DERIVED RELEASE LIMITS (DRL's) for AIRBORNE and LIQUID EFFLUENTS from the CHALK RIVER NUCLEAR LABORATORIES DURING NORMAL OPERATIONS

AECL-7243

ATOMIC ENERGY KSM L'ENERGIE ATOMIQUE OF CANADA UMITED V^&jf DU CANADA LIMITEE

DERIVED RELEASE LIMITS (DRL's) FOR AIRBORNE AND LIQUID EFFLUENTS FROM THE CHALK RIVER NUCLEAR LABORATORIES DURING NORMAL OPERATIONS

Limites calculees pour la liberation des effluents liquides et en suspension dans I'air provenant des Laboratoires nucleaires de Chalk River au cours des operations normales

J.F. PALMER

Chalk River Nuclear Laboratories Laboratoires nucle'aires de Chalk River

Chalk River, Ontario

February 1981 feVrier ATOMIC ENERGY OF CANADA LIMITED

DERIVED RELEASE LIMITS (DRL's) FOR AIRBORNE AND LIQUID EFFLUENTS FROM THE CHALK RIVER NUCLEAR LABORATORIES DURING NORMAL OPERATIONS

J.F. Palmer

Chalk River Nuclear Laboratories Chalk River, Ontario KOJ 1JO 1981 February AECL-7243 L'ENERGIE ATOMIQUE DU CANADA, LIMITEE Limites calculees pour la liberