Feeding / Animal Commercial Vegetation Feed Transport Products Foods V / , J y da 1 = t A .WS.WV -•vwwvwww W,™W,v> DATA STORAGE 1 Animal Products ——— Environmental Concentrations ———— Commercial Foods Individual Dose Model FIGUR . Logica3 E l Structur e DESCARTEth f o e S Environmental Accumulatiod an n Distribution Models Environments (DESCARTES) [14]. The DESCARTES model tracks and calculates the accumulation and transfer of radionuclides from initial atmospheric deposition and interception through various soil, vegetation d animaan , l products compartments. This model containf fouo rt se couple sa d linear differential equations that give mode s dynamith e it l c nature, generating daily soid an l vegetation concentrations. Other portions of the model use these daily concentration dat equilibrium-typd aan e equation o calculatst e time-dependent radionuclide concentration animan i s l products. Environmental concentration data needesubsequene th y b d t individual dose mode e storear l largn i d e binary files. Figure 3 illustrates the entire environmental accumulation model. e modeTh l functioe visualizeb y a seriema n s f a o sequentiads l operations. The biomass submodel generates daily biomass values for each plant type modeled. These value e the ar s e soind vegetatio th an use l n i d n submode o determint l e daileth y concentration f radionuclideo s n soid i s an l vegetation. Results are calculated for every grid node, providing the concentration in vegetables, grains, and fruits directly consumed by people and in plants (grass, alfalfa, silage, grain) used for animal feed. Animal- feed concentration e thear s n use o determint d e concentration n animai s l products (beef, venison, poultry, eggs, milk), also on a grid basis. Finally, the radionuclide concentrations in commercially distributed vegetables and mile calculatedar k . The commercial food distribution systems were reconstructed from records and reports available froe U.Sth m . Burea f Censuso u e Washingtoth , n State Dairy Herd Improvement Association, the Washington State Dairy Products Commission, and other governmental and dairy industry organizations [15]. They provide some informatio amoune th n milf to no k produce d sol eacn an di d h county, the locations of individual dairies and distributors, and dairy industry practices in the 1940s. Additional information was obtained through interviews with dairymen, farmers, ranchers agriculturad ,an l extension agents [15]. These key contacts provided information that was then supplemented and 69 organize y locab d l experts int a detaileo d source/distribution networkA . similar undertaking was needed for the distribution system for fresh leafy vegetables [16]. Like the preceding source term and transport models, the DESCARTES code create 0 realizations10 environmentae th f so l condition eact sa h nod r eacefo h time step. Value f radionuclido s e concentration e store ar sy r lateb fo de us r the individual dose model. 3.4. Aquatic Pathway Modeling Extensive environmental monitorin s performegwa n aquatido c organismn i s e Columbith a River durin e latteth g r year f Hanforo s d Site plutonium- production operations. Many thousands of river water and fish samples were collected. HEDR Project staff are cataloging this information and using it to develop seasonal- and species-dependent bioaccumulation factors. The bioaccumulation factor beine sar g develope threr dfo e type residenf so t fresh- water fish; omnivores, first-order predators d second-ordean , r predators. The e alsyar o being develope r duck fo othed san r game e arebirdth an i stha t might have been contaminated via the Columbia River pathway. The Columbia River supports major stocks of anadromous salmon. These fish return to the river to spawn. However, the limited monitoring data indicate that they do not eat while returning upstream, and so their radionuclide concentration representative sar portione Pacifie th f th e o f so c Ocean where they lived prior to returning to the Columbia River. Annual estimate f concentrationso f radionuclideso e beinar s g assembled wild e an ,b l user estimatinfo d l locationg al dose r fo s s alon e rive th r gpeopl fo r o wh e caught and ate salmon. It is interesting to note that, along the 350 miles of Columbia River downstrea e Hanforth f o md Site, onle threth y e large towns immediately adjacent to the Site used Columbia River water for domestic drinking water [11]. Drinking potentiae waterth d r municipa,an fo l l water treatment plants o removt e radionuclides s alsi , o being considered. 4. INDIVIDUAL DOSE MODELING The primary thrust of the HEDR modeling efforts is the preparation of a complete system from which individuals may receive estimates of their dose from past Hanford Site operations. To date, the project has not prepared dose r specififo s c individuals. However e projecth , d releasdi t e initial estimate n 199i s r representativ0fo e individuals [17]. Detailed doser fo s specific individuals will be calculated within the next year. e individuaIth n l dose models e huma,th n recepto introduces ri d inte oth calculation modee Calculatior Th .fo l Individuaf no l Doses from Environmental Radionuclides (CIDER) calculates dosr foufo e r pathways: submersion i n contaminated air, inhalation of contaminated air, irradiation from contaminated surfaces, and ingestion of contaminated farm products and vegetation. The CIDER code treats people differently as they age, including the prenata d nursinan l g periods e ColumbiTh . a River Dose (CRD) model calculates doswatevia e r immersion, drinking consumptioand , residenof n t fish, game birds, salmon d oceaan , n shellfish. 4.1 Initial Reference Individual Results e largesTh t doses resulting from Hanford operations occurre mide th -n i d 1940s [17] e mos.Th t important radionuclid s iodine-13wa e 1 releasee th o t d atmosphere. The most significant exposure pathway was consumption of milk produced by cows on pasture downwind of Hanford. The iodine-131 releases were essentially routin continuoud ean s durin e firsth g t perio f sito d e operation. 70 Infants and young children who drank milk from cows that ate fresh pasture are likel o havt y e receive e highesth d t doses. Dose r individualfo s n thii s s group ranged from about 0.15 Gy (15 rad) to 6.5 Gy (650 rad) to the thyroid. The uncertainty on the initial dose estimates is fairly large: the 95th percentile reportereference th r fo d e locatioy G whict 5 a nmediae 6. th hs nwa is nearly 23 Gy (2300 rad). Recent wor gives kha bettea n r estimat overale th f eo l patter f iodineno - 131 deposition n estimat e A depositione exten.th th f f o to e , scaleo t d thyroid referencdosa o et e infant drinking milk fro domestia m fresn o w hcco pasture, is given in Figure 4 [18]. This figure indicates that thyroid doses 5 rad( o infant)t y i nmG o dranexces0 wh 5 s kf o smil k from back-yard cows could have extended to nearly the Washington/Canada border. Radiation doses from release Columbie th o st a River range from abou0 5 t /LtSv (5 mrem) to 1.8 mSv (180 mrem) for the period 1964-1966, which is near the perio highesf o d t release majoe Th . r radionuclides frorivee mth r pathwae yar zinc-65, phosphorus-32, arsenic-76, and sodium-24. The range of doses is largely dependen e amounth f n fresho o tt , resident fish consumed. Drinking water contributes onl smala y l dose, althoug e residentth h nearlf o l f o sal y the local downstream communities received one. 4.2. Epi demiological Activities The HEDR Project is cooperating with a separately funded project, the Hanford Thyroid Disease Study (HTDS), being performed by the Fred Hutchinson Cancer Research Center in Seattle, Washington [19]. The HTDS is performing a pilot stud o determint y f sufficieni e t informatio e gathereb n ca o nt d complete a full-scale dose-response epidemiological investigation. The HTDS staff have prepare n extensiva d e questionnaire detailing life activitied an s health history, targeting individuals who were born in the Hanford vicinity in the mid-1940s. Portions of the survey results are being forwarded to the HEDR Projec r dosfo t e analysis. Results froe HTDth mS pilot t no stud e ar y expected until 1994. . UNCERTAINT5 D SENSITIVITAN Y Y ANALYSES The HEDR Project has included the concepts of uncertainty and sensitivity analysis from its inception. A definitive uncertainty and sensitivity analysis plarecentls ha n y been completed [20]. 5.1. Approach for Uncertainty Analysis Uncertainty analyses are being conducted for essentially all dose predictions. These analyse mose s th leat o t appropriatd e interpretatiof o n the predicted doses because they provide a measure of the precision of the estimate e MontTh .e Carlo technique wile use b o lestimatt d l dosal e e uncertainties e applie,b becausn ca d t i consistentle ye HEDacrosth Rl al s models, becaus coss i t i eeffectiv d un-biasedan e d becaus an easils ,i t i ey applie o suct d h complex models. e samplinTh g f Latistratego e non Hypercubs i y e samplin r thosfo g e model parameters thae infrequentlar t y sampled r thosFo .e parameters thae ar t frequently sampled r instancfo , daila n o ey basis, simple random samplins i g used. Results will generally be presented as a boxplot. One boxplot figure provide e predicte th e rang th sf o e d doses e subjectivth , e confidence intervals estimated ,an centrae th f so l value (the mea median)d an n . Thee yar easily understoo d e interpretedb an d l results n al ca e use r b d fo dn an , ca , obtained directly from the output of the Monte Carlo technique. 71 1945 Total Doses overage iodine deposition I Less I tharod1 thyroino 0. t s d rod 0 thyroio st 50 10 - 0d I 0.1 - 10 rods to thyroid 500 - 1000 rods to thyroid F I 10 - 5.0 rods to thyroid A/ State tes ilii 5.0 - 10.0 rods to thyroid / A County foes fl.O - 50.0 rods to thyroid A/ Study area 50.0 - 100 rods to thyroid A/ River FIGUR . Spatia4 E l Distributio f Potentiao n l 1945 Thyroid Dos o Referenct e e Infants Drinking Milk from Cows Fed Extensively on Fresh Pasture 72 5.2. Approac Sensitivitr fo h y Analysis Sensitivity analyse e beinar s g performe l HEDal R n o computationad l models. Sensitivity analyses provide a method for 1) effectively interpreting the dose estimates and their uncertainty and 2) prioritizing individual parameters according to the uncertainty of the predicted dose. The results of the sensitivity analyses will allow development of the most cost-effective strategy for evaluating the uncertainties in the model parameters. Sensitivity analyses are being performed using measures from multiple regression (coefficien f o partiat l determinatio e standardizeth d an n d regression coefficient) multiple Th . e regression beine sar g performe botn do h originathe l paramete rran valuethe k transformeand s d values. Multiple regression is cost-effective because the software is readily available and the approact labono s ri h intensive e appropriatenesTh . e multiplth f o s e regression approac s measurei h d wite coefficienth h f determinationo t . Demonstration application f sensitivito s y analyses using multiple regression have been complete r DESCARTEfo d f e HEDentiro th d CIDERRt r an Sse e Fo . models, the sensitivity analyses are being done hierarchically, starting with the dose results and working backward through the various pathway, transport, and source term models. 6. PLANS FOR HEDR MODEL VALIDATION Complete validatio saie b consiso t dn ca n fouf to r steps: peer revief wo e modelth s thee a beinsar y g developed, verificatio e computeth f o n r implementations as the codes are developed, verification of the assumptions and parameters going into the codes, and comparisons of the results to actual measurements e HEDTh .R models have been subjecte numerouo dt s reviewe th y sb d otheran P s TS (e.g. RATCHEe P revie,th TS f o wT code, extensive discussions with the TSP during the development of the surface-water modeling effort). Internal independent testing of the various codes is underway to assure correct implementation of the models. The assumptions and parameters have been independently publishe d continuan d o undergt e o scrutiny [21]. Plans have been developed for comparisons of predicted results with historical measurements [22]. 6.1. HEDR Validation Philosophy The HEDR models are used to describe the potential for radiation dose to individuals living in a large spatial area, over long periods of time, by a numbe f potentiallo r y important exposure pathways t woulI e .highlb d y desirabl o validatt e e variouth e s model t pointa s s throughou e spatiath t l domain arean ,i f higso h deposition, light deposition d sporadi,an minimar co l deposition. It would also be desirable to observe the variation in time of radionuclide concentrations in each of the pathways at these various locations. A high level of coverage of the various space/time/pathway combinations used in the primary dose calculations would lead to the most rigorously defensible validation. However, data are not available to support such an ambitious validation program. Contemporaneous data do not address all the necessary pathways, over space or over time, needed to provide a complete validation. The data sets that have been selected for validation were chosen provido t bese th et example f coveragso domaie th timen f i eno spacen i , d ,an for as many pathways as possible. We believe that the tests defined provide e project aneede th reasonabl th f o d sthar ,an fo t t sufficiense e t coverage e spatialth f o , temporal d pathwaan , y variable e s achievei th s r fo d demonstratio e adequac e HEDth th f R o n f o approacy d implementationan h . Evaluation of the results of the validation tests is a necessary component of the validation. The general HEDR philosophy is to compare the 73 predicted e surrogatvalueth f f doseo o s r eo , measurement closes o dost t e available (e.g., concentration f radioiodino s n sagebrush)i e , wite th h measurements. The purpose is to understand the differences between the calculate e dmeasurements th dose d an s . Thus e statisticath , l methods that wil e usee b aimel ar dt illustratina d g these difference o thas e cause th t s can be understood and recommendations for improvements in the models can be made. 6.2. Data Sets Available for Validation e modelin Th releasee th atmosphere e Columbi f th th o g o o st t d a an eRive r is being performed independently. Data sets have been identifie r eacfo d h pathway. 6.2.1. Atmospheric Release Data Sets Hanford historical monitoring date availablar a n publishei e d [23d ]an draft form for the period 1945 through 1951. Hanford monitoring of that period focussed on vegetation (usually sagebrush). Recently developed modifications account for biases in the measurements that were contemporaneously unknown. These data are essentially all that are available for these time periods of high interest to the HEDR Project. The data are uneven in coverage of space (most monitored locations are either on or close to the Hanford Site) and in coverage of time (the monitoring, with a few notable exceptions, was not routinely performed at repeated locations). Thus, while ther ovee ear r 3500 samples reporteyeae th r r 1946dfo , sequential sets are available for only a few locations. Richland has a complete history for each month of 1946, consisting of a total of about 550 values; Pasco and Kennewick combined have a complete history for 1946 consisting of a total of about 645 values; and Benton City, Washington, has a complete history for 1946 consisting of a total of about 200 values. e earliesth f o te Ion setn f dato s a available t appeari , s froe th m spatial distribution of the samples taken on April 13, 1946, that three vehicles were sent out with instructions to sample vegetation at intervals on preselected routes e vehiclOn . e madnorthweste th looa e o t p . Another went nort thed an hn east e thirTh . d went sout thed an hn west alon Oregoe th g n side e Columbith f o a River Gorge. Concentration measurement e availablar s e from approximatel 3 vegetatio8 y n samples from throughou e regionth t . One of the singular events in the history of Hanford Site operations was the Green Run experiment that began on December 2, 1949. This experiment resulted in the atmospheric release of over 6000 Ci of iodine-131. The experimen developmene s parth twa f to monitorinf to g method r intelligencsfo e efforts regarding the emerging Soviet nuclear program. About 618 samples taken during the month of December 1949 are available from throughout the HEDR atmospheric dispersion domain. An event similar to the 1949 Green Run occurred at the PUREX facility in 1963, although by accident and with a much smaller release. An acute release f iodino e fro60-e th m m stac t PUREa k X occurred from Septembe , 19635 o t ,2 r as a result of inadvertently charging short-cooled fuel elements into the dissolver. Plant operations were shut e abnormadow th s soo a ns a n l release detecteds wa d step,an s were taken immediatel retaio yt e iodin mucth s a nf o he as possible within the plant. Laboratory analyses of stack effluent samples were made, and the routine program of environmental monitoring was augmented with additional sampling. Measurements of wind velocity and temperature were made routinely at the site meteorology tower. No significant rainfall occurre e HEDth Rn i ddomai n durin e periodth g o protectivN . e measures were taken following the release. There were no significant atmospheric nuclear tests in the several months prior to the accident. Several hundred environmental measurement e availablear s . 74 Thousand f thyroio s d radioactivity measurements were mad n Hanforo e d workers employed in the nuclear fuel reprocessing facilities during the years 1944 through 1946. At that time, these measurements were used as a qualitative measurement of radioactive iodine in worker thyroid glands. Called "thyroid checks," the measurements were performed in the general plant environment using portable radiation detection instruments. The results of thyroie th d checks were compared wit screenina h g leve r tolerablfo l e thyroid exposur o t ensure e that t receivworkerno d di es excessive iodine-131 exposures. Nearly 7900 measurements between June 1945 and August 1946 are availabl d documentedan e . More recent Hanford Site data on atmospheric dispersion include a data set of coupled monthly source terms and environmental measurements of atmospheric krypton-85. These data were collecte networa n o d k established with the restart of the PUREX facility in late 1983 and through its operations until 1988. 6.2.2. Columbia River Release Data Sets Modeling of transport of radionuclides released from Hanford production reactor e Columbith y b s a Rive a mode f ro l involve e thaus te th accuratels y reproduces the flow characteristics of the river, by which the radionuclides are diluted and in which they undergo radiological decay as they travel down stream. Inputs to the model are the water discharge of the Columbia River upstrea f Hanforo m d dischargean d e downstreath f o s m tributaries. Outputs depend on the quantity of water and on the length of time it takes to travel e next froe placth on m.o t e Measured water surface elevation d actuaan s l water discharge hydrographs from the U.S. Army Corps of Engineers at the various Columbia River gauging stations (e.g., Hanford Site locations, John Day, The Dalles, and other locations) are available from the Army Corps of Engineers and from Hanford Site sources. Numerous measurements were taken of radionuclide concentrations in Columbia River water during the 1960s. Monthly composite samples are available for phosphorus-32, zinc-65, and chromium-51 at several locations downstrea Hanfore th f o md release points. Concentrations of five radionuclides in Columbia River fish are being estimated using bioaccumulation factors. Data for the years 1960 through 1966 are being used to develop the bioaccumulation factors. The data for 1967 are being reserve r validatiofo d n use .A simila r procedur s beini e g user fo d Pacific Ocean salmon and Mil lapa Bay oysters. Hanford worker sTri-Citiee liveth n i d s ared weraan e routinely exposed o contaminantt n Columbii s a River water through drinkin d recreationaan g l activities. Tens of thousands of whole-body radioactivity measurements were made on Hanford workers employed throughout the Hanford operations during the years 1959 through the present. These measurements were used to estimate exposure to radioactive substances in the workplace. Almost all of the whole- body counts taken during the period of reactor operation indicate the presence f zinc-65o , sodium-24, cesium-137 (from fallout) d naturallan , y occurring potassium-40. The HEDR Project has acquired all of the routine, worker- related whole-body counts from 1959 through 1971. In all, the database consists of over 40,000 records. . SUMMAR7 Y The Hanford Environmental Dose Reconstruction Project has prepared a state-of-the-art set of environmental models for estimating historical doses o reat l individuals e techniqueTh . s develope r applicatiofo d f uncertainto n y analysi e model th e newo ar t sse model .Th e approachinar s g operational readines e beginninar d an so underg t g o extensive validation efforts. 75 REFERENCES [I] PACIFIC NORTHWEST LABORATORY, Air Pathway Report: Phase I of the Hanford Environmental Dose Reconstruction Project, PNL-7412 HEDR, Pacific Northwest Laboratory, Rich!and, Washington, USA (1991) ] PACIFI[2 C NORTHWEST LABORATORY, Columbia River Pathway Report: Phasf o I e the Hanford Environmental Dose Reconstruction Project, PNL-7411 HEDR, Pacific Northwest Laboratory, Rich!and, Washington, USA (1991) ] SIMPSON[3 , J.C., Effecte Los f th Correlatioo s f o s n Structur n Phaso e I e Dose Estimates, PNL-7638 HEDR, Pacific Northwest Laboratory, Richland, Washington A (1991US , ) ] SIMPSON[4 , J.C., Dose Estimate Variabilit yr ModeAi Cause ly b d Uncertainties, PNL-7737 HEDR, Pacific Northwest Laboratory, Richland, Washington A (1991US , ) ] NAPIER[5 , B.A., Selectio f Dominano n t Radionuclidee th r Phasf o fo s I e Hanford Environmental Dose Reconstruction Project, PNL-7231 HEDR, Pacific Northwest Laboratory, Richland, Washington A (1991US , ) [6] NAPIER, B.A., Determination of Radionuclides and Pathways Contributing to Dose in 1945, BN-SA-3674 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [7] HEEB, C.M., Iodine-131 Releases From the Hanford Site, 1944 through 1947, PNWD-2033 HEDR Vols. 1-2., Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [8] WALTERS, W.H., DIRKES, R.L., NAPIER, B.A., Literature and Data Review for the Surface-Water Pathway: Columbia Rive d Adjacenan r t Coastal Areas, PNWD- 2034 HEDR, Battelle, Pacific Northwest Laboratories, Richland, WashingtonA ,US (1992) ] NAPIER[9 , B.A., Determinatio y RadionuclideKe f o n d Parameteran s s Related to Dose From the Columbia River Pathway, BN-SA-3768 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1993) [10] HALL, R.B., JERMAN, P.C., Reactor Effluent Water Disposal, HW-63653, General Electric Company, Hanford Atomic Products Operation, Richland, Washington, USA (1960) [II] FRESHLEY, M.D., THORNE, P.D., Ground-Water Contributio Doso nt e from Past Hanford Operations, PNWD-1974 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [12] RAMSDELL, J.V., JR., BURK, K.W., Regional Atmospheric Transport Codr eFo Hanford Emission Tracking (RATCHET), PNL-8003 HEDR, Pacific Northwest Laboratory, Richland, Washington A (1992US , ) [13] HOLLY, F.M., JR., YANG, J.C., SCHWARZ , SCHAEFERP. , , HSUJ. , , S.H., EINHELLIG , CHARIMAR. , : Numerical Simulatio f Unsteado n y Wate d Sedimenan r t Movemen Multipln i t y Connected Network f Mobile-Beo s d Channels, IIHR Report No. 343, Iowa Institute of Hydraulic Research, Iowa State University, Iowa City, Iowa, USA (1990) 76 [14] IKENBERRY, T.A., BURNETT, R.A., NAPIER, B.A., REITZ, N.A., SHIPLER, D.B., Integrated Codes for Estimating Environmental Accumulation and Individual Dose from Past Hanford Atmospheric Releases, PNL-7993 HEDR, Pacific Northwest Laboratory, Richland, Washington A (1992US , ) [15] BECK, D.M., DARWIN, R.F., ERICKSON, A.R., ECKERT, R.L., Milw FeeCo kd Intak d Milan e k Productio d Distributioan n n Estimate r Phasfo s, PHI-7227I e HEDR, Pacific Northwest Laboratory, Richland, Washington, USA (1992) [16] MARSH, T.L., ANDERSON, D.M., FARRIS, W.T., IKENBERRY, T.A., NAPIER, B.A., WILFERT, G.L., Commercial Productio d Distributioan n f Freso n h Fruitd an s Vegetables: A Scoping Study on the Importance of Produce Pathways to Dose, PNWD-2022 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [17] TECHNICAL STEERING PANEL, Initial Hanford Radiation Dose Estimates, Departmen f Ecologyo t , Olympia, Washington A (1990US , ) [18] NAPIER, B.A., SNYDER, S.F., Determination of the Feasibility of Reducing e Spatiath l HEDe Domaith R f o Dosn e Code, BN-SA-3678 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [19] HANFORD THYROID DISEASE STUDY, Newsletter, Fred Hutchinson Cancer Research Center, Seattle, Washington A (1992,US ) [20] SIMPSON, U.C., RAMSDELL, J.V., JR., Uncertaint Sensitivitd yan y Analyses Plan, PNWD-2124 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington (1993A US , ) [21] SNYDER, S.F., FARRIS, W.T., NAPIER, B.A., IKENBERRY, T.I., GILBERT, R.O., Parameter e sEnvironmentath Usen i d l Pathways (DESCARTESd an ) Radiological Dose (CIDER) Modules of the Hanford Environmental Dose Reconstruction Integrated Codes (HEDRIC) for the Air Pathway, PNWD-2023 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington, USA (1992) [22] NAPIER, B.A., GILBERT, R.O., SIMPSON, J.C., RAMSDELL, J.V. THIEDE; JR , , M.E., WALTERS, W.H., HEDR Model Validation Plan, PNWD-2156 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington A (1993,US ) [23] DENHAM, D.H., DIRKES, R.L., HANF, R.W., POSTON, T.M., THIEDE, M.E., WOODRUFF, R.K., Phase I Summaries of Radionuclide Concentration Data for Vegetation, River Water, Drinking Water, and Fish, PNWD-2145 HEDR, Battelle, Pacific Northwest Laboratories, Richland, Washington A (1993,US ) Next page(s) left blank ' ' DOSE RECONSTRUCTION STUDIE SELECTET SA D NUCLEAR WEAPONS FACILITIES IN THE USA C.W. MILLER, J.M. SMITH, L.S. DENHAM Divisio f Environmentano l Hazard Healtd san h Effects, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United State f Americso a Abstract The Centers for Disease Control and Prevention (CDC) is involved in dose reconstructions at six nuclear weapons facilities in the United States. CDC is directly responsible for the conduct of four of these studies, and it provides technical support for the other two. We expect that the two most recently initiated studies will be conducted in five phases: retrieval and assessment of data, initial source term development and pathway analysis, screening dos exposurd ean e calculations, developmen methodf o t r sfo assessing environmental dose calculatiod an , f environmentano l dose exposuresd san n I . additio thesno t e technical phase studiese th f so , significant public involvementn a wil e b l integral part of the dose reconstruction process. In this paper, we review the status of currene th t dose reconstruction discusd san s CDC's approac doso ht e reconstruction. 1. INTRODUCTION Researchers who study community exposure to contaminants from nuclear facilities have difficulty establishing causal relations between contamination exposure and elevations in cancer rates. Often missing from such studies are comprehensive exposure and dose estimates for the study subjects. If a thorough quantitative analysis of all doses receive exposey db d persons dosa , e reconstruction performes i , conjunction di n with epidemiologic studies, the statistical power of the resulting analysis will be significantly enhanced [1]. e SecretaryTh , U.S. Departmen f Energo t ye Secretary(DOE)th d an , , U.S. Department of Health and Human Services (HHS), signed a Memorandum of Understanding which took effect December 24, 1992. This memorandum sets forth the guidelines for managemene th n i S conducd HH DO d an t Ean analytif o t c epidemiologic researc HHSy hb . The Secretary, HHS, delegated responsibility for implementing that portion of the memorandum concerning studie f personso s vicinitlivine th gn i energy-relatef yo d facilities e Nationath o t l Cente r Environmentafo r l Health, Center r Diseasfo s e Controd an l Prevention (CDC). CDC's program includes dose reconstruction activities at DOE nuclear weapons facilities. CDC has dose reconstructions under way at four DOE sites. CDC is also providing technical supporo statetw o st t thainvolvee ar t n dosi d e reconstructions. Dose reconstructions are under way at other sites in the United States (e.g., dose assessment studies in the former Pacific Island nuclear test sites and assessments of the exposure to 1-131 tha Americae th t n people received fro Nevade mth a atmospheric bomb tests)t bu , these do not directly involve CDC staff. Any dose reconstruction for a nuclear facility must be technically sound, and it must include significant public participation. Neither of these aspects of a study can be emphasized at the expense of the other if the study is to be credible to the scientific communitgenerae th o t ld publicy an purpos e Th . f thieo s pape revieo t s i rcurrene wth t status f CDC'o s dose reconstruction activitie o discust d an ss CDC's approaco t h conducting dose reconstruction studies begun after September 1992. 79 DosC e CD Reconstruction • s TechnicaC oCD l Support Figur . Locatione1 f U.Sso . Departmen Energf o t y nuclear weapons facilitie whict sa e hth Center r Diseassfo e Contro Preventiod an l involvens i dosdn i e reconstruction activities 2. CURRENT DOSE RECONSTRUCTIONS INVOLVING CDC As stated above, CDC is currently involved in dose reconstruction activities at six locations in the United States (Figure 1 ). These projects encompass a variety of nuclear weapons related-facilities, and they are in different stages of development. 2.1. Studies directed by CDC 2.1.1. Hanf ore/ Environmental Dose Reconstruction Project Hanford, Washington productioe th sit a r es fo wa ,f weapons-grad no e plutonium beginnin Decembegn i r 1944 Hanfore Th . d Environmental Dose Reconstruction Project was initiated in 1988 by DOE, and transferred to CDC under the memorandum between HHS and DOE. The work is performed by a contractor under the direction of an independent Technical Steering Panel. Individual doses wil calculatee b l numbea r dfo f o r radionuclides (Table I), but the primary contribution to offsite exposures appears to be cause y chemicab d l reprocessing facilities releasing 1-131 inte atmosphereth o . Researchers currently estimat f 1-13o ) Ci 1 e 10x wer 5 tha (6.q 5 110 8B e 2. t9 x released from these facilities between Decembe , 1944 Decembe26 d r an , , 19431 r 7 [3]e .Th Hanford methodology will als usee ob o calculatdt e dose r studfo s y subjecte th n i s Congressionally-mandated Hanford Thyroid Disease Study. The current contract for developing and implementing a methodology for calculating radiation doses expires in May Hanfore 1994th t bu ,d project will continue beyond that date. 2.1.2. Fernald Dosfmetry Reconstruction Project The Feed Materials Production Center located near Fernald, Ohio, was a large-scale, integrated facility that produced uranium metal products used as feed materials in DOE defense programs e requese U.Sth th t f .A o tCongress . initiateC CD , a ddos e reconstruction at Fernald. A contract for this work was awarded in 1989, and the estimates of primary radiological impacts from the site should be completed by December 1993. The principal concerns at Fernald are uranium released as a result of the production 80 TABLE I. RADIONUCLIDES CONSIDERED IN DOSE ESTIMATING CALCULATIONS FOR THE HANFORD ENVIRONMENTAL DOSE RECONSTRUCTION PROJECT [2] AIR PATHWAY WATER PATHWAY 1-131 P-32 Ru-103 Zn-65 Ru-106 As-76 Co-60 Np-239 Ce- 144 Na-24 Te-132 Mn-56 Pu-239 Cu-64 1-129 Cr-51 Sr-90 1-131 Cs-137 Te-132 Ar-41 Sr-90 Kr-85 H-3 Cs-137 processes and radon released from silos containing waste material from the extraction processin f uraniugo m ore. Current median estimate f releaseso s from Fernal r 1960dfo - 1962 are 7.3 x 104kg U to the atmosphere; 2.3 x 10* kg U to surface waters; 5.9x 10U Bq (1.6 x 104 Ci) Rn-222 to the atmosphere; and 2.9 x 1014 Bq (7.9 x 103 Ci) Rn-222 decay products to the atmosphere [41. In addition to conducting the dose reconstruction, CDC has initiated a study of the feasibility of using the results from the dose reconstruction to perform an epidemiological study around the Fernald facility. 2.1.3. Savannah River Site Dose Reconstruction The primary activit Savannae th f yo h River Site located near Aiken, South Carolina, was the production of tritium for nuclear weapons. At the request of DOE, CDC has initiate dosda e reconstructio t Savannana h Rive accordancn i r e wit terme e hth th f so memorandum between HHS and DOE. A 2-year contract to perform Phase I of this dose reconstructio awardes nwa Septemben di r 1992. (Phas describes i eI subsection di n 3.1.1.) CDC's contractor expect examinso t least ea t 25,000 boxe f recordso s associated with the Savannah River Site. 2.1.4. Idaho National Engineering Laboratory Dose Reconstruction The Idaho National Engineering Laboratory, located in southeastern Idaho, is a reactor-testing and research site rather than a nuclear weapons production facility. At one tim anotherr eo , more tha differen0 n5 t nuclear reactors have been operationa thit a l s site since 1951. It is the site of the SL-1 incident that in 1961 resulted in three fatalities. At requese Idahe th th f oo t Departmen initiates f Healtho ha t C dosda CD , e reconstruction t Idaha o National Engineering Laboratory unde memorandue rth m CDCbetweed an S . nHH A 2-year contract to perform Phase I of this dose reconstruction was awarded in Septembef Aprilo d , en 1993 e rth f 1992, o CDC' s A . s contracto identifies ha r d 2200 document site eth t thaspertinena e ar doste th eo t reconstructio n project. 81 TABLE II. MATERIALS OF CONCERN SELECTED FOR DETAILED STUDY DURING PHASE ROCKE TH F YO I FLATS HEALTH STUDIES RADIOACTIVE MATERIALS NON-RADIOACTIVE MATERIALS Americium-241 Beryllium Plutonium-238, 2392 24 , , 240 1 ,24 Carbon tetrachloride Thorium-232 Chloroform Tritium Méthylène chloride Uranium-233, 234, 2358 ,23 Tetrachloroethylene 1,1,1 -Trichloroethane Trichloroethylene 2.2. Studies directed by States DOE has entered into agreements with some individual states to investigate potential health impacts of DOE facilities located in those states. CDC is providing technical support to two states that have initiated dose reconstruction activities under their agreements with DOE. 2.2.1. Rocky Flats Health Studies Rocke Th y Flats Plant near Denver, Colorado, produced component r nucleasfo r weapons. Under its agreement with DOE, Colorado initiated health studies at Rocky Flats in 1990. Phas f theso eI e studie toxicologicaa s i l revie dosd wan e reconstructionA . contrac r Phasinitiates fo t wa schedule es I i 199dt n i i completed e 0b an o dfalt e lth n di of 1993. During Phase I, 12 radionuclides and 7 nonradioactive materials have been selected for detailed study (Table II). Phase II of the Rocky Flats Health Study is a toxicity assessment and risk characterization. This phase started in October 1992, and it should be complete latdn i e 1995 Phase Th . I woreI k will provid independenn ea t reviee th f wo Phas eI results t wilI . l also includ detaileea d assessmen f availablo t e environmental sampling datrecommendationd aan r additionafo s l monitorin measurementd an g o t s identify offsite contamination. 2.2.2. Oak Ridge Health Studies Oak Ridge, Tennessee site f threth e o s i , e majoinstallationsE DO r gaseoua ) 1 ( : s diffusion plant for the enrichment of uranium, (2) a facility for fabricating and assembling nuclear weapons components, and (3) a multipurpose research laboratory. Tennessee entered into an agreement with DOE for health studies at Oak Ridge in 1991. Phase I of these studie feasibilita s i y study contractoA . r began wor Phasn ko Aprin i eI l 1992d ,an this phase shoul completee db d1993n i contractoe .Th gatherins i r characterizind gan g information regarding past or present releases of chemicals or radioactive substances from the site f sufficienI . t informatio founs ni d during Phas shoo t eI w that releases froe mth Oak Ridge facilities probably occurred, a second phase will be initiated to determine the associated doses receive individualy db Ridgk s Oa vicinite e livin e siteth th g n i f .yo 82 . CDC'3 S APPROAC DOSO HT E RECONSTRUCTION e Obasith nf experienco s e gained fro s involvemenmit n multipli t e dose reconstruction studies, CDC has developed an approach for performing dose reconstruction studies thaimplementins i t i t studiee th Savanna e r th gfo s t a unde y hwa r IdahRivee th t ora SitNationad ean l Engineering Laboratory. Technical phase publid san c involvemen bote ar th integral part f thiso s approach. Also technicae th , l phases being t identica no e phase th e ar o t ls C thae beinCD usear ty gb d use n othei d r dose reconstructions. 3.1. Technical phases Five technical phases are tentatively planned for the Idaho and Savannah River dose reconstructions. Each phase will build on the results of the preceding phase. However, some phase begiy sma n befor precedine eth g phas bees eha n completed resulte th d san , of one phase may lead investigators to return to a prior phase for additional information. 3.1.1. Phase I: Retrieval assessmentand dataof In this phase wile w ,l loo r informatiofo k botn no h radionuclid chemicad ean l releases tha necessars i t orden yi perforo t r mdosa e reconstructio operatine th r nfo g life nucleae oth f r facility. This information include seffluen) 1 dat n environmentad ao an t l monitoring methods and results, 2) the processes used at the facility that involved radionuclides or chemicals, 3) the location of contaminant release points, and 4} the analysis procedures used by the facility. Wherever possible, we will use primary sources of data, such as logbooks and laboratory analysis sheets, in addition to summary reports. Source f informatioso n will most likely include onsit offsitd ean e repositories wels a ,s a l interviews with worker communitd san y residents. Som thesf eo e materials will probably require declassification before they can be released to the public and used for dose reconstruction. The primary product of Phase I will be a data base identifying each item found abstractn a , describin materiae gth briefn i l indication a , f wherno itee eth ms i located, and an initial evaluation of the usefulness of that item for dose reconstruction purposes. 3.1.2. Phase II: Initial source term development and pathway analysis During Phase II of the dose reconstruction, the data located during Phase I will be use reconstrucdo t historicae tth l source terms (i.e. pollutante ,th s release facility)e th y db . Radionuclides and other pollutants that the facility released into the environment will be identifie theid dan r chemica physicad an l l form wil reconstructee lb functioa s da timf no e and location. This reconstruction will very likely involve modeling the processes at the nuclear facility as well as evaluating effluent monitoring data. Environmental monitoring usee b validato ddaty t ama e reconstructee somth f eo d source terms resulte Th . s will include an analysis of the uncertainty associated with the various source term estimates. Phase II will also include a preliminary analysis of the potential pathways by which persons living near the site could have been exposed to the released materials. No standard, accepted methods exis r performinfo t f theso l gal e tasks wile W l. develop method r modelinsfo g specific processe snucleae useth n di r facilitier fo d san using environmental monitoring dat validatao t e source term estimates additionn I . t no f ,i enough informatio availablens i , site-specific research requirestudiee b y ordesdma n i o rt answer questions relate specifido t c locations, suc questions ha s abou efficience th t f yo the monitoring equipment for a particular process or the bias associated with a particular historical environmental sampling procedure. 83 3.1.3 Phase III: Screening dose exposureand calculations A large number of contaminants will probably be identified during Phases I and II. Durin dosge th Phas ef o reconstruction I eII resulte th wil e e f Phasso w , us l perforo t I eI m screening dose and exposure calculations. Using simple, well-documented environmental transpor dosimetrd an t y models [5] wile ,w l identify contaminant exposurd san e pathways wit lowese hth t potentia environmentar fo l l exposur f personeo s nearby; assumptions will be deliberately designed to overpredict exposure. This process will not entirely eliminate contaminants or pathways of exposure from further consideration, but it will assist in priority setting. We will repeat the screening calculations using more realistic modeling assumptions in order to identify materials and pathways with the highest potential for causing human exposure [6]. A critical aspect of all these calculations will be the values chosen for parameters used in the models and how likely these parameter values are to result in overpredictions or underpredictions of actual doses and exposures. 3.1.4 Phase IV: Development of methods for assessing environmental doses Usin resulte gth s from Phase III wilPhas,e n i w l concentratV eI developinn eo g site-specific model parameterd san value thosr sfo e contaminan exposurd an t e pathways foun havo d t highes e eth t potentia r causinfo l g har mpeopleo t methode Th . s developed will includ quantitativea e uncertainty analysi l calculateal r sfo d results. Model parameted san r values publishe scientifie th dn i c literatur oftee ear n designed o estimatt e exposurth e e receive y hypotheticab d l persons e goa[7] f dosTh o l. e reconstruction, however, is to estimate, to the extent possible, actual exposures and doses receive reay db l persons r goa selectinn Ou i l. appropriate gth t ea modele us r sfo a given sit eseleco t wil e simplese b l th t t models capabl f accomplishineo tase gth k [8]. The interaction among screening calculations, model uncertainty, and model development wil consideree b l thin di s process [6]. 3.1.5. Phase CalculationsV: environmentalof doses exposuresand Finallye precedinth e resultl th al , f o gs phases wilusee b l o perfordt e mth environmental dose calculation r eacsfo h nuclear facility. Extensive informatio locan no l demographics and lifestyles since the facility was built will be incorporated into the assessments. These results will be used to help CDC determine the feasibility of future epidemiologic studies at the site. We will work with epidemiologist risd ksan analysis specialist determino st e eth e radiologicaforth f mo l dose calculatio r chemicano l exposure estimate tha s mosi t t appropriate for epidemiologic purposes. Such factors as the age and gender distribution exposee oth f d population exposee ,th d person' t firsa e t exposuresag duratioe ,th e th f no person's exposure lengte exposee th th d f ho an , d person' importane b sy lifema t factors to ascertain for health studies at some sites and for some contaminants. 3.2. Public Involvement publie essentian a Th s ci l partne dosn i r e reconstruction studies. This research originated in part because of public concern about health effects from exposure to radiation and other potential hazards from the production of nuclear weapons. Opportunitie r publisfo c comment wil incorporatee b l d intdesige o th conduc d nl an al f o t studies accompliso T . workins hi thisC CD ,g closely with numerous interest groups, member publice th stat d f so an ,e health departments. Depending on the needs of each study, CDC or its contractors will use various basic method r involvinsfo publice gth . These include producing publications sucs ha newsletters and fact sheets; conducting public workshops and meetings with comment and discussion periods; installing toll-free telephone numbers; organizin meetingc ho d ga s 84 with individuals or small groups; devising a media relations plan that includes press releases; and making study documents accessible to the public. The most basic aspect of CDC's public involvement program, however, is the open and honest attitude with which CDC staff and their contractors perform a study. We will make plans, results, and all document sstudiee useth n i ds availabl wile publice w lth d discuso et an , s them candidly with anyone. Facility documents studie e useth availabl e dn i sar anyoneo t o ewh wishes to examine them. In addition, CDC is working with numerous public interest groups, members of the public, and state health departments to establish site-specific community panels that would relay community concern CDCo st . . CONCLUSION4 S CDC has begun reconstructing contaminant exposures and doses of persons living near somnucleaE eDO r weapons facilities usine ar phasega e W . d approac perforo ht m the most recent of these studies. The manner in which each phase will be implemented, anresearce dth h neede supporo dt t that implementation, wil tailore e specifie b l th o dt c site under study. However, of overriding importance for all of these studies is the need for a combination of significant public involvement and a thorough scientific review. REFERENCES [1] SHLEIEN, B., RUTTENBER, A.J., SAGE, M., Epidemiologie studies of cancer in populations near nuclear facilities. Health Phys. 61 6 (1991) 699-713. [2] SHIPLER, D.B., NAPIER, B.A., HEDR Modeling Approach, Rep. PNWD-1983 HEDR, Battelle Pacific Northwest Laboratories, Richland, Washington (1992). [3] HEEB,C.M., Iodine-131 Releases From the Hanf ord Site, 1944 Through 1947, Volume 1 - Text, Rep. PNWD-2033 HEDR Vol. 2, Battelle Pacific Northwest Laboratories, Richland, Washington (1993). [4] VOILLEQUE, P.G., MEYER, K.R., SCHMIDT, D.W., KILLOUGH, G.G., MOORE, R.E., ICHIMURA, V.l., ROPE, S.K., SHLEIEN, B., TILL, J.E., The Fernald Dosimetry Reconstruction Project , Radionuclid,3 Taskd an s2 e Source Term Uncertaintied san s- 1960-1962, Draft Interim Report for Comment, RAC No. CDC-2, Radiological Assessments Corporation, Neeses, South Carolina (1991). ] NATIONA[5 L COUNCI RADIATION LO N PROTECTIO MEASUREMENTSD NAN , Screening Technique r Determininsfo g Compliance with Environmental Standards, Releasef so Radionuclide Atmospheree th o st , NCRP Commentar , Bethesda3 . yNo , Maryland (1989). 16] HUFFMAN, F.O., "An Introduction to Uncertainty Analysis for Environmental Dose and Risk Assessment," Continuing Education Lecture Twenty-Sixte ,Th h Midyear Topical Meeting of the Health Physics Society, Coeur d'Alêne, Idaho (1993). [7] U.S. NUCLEAR REGULATORY COMMISSION, Calculation of Annual Doses to Man from Routine Release f Reactoso r Effluent Purpose th r s fo f Evaluatin eo g Compliance with 10 CFR Part 50, Appendix I, Regulatory Guide 1.109, Washington, DC (1977). [8] NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS, Radiological Assessment: Predicting the Transport, Bioaccumulation, and Uptake by f Radionuclideo n Ma s Release Environmente th o dt , NCRP , BethesdaRepor76 . No t , Maryland (1984). Next page(s) left blank 85 POST-CHERNOBYL DOSE ASSESSMENT STUDIES THYROID DOSE RECONSTRUCTION IN THE AFTERMAT CHERNOBYE TH F HO L RELEASE I.A. LIKHTAREV, G.M. GUL'KO, I.A. KAIRO, B.G. SOBOLEV Ukraine Scientific Centr r Radiatioefo n Medicine, Kiev, Ukraine Abstract Various retrospective method r reconstructinfo s g thyroid dose e e discussedth ar s l al f O . available possibilities the methods selected as most reliable are those based on direct measurements of iodine-131 activit thyroie th . yin d gland, air, water, milothed kan r foodstuffs absence th n I f . eo direct measurements, radionuclide ratio methods seem promising (ratio of 131I to IWI, WC and 137Cs release varioun i th d n i ean s media) does a , s "geographical extrapolation". Method modeld san e sar described whereb bees ha n t y i possibl reconstruco et thyroie th t d doses receive inhabitante th y db s of several district f Ukrainso e afte accidene th r t Chernobyla t , with dose estimates being made both in the areas covered by instrumental measurements and in areas where ml activity measurements were t conductedno examplen a s .A spatiae th , l distributio thyroie th f no d dose groupe s receiveag o stw y db amon inhabitante gth Chernigoe th f o s v regio showns ni . INTRODUCTION Irradiation of the thyroid gland is one of the most serious problems in accidental exposures at nuclear facilities. This conclusion is based on the following considerations: The potentially high levels of thyroid exposure among the population resulting from the large amounts of activity present in a nuclear reactor in the form of iodine radionuclides and the physical, chemica biologicad an l l propertie iodinef so ; The possibility of identifying medical after effects of irradiation given by the relatively low incidenc spontaneouf eo s thyroid cance conjunction i r n with high collective doses (especially among the cohort of children). Any retrospective dose reconstruction must be based on data obtained up to several years after the accident and will be impracticable unless there is a functional or stochastic link between these data andosese dth . All models and procedures for reconstructing doses must satisfy two conditions. First, they must demonstrat mechanisea interrelationshir mo least p(a t approximately) betwee date nth e a th use d dan dose otherwiss— e blac e (casth f keo box use)e b thedn onlyca r interpolatioyfo limitea n i d range of values. Second, they must allo onlf w (i principle n yi range )th uncertaintief eo determinede b o st . Dependin thei n modelresulte subdivided e go b th en r l n al ,sca d typesinto otw : those which estimate mean dose r grouppopulatioe sfo th f o s territoryy nb r occupationo e ag , thosd an , e which allow these mean group levels of thyroid exposure to be personalized (individualized). This divisio modele th f no s intclasseo otw rathes si r arbitrary, sinc secone eth d typ modef eo l can be considered a development of the first. 1. ANALYSIS OF RETROSPECTIVE DOSE RECONSTRUCTION METHODS 1.1. General description of methods What data may be used to reconstruct thyroid doses in the aftermath of an accident? This is a most important question. Table 1 shows the potential of various methods of carrying out such dose 89 TABL POSSIBL. E1 E METHOD RETROSPECTIVR SFO E THYROID DOSE RECONSTRUCTION Methods Potential Problems Moderate Moderate Radionuclide ratios: )37Cs fallout Moderate Moderate 137 Chuman i s n body Low Low ""Sr fallout Low High ^'Pu fallout Low High a9l fallout High High thyroin i l n9 d gland High High "C in trees High High Direct measurement f 131o sI activit thyroin yi d gland High Moderate (May-June 1986) Direct measurements of 131I activity in thyroid gland, High Moderate supplemente survey db y results estimates. The methods are graded according to their feasibility (from the authors' point of view) on three-stea p scale: high, moderat thi n lowr I eo s . context, "feasibility" mai o refertw n o factorsst e th : possibility of constructing a model (system), and the level of technical and fundamental difficulties encountere processe th n di . The most accurate and reliable estimates are obtained from direct measurements oI f 131 activity in the thyroid gland, particularly when use is made of data relating to "real" behaviour patterns. A further possibility is to use radionuclide ratios or different kinds of interpolation and extrapolation (based on geographical aspects, age groups, or behaviour patterns). 1.2. U9l as a tracer of ml fallout Where radionuclide ratio concernede sar mose th , t promising method, despite major technical problems and rather high costs, is the use oI f 129 [1]. Figures 1-4 illustrate an analysis of this type. An ecological model for the 129I to 131I transition consists of three sub-models. In the first, data densite th n soif o yo l contamination particulaa witt a Ih 129 r locatio usee nar reconstruco dt timee th t - integrated 131I concentration in a cubic metre of air, as shown in Fig. 1. From literatur resultsr eou datd ,aan give Tabln ni t appeari , e2 disregarn sca thae w e t dth valuesI focontenr t in the upper soil layer resulting from global fallout. As shown in Table 2, the 129I soil contaminatio129 n in the areas around the Chernobyl nuclear power plant are at least 1-2 orders of magnitude higher tha soutn ni h Ukraine USSRe e Chernobyprioth A th , o t US r, e Japath l r no accident. Oothee nth r hand, some sources indicate thaiodine th t absorbes ei ver a rate t w da ylo , giving every reason to believe that all the I present in the upper soil layer originated from Chernobyl. 129 131 transitioe Th n fro time-integratee mth d concentratioI thao t seemf It o 129 f depeno o st r ai n di exclusivel falloue th n yo t scenario, which therefore needexaminee b o st greaten di r detail. All possible fallout scenarios must be compatible with the known characteristics of the Chernobyl accident [8], which are as follows: 90 GD Areal ground depositio 129f no I m-2q (B ) Il II II Global level of 1291 II Migration in soil soin i l li Time-integrated air concentration of 129I V -deposition velocity grouno frot r d"mai m d( 1 ) (Bq d m-3) II Modee th f o l radioiodine fallout dynamics II O,131 Time-integrated air concentration of m-3d q ) (B FIG. 1. Submodel for transfer from 129I areal ground deposition to time-integrated 1I concentrations in air. The reactor was shut down on 26 April; The first release on 26 April was the largest; l releaseAl s fro reactoe mth r crater cease May6 y db ; Fallout continue days0 1 r ;dfo m 8 ThI tlo e129 activity ratio in the nuclear fuel at the moment of the first release was 5.5 x 10". Figure 2 illustrates the effect of differing fallout scenarios on the transition from the integrated 131 contexe specifie th Ith n , i f concentratio thato o t cIf to fallou 129 f o r tai characteristicn i s mentioned above. In scenario 1 almost all Ith activite129 y fell on the locality in the first two days and only a small part seven days later (on the tenth day). In scenario 2, after intensive fallout on the first day and a seven-day interruption, the 129I fallout on days nine and ten was only slightly less intensive than immediately after the accident. In the second sub-model (Fig. 3) the time-integrated 131I activity in air is used for the purpose of predictin e time-integrateth g d concentratio f thio n s iodine isotop r kilogrape e m weighf o t vegetables. e thirTh d sub-model describeI transpors131 t into cow's milresula s kf a consumptio o t f no contaminated feed and the integrated intake of I activity from cow's milk and green leafy vegetables (Fig. 4). It is assumed in this model that tw o131 types of feed were contaminated: pasture grass and freshl t haycu y . Both these type f feeassumee o s ar d havo dt e been constantly available durine gth period under examination (end of April, May and June). 91 Mode Q"r lfo 9 Corresponding1 modeQ" r lfo 00 00 e-i - 129 e-i 131 tJ-l 0 1J-1 0 where f(i+l) - relative function of intake rate of 1 8 K0 = (j'JWo = 5.5 -10- 129i of 129J into the areal air Q129 131 V * 129 " * - 4o I/(T+l)Je-xlE9tdt oo 1. 131 .131 /• 2 .131 2 gl \ j ^ " ~ in X129 , 2 2 Kl " E Ä 1+" ^— "+ •VO^E'6 V 3 10 J i 2. 1 13 \ *13 1 /^ Q . -X^'-e E 1+76 r+TC r 131 3 ~ Q3 » ,129 , i 131 -A,, 1+— + — Ko-A-E'r 6 E V 4 + 4 J 1 if FIG. 2. The influence of possible models of I fallout (contrast scenarios) on corresponding models 129 of 131I fallout. e abovTh e mode uses wa ld with recently obtaine densitde datth n 129f ao y o I contaminatiof no settlemento soie tw t th la northern si n Ukraine wit(Tabld reference an h th ) e2 e parameter values cited in Table 3. A comparison of the early results of our calculations with the doses obtained from instrumental measurements of I activity in the thyroid gland is given in Table 4. The model calculation results given in Table 4, 131represent total doses to the thyroid gland from inhalation and ingestion, assuming contrastino tw g 129I fallout scenarios employin(Figd an , scenario, .4 2) d g an age-dependens1 t model parameter values for four-year-old children and adults. 1.3.14C as a tracer of 131I fallout In the authors' opinion 14C is a promising tracer for 131I fallout, for the following reasons. Since a considerable portio carboe th releases f no n wa gaseoun di s form t shouli , d correlate well wit 131ha I gaseous aerosol cloud in its distribution kinematics and its passage into the biomass metabolic cycle. factn I 129d long-livee , Iar an onl C y14 d marker iodine th f o se component fro Chernobye mth l accident. These markers hav advantagn a e e over 137Cs, ^Sr, plutoniu transplutoniue th d man m elements, in that they are isotopes of important environmental bioelements. A unique property of 14C thas i becomet i t s tre e fixeth e n rindi g correspondin accidente yeae th f th o r o g t goo A . d illustration of this claim is given in Fig. 5 [21]. 92 Time-integrated air Time-integrated airTime-integrated air (B qm-3d ) Fresh forage, Inhalation leafy vegetable = C - time-integreted sex-specifid an e ag Vfrfi - c concentratio edibln i e ventilation rate (m^ d"l) f j|. 3 - portio plankg'^pef nq o (B t^I q rB j n a o m via direct deposition onto plant surface) V- deposition velocity (Bq m"2 d"* per Bq 131lm-3ofair) R-fractio f aeriano l deposition retainen do plant Y -plant yield ( kg m'2) t - time of exposure of crop to aiborne contaminatio) n(d - effectiv | X e removal constan planr tfo t surface - fractioT depositef no d nuclide translocateo dt e edible part f planso t FIG. 3. Submodel for approximation of accumulation of atmospheric 131I by vegetation via direct deposition onto plant surfaces. maie Th n problem which arise usinn si thyroir gfo 14C d dose reconstructio develoo t w ho p s ni method quantitative th r sfo e interpretatio peakconcentratioe e th th f n nsi o thif no s isotop tree th e n ei rings of 1986 as reference values characterizing the 131I fallout intensity in different areas. In the simplest linear case, the authors would expect that a coefficient could be found for the relationship betwee 131e nIth concentratio May-Junn i r ai n e i peae amplitudth C 14 th n 198 ki e d th 6an f o e corresponding annual ring mora n I .e complex variant this transition coul made db e usin chaie gth n 14 tren Ci e ring - 129,soi n i I l 1986 n quits i todai r t I ai e. y - 131 likeln i I y that this last syster mfo mapping 131I fallout wil mose l th prov e t b effectiv o et e (though als mose oth t costly). 1.4. B7tracea Cs sa 131f ro I fallout Cs is traditionally used as a radioiodine tracer [26]. However, allowance must be made for possibl137e uncertaintie e estimatesth n i s , especiall e cas th f prolonge eo n yi d falloucomplea d an t x meteorological situation (separation in the release, combination of dry and wet fallout). 93 c„ Fresh forage, Leafy vegetables Cows' milk Ingestion with leafy vegetables Qy=Cp*MY C,, time-integrate- , d Q vtim- e integrated 131I concentratio miln i k activities intaked wit leafe hth y vegetables Kf. - feed intake of cow (kg d" Mv - age dependent average ' dietary intake of leafy vegetables______ Kf transfem- r fromw feeco o dt milk Ingestion with cows' milk == Qm Cm*Mm = 1 }l Dth= Kin2(Qm+Qv)+ Q mtim- e integrated - l activities intaked with cows' milk +KinhQinh Kjn(T - age dependent dose dependene ag - m t M average conversion factor for ingestion dietary intake of milk______Kjnj, - the same for inhalation FIG . Submode4 . approximatior fo l f time-integrateno d 131I activities intake with cow's milleafd kan y vegetables. TABLI SOI. E2 L CONTAMINATION ARISING FROM GLOBAL FALLOUD TAN CHERNOBYE TH 129 L ACCIDENT (from reference currenr ou d tan s data) Country, location, year 121 activity Units References UK, Berkshire, 1988 Ukraine, Polesskoe district, 2.0 mBq-kg'1 Our data Vilcha, 1992 0.33* Bq-nv2 Ukraine, Makarov district, 0.95 inBq-kg-1 Our data Maryanovka, 1992 0.157* Bq-m-2 South Ukraine, near the Black convero T * t from mBq-kg" Bq-m'o t 1 factoa 2 0.16f o ruseds 5wa . 94 TABL PARAMETEE . LISETH 3 F TO R VALUE SMODEE USETH DN I L Symbol Description Numerical value Units Rcfe-rence Tw Weathering half-life 10.5 for *31i d [9] 10.5 for 129l d U1 T Radiological half-life r 8.0fo I4 d-1 [10] r 1JJ Ar Radiological decay constant 0.086 for I d-' [10] AH, Weathering rate constant 0.066 for "11 d-l [9] AE= Effective loss constant 0.152 for "*I d-1 [9] 0.066 for 129i d-1 Ar+Aw V Deposition velocity o frot r mai 864 md'1 [11] ground for dry deposition (Bqm-2d-l per Bq m~3 of air) R Fractio aeriaf no l deposition 0.25 unitless 111] retained on plant Tf Fractio depositef no d nuclide 1 unitless [12] translocate ediblo dt e partf so pasture grass or leafy vegetable ipfnl Ecological plant suiface half-time 14 d [131 1 "•ecol Decay costant for weathering of 0.049 d- [13] particulate vegetatiof sof n ME= Effective removal constanr fo t 0.135 for « ll d-1 [13] ^r+^ecnl plant surface tc Time of exposure of fresh forage 30 d [H] airboo t m contamination during the growing season tv Time of exposure of leafy 90 d [11] vegetable airborc st n contamination during the growing season Yf Fresh forage biomass yield (wet) 1.8 kgm"^ [11,14] Yv Leafy vegetables yield (wet) 1.5 kgnr2 [11,14] 1 Ko. Dair feew ydco intak f freseo h 50 kgd- [15-17] forage (wet) Kfi„ Feed-to-milk transfer coefficient 0.01 dL-* [H] for dairw yco (PCI L-l /pCid-1) Age-dependent inhalation rate y 4 r fo 0 7. 3 1 [18] Vinh m d- 23 for adult m3d-l [18] Mm Age-dependent average dietary y 4 r 0.5fo 7 L d-1 [15] milk intake 0.40 for adult L d-1 [15] 1 Mv Age-dependent average dietary y 4 r 0.0fo 8 kgd- [19] intak leaff eo y vegetables adulr 0.1fo 0 t kgd-1 [19] Kinh Age dependent dose conversion 1.9E-8 for 4 y Sv/Bq [20] factor for inhalation 3.5E- adulr 9fo t Sv/Bq [20] Kin(7 Age dependent dose conversion 2.1E-6 for 4 y 4.4E- Sv/Bq [20] factor for ingestion 7 for adult Sv/Bq [20] 1.5. Other approaches which employ the radionuclide ratio method completo T picturee eth shoule w , d mentio othee nth r long-lived isotopes released froe mth damaged reactor at the Chernobyl nuclear power plant which are theoretically capable of being used as ml tracers. They include ^Sr, 239Pu and some transplutonium elements. However, they differ greatly from iodin thein ei r physical, chemica biologicad an l l propertie cannod san t therefore provide a satisfactory basis for retrospective thyroid dose reconstruction. 95 TABL . THYROIE4 D DOSES CALCULATE MODELLINY DB MEASURED GAN D DIRECTLY District, place Age group y DUcG , D*, cGy Da, cGy (direct (modelling, (modelling, measurement) scenario 1) scenari) o2 Polesskoe, d ol . yr 4 106 141 151 Vilcha Adult 19 25 33 Makarov, 4 yr. old 51 67 48 Maryanovka Adult 9 11 13 . RETROSPECTIV2 E RECONSTRUCTIO THYROIF NO D DOSES (USIN EXAMPLE GTH F EO THE CHERNOBYL ACCIDENT) 2.1. Possible way estimato st e doses Our analysis of possible methods has shown that in the situation which has actually evolved in Ukraine in the aftermath of the Chernobyl accident the most appropriate methods for reconstructing populatiodosee e th th o st presene th t na followsts a tim e ear : Dose estimates based on direct instrumental measurementsI activitof131 y in the thyroid gland drawind an modeln go s describin intake gth e function and/or data from population surveys; Dose estimates based on the I content in foodstuffs, water and air, and using average daily intakes and/or data from populatio 131 n surveys; Extrapolatio thyroif no d dose estimates obtained from population group whicr sfo h such doses have been established to those parts of the population (effectively the majority of the inhabitants of Ukraine whor )fo m direct measurement radioactivitf o s thyroie th n yi d glan Mayn di - June 1986 are lacking. 2.2. Dose estimation based on direct measurements of ml activity in the thyroid gland All dose estimates are based on over 150 000 instrumental measurements of radio-iodine activity in the thyroid gland which were taken in May-June 1986 [22]. Figur showe6 s average dose threr groupe speoplfo e eag liveth o f districtso en dwh i s around Chernobye th l plant. These estimates were obtaine basie th instrumenta f so n d o l measurementI 131 f so activity in the thyroid gland. The range of doses for the youngest children (up to seven years old at accidente time th th f eo cGy0 adule 30 ) .extendo Th t t y dose cG lowee s sar w frofactor y fe b rm a s of 2-8. A more detailed procedure for calculating these doses is given by Likhtarev et al. (1993) [22]. 2.3. Evaluating the quality and reliability of results from direct measurements of ml activity thyroie inth d gland As noted above, thyroid measurements are the basis for all our calculations. It is therefore important to evaluate the quality and reliability of the results from these measurements. This has been done in two stages [23]. In the first stage an initial verification of the data was carried out. The next stage involved an evaluatio uncertaintiee th f no measuremene th n si t results. 96 100 1965 1978 1975 1988 1985 1998 contenC FIG14 . 5 .trees n i t . Three main type f uncertainto s e identifieb e resultn th ca y f n thyroii do s d gland activity measurements, namely those due to: Peculiarities of the recording instruments and measuring procedures; Variability in the anatomy of the thyroid gland; Additional source f radiatioo s n outsid e thyroith e d gland arising from incorporatiof o n radionuclides. These uncertainties can be quantitatively evaluated by the following means: Statistical analysis of the results from control source measurements; Modelling of the measurement procedures with the aid of a physical thyroid gland phantom; Mathematical modelling of the measurements; Statistical analysi f anatomicaso l variabilit thyroie th n yi d gland (mas depth)d an s . Some of the thyroid gland measurements were accompanied by regular checks witI h131 calibration sources [23], thus providing an opportunity for an analysis of the results of such measurements r thisFo . purpose measuremente th l al , s were subdivided int series3 o4 essentiae Th . l features of a series were: the same instrument (not simply the same type), the same reference source, and more than three measurements separated fro anothee houmn on a morer y ro rb . Statistical analysis of these serial measurements mad possiblt ei evaluato et qualit e dataresulte e th th Th f .y o s obtained permit the conclusion that over 80% of the thyroid gland activity measurements performed by spectrometer are of acceptably high quality [23]. 2.4. Evaluating uncertainties in the results of direct measurements In orde evaluato t r uncertaintiese eth , informatio needes mase ni th sn do distributio e th f no thyroi thicknese th dn glano tissuf d so dan e coverinexposee th n i t gdi population have W .e studied 97 cGy cGy 1. Pripyat (city) . Makaro6 v . Chernigo11 v . Narodich2 i 7. Borodyan . Koroste12 n . Polessko3 e 8. Vyshgorod 13. Repkinsk . Chemoby4 l 9. Ovruchskoe 14. Kiev o- Suyatoshins k . Ivanko5 v 10. Kozeletsk 15. Chernigov (city) 16. Olevsk FIG. 6. Average dose to thyroid gland. these parameters as well [23]. Thus, Fig. 7 shows the age-thyroid mass dependence for inhabitants of Kiev. At the same time the effect of thyroid mass variability on the measurement results was modelled by means of a neck phantom [24]. Comparison of these data with the actual mass variability enabled concludo t s u e that such variability gives rise onl insignificano yt t uncertainties withi nsingla e eag group. Note, however, thadose th t e estimates themselve highle ar s y sensitiv valuee th thif o et so s parameter. The dependence found between age and thickness of thyroid covering tissue for inhabitants of Kie compares vwa d wit date hth a fro measuremente mth s obtained through phantom modellingn O . the basis of this comparison correction factors were calculated which allowed the reduction in 131I emission caused by these tissues to be accounted for. Comparison of the phantom study with the actual distribution of thyroid mass and covering tissue thickness showed tharange th t uncertaintief eo measuremene th n si t resultvariabilito t e sdu y of anatomical parameters, instrumental peculiarities and possible deviations from standard measurement geometr 25-40s yi % [23]. Another important conclusio thas nage-thyroii e th t d mass dependenc r inhabitantefo Kief so v correspond valuee th o st s recommende Publication di (Fig6 n) [20]5 7 . . This conclusio bases ni n do apeopl3 stud16 f eyo [23]. The next step after evaluating reliability is to correct low-quality data with the aid of high- quality results correctioa thao d T . en t n procedur developes ewa d which use comparisosa e ag e th f no dependences in low- and high-quality data. 98 102 - ICH 6 o 5 P - Kie* u *'•»* ö> W V) aV) £ 181 •c •m O 18» 10 20 38 48 50 60 70 Age (y) FIG. 7 Age-dependency of the thyroid mass for the city of Kiev 2.5. Appraisa modee th calculatinr f o lfo l g basi e dose th instrumenta f so n so l measurements furtheA r possible sourc uncertaintief eo inadequacs si calculatioe th f yo n model r exampleFo . , it was assumed in our calculations that 131I fallout occurred over a short period (one day) [22]. But in actual fact there was extended fallout (for up to 2 weeks). We therefore performed calculations to evaluat falloue effece th e th f o t scenari thyroin oo d dose estimates. Three type f scenario s o were considered a singl: e fallout even day1 ( tprolonge d )an d fallout ove day5 r t eithea s r fallinr o g constant intensity. Our conclusion is that using a model with a single-event scenario produces the most conservative dose estimates, whil prolongeea d fallout scenario with constant intensity producee sth lowest values. A further critical point for dose estimates is selecting the function describing the intake of 131I into the body. In the first and second stages we used models with both sudden and prolonged intake, e formeth r bein typicaga l inhalation model, whiln "ecological a lattee s eth wa r e (involvinon " g foodstuffs contaminated with radioiodine). The next stage in the development of a dosimetric calculation model is to use what are called "realistic intake functions". For example, we can use the dynamics of 131I activity in air, milk or intakn watea s a er function. This metho s appliedwa estimato dt e thyroieth d doses receivey db inhabitants of Kiev [25]. . ESTIMATIN3 DOSEE GTH S RECEIVE GROUPE TH COVERE T Y DB SNO DIRECY DB T MEASUREMENTS All the direct measurements of 131I activity in the thyroid gland were performed in districts situated aroun Chernobye dth l plant May-Junn I . e 1986 measurements were taken from some 30-90% of the children and 1-10% of the adults in these areas. Unfortunately, the measurements in many settlement t onlsno y faile inhabitantse coveo dt th l al r t eve, no the ngroupd e e coveydi ag th l f so ral 99 J. O ————l ———— ——— 1 ——— — i— —i i - 1 - ' - : _ j j ( _ ( ) , <> - ( j K - i: <• <' i 102 — 1 — ~ i <• ^ fi o C. O Ü _ u ii o i! y - t) lj [; o - i QJ < ) il —8-, W V 1 f. o ) s C < c | c U H c C) - t n 1! t ) t l: " <•> |: o ti c - n - o i _ 0 5; _ 0 t: - - 1R0 0 0-0,5 0,5-3,5 3,5-7 7-11 11-15 15-18 >18 AGE GROUPS, years FIG. Age-dependenc8 . f meayo n thyroid villagdosee th r f Rudkaeso fo . population r certaiFo . n affected district have savailablw o en e measurement dat therefor e t allaa W . e nee procedura woro dt t kou r reconstructinefo e dosegth s receive thosy db e people from whom measurements wer t takeeno n durin iodine gth e perioaccidente th f do . Such a procedure was developed for the Chernigov region (situated to the east of the Chernobyl plant) [23]. It included the following stages: Dose estimation based on direct measurements of 131I activity in the thyroid gland of 48 000 inhabitants of the region; Development of a model for the age-dependence of the dose; Estimatio e parameterth f e age-dependeno nth f o s t dose model using data from direct measurements; Development of an extrapolation model describing the dependence of the thyroid dose, on the densitCs pola 137 e fallouf yth o d r co-ordinatean t settlementf so s with referenc Chernobye th o et l plant; Estimatio parametere th f no extrapolatioe th f so n model using data from direct measurements; Estimatio age-dependence th f no thyroie th f eo dl settlement al dos r efo regione th n si . strictlA y valid age-dependenc dose th ef e o emerge districtl al region e r th d fo observef e so Th . d values can be approximated by the empirical formula D(age aK €Xp( = -)b "«*>, where D(age) average isth e givea dos (cGy)r e efo nag ; K is a scale parameter describing radioiodine intake; a parametea s i r representing thyroid dos neonaten ei s (age zero); b is a parameter defining the age-dependence of the dose (year"1). 100 Lognormal distribution of the doses in any age group was assumed since precisely this distributio founs nwa d amon persone gth s measured examplen a s A . , Fig give8 . individuae sth l doses measured and the estimated mean values in each age group for the inhabitants of one settlement. This figure demonstrates the agreement between the doses calculated on the basis of direct measurements and those obtained on the basis of model calculations of mean values for each age group, and also e possibilitth f reconstructino y ge group doseag r whicn fo i s ho thyroi n ther e ar ed activity measurements. The next step in reconstructing the doses received by the population of districts in the region where no thyroid monitoring was performed is to extrapolate the scale parameter K of the age model to settlements in those areas. The extrapolation procedure was carried out using data on density of Cs137 fallou d polaan t r co-ordinates relative Chernobyth o t e l plant (radionuclide ratid an o geographical extrapolation methods) [26]. The resulting spatial distribution of mean thyroid doses to children (under 6 months) and adults (over 18) in the Chernigov region is given in Figs 9 and 10. The doses for other age groups lie in the region between the values given as examples. The highest doses were found in the west of the regione districtth n i , s closesChernobye th o t t l plant, with maximumr fo mea y G n 3 dose3. f o s r adultsfo y G . childre5 0. d nan thyroie Th d doses decreas west-easa n ei t direction acros regione sth , which corresponde th o st decrease in density Cosf fallout and the drop in doses with increasing distance from the Chernobyl plant. Exactly the sam137 e sort of decrease is observed in the areas where thyroid measurements were conducted. Deviations from this tendency can be found, in certain smaller districts in the north-east, however, because of the enhanced density Cosf 137 contamination in the area, adjoining the so-called Bryansk caesium hot spot in Russia. Chernobyl Power •S3 Plant OJ W FIG . Thyroi9 . d dose distributio Chernigovskaye th r nfo a Region (children bor 1986)n i . 101 Ci- CO Chcrnobyl •si ça Power u Plant FIG. Thyroi10 . d dose distributio Chernigovskaye th r nfo a Region (adults). lowese Th t thyroid dose predictee sar south-eas e th r Chernigoe dfo th f to v regio bordee th t na r wit Poltave hth a region, wher Cvaluee seth 137 fallour sfo t densit vere yar y low. This report present approacher sou mose th to s t genera l way reconstructinf so g thyroid dosd ean some methods for performing such dose estimates in Ukraine in the aftermath of the Chernobyl accident. ACKNOWLEDGEMENTS e authorTh s would lik o exprest e s their . ParetzksincerG . H e. e thankDr (GSF : to s , [Gesellschaft für Strahlen- und Umweltforschung = Radiation and Environmental Research Company], Munich, Germany s unfailinhi r fo ) g r organizinsupporfo d an te join th g t work; Dr. K. Henrichs (Siemens AG, Munich, Germany) for the joint work on evaluating data quality and interpretin resulte gth s from thyroid dose reconstructio r inhabitantnfo e Chernigoth f o s v region; . PröhG . l Dr (GSF, Munich, Germany contributios hi r fo )wore th evaluatin n ko o nt g data quality and interpretin resulte gth s from thyroid dose reconstructio inhabitantr nfo Chernigoe th f so v region; . RotP . h Dr (GSF, Munich, Germany) helpeworo e th moden wh ,ko n di l measurements usinga interpretatioe phantoth n o d man thosf no e data; M.G .. ZelenskiBuzynniV . A d an jj (Scientific Centre for Radiation Medicine, Kiev, Ukraine date th ar the)fo y provide measurementn do 14f contenC so t in tree rings; Dr. A.K. Cheban (Scientific Centre for Radiation Medicine, Kiev, Ukraine) for help in collecting information on the anatomical parameters of the thyroid gland. REFERENCES 1. Kairo I.A., Gulko G.M. Thyroid dose reconstruction based on deposition. Work shop WHO, 21-23 March, 1993. Munich, Germany. 2. Wilkins B.T. Investigation e naturath f iodinen o i s l environment9 -12 : Resultd an s implications: Report of National Radiological Protection Board - NRPB-R225 - Chilton, 1989. -23 p. 102 . Iodine-123 n d Soii vegetatio9 an le environth n i nf Nucleao s r Fuels Reprocessing Plants/Rickard W.H. t al.//USAEe , S Report BNWL-185 - 1974 . 2 t - P.44. P 0- . 4. Iodine-12 e hanforn foragi th 9 d dee n an o erd d sitothean e r pacific northwest locations./Price K.R., Cadwell L.L., Schreckhise R.G., Brauer F.P.//PNL-3357.- Richland, Washington, 1981.. p 7 1 - 5. Muramats , OhmomuY. . Iodine-12oY iodine-12d 9an 7 inenvironmental samples collected from Tokaimura /Ibaraki, Japan. //The Science of the Total Environment.- 1986. - VoL48. - P. 33-43. 6. Muramats , OhmomuY. , SumiyoY. . DeterminatioaM iodine-12f no iodine-12d 9an n 7i environmental samplas collecte f Radioanalyticao n Japan. i dJ / / . d Nucleaan l r Chemistry, Articles.-1988.-Vol - P.181-189.L 123.o N - . . Kuznetsov7 , Yu.V., Rosyanov, S.P., Vinogradova, V.K., Gavrilov, V.M., Determinatio f iodine-12o n watern i 9 , d soivegetatioan l n samplee neutroth y b sn activation method. Radiokhimiya No. 3 (1990) 150. 8. Izraehl, Yu.A., Vakulovskij, S.M., Vetrov, V.A., Petrov, V.N. Rovinskij, F.Ya., Stukin, E.D. Chemobyl: Radioactive contamination of the natural environment. Gidrometeoizdat, Leningrad (1990). 9. Schwarz, G.,and Hof&nan, F.O. Imprecision of dose predictions for radionuclides released e environmentth o t n applicatioA : a Mont f o n e Carlo simulation technique.// Environment International.-1980.-Vol. 4.-pp. 289-297. 10. International Commission on Radiological Protection. Report of a Task Group of Committe e ICRth n datf Po o a 2 euse n ICRi d P Publicatio . Radionuclid30 n e Transformations. Energ Intensitd yan f Emissionsyo . ICRP Publication 38.// Annalf o s ICRP-Oxforde th : Pergamon Press,-1983.-Vols.ll-13. 11. Soldat, J.K. Radiation doses from iodine-129 in the environment//Health Phys.-1976.- - P.61 Vol. 30 . . 12. Soldat, J.K.; Brauer, P.P.; Cline, J.F.; Fager, J.T.; Klepper, B.; Rickard, W.H.; Baughan, B.E. and Watson, D.G. The Radioecology of Iodine-129:An Interim Report, Report No. BNWL-1783, 1973. (Battelle Pacific Northwest Laboratories, Richland, Washington). 13. Gamer . TransfeRJ , f radioactivo r e materials fro terrestriae mth l environmenn ma o t t and animals.//CRC Crit. Rev. Environ. Control.-1971.-Vol - P.3372. . . 14. Peterson, H.T.,Jr. Terrestrial and aquatic food chain pathways.//Radiological assessment, a textboo environmentan ko l dose analysis./Till,J.E.; Meyer, H.R., eds/-Springfield: VA , National Technical Information Service; NUREG/CR-3332, ORNL-5968; 1983. 15. Book, S.A.; .Gamer, R.J.; Soldat, J.K.Bustadd an , , L.K. Thyroidal burdenI fro129 m f so various dietary sources.//Health Phys. -1977.-Vol.32.-P.143. 16. Shor, R.W.; Fields, D.E. Agricultural Factors affecting the radionuclide foodchain pathway: Green forage consumtio dairf no y cows.//Health Phys. 1980.- Vol. 39.- P.325- 332. 17. National Counci Radiation o l n Protectio Measurementsd nan . Radiological assessment: Predictin transporte gth , bioaccumulation f radionuclideo n uptakd ma an , y eb s released environmente th o t . Bethesda : NCRPMD , ; NCRP Repor ; 198476 t . 103 18. International Commission on Radiological Protection. Report of the Task Group on Reference Man. ÏCRP Publicatio 23.-Neo nN w York:Pergamon Press, 1975. 19. Agricultural Research Service. Food Intak d Nutritivan e e Valu f Dieto e f Meno s , Women, and Children in the United States, Spring, 1965, USDA Report No. ARS-62- 18 (U.S. Department of Agriculture)- Washington, 1969. 20. International Commissio Radiologican no l Protection. Age-dependent Dose Membero st s of the Public from Intake of Radionuclides: Part 1. ICRP Publication 56., ISSN 0146- 6453.//Annals of the ICRP-Oxford: Pergamon Press, 1989.-Vol.20.-No. 2.-122 p. 21. Buzinny M.G., Zelensky A.V., Kovalyukh N.N., Skripkin V.V. Sanin E.V. Retrospective reconstruction of the ^C release to the atmosphere after the Chernobyl accident. The main method e thyroith r sfo d dose reconstructio e Ukraineth n ni . Proceedings: Actual questions of the prognose, current and retrospective dosimetry after the Chemobyl accident. Kiev, 27-29 October, 1992. Kiev, 1993. - P. 118- 124 (in Russian). 22. Likhtarev I.A. Shandala N.K. Gulko G.M. Kairo I.A. Exposure doses to thyroid of the Ukrainian population after the Chernobyl accident. Health Physics. June 1993, v.64, N 6, p.594-599. , LikhtarevA . 23 . Gulko. I SobolevM .G . . . . KairoI ChepurnoyA B G , , . L N , , , A , K. Cheban , NikonovA . . DjachkovD , A . I , . PnihlG , . RothP , . HenrichsK , , Reliability accuracd an e 13th 1 j f thyroi yo d activity measurements performe Ukraine th n di e after the Chernobyl acciden 1986n i t . GSF-report 19/93, Munich, 1993. 24. Alt, P.: Entwicklung eines Standard Schilddrbsen-Halsphantoms sowie Aufbau und Kalibrierung eines MeJIstandes zum Nachweis von Radiojodisotopen in der menschlichen Schilddrüsen; Diplomarbeit Fachbereich Physik, Johann-Wolfgang- Goethe-Universität Frankfur Mainm a t , 1990. 25. Likhtarev LA., Gulko G.M., Kairo I.A. s LP.,Lo , Henrich , ParetzkK. s e H.G. Thyroid exposures resulting e froChernobyth m l e effectivenesth acciden d an f to s countermeasure e Ukraineth n i s . Par : Dos1 t e estimate e populatioth r fo s f Kievo n . Health Physics (wil publishee lb 1993)n di . 26. Likhtarev I.A., Gulko G.M., Sobolev B.G., Kairo I.A., Chepurnoi N.I., Vasiljev A.Yu., Ivanovsky D.A. The main methods for the thyroid dose reconstruction in the Ukraine. Proceedings: Actual questions of the prognose, current and retrospective dosimetry after the Chemobyl accident. Kiev, 27-29 October, 1992. Kiev, 1993. - P.92-98. (in Russian). 104 DOSE ASSESSMEN RECONSTRUCTIOD TAN N AREAE TH RUSSI F SN O I A CONTAMINATED AFTE CHERNOBYE RTH L ACCIDENT I.I. KRYSHEV, K.P. MAKHON'KO, T.G. SAZYKINA Institute of Experimental Meteorology, Scientific Production Association 'Typhoon', Obninsk, Russian Federation Abstract e papeTh r focusemethodologe th n o s f doso y e assessment d reconstructioan ne observationth base n o d f radioactivo s e contamination in the areas of Russia following the Chernobyl accident.Special attentio e earlgives th i n o yt n stage aftee th r accident — the period of "iodine hazard".The combined internal doses for thyroid gland through the food pathway and from inhalation of iodine—131 were estimated for various population e regionth group f Russin O si s a impacte e accidentth y e b d Th . specific feature f accidentao s l contaminatio e environmenth f o n t with iodine—13 e analyzee locaar 1th r l fo dare — aSosnovn i r Bo y the Leningrad Region r whicfo ,h detailed radioecological data are avaliable. 1.INTRODUCTION The accident at the 4—th unit of the Chernobyl NPP occurred at Ol.23 loca 6 lApri2 s recorde time wa n lo th d e198 y an b 6d radiological monitoring service of State Hydromet (State Hydroraeteorological Service) at O9.OO during routine surface- based measurement f exposuro s e gamma—dos e Chernobyth rat t a e l P sit NP e accidene th e tim f th USS[1]e o ed 224 th tt ha R A 7. meteorological stations equipped with gamma—detectors, 475 points provided with trays to sample radioactive fallout and 73 points r havinai filter o t gdetermin s e radionuclide concentratio e monitorine airTh th . n i n g networ s augmentewa k d after the accident. Together with State Hydromet, the studies were carried out by specialists from Nuclear Engineering Ministry, Health Care Ministry, Ministry of Defense, Ministry of Geology, Academy of Sciences and others. 1.1. Radioactive contaminatior ai e th f o n Immediately after the accident, radioisotopes of iodine were of major radiological hazard. Also, the presence of a goo s d wa radioiodinindicator ai e radioactivit th e f th o r n i e y dispersal . Accordin e monitorinth o t g g data weea , k after accidente th , radionuclides coul e arrange b e followind th n i d g orde y inpub r t o totat l activit e atmospherith f o y c fall—out: 1—13 > Zr—91 > 5 Ba -14O >Y-91 >Te-132 >Sr-89 >Cs-137 >Cs-134 >Sr-9O >Pu-239,24O >Pu238. A short—duration increas n totai e l activit f gamma—emittero y s e atmospheriith n c fall—ou s reportewa t d ovee mosth rt parf o t Russia (Bryansk, Tula, Kaluga, Orlov, Voronezh, Smolensk, Gorky, Rostov, Tambov and Penza regions, the Kola peninsula, 105 Sverdlovsk, Khabarovs d Vladivostock)an k n separatO . e areas, maximum values were four orde f magnitudo r d moran e e above th e background levels occurring befor e accidentth e . In the first days after the accident, permissible levels of iodine—131 in the air were exceeded over the major part of Belorussia, Ukrain d centraan e l areae f th Russiao s y B . standard f o s radiation safety, permissible concentratior fo n total activit l iodins al wa f eo yt I 5 specieBq/m5. s 3wa s virtually onle aerosoth y l fraction whic s determinehwa t thaa d t time for iodine—131 level in the air. Measurements of iodine—131 using seguentially placed filter and cartridge with activated carbon led us to estimate the aerosol fraction of iodine—131 as 15% for r.emote distances from the Chernobyl NPP during the first days afte e accidentth r . 1.2. Radioactive contaminatio f soio n l Immediately afte e accidentth r e sois contaminateth wa ,l d with short—lived nuclides: iodine—131, tellurium and iodine—132, neptunium—239, zirconium and niobium—95,barium and lanthanuml4O, yttrium—91, strontium—95. Maximum concentratio f radioiodino n e e soiith nl occurred duriny dependine Ma th 8 Apri9 2 g o n t o l g trajectory of the plume and local meteorological conditions. In a numbe f caseso r , second maxim e wash—oua th occurre o t f o e t du d iodine—131 from the lower troposphere. Fig.l shows level f soio s l contamination with iodine—13s a 1 y 1986Ma r 5 osom.1 fFo e areas where iodine—13t no s wa 1 measured, the estimates were made using correlation relationships between soil concentration of 1—131 and Cs—137. Thousands, sq.km 10-130, kBq/sq.m 130-550 550-1380 1380-3170 3170-5700 Bryansk Tula Kaluga Orel Fig.1. Soil contamination with 1-131 for several regions of Russia Impacted by the Chernobyl accident y 1986Ma 5 1 )(a f so 106 1-131, KBq/m2 100000p 10000 - 1000 - 100 = 10 100 1000 10000 Cs-137, kBq/m2 Fig.2. A relationship between the density of soil contamination with 1-131 and that with Cs-137 of accidental origin (on 15 May 1986) e correlatioTh n coefficien r thesfo t e values e oveEuropeath r n part of Russia was r=O,91 (Fig.2). Thus to reconstruct soil contamination fields for 1—131, a more detailed data base for Cs —13s helpfuwa 7 o usee heaviest lTh . t contamination with 1—131 s reporte e northerwa th n i d n Ukraine, eastern Beloryssid an a adjoining central areas of Russia. Isolated "patches" occurred near the western border of the former USSR in the vicinity of Baltiysk—Kaliningrad and in the areas between Gomel and Bryansk and those south to Tula. 1.3. Radioactive contaminatio f surfaco n e waters The highest contamination of aquatic ecosystems occurred e th firs n i t period afte e accidentth r : late April—early Ma y 1986 f O majo. r radioecological significanc t a etha t s timwa e iodine—131 whose maximum concentratio e surfacth n i n e watef o r some areas was in excess of permissible concentration in drinking water (37 Bq/L) by dozens of times [2,3]. 107 N water monitoring posts continuous terrestrial monitoring posta 30-ktn zone GULF OF FINLAND osnovy Bor Kovash river Kop&rskayaBay Fig.3. Locatio Sosnove th f no r yBo Leningrad Region 2 DYNAMIC F IODINE-13O S 1 CONTAMINATIO E FOODSTUFFTH F O N S AND THE ENVIRONMENT (LOCAL AREA - SOSNOVY BOR, LENINGRAD REGION) e ChernobyTh e th radioactivl o t acciden d e le t contaminatio f areao n s remote e frosourcth m e Specifically, some areas of north — western Russia appeared to have been affected Consider peculiar features of the radioactive contamination of Sosnovy Bor Leningrad region (Fig 3) for which detailed data of radioecological monitoring are available 13,5] These data were collected by the Laboratory of Ecological Studies in Sosnovy Bor responsible for environmental monitoring around the Leningrad NPP e programmTh f o radioecologicae l monitorine th area f o g included determinatio f radionuclido n e concentratio n surfaci n e air aerosols, atmosperic depositions, soil, plants, sea and fresh water, bottom sediments, algae, fish, vegetables, fruit, mushrooms, berries, milk and other local agricultural production e totaf Th o 6,5Ol O environmental samples were collected an d measured in 1986 According to the observational data from Sosnovy Bor, air samples of aerosol exposed from 15 2O on April 28 to 11 OO on April 29 in 8 sampling points showed a variety of radionuclides Mo-99, Ru-lO3, Ru-106, 1-131, 1-132, Te-132, Cs-134, Cs-136- Cs , 137, Ba-14O, La-140, Ce-141, Ce-144, Np-23 d other an 9e sam Th es radionuclides, thoug t highea h r concentrations, were reporten i d 108 Finland near "Loviisa d "Olkiluotoan " " nuclear power plant. s The major contributors to the activity of aerosols were: 1—131, Cs-137 and Cs-134, Te-132, Np-239 . e 1—13Th 1 activit n aerosole i ystud th yf o s area ranged from 2.4 to 5.6 BqXmS i.e. was as great as maximum permissible concentration (5.5 Bq/m3). e soiTh l samples collecte n Apri o d, 1983O l 6 revealee th d same radionuclide s a aerosols d atmospherian s c depositions. f activito Abou % f man-mado y7O t e radionuclidey b s mad p wa su e short-lived radionuclides: 1-131,132, Te-132, about 11% - Cs—137. Concentration of Cs—137 in soil varied from O,6 to 1,O kBq/k y e sampleweightdr gth n f I perenniao s. l grass collected Aprin o 0 19863 l e activitth , gamma—emmitterf o y s ranged fro7 1 m y weightO kBq dr 24 e inpu g Th o /k t f short—liveO. o t d nuclides (1—131,132, Te—132) was 75% and cesium radiosotopes (Cs—134,136, 137) accounted for 14% . Since May 2, 1986 analysis was made of 1—131 contamination of mild othean k r locally produced foodstuffe sTh (Tabl . 1) e maximum concentration f 1—13o s 1n mili k (16O Bq/L) occurren o d May 14, the next day after the cattle was taken to pastures. Concentratio f o n1—13 n foodstuffi 1 d drinkinan s g water changed ia similan r way e maximu.Th m contaminatio f 1—13o n 1 occurren o d n drinkini 3 Ma2— y g water, bread, lettuc d onionan e . Usagf o e atmospheric precipitation for irrigation led to an increase in 1131 contamination of vegetables, even though they were grown in greenhouses. wate4 Sinc r irrigatioy fo rMa e s takewa n n froe th m Kovas e hcontaminatio th rive d an r n level went down. The atmospheric fall—out and radionuclide wash—off from the catchment surfac n April—Mai e y 1986 caused contaminatiof o n fresh and sea waters. The 1—131 concentration in the river water was the highest in early May 1986 and over the month it fell from ISO Bq/L to O.7 Bq/L. 3.DOSE RECONSTRUCTION AND RISK ASSESSMENT OF RADIOACTIVE CONTAMINATIO E ENVIRONMENTH F O N T WITH IODINE-131 First we consider the assessments of the internal dose for thyroid e glandpopulatioth f e areo sth f Sosnovo an i r n Bo y in Leningrad Region, wher e detaileth e d date availablar a n o e TAB. 1-131 L. 1 CONCENTRATIO N WATEI N D LOCAAN R L FOODSTUFFS, SOSNOVY BOR, BQ/KG WET WEIGHT Component 3O April 2 May 3 May 4 May 12 May 2 June Drinking 1 . 5 110 56 56 11 5 . 1 water Milk 85 67 7O 70 7 . 4 Cottage cheese - - - 81 - - Bread 110 67 25 2 . 2 — Lettuce 63 520 670 - 63 - Spring on.ion 14 96 - 26 — Tomato 10 15 4 Cucumbers 4 4 11 15 Irrigation water 133O 310 740 Fish SO 109 TABL 2 PARAMETERS FOR THE DOSE ASSESSMENT OF THYROID GLAND EXPOSURE TO 1-131 THROUGH THE FOOD PATHWAY [6,7,8] Parameter Age group 1 year 5 years 1O years 15 years Adults Dose factor of conversion , 4 . 3 2..5 1 ,3 0.8 . O .5 microGy/Bq Consumption of milk , L/day 1 .O O. 8 0, 75 0..7 0.7 Consumption of water, L/day O.6 0. 8 0. 95 . 1 2 2 .0 Consumption of bread and baked goods , kg/da- y O. 12 0,, 17 09 1 ., O .20 Consumption of vegetables , kg/day — 0.. O5 0 ., 10 0.. 10 0. 12 Consumption of fish, kg/day ^~ 0. 05 O . 08 O , 10 O . 16 Dose, mGy 10 15 Adults Age groups Fig.4estimatee Th . d internal dose thyroir sfo d gland of population throug fooe hth d pathway ( May-July 1986, Sosnovy Bor, Leningrad Region) the dynamics of the content of iodine—131 in the surface air, milk, drinking wate d locaan r l foodstuffs e parameterTh e dosth er fo sassessmen t throug e footh h d pathwa e presentear y e calculatio Th Tabln i d . 2 e n results show that young children under 1 have the highest thyroid exposure doses (Fig.4). The exposure doses for this critical age group are approximately five times higher than those for adults. A major con-tribution to the dose formation for the children is the consumptio f milko n . Next n orde i f ,o importance re th s i , consumptio f watero n , vegetables, brea d bakean d d good f homo s e manufacture. The parameters for dose assessment and estimated exposure doses for thyroid gland from inhalation of the contaminated air in May—June 198 e give 6e ar highes Tabln Th i n . 3 e t estimatee ar s 110 TABL.3. ESTIMATED EXPOSURE DOSES FOR THYROID GLAND FROM INHALATION OF 1-131 IN MAY-JUNE 1986 (THE AREA OF SOSNOVY BOR, LENINGRAD REGION) e grouAg p Parameter 1 year 10 years Adults Dose factor of conversion, microGy/Bq 2. 19 O. 65 O. 27 r inhaledai e Amounth , f o t m3/day 3.8 15 22 Inhalation dose for 1—131 (aerosols), microGy 60 7O 4O Inhalation dosr 1—13fo e1 (aerosols, plus gaseous phase), microGy 300 350 2OO obtained with allowanc botr fo eh aeroso d gaseouan l s formf o s iodine radioisotopes. It is easily seen that the doses through the food pathway excee e highesth d t estimate e doseth sf o s from inhalation almosn ordea f magnitudey o rb t . The combined internal dose for thyroid gland through tthe food pathwa d froan ym inhalatio e criticath r e groufo ag ln p (young children 6 mGy7. , s wa whic) s approximateli h 2 timey s lower than the permissible limiting doses for individuals. The contribution from the other radionuclides to thyroid gland irradiation (1-132, Te-132, etc.) is over an order of magnitude lower, as compared to 1—131. For other regions, the individual expected internal dose for thyroid gland through the food pathway was estimated with e followinth g empirical formula: Da =Ka*Ra'A, where Ka is the iodine—131 transfer coefficient from ground depositions with e humaa foodos th o t d en s i organism a R ; m2 , facto e tota e grou f conversioth Gy/Bq, o ag r s la e pi th A ; r fo n deposition of 1—131, Bq/m2. Measurements of 1—131 depositions from the atmosphere were e territortaketh n i n f e Russipointo yth t a s relativeln i w fe y number. Therefore we used for the dose assessment the estimates of soil contamination with 1—131 obtained on the basis of a statistical relationship between depositions of 1—131 and Cs—137 s a wel, s froa l a mmor e detailed data basn o soie l contamination with Cs—137. In this case, the following values of 1-131 depositions (recalculated for 15 May 1986) approximately correspond to the Cs —137 isolines: 5 55 148Cs-137 5 O,18 kBq/m 7 3 2 1-131, kBq/m2 133 55O 138O 317O The values of Ka were estimated from the data of monitoring ovee contenth r f e loca1—13o tth ln i 1foodstuff d drinkinan s g water as well as using the model of multiple pathways for the iodine—131 migratio n fooi n d chainn thiI s. s case e densitth , y of soil contamination with s recalculate1—13wa y 1Ma 5 1 r fo d a result e s 1986followinA th . , ge transfeth value f o sr 111 TABL.4. COMPARISON OF THE ESTIMATED EXPOSURE DOSES FOR THYROID GLAND OF THE POPULATION WITH THE ESTIMATES BASED ON DIRECT MEASUREMENTS OF THE IODINE-131 CONTENT IN THYROID GLAND Weighted average of individual dose, cGy Region Age From the data Indirect assessment group of direct e modebaseth n lo d measurements of multiple pathways of 1-131 of the 1—131 migration [6,9,10] in trophic chains Gomel Region Chi Idren 1OO 16O +_ 8O Gomel Region Adults 42 55 ± 20 Gomel Region Idrei Ch n 100 160 + 80 Adults 65 55 ± 20 Bryansk Region Children 37 - 80 9O ± 4O Adults 1O - 24 30 ± 15 Tula Region Chi Idren 40 - 50 35 ± 15 Adults 5 - 14 1O ± 4 Orel Region Children 10 - 20 33 + 18 Adults 2 - 7 10 ± 4 Kaluga Region Chi Idren 25 - 43 36 ± 18 Adults O — 14 11 JL. 5 coefficienKa t were obtaine r varioufo de e group th ag sf o s population : Age : 1 year 5 years 1O years 15 years Adults Ka, m2 : 0.28 O. 32 0. 36 O. 36 O .47 The model estimates are relatively rough because of a number of factors introducing a considerable uncertainty into e dosth e calculations. Among these factors are: rather little direc e tconten th dat n e o environmentaf a1—13o tth n i 1 l objects d fooan d chains; e errorrecalculatioth n i s e densitth f o f no y soils contamination with Cs-137 to that with 1—131; errors in the assessment of the transfer coefficients ; inaccurate knowledge of the diet; the assumption that essentially the local foodstuffs were used; the assumption of no countermeasures taken. The calculations based on direct measurements of the content of 1—131 in thyroid gland are more accurate. However, these data are lacking for most regions of Russia. Table 4 present e weighteth s d averages ovee contaminateth r d areaf o s the exposure dose for thyroid gland from the data of direct measurements and using the model of multiple pathways of the iodine-131 migration through trophic chains. Comparing the two method f o s assessment• shows e thamethoth t f o dindirec t assessmen e mode th tf multipl o baseln o d e pathways provides higher e exposurvalueth f o s e dos s compare a ee estimateth o t d s from the data of direct measurements of 1—131. However, on the whole, agreement betweeo methodtw e f doso sth n e assessmens i t sati sfactory. This suggests thae proposeth t d metho f o estimatind e th g exposur er thyroidosfo e d glan de mode base th f multiplo n lo d e pathway is efficients . Note thaestimatethe t d doseare s averaged over sufficiently large territories r personFo . s living 112 TABL.5. THE ESTIMATED COLLECTIVE DOSES AND RADIATION RISK OF THYROID CANCER FOR THE REGIONS OF RUSSIA IMPACTED BY THE CHERNOBYL ACCIDENT Region Collect ive Radiation risk dose,Manv *S Children Average (0—5 years value old).maximue th r fo m values region Bryansk 120555,0 2,9*lO(-3) 6 ,7* Tula 96230,0 5,0 ' 1 0 ( -4 ) 4.6" 10 (-5) Orel 44791 ,0 4,9E10(-4) 4, 1" 10(-5) Kaluga 19O61 ,0 5, 2' 10 (-4) 1 .7" 10(-5) e "patchesith n f o "radioactiv e contaminatio e individuath n l exposure r dosethyroifo s d glan n substantiallca d y exceee th d average values. The estimated collective doses and radiation risk of thyroi e dregionth cance r f o Russifo sr a e impacteth y b d Chernobyl accident are given in Tabl.5. Note that these assessments were made on the basis of the risk coefficient r=8*!O(—4) Sv—1 postulated without e Chernobyresorth o t t l data. It seems very important to assess the risk coefficients, using the models of dose reconstruction and the data of medical monitorine valueth e areath f o radiatiof o s sn i g n risk coefficients. 4.CONCLUSIONS Radioisotope f o siodin e presente e mosth td serious hazard immediately afte e Chernobyth r l accident. A rather close correlation was found between atmospheric deposition f 1—13o s d soi1an l contamination with = Cs—13 r ( 7 0.91). Therefore a considerably more detailed data base on soil contamination with Cs—137 can be used for the reconstruction of the fields of soil contamination with 1—131. A model of multiple pathways of the 1—131 migration through food chain developewas s verifieand d d agains observationathe t l data. Exposure dosd radiatioan e n risk assessments were madr fo e various age groups of the population living in the contaminated areas of Russia. Children unde 1 werr e foun havo e highest d th e t exposure doses of thyroid gland. For this critical age group the exposure doses are approximately 5 times higher than those for adults. A major contributio e dosth e o t formation r childrefo n s i n e consumptioth f milko n . Next n ordei ,f importance o r e th s i , consumption of water, vegetables, bread and baked goods of home manufacture. e doseTh s throug e footh h d pathway were show o t exceen d considerabl n ordea f y magnitudeo r(b y e highes)th t estimatef o s e doseth s from inhalation. e mosth tr Fo contaminated area f Russio se levelth a f o s radiation risk for children resulted from the Chernobyl accident e comparablar e witr exceeo he spontaneou th d s ris f thyroio k d 113 e majoritcancerth n I f contaminate.o y d areae valueth s f o s radiation risk lower thae spontaneouth n s ris f thyroio k d cancer t exceebu naturae th d l background radiation risk. Comparing the direct and indirect methods of dose assessment showed that the method of indirect assessment based e modeth f multipln o o l e pathways provides higher e valueth f o s exposure dose which remain, however, within the confidence intervals. It is very significant that the models of dose reconstruction and the data of medical monitoring in the areas e Chernobyoth f l accident als oo t solvenabl e eon e inverse problem e assessmenth n o s f radiatioo t n risk coefficients. This can lead to a certain reassessment of their values in the future, taking into consideration the Chernobyl data. ACKNOWLEDGEMENTS e authorTh e mosar s t gratefu o G.Linslet ls proposa hi r o t fo y l prepare this paper; to S.M. Vakulovsky, I.V. Dragolybova, A.I. Nikitin, L.D. Blinova, L.P.Bochkov, V.S. Kosykh d T.Aan , . Muidinov r fo asom e source materia r thifo ls pape d helpfuan r l discussions. Specia o T.Vt l e .thankdu Koretskaye ar s d E.Lan a . Mikhailova for translation into English,to L.V.Makarova for techical assistance. REFERENCES [1] The Accident at the Chernobyl Nuclear Power Plant and Its Consequences. (Information compilee IAEth Ar Expertfo d s Meeting, Vienna, 25-29 Aug.1986) USSR State Committen o e the Utilization of Atomic Energy, Moscow (1986). [2] IZRAEL Yu.A.et al., Chernobyl: Radioactive Contamination e Environmentoth f , Gidrometeoizdat,Leningrad (199O5 )42 PP. ] KRYSHE(3 V . I.IRadioecologicaal t .e l Consequencee th f o s Chernobyl Accident, Nuclear Society International,Moscow (1992) 14] KRYSHE V. RadioactivI.Ial t a . e Contaminatio f o NPP'n s Areas . USSR Nuclear Society,Moscow (199O). ] BORZILO[5 V V..A Ecologica, ) .s .KRYSHEEd ( . d GeophysicaI an l. I V l Aspect f o sMonitorin P AreasNP g , Gigrometeoizdat,Moscow (1992). ] Internationa[6 l Chernobyl Project. Technical Report. IAEA,Vienna (1992). ] MOISEE[7 V A.A., IVANOV V.I.,Reference Boo Dozimetrn o k d an y Radiation Hygiene, Energoatomizdat,Moscow (199O). [8] The Methods of Calculating the Radionuclide Transport in e Environmenth d Exposuran t e Doser fo Populations , Interatomenergo,Moscow (1992). [9] Nuclear Accidents and the Future of Energy. Lessons Learned from Chernobyl. (Proc.Int.Conf.Paris, 1991), French Nuclear Society,Paris (1991). [1O] Chernobyl e FivTh .e Hard Years, Izdat.Moscow (1992). 114 CEC/CIS JOINT PROGRAMME TH N EO CONSEQUENCES OF THE CHERNOBYL ACCIDENT G.N. KELLY . CECILLL , E Commissio Europeae th f no n Communities, Brussels Abstract This paper summarises the CEC/CIS joint programme on the consequences of the Chernobyl accident e joinTh t. programm s initiatewa e n 199i d 2 followin signature th g n a f o e Agreement between the Commission and the relevant Ministries in Belarus, Russia and Ukraine e scop contend Th e programman e.th f o t e describear e d together wite hth management structure tha bees tha n implemente ensuro dt e successfueth l conduce th f to projects. Progress made during the first year, within each area of the programme, is summarised and priorities for, and the direction of, future work are indicated. 1. INTRODUCTION AND BACKGROUND The accident at Unit 4 of the Chernobyl nuclear power plant occurred on April 26, 1986. The subsequent month yeard unprecedentew san ssa d technica scientifid an l c e worth n ki former USSR to evaluate the amount and composition of the radioactive materials released and to assess and mitigate the consequences of the accident. One of the major consequences of the accident was the contamination by radionuclides of large areas of, primarily, three Republic e formeth f o s r USSR, namely Belarus, Russi Ukrained aan aren f A soma.o e 2 25,000 km (abou2 t 15,000, 8,000 and 2,000 km in Belarus, Russia and Ukraine, respectively) initialls wa y denne affectes da d (contamination leve km' i excescaesiuf n C i l o 5 2 f so m 137); thin i s area ther aboue ear t 2200 settlements with about 800,000 people (about 45%% ,24 and 31%, respectively in Belarus, Russia and Ukraine). A level of contamination of 1 Ci km' s sincha 2 e been adopte somn di e Republic defino t s affectee th e d area within which ther severae ear l million vas e peopleth tr majoritFo . peoplef yo additionale th , dose they will receiv e futurth n ei e from continuin affectee th livgo t n ei d areas wil significantle b l y less than that from natural radiation more Th .e exposed grouppopulatioe th n si n (some tens of thousands) are currently receiving annual doses a few times those from natural background radiation. Significant contaminatio territorf no y outsid formee eth r USSR also occurred (albei scala n t leveleo a t considerabld an s y les se forme thath n ni r USSRd an ) measures continue to be taken in some countries (eg, Scandinavia, United Kingdom) to mitigate its consequences. In order to alleviate the consequences of this widespread and persistent contamination and to establish acceptable conditions for those continuing to live in affected areas, numerous administrative and policy decisions have been taken in the three Republics. These have affected, and will continue to affect in the future, the lives of hundreds of thousands if not millions of people, including their health, way of life, agriculture and socio-economic conditions. A wide range of measures were taken to mitigate the consequences of the accident including decontamination of more highly contaminated surfaces, relocation of people to less- or un- contaminated settlements, restrictions on and modification of agricultural practice, the importation of food supplies from unaffected regions, etc. In addition, major improvements were madinfrastructure th o et e of some regions housing, ,eg , transportation, energy and water supplies, etc, and compensation paid to those continuing affectee livth o t n ei d settlements amoune ,th t varying wit contaminatioe hth nr levelfa y B . majorite th resourcee th f yo relievinr sfo consequencee gth accidene th f so t have beend an , 115 continue to be, spent on compensation and infrastructure improvements, notwithstanding e facth t that these hav einfluenc y littl radiatioe an f th ei n o e n level riskd an swhico st h people continue to be exposed. The policies adopted by the authorities to reduce the longer term consequences of the accident gave rise with tim muco et h oppositio anxietyd nan . This escalated considerably late inth e origins 1980it d san s wer unconnectet eno d wit broadee hth r socia politicad an l l changes that were occurring in the former USSR at that time. The adequacy of the policies being adopted to assure acceptable living conditions became the subject of heated debate and disagreement between various scientific factions and interest groups and between the Republics and central government. This contributed to a general loss of confidence among those affected in the measures being taken to secure their well being and in the credibility of those giving them advice, in particular officials and scientists. This process had several negative effects, in particular, many people left the affected settlements, especially the professional classes, with major social implications for those remaining and for the continuing viabilit somf yo e settlements adoptioe ;th differenf no t standard policier so n si each Republic (and occasionally within different region same th f eso Republic) compounded the loss of confidence among the affected population. The subsequent break up of the former USSR further exacerbated matter eacs sa h Republi responsiblw no s ci financinr efo g its own countermeasures' programme as opposed, formerly, to being funded centrally from the former USSR government. Considerable resources are being spent by the three Republics on moderating the consequences of the long term contamination of their territories. In the Ukraine and Belarus currene th , t level expenditurf s o orde e th f ro oftee ear n percen theif to r respective annual Gross Domestic Products (GDP); similar leve expendituref o l , albei differena t a t t percentage of GDP, is being incurred in Russia. Annual levels of expenditure at or about these levels are being anticipated by the respective Republics for the foreseeable future. These level fundinf so unlikele gar sustainable b o yt eithen ei mediue rth longer mo r term, give othee nth r more pressing economic, socia environmentad an l l problemse faceth y db three States. Indeed, give e otheth n r environmental problems they face (from both radioactiv conventionad ean l pollution mattea s i conjecturr t )i fo r e whether e somth f eo considerable funds currently being allocated to mitigate the Chernobyl consequences could not be better directed elsewhere. Reduction of the levels of funding or even their re- allocation to other priorities in the affected areas will, however, present formidable political sociad an l difficulties even when such action coul justifiee db objectivn do e considerations. The difficulties that would be encountered in attempting to effect such change would include: resistanc e reductioth o et r removano compensatiof o l n payments (probable yth major contributor to the overall costs of remedial measures); the need to avoid further alienation of the population and diminution in their belief in scientists and officials, especially given the frequent changes and arguments over policy in the past and promises of remedial measure t havinsno g been fulfillede probleth d changinf man o ; currene gth t expectation f thoso s e affected with regar theio dt r future situation. Clearly sucy an ,h process would carefulle neeb o dt y manage matterf di made b s o et wer t worseeno . Given the very substantial human and monetary resources that have been, and continue to be, spent by the three Republics to alleviate the consequences of the Chernobyl accident, it is evident that any contribution made by the CEC can only be modest in comparison. However, with proper targeting, such support could have an influence and benefit far beyond that measured in purely monetary terms. The scope and content of the CEC/CIS joint programme on the consequences of the Chernobyl accident have been formulated with primthia s sa e objective. 116 2. THE CEC/CIS PROGRAMME e programmTh s initiallwa e y conceive r implementatiofo d n withi e framewornth f o k CHECIR (Chernobyl Centr r Internationafo e l Research) whic s establishehwa n a y b d agreement between the former USSR and the International Atomic Energy Agency (IAEA) in 1990. However, becaus politicae th f eo l changes that occurre formee th n di r USSRn i 1991, a different procedure had to be followed. This culminated in an agreement being signe Junn di e 1992 betwee Commissioe nth thre e Statew th e d ne Belarusf so an n , Russia Ukraind an establiso et joine hth t programm workf eo . This marke formae dth l beginning of the programme but much preparatory work had already been undertaken in anticipation agreemenn oa f t being reached. 2.1 Scope and content of the joint programme The main purpose of the joint programme is to complement and assist those in the three Republics responsible for evaluating and mitigating the consequences of the accident. An important by-produc gaio t improven s na i t d understandin knowledgd gan healte th f eo h and environmental impact of radioactive contamination and of how it can be reduced; this will be invaluable for the management of any future accident. The programme can be conveniently categorised under three broad headings: the evaluation of measures to mitigate the consequences of the accident the evaluation of the health and environmental consequences of the accident off-site emergency management Centra eaco t l thesf ho e area reliabla s si e understandin behavioue th f go radioactivf o r e contamination in the environment and its transfer to man. Consequently, this aspect was given priority withi e firsnth e tprogramme th yea f o r , with lesser resources initially allocated to the evaluation of mitigation measures and to off-site emergency management. logisticar Fo organisationad an l l reasons, few resources coul allocatee db evaluatioe th o dt n of health consequences during the first year of the programme; this will change in the second year when projects in this important area will be phased into the ongoing programme. joine Th t programm s beeeha n formulate mako t d f limiteeo bes e resourceC us tdE o t s complement the on-going work in the three States. Much is already known of the current radiological situation (both healt environmentald han affectee th n )i d territoriew ho f o d san it might develop in the future from the extensive investigations that have been, and continue to be, made by CIS scientists since the accident. These investigations provide the scientific basis for the policies currently adopted to mitigate the consequences of the acciden ensuro t d tean acceptable living condition thosr sfo e remainin affectee th gn i d areas. An improve mord dan e comprehensive understandin radiologicae th f go l situation could, however, assist in achieving a more effective use of the considerable resources currently being allocated to mitigate the consequences of the accident. The joint programme will contribute to an improved understanding in a number of ways, not least through the synergy resulting from the integration of scientists with different backgrounds and experience. The upgrading of the local scientific infrastructure through e provisioth f westerno n technolog equipmend yan t (and trainin s useit )n gi will also contribute greatl thio yt s proces wils exchange a s th l scientistf o e s betwee institutee nth s involve programmee th n di furtheA . r benefit t foresee outsee no ,programmee th th t f na to , will be its contribution towards maintainingeffective interaction between scientists from the respective States. This has diminished since the break up of the former USSR but such 117 interaction remains important for, inter alia developmene th , countermeasuresf to ' policies tha e capablar t f receivineo g broad public acceptance e adoptioth ; radicallf no y different approaches by the respective States would probably be counterproductive in this respect. Finally, notwithstandin qualite gth competencd yan wore th f keo already carriey b t dou scientists in the three Republics, the involvement of EC scientists will help restore the credibility of the CIS scientists both with officials and the public in affected settlements; this was partially lost in the affected regions in the years following the accident. 2 Programm2. e managemen practicad tan l aspects A Coordination Board has been established to monitor and supervise the implementation of the joint programme. It comprises three representatives from the Commission and one representative, plus an observer, from each of the three CIS States. A secretariat has been create suppordo t Coordinatioe tth n Boar works Coordinatioit e n di Th . n Board meets twice functions it yea a d ran s include, inter alia approvae th , l of joint projects appointmene th , t of coordinators, the approval of external publications, the provision of guidance on priorities, e approva th e distributioth f o l f financiano l resource r locafo s l support, exchangf o e scientist acquisitioe th d san equipmentf no . Progress report eacn so h projec made ar t t ea each meetin Coordinatioe th f go n Board. r eacFo h project approve Coordinatioe th y db n Board, scientific coordinator appointee sar d CISe th .d Theian C rE coordinat o rolet e e th sar n i varioue wore th e th f ko s instituten si the EC and CIS, respectively, and jointly to progress the projects to successful completion repord an thein o t r outcomes. offic C s beeE ha en n A installe s locatei d Zelenn an di d s outsidyMy e restricteeth d zone about 30 km from the Chernobyl nuclear power plant. Its main function is to provide practica d logisticaan l l support (eg, transport, accommodation, communications, interpretation and translation, distribution of dosimeters, etc) for those attending meetings and/or undertaking experimental and other projects in and around the restricted zone. In addition laboratorC E n a , beins yi g establishe Chernobyn di provido t l e suppore th r fo t experimental projects; this facility and its equipment are also available for use by CIS institutes participatin programmee th n gi possibilite Th . establishinf yo g complementary facilitie Belarun i s Russid san undes ai r consideration. . ACHIEVEMENT3 FIRSE TH TSN YEAI THF RO E JOINT PROGRAMME Only a brief summary of progress and achievements within the first year of the programme gives i n here; further detailfoune b referencn n di s ca e [1]. Seven projects were initiaten di firse th t year: fiv thesf eo e were concerned wit environmentae hth l behaviou radioactivr ro e contamination wite on ,h decision support system off-sitr sfo e emergency managemend tan one with interventio besw n mitigat o levelt ho d consequencee san eth accidene th f so r fo t those continuin livgo t affecte n ei d areas addition,n I . numbea initiativef ro s were taken facilitato t e implementatioth e e healtth f no h related projects which were scheduleo dt commence durin secone gth dprogrammee yeath f o r . Progres eacn si thesf ho e areas si summarised. The financial resources provided by the Commission for the first year of the programme were abou 2 MECUt a furthe; MEC1 r s contributeUwa y thos b dinstituteC E e s participatin programme th gn i cosa n eto shared basis. Abou Commission' e thire th tf on do s financial contributio s allocate e direc nwa th participantS r CI tfo d benefi e th f n o i st particular for the purchase of equipment, the exchange of scientists and for local assistance. A more detailed breakdown of the distribution of resources between these three areas can be foun referencn di e [1], 118 1 Evaluatio3. measuref no mitigato st consequencee eth accidene th f so t elementy ke programme e th Onth f so f edevelopmene o th s ei computerisea f o t d decision aiding system which can be used to evaluate mitigation strategies, either those being implemented, planned or proposed in the affected territories of the CIS. The system will provide decision makers with a valuable and easily applied means for exploring the various policies and assess their implications in terms of cost, exposures to radiation and their social impact including effects on public attitudes and the likelihood of a policy gaining public acceptance. The latter is of particular importance as experience following the accident showed that considerations of a social nature had the greatest influence in determining the policy adopted. Much of the technical data needed by the system exists but is dispersed through many institute CISe th e consolidatio ;n th si validatiod nan thesf no e data, with improvement where necessary, have been important first steps in establishing an effective system. Each of the projects concerned with the behaviour of radionuclides in various parts of the environment (see belowmajoa s ha r) e rolconsolidation plao th t e n yi , validatiod nan improvemen f dato t a needed course du directioe n eth i ; thesf no e environmental projects will, inter alia influencee b , systeme neede th th f y so db . Dat socian ao l attitudes with regard to mitigation measures are sparse and this aspect has been explored through pilot social survey affecten a n si d settlement; fuller surveys will subsequentl carriee yn b i t dou representativa e rang settlementf eo orden si compilo rt appropriatn ea e data bas thin eo s aspec inclusior tfo systeme th n i . A prototype versio systee th f n mo schedules i 199f o completiowilr d d 4dfo an en l e th y nb be a valuable aid for those responsible to explore the implications of alternative mitigation policies wit hviea makinwo t resourcef go best e us s availabl improvinr efo conditione gth s of those continuin livgo t affecte n ei d areas. 3.2 Environmental behaviour of radioactive contamination maie Th n purpose projectf so s implemente thin di s area are provido :t inpun ea reliablo tt e assessment healte th environmentad f so h an l consequence accidente th f so contributo ;t o et the data bases needed for the decision aiding system for evaluating countermeasures; and to gain an improved understanding of the environmental behaviour of radionuclides that will be invaluabl respondinn ei futury an ego t accident. Five projects have been implemented during the first year in this area and are concerned with various processes by which material is transferred through the environment, or with transfer through particular parts of the environment. They comprise: resuspensioe th redistributiod nan contaminatiof no n transfee th depositef o r d materia agriculturao t l l producinfluence th d ean e of agricultural practice the transfer of deposited material to and within water bodies around Chernobyl the decontamination of surfaces and foodstuffs transfee th depositef ro d materia naturan li semi-naturad lan l environments. Considerable information already exist n mano s f thesyo e topics froe extensivmth e programme of work undertaken by CIS scientists following the Chernobyl and other accident e formeth n si r USSR. Littl thif eo s information, however previousld ha , y been 119 exposed to review outside the CIS or compared with western experience. In this context, one of the main initial aims of the programme has been to consolidate and validate existing informatio identifo t d initiatd nan yan e additional experimental projects which could further the programme objectives set out above; comparison with western data and intercomparison variouf so s experimental procedure importann s a hav d eha t rol thin ei s respect. Within each project, experimental field campaigns were successfully conducted, notwithstandin gnumbea infrastructuraf o r logisticad an l l difficulties experiencede Th . succes thesf so e activities particulan ,i establishmene rth effectivf to e working relationships betwee varioue nth s institutes, augur future s th wel r efo l outcom programmee th f eo . 3.3 Health consequences Projects in this important area will be formally integrated within the programme during its second year numbeA . initiativesf ro , however, have already been mad respono et d more quickly to an apparent major increase in the incidence of thyroid cancer in children in some e contaminateoth f d States. Some increas thyroin ei d cancer s anticipatewa s thosn di e settlements where restriction e consumptioth n o s f locallno y produced food beeha dn delayed; this delay resulted in very high exposures of the thyroid gland of some people. However, neithe e magnitudth r e excesth f o es numbe f caseo r s being reportee th r no d relatively short time after the accident at which they are occurring were expected. A panel of thyroid experts was established by the CEC in early 1992 to evaluate the situation panee Th . l concluded thatt possibl t no present a , s predico et wa t i ,future th t e extent of the incidence of thyroid cancer but stressed the importance of long term monitorin populatione th f go stronglt I . y recommended that actio takee nb n urgentle th t ya public health leve provido t l e assistanc diagnosie th r efo treatmend san thyroif to d cancer scientifie th t a d c an leve increaso t l e understandin aetiologe th f go thyroif yo d cancersA . more detailed report on the findings of this panel are contained in reference [2]. The content of future projects within the health area of the joint programme will reflect these recommendations. Preliminary investigations have also bee ne feasibilitth mad f o e f conductino y g epidemiologica hundrew fe l studiee dth thousann o s calleo ds d "liquidators wero wh "e involve restorinn di damagee gth d reacto safa o et r conditio cleaninn i d n an highl p gu y contaminated areas around the site; many of these workers received substantial exposures. 4 Off-eit3. e emergency management Following the Chernobyl accident there was a recognition in many countries that additional resources for, and improvements in, off-site emergency management were needed. The widescale dispersion of material released during the Chernobyl accident was a salutary lesson wert i f ,i e needed, that pollution doe respect sno t national boundaries; this experience led to various protocols being established to improve communication between countries, with a view to enabling a more timely response to any future accident. Notwithstanding these arrangements, more needdone b thin o esi t s area. Significant western resources are currently being provided to assist in improving reactor Easterd an S n s CI eviden i Europ e t safeti th t tn bu ei y tha t this canno achievee b t d immediately. In the interim, increased attention needs to be given to ensuring the efficacy of off-site emergency arrangements which provide the last line of defence in mitigating the consequences of a nuclear accident. Against this background a collaborative project was initiated to develop a decision support system for off site emergency management that would be generally applicable in the EC and 120 the CIS. Independent systems were already at an advanced stage of development in both bese th t d featurean S eacf CI o beinse e har th g d incorporatean C E e th d int joine oth t system. Through this approach duplication of effort is being minimised and best use is being made of the resources available; in addition the potential exists to test the performanc systee th f eo m using data obtained durin Chernobye gth l accident. The software/hardware configuration being used in the CEC system, RODOS (Real time On- line DecisiOn support System), has been adopted as the platform for the joint system and demonstratioa n versio completes nwa 1992 n systede i Th . m (hardwar softwared ean o t s i ) be transferred to each of the three States to facilitate its further collaborative development and a pre-operational prototype is scheduled for the end of 1994. Once operational, this system will provide an effective and timely means for exchanging information on future accidents thus enabling appropriate measure takee b neighbourino n st i g countries. 3.5 Equipment, local assistance and exchange of scientists Fro outsee recognises mth wa t i t d tha locae tth l infrastructur insufficiens ewa supporo t t t the needs of the envisaged programme. In particular, there were inadequate laboratory facilities and equipment, both within the restricted zone and nearby, for the scale and natur plannee th f eo d experimental programmes. Moreover equipmene th , t tha exisd di t t was dispersed over many institutes. Resources from within the programme were therefore allocate establishmene th r dfo regionaa f to l radiochemical laboratory withi restrictee nth d zone. In addition, other equipment, essential for the conduct of the programme, was purchased for use by particular CIS institutes who were participating in the programme. Resources have also been provide locar dfo l exchange assistancth r fo scientistsf d eo ean . The latter is regarded as a particularly important part of the programme and is a matter likel receivo yt e greater resource futuree th n si . SECONE 4.TH THIRD DAN D PROGRAMM YEARE TH F SO E The seven projects initiated during the first year of the programme were continued in the second year, with the bulk of the work being carried out during 1993. In addition, a further three projects in the health area were begun. These are concerned, respectively, with biological dosimetry including cytogenetics, epidemiology and patient treatment. There was a significant increase, to about 4 MECU, in the financial provision made by the Commission for the second year of the programme; in addition, a further 2 MECU is being contributed by EC institutes participating in the programme on a cost shared basis. A further increas Commission'e th n ei s contributio abouo nt MEC7 t Uforesees i e th r nfo third year of the programme (to be conducted largely in 1994); this will be supplemented b furtheya MECr3 participatiny Ub institutesC gE projectn te . Eace th sf hbeino g carried secone th n i dt programme yeath ou f ro e wil continuee b l thire th ddn i year and addition ,i n a further six projects will be initiated. These will be concerned with: retrospective dosimetry, molecular biological characterisation of thyroid cancers, thyroid cancer diagnosis and treatment, an atlas of radionuclide contamination of the affected territories, pathway analysis and dose distributions in the affected settlements and, finally, the separation of the ongoing projecterrestriae th n o t l environment into transfer, respectively planto t , d san animals. 5. FUTURE PERSPECTIVES e compleTh x political contex whicn i t h this collaborative programm s launchewa e s di evident. It was originally conceived to be a collaboration between the Commission and the 121 former all Union Ministry of Atomic Power and Industry (MAPI) within the CHECIR framework t finallI . y materialise Agreemenn a s da t betwee e Commissionth thred nan e independent States. experimentaMuce th f ho lprogramme parth f to beed eha n planneo dt take place withi e restricteth n d zone around Chernobyl; consequently e resourceth , s available for local infrastructure and support were largely concentrated in or nearby this area. Followin break-ue gth USSRe th f po , however, almos whole restrictee tth th f eo d zone falls withi territore nth Ukrainee th f yo . Some dissatisfaction with this situatio sincs nha e been expressed by the other two States, in particular they have noted that the consequences of the Chernobyl accident are not exclusive to Ukraine and that there were equally pressing problems in both Belarus and Russia. Furthermore, they have questioned the logic of conducting most experiment restrictee th n si d zon opposes ea regionn i o dt s where people continuine ar livego t ; informatio lattee th morclaimef s n ri no o e eb direco dt t relevanco et e resolutioth f publino c health issues additionn I . numbea f o , Chernobye f o ron t bu s i l regions in the former Soviet Union where significant and extensive radioactive contamination exists; these have equally pressing problems worthy of attention from both humanitaria scientifid nan c viewpoints. Against this background, consideration needs to be given to alternative ways of implementin programme gth achievo et morea e equitable distributio worf n resourceo d kan s between the three States. In addition, the extension of the Agreement to include other contaminated regions of the former USSR needs to be addressed. The establishment of EC liaison office Belarun i s Russid an s coordinato at participatioe eth institutef no e th n si respective States within the present programme is a modest step in this direction; it is unlikely, however, to be sufficient, either in terms of satisfying the aspirations of the two States or in terms of optimising collaboration with them. The most promising and practical means of circumventing these difficulties and further enhancing the efficacy of the programme woul creato t e d b regionae a l networ centresf ko eac,n i wit e h hStateon . Such networa k will, inter alia: consolidat extend e an successfu e dth l collaboration establishe firse th tn di year of the programme and contribute to the integration of the respective scientific communities for infrastructurn e basia m th f o s usee b thadn morca t e e widelth r yfo implementatio coordinatiod nan othef no r CEC/CIS assistance programmes provid visiblea e presenc eacn ei h State which, with proper targeting, could be used as one of a number of means of public communication with a view to restoring and/or increasing public confidenc radiologicae th n ei l information and advice they are being given enable more effective collaboratio scientistS nCI betwee d an s C throughnE , firstly, the establishment and equipping of laboratory facilities in each State and, secondly provisioe th , infrastructurn a f no suppord an e e eacn th i t f ho widely dispersed regions in which investigations will be carried out. Give majoe nth r benefits that could result, serious consideration wil givee lb establishinno t g regionaa l networ centref ko s withi future nth e implementatio programmee th f no . 6. SUMMARY The programme has been successfully launched, albeit later than originally intended consequent upon the political changes that occurred in the former USSR. Much preparatory work was, however, undertake anticipation i Agreemene th f no t whic signes e hth wa y db 122 contracting parties in June 1992. This enabled the formal programme, and in particular the experimental field campaigns, to begin promptly once the Agreement had been signed. This preparatory phas s intensivwa e involved an e d considerable interactio d negotiationan n interestee betweeth f o l nal d parties. Numerous practical difficulties were encounteren di establishing the programme, not least the considerable logistical problems associated with conducting major experimental project distanr fa t sa t locations unfamilian i , r surroundings and within a less developed infrastructure than is common in the EC. Moreover, these difficulties were exacerbate majoe th y rdb economic changes taking sam e placth t eea time withi respective nth e States. These problems, however, were largely overcome througe hth commitmen e manth f yo t participant o ensurt s e succese programmeth eth f o s . Much experienc s beeha e n gaine thin i d s firs e tprogramm th yea f o r e useeb o that dn ca t advantag optimisinn ei future gth e programme. Inevitably, e efformucth f tho withi e firsnth te programm yeath f o r s beeeha n spenn i t identifyin establishind gan g effective working relationships with appropriate instituten si the CIS. While this was a time consuming process it was essential in order to create a solid platform on which the future programme could be based. It was also important to spend significanteffort in identifying and evaluating the considerable information that had already bee scientistnS gathereCI e th s y dfrob m their extensive investigation orden si avoio t r d repeating what had already been done. At a technical level, the experimental field campaigns were all conducted successfully and profit wil takeexperience e b l th f no e gaine futurn di e campaigns conceptuae Th . l basif so a decision support system for evaluating different mitigation strategies has been developed; more remains to be done, however, in terms of interacting with and making best use, within systeme resultth e experimentae th th f o ,f so l investigations wel w neee thir lno Th d.fo s si recognise stepd dan s have been take ensuro nt e that thi s achievei s futuren di . More progress than anticipated has been made in the area of off-site emergency management. An agreement to jointly develop a decision support system for this purpose was reached and the agreed hardware/software configuratio providesystee e b th o f t n mo s thre e i eac o dt th f eho State facilitato st futurs eit e development. In summary, progress in the first year of the programme has exceeded expectation when taking account of the difficulties associated with establishing an ambitious programme in unfamiliar surroundings. A solid foundation for the programme has been established on whic s futurhit e succes builte b n . sca Many practica logisticad an l l difficulties remain but, given the commitment of the participants, these should not prevent the broader programme objectives being achieved. The second year of the programme is now underway and progressing satisfactoril accordancn i d yan e with expectations numbeA . f additionao r l projects have been identified for implementation within the third year and these will broaden the scope of the joint programme significantly. [1] COMMISSION OF THE EUROPEAN COMMUNITIES, Annual Report of the Coordination Board of "The Agreement for International Collaboration on the Consequences of the Chernobyl Accident", (1993), to be published in the EUR series of reports. [2] COMMISSION OF THE EUROPEAN COMMUNITIES, Thyroid Cancer in Children living near Chernoby Experl- t Panel Repor Consequencee th n to Chernobye th f so l Accident, (edite Williamsy db , PuicheraD. , , KaraoglouA. , Chadwickd an . A , , K.H., serieR publishee reportsb f EU so o t e th n .di Next page(s) lef3 t 12 blank A SHORT NOT RECENN EO T USA/CIS COLLABORATIVE STUDIE IMPACN SO T ASSESSMENT W.L. TEMPLETON Battelle Pacific Northwest Laboratories, Richland, Washington, United State f Americso a The accident at Chernobyl NPP in April, 1986, resulted in large-scale contamination of surface water caused by direct deposition of airborne material on the water surface, run-off from the drainage areas, and migration in groundwater. Following an initial large pulse of short lived fission products, the main contaminants have been strontium-89, strontium-90, caesium-134 and caesium-137. In 1989 formee th d ran SovieA US t e Unioth n signe Memoranduda Understandinf mo g (MOU conduco t ) t collaborative studies on Aquatic Radioecology and Dose Assessment. In 1993 separate MOUs with Russia and the Ukraine were signed. Initially the studies were focussed on the Pripyat and the Dnieper Rivers, with emphasis on the Kiev and lower reservoirs. The first study estimated radiation doses for the years 1986, 1987, 1988, 1989 and 1990 to member publie th f so c living downstrea Chernobymf o l alongsid reservoire eth Dniepee th f so r River from radioactivity in river water, fish, and associated pathways. Dose estimates for people who might have consumed fish from the Chernobyl NPP cooling pond were also calculated. The Pripyat River discharges into the Kiev Reservoir. The lower part of the Pripyat River and the upper portion of the Kiev Reservoi zone m generalld k an 0 e withi,3 li r e th yn contai e highesnth t concentrationf o s radionuclides outsid cooline eth g pond. To provide representative radiation dose estimates from the aquatic pathways to people living alongsid Pripyae eth Dnieped an t r Cascades, four groups were defined e fouTh r. groups represent professional fishermen, recreational fishermen, local residents (average consumer) who eat fish occasionally (e.g. when givea gif s t na from recreational fishermen), e purposeandth r ,fo f o s investigatin impacte gth irrigatiof so lowee th n nri Dnieper area t irrigate grouea a , o pwh d produce. e professionaTh l fishermen e confuseshoulb t no d d with commercial fishermen, since thee ar y employed by the collective farms to harvest fish for the use of the members of the collective farm. Ther commerciao n s ei l purposefishine th r gfo marketinf so generae th o gt l public. Estimated annual radiation dose commitments were measured in terms of the effective dose equivalent in Sieverts for each year, location and exposure scenario combinations. For the groups consuming more than a few kilograms of fish per year (professional and recreational fishermen), the pathwa mosf yo t importanc consumptioe th s ei professionae th fishf r no Fo . l fisherme 198n ni d 6an 1987 fishing in the lower Pripyat River and upper Kiev reservoir doses were in the range 2.2E-01 to 2.8E-03 Sv/year. Potential recreational fishermen on the Chernobyl NPP cooling pond over the years 198 199o 6t 0 could have received range doseth n ei s 9.6E-0 1.4E-0d 2an 2 Sv/yeare th r Fo . average consumer o eatswh , fish rarely e drinkinth , g water pathway becomes relatively more important, providing more than half of the total dose per year. Doses to average consumers drinking untreated river water fro lowee mth r Kiev reservoir ranged between 1.2E-0 IE-0. 2 d 54an Sv/year ove five rth e s apparenyearswa t I . t fro resulte mth s thapathwaye th t s relate irrigatioo dt f foono d lowecrope reservoirth o t stw ra s (Kremenchu Kakhovkad gan secondarf o e )ar y importance, always less than an order of magnitude of the contribution from drinking water and fish consumption of the average consumer majorite populationth e th r f Fo o y. aquatie th , c significana pathway t no e ar st problem. However, radiation doses may be relatively high for people deriving a subsistence living from fish, or from professional fishermen with a very high proportion of fish in their diets. The contributor thio st s study included B.A. Napier, W.L. Templeton (PNL); I.N. Ryabov (RAS)d an ; I.I. Kryshev, T.G. Sazykina (S.P.A. Typhoon). 125 The second study on aquatic pathways was to calculate the radiation dose rate for the aquatic Chernobye biotth n ai coolinP lNP g pond Pripyae th , Dnieped an t Kie e othed rth Riversvr an rfo d an , downstream reservoirs for the years 1986, 1987, 1988 and 1989. During the first month following the accident, the main radionuclides in the aquatic systems were iodine-131, barium-140, zirconium- 95, niobium-95, ruthenium-106 and cerium-141. The concentrations of these radionuclides in the Pripyat River decreasemiddle r morth o y n f Julyfactoa eb eo te y f db ,o r 1986, after which time strontium-90 and caesium-137 became the critical nuclides. In the Pripyat River in May 1986 aquatic plants received the highest doses » 85 mGy/d with strontium-90, barium-140 and cerium-144 contributing most of the total dose. The dose to fish was about a factor of ten lower than to aquatic plants. However concentratione ,th watee th n rsi fro shore mth t lived radionuclides decreased rapidly. Althoug half-livee hth f strontium-9o s caesium-13d 0an similare 7ar concentratione th , f caesiuso m declined more slowly than those of strontium, suggesting that caesium was being transported from the terrestrial watersheds. Annual doses to fish from caesium-137 in the upper part of the Kiev reservoi yeare th r s rfo 1987 mGy5 ,198 0. d 198 d ,an 9 8 an respectively wery emGy2 mG 1 , . Annual doses in the Kanev reservoir were about 200 /*Gy for the same years. Based upon these estimates it is unlikely that any deleterious effects will be detected at the population level, except for perhaps biota Chernobye inth coolinP NP l g pond contributorse Th . thio t s study included G.B. Blaylock (ORNL); W.L. Templeton (PNL); I.N. Ryabov (RAS); and I.I. Kryshev (S.P.A.Typhoon). 126 ASSESSMENT IN THE VICINITY OF DUMPED RADIOACTIVE WASTE THE INTERNATIONAL ARCTIC SEAS ASSESSMENT PROJECT (IASAP) K.-L. SJOEBLOM, O.S. LINSLEY Divisio f Nucleano r Fuel Cycl Wastd ean e Management, International Atomic Energy Agency, Vienna Abstract The IAEA has initiated the International Arctic Seas Assessment Project (IASAP) to address widespreae th d concern ove possible rth e healt environmentad han l impact radioactive th f so e wastes dumped in the shallow waters of the Arctic seas. The work is being carried out by the IAEA as part of its responsibilities to the London Convention 1972. It is envisaged that the project will last for four IAEe th co-operatioAy n i b n ru e yearb d ns an wit Norwegiae hth Russiad nan n Government witd san h involvemente th , throug IAEAe hth f experto , s from relevant IAEA Member States projece Th . s i t aime producint da independenn ga objectivd tan e assessmen potentiae th f o t l radiological implications dumpine o th faddreso t d questioe gan s th f possiblno e remedial measures same th t e A .time s i t i , intende provido dt efocua reportinr fo s g national researc assessmend han t mechaniswora d kan r mfo encouraging international co-operation and collaboration. 1. INTRODUCTION Internationae Th l Arctic Seas Assessment Project (IASAP initiates wa ) Februarn di y 199o 3t address widespread concern over the possible health and environmental impacts associated with the radioactive waste dumped in the shallow waters of the Arctic seas. The project is being executed as a part of the IAEA's responsibilities under the Convention on the Prevention of Marine Pollution by Dumpin Wastef go Othed san r Matter (London Conventio n'72) C 197L .r 2o In this report a brief history of the dumping of radioactive wastes at sea is presented to provide some perspectiv dumpine th r efo g activitie Arctie th IASAe aime n th si c th f seaso d P sprojecan e ar t described together with the plans for its implementation. . RADIOACTIV2 E WASTINTERNATIONAE TH D E DUMPINAN A SE T LGA SYSTER MFO ITS CONTROL 2.1 brieA . f histor dumpinf yo g activities The first recorded sea disposal of radioactive wastes took place in 1946 at a site in the northeast Pacific Ocean, about 80 km off the coast of California. In subsequent years, as sea disposal became increasingly widely used as a radioactive waste disposal option, the pressure for it to be controlled also increased. Figur givee1 summarsa dumpine th f yo g operations officially reported before 199e 3th [1]f O . total amount of radioactive material (46 PBq), more than 98% has been disposed of in the North Atlantic Ocean thereoeastere % th 92 , n i fn basin. Figur showe2 annuae th s l dumpinge th rat t ea northeast Atlantic dumping sites up to 1982. The radioactive waste referred to in Ref. [l] originated from the application of radionuclides in research and medicine, from the nuclear industry and from military activities and was packaged, usually in metal drums lined with a concrete or bitumen matrix. Some unpackaged wast liquid ean d waste were also dispose betweef do n 195 1960d 0an . Reference [1] does not include the data supplied recently by the Russian Federation on the dumping activitie formee th f so r Sovie tRussia e Unioth d nan n Federation. 129 West Pacific 16 sites site5 1 s 5 sites 0.5q 5PB 42.31 PBq 0.0q 2PB FIG . Location1 . quantitied san leve w lo lf swasteo s dispose oceanse th n i f d,o excludin dumpine gth g operation formee th f so r Sovie Russiate Unioth d nan n Federation [1]. PBq(1015Bq) Total Radioactivity 8 - North-East Atlantic Sites 1949-1982 5 - 4 - *> - 2 - 1 - ~i—i—i—i - -ji-i - J=p-cp"' 2 yea8 r0 8 8 7 8 7 4 7 2 7 0 7 8 6 8 6 4 6 2 6 0 6 8 5 6 5 4 5 2 1955 0 FIG. 2. Total radioactive material disposed of annually between 1949 and 1982 at the Northeast Atlantic Ocean sites [1]. In May 1993 the Russian Federation provided information to the IAEA about the high and low level radioactive waste dumped in the Arctic seas during the years 1959-1992 [2]. The total amount of radioactivity dumped was more than 90 PBq. The items dumped included seven nuclear submarine or icebreaker reactors with fuel containing a total of 85 PBq; ten reactors (without fuel) containing 7 PBq3. ; liqui levew dlo l waste containin soli d 9 PBqan g0. d ; intermediat levew lo l d wastean e containing 0.6 PBq. The packaged and unpackaged solid waste and the nuclear reactors were dumped shalloe th n i Kare wa th bayaSe n i Novayf so a Zemlya, wher depthe dumpine eth th f so g sites range trouge th n Novayf i ho d liquie an leve Th w a, . dlo m Zemlya lm 5 0 dept13 a 38 t o a frot f , ho 2 m1 wast discharges ewa opee th nn d i Barent Kard an s a Seas. Figur showe3 approximate sth e location of the Arctic dumping sites. Information was also provided on the waste disposed of in the Sea of Japan. Her overale eth l quantitie considerable ar s y disposae smalleth d an rl dept greaters hi . internationae 2.2Th . l control system e firsTh t Unite n 195i 8a d Se recommendeNation e th f o s Conferencw La d e thath e th n t o e IAEA should assist State controllinn i s e dischargth g f radioactivo e e materials inte seath o n ,i promulgating standards, and in drawing up internationally acceptable regulations to prevent pollution radioactivy b a se e oth fe material amountn i s s that marins woulhi d dean affecresourcesn ma t e Th . IAEA duly set up successive scientific panels to provide specific guidance and recommendations relevan disposae th o t t f radioactivo l e waste firse t seaTh sa t . IAEA experts meetin subjece th n go t was held in 1957 and the first publication was issued in 1961. Conventioe Th Preventioe th n no Marinf no e Pollutio Dumpiny nb Wastef go Othed san r Matter was establishe entere d 197n di an 2 d into forc 1975n ei . This convention became well knowe th s na 'London Dumping Convention' but has recently been renamed as the 'London Convention 1972'. The Convention is recognized as the main international mechanism for the control of waste dumping at sea. 131 70° 70 40° • = Reactors containing fuel 85PBq (1965-1981) • = Reactors without fuel 3.7 PBq (1965-1988) SoliA= leve w dlo l waste q PB 6 0. (1964-1991) $ Liquig= levew dlo l waste 0.9 PBq (1960-1992) FIG. 3. Sea disposal of radioactive waste in the Arctic Seas by the former Soviet Union and the Russian Federation. Conventioe Th n prohibits, inter alia, dumpine th higf go h level radioactive waste required san s that low level radioactive wastes be dumped only after a special permit has been issued. The London Convention gav IAEe e th tas e Adevelopinf th k o gdefinitioa higf no h level radioactive wastes which unsuitable ar disposar efo mako t seat a ld e, an recommendation nationao st l authoritie issue th en so of special permit ocear sfo n disposa f otheo l r radioactive waste r radioactivso e matters. In 1975 the IAEA published the Provisional Definition and Recommendations requested by the London Conventio s subsequentlha d nan y kept them under review developmene Th . IAEe th f Ao t definitio recommendatione somd th nan f eo illustrates si Tabln di . eI In 1983, following the concerns of some of the Contracting Parties to the Convention over the possible healt environmentad han l risks which coul producee db radioactive th y db e waste disposal 132 TableI DEFINITION AND RECOMMENDATIONS IAEA !NFCIRC/205/Add. 1 IAEA !NFC!RC/205/Add. 1/Rev1 . Safety (1986Serie8 7 . ] [5 )sNo (1975) [3] (1978) [4] High level wastes unsuitable for dumping at sea e; T1/2 > 50/y a a TO"x 7 1 3. TBq/kg, TBq/kB 0 1 x g 7 3. x 105 * TBq/kg bu tTBq/y/sit 7 "63. R a< e but 3.7 x 10'8 TBq/kg "6Ra ß/K B/r, Tia > 0.5 y B/K; T,,2 > 1 y 3.7 x IG'2 TBq/kg, but 10'x 7 3 3. TBq/kg x 10'2 2 TBq/kg ^Sr + 137Cs 3.7 x 10'3 TBq/kg 3 3 3 H HB/x+ y 5 ; 0. T,, < 2 H + B/K; T1/2 < 1 y TBq/k7 3 g TBq/k7 3 g 3 TBq/kg Irradiated reactor fuel and wastes fro firse mth t extraction processes of reprocessing of irradiated fuel. Dumping site Dept t leasha t 200 , clea0m f o r Oceans between 50° N and 50° S Oceans between 50° N and 50° S continentae th l shelf Average dept 400h> 0m Average dept 400h> 0m t neaNo r continental margins, open t neaNo r continental margins, open sea islands or inland seas sea islands or inland seas. Not in area f volcaniso c activity, ocean trenches, middle ocean ridges etc. Reporting Record-keepin reportind gan g Record-keeping and reporting to IMO Record-keeping and reporting to tolMO IMO. Notification of intention to dum monthx psi advancen si . operations, a voluntary moratorium on radioactive waste dumping at sea was imposed pending a wide ranging review of the issue. The IAEA has provided technical input to aid this discussion which is expected to be concluded in 1993. 3. PERSPECTIVES ON THE ARCTIC SEAS DUMPING (a) In the context of the London Convention Londoe Th n Convention prohibit higf disposae o sth ha levese t a l l waste (see mucTabld an h) eI of the material dumped in the Kara Sea falls into this category. It should be noted however that most of the spent fuel was dumped in the years before the London Convention came into being (1972 beford )an USSe eth R becam eContractina g e Partth o yt Convention (1976). In the years since the voluntary moratorium on radioactive waste dumping was established (1983) low level radioactive waste disposal has continued in the Arctic seas. Londoe Th n Convention specifies location depthd san s below whic dumpine hth leve w lo lf go wastes coul permittede db , when appropriate notification reportind an s g have been made (Tabl. eI) The Arctic dumping sites do not fit within these specifications and, in particular, many of the dumpin gvern i site ye ar sshallo w watersothee th rn O han. t shouldi notee db d that, e prioth o t r London Convention, dumpin f radioactivgo e waste beed sha n carrie shallon i t dou w coastal waters othen i rworl e partth f dso [1]. 133 (b) In the context of the hazards presented Insufficient information is currently available to properly evaluate the hazard to humans and the environment that coul e presenteb d e dumpeth y db d wastes e firsTh .t joint Norwegian-Russian exploratory cruise in summer 1992 was not able to sample in the immediate vicinity of the dumped wastes, but samples taken in the Kara Sea showed that the present levels of radioactive contamination e lowear r similao r conclusioe otheo t rth a area d se r an s reache nwa d thainfluence th te th f o e dumped wastes on the general level of radioactive contamination in the Kara Sea is insignificant [6]. It was noted, however, that local effects in the vicinity of the dumping sites could not be excluded. result e recene Th th f so t Norwegian-Russian cruise (September-October 1993) should hel clarifpo t y the situation. Whil t eappeari s tha tsignificano thern e ear t regiona globad an l l effect t presena s t froe mth dumped wastes e graduath , l deterioratio waste th f eno package containmentd an s s could leao dt impacts in the future. These could occur as a result of the contamination of the marine food chain, possibly resultin radiatioe th n gi n exposur f humaneo s throug consumptioe hth f othefisd no han r marine foodstuffs. Since the wastes are lying in shallow waters, the possibility of radiation exposure by other routes movemene , sucth , h as transpor d wastan te th f eo t package naturay sb l events (icr eo storm action), or deliberate human action cannot be ruled out. The timescales for consideration are very long (ten thousandf so yearsf so ) and, therefore possible th , e impac climatif o t c chang alss eha o takee b o nt into account orden I . provido t r e answer theso t s e question s necessari t i s havo yt ea thorough understanding of the present and future physical, chemical and biological characteristics of the environment surrounding the wastes and of the wastes themselves. preliminarA y assessmen indicates tha d that even unde mose rth t pessimistic release conditions, the wastes will not cause a significant global radiological impact, but recognizes that to evaluate the possible loca e riskregionad th an t l a s l scales will require considerably more information thas ni currently generally available [7]. 4. INTERNATIONAL ARCTIC SEAS ASSESSMENT PROJECT (IASAP) — AIMS AND IMPLEMENTATION 4.1. Objectives The objectives of the project are: (1) To assess the risks to human health and to the environment associated with the radioactive waste dumpe Kare Barentd th aan n d i s Seasd an ; examino T ) e(2 possible remedial actions relatedumpee th o dt d wasteadviso t d whethen eo san r the necessare yar justifiedd yan . projece endorseTh s Contractingwa e t th y db Partie Londoe th o st n Convention 15te 197th ht 2a Consultative Meeting in November 1992. The IAEA was requested to report its findings to the Convention at the earliest opportunity. 4.2. Project implementation projece Th organizes i t foun di r working groups: (1) Source terms, (2) Existing environmental concentrations, (3) Transfer mechanisms and models, (4) Impact assessment and remedial measures. 134 The work is being carried out using normal IAEA mechanisms: Consultants, Advisory Grou Technicad pan l Committee meetings, a Co-ordinated Research Programme, Research and Technical contracts. The project will be carried out in co-operation with the Norwegian and Russian Governments anticipates i t i d an d tha t wilfroi tn ru lm 199 1996o 3t . . IASA5 P WORK PLA PROGRESD NAN S 5.1. Source term In May 1993 the Government of the Russian Federation provided the IAEA with official informatio dumpee th n no d wast promises ea 15te th ht da Meetin Contractine th f go g Partiee th o st London Convention [2], but detailed information on the radionuclide composition of the dumped waste or on the characteristics of the fuel in the different types of reactors dumped was not included. To obtain the detailed source term information needed for performing an impact assessment, it will necessare b investigato yt archivee eth formee th f so r Soviet reconstrucUnioo t d nan historye th t f o reactoe th r fuel prio dumpingo rt thir sFo . purpose, research contract beine sar g placed with Russian institutes. Another group of questions concerns the protection barriers provided for the dumped reactors and the properties of the containments of the low level wastes. Basic information on the treatment of each typ f wasteo e before dumping must agai obtainee nb d fro Russiae mth n archives. reactore Mosth f o shieldete sar d with meta concretr o l filled ean d wit hpolymera , furfuralt I . bees ha n estimate designere th y db s that the saf e severar yar efo l hundred yearsf so . However, more advanced studies need to be done in order to make realistic predictions of releases of the different radionuclides from each of the dumped reactors. In this context, the collection of information on the physica chemicad lan l characteristic investigatioe furfuraf so th d an l stabilits it f no y against radiation, heat, saline water, etc. is necessary. In the framework of the IASAP project, it is planned that studies of this type will be conducted through international co-operation. Visual investigation of reactors and other wastes by means of underwater cameras during the exploratory cruises as well as in situ radiometric measurements and water and sediment sampling are of crucial importance for the source term evaluation. Participation of scientists from different countrie internationad san l organizations will hel givinn pi necessare gth y international credibilito yt these studies. The source term working group will hold its first meeting in late 1993. At that meeting, the result firse th tf scontractuao l report wil discussede b l firse th , t information packag modelline th o et g groups will be prepared and future work will be discussed. 5.2. Existing environmental concentrations Informatio levele th radioactivf n so no e contaminatio targee th n ni t areothed aan r e areath f so Arctic seas wil collectee b l inpus dglobaa a o t l data base whic undes hi r developmen IAEA'e th t a t s Marine Environmental Laboratory (IAEA-MEL). 5.3. Transfer mechanisms and models An IAEA Co-ordinated Research Programme (CRP) entitled Modelling of the Radiological Impact of Radioactive Waste Dumping in the Arctic Seas has been established. Several national laboratories, known to have expertise in marine radiological assessment, have been invited to 135 participate. IAEA-MEL will participate in the CRP as one of the modelling groups. The objective of develoo t s i P p realistiCR e reliablth d can e assessmen- t co modelArcti e o t th areaa r d cSe fo s an s ordinat efforte eth f differeno s t laboratorie fielde th n .si A staged approach to the final modelling assessment is being taken. In the early stages, when data is incomplete, a relatively simple preliminary modelling exercise will be conducted using unit releases. As more information becomes available, the exercises will become increasingly realistic. The final results of the modelling exercise will form the basis of the assessment for the London Convention. e firsTh t test scenarios were develope meetina t da g hel Viennn di Junn ai e 1993 with experts fro Russiae mth n Federation, Denmark/Norway Unitee th , d Kingdo IAEA-MELd man . These test scenarios are based on assumed unit releases into a simplified environment. The scenarios will be sent thoso t e modelling groups which agre participato et programmee th n ei firse th tt meetinA . e th f go CRP in early 1994, the results of test scenarios will be compared and analysed and a second test case, with improved source terenvironmentad man l information, wil developede b l . This meeting will provid opportunitn ea modele th modellinr d yfo san g approache criticalle b o st y analysed. Expertn si e fieldth f physicao s l oceanograph procesd an y s modelling wil e inviteb l o attent d orden i d o t r facilitat reviewe eth . greaA t dea informatiof o l neede s ni oceanographicae th n do ecologicad lan l feature areae th f ,so as well as on the living habits of possible critical groups. In order to obtain this information, contracts are being placed with relevant Russian institutes. 5.4. Impact assessmen remediad tan l measures The impact assessment working group leads and advises the other groups. It will follow and monito e informatioth r n stream fro e sourcmth e ter m e resulte sit th th groue f d specifio san p c ecological studies, and review the progress of the modelling group. It will also evaluate the need for and feasibility of remedial actions. This group will be mainly responsible for preparing the final I ASAP report and the recommendations for presentation to the London Convention 1972. The first meeting of the group will be held in May 1994. A small meetin technicaf go l experts wil hele b learl n di y 199 4discuso t evaluatd san e available possible engineering solutions for remediation. 6. CO-ORDINATION One of the basic ideas in establishing the IASAP project was to provide a mechanism for co- ordinating international efforts in the field. The co-operation with the Norwegian-Russian expert group is recognized as being essential to the IASAP project. At a meeting of the representatives of e Norwegian-Russiath n expert grou representatived pan y 1993 IAEe Ma th ,n f a smalA i o s- co l ordinatio comprisep u t membee nse on bod s f o dywa r from Norway Russiae th , n Federatiod nan IAEAe th . It has also been agreed that the results of the IASAP project will be made available to AMAP1 as one component of the overall review being conducted by that organization of the impact of all types of pollution on the Arctic seas. AMA componena s Pi Arctie th f co t Environmental Protection Strategy (AEPS adoptes )a Ministery db s of eigh1 t Arctic Nation thein si r Declaratio Protectioe th Arctin e no th f no c Environment, 1991. 136 . 7 CONCLUSION The dumping of radioactive waste in the Arctic seas has caused concern in many countries and s stimulateha d researc assessmend han t wor nationan ki l laboratories IAEe establishes Th . Aha n da international project in this topic area. The project aims to produce an independent and objective assessment of the potential radiological implication dumpine addreso th t f d so questioe an gsth possiblf no e remedial measures. At the same time, it is intended to provide a focus for reporting national research and assessment mechanisa wor d kan r encouraginmfo g international co-operatio collaborationd nan . REFERENCES [1] INTERNATIONAL ATOMIC ENERGY AGENCY, Inventory of Radioactive Material Entering the Marine Environment: Sea Disposal of Radioactive Waste, IAEA-TECDOC-588, IAEA, Vienna (1991). [2] Official Information supplied to IAEA on 21 May 1993 by the Russian Federation in accordance with the request of the 15th Consultative Meeting of Contracting Parties to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter. [3] INTERNATIONAL ATOMIC ENERGY AGENCY, Provisional Definition and Recommendations Concerning Radioactive Wastes and Other Radioactive Matter Referred to in Annexes I and II to the Convention on the Prevention of Marine Pollution by Dumping of Waste Othed san r Matter, INFCIRC/205/Add.l, IAEA, Vienna (1975). ] [4 INTERNATIONAL ATOMIC ENERGY AGENCY e IAETh , A Revised Definitiod an n Recommendations of 1978 Concerning Radioactive Wastes and Other Radioactive Matter Referred to in Annexes I and II to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, INFCIRC/205/Add.l/Rev. 1, IAEA, Vienna (1978). [5] INTERNATIONAL ATOMIC ENERGY AGENCY, Definition and Recommendations for the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972, Safet y, IAEA Serie78 . , sNo Vienn a (1986). [6] STRAND, P., et al., "Survey of artificial radionuclides in the Kara Sea", Environmental Radioactivity in the Arctic and Antarctic (Proc. Int. Conf. Kirkenes, Norway, 1993) (STRAND, P., HOLM, E., Eds), Scientific Committee of the Environmental Radioactivity in the Arctic and Antarctic, 0steras, Norway (1993). [7] BAXTER, M.S., et al., "IAEA programmes relevant to the radioactive waste dumped in the Arctic Seas: Par . Arcti2 t c Seas Assessment e ProjecIAEth t Aa t Marine Environment Laboratory", Environmental Radioactivity in the Arctic and Antarctic (Proc. Int. Conf. Kirkenes, Norway, 1993) (STRAND, P., HOLM, E., Eds), Scientific Committee of the Environmental Radioactivit Arctie th Antarctic d n yi can , 0steras, Norway (1993). 137 and of uncertainty associated wit moder hou correspondinf o l g population-average dosusin0 eD( ggeneraa l analytical framework for undertaking integrated analysis of uncertainty and interindividual variability [29, 31, 36, 32].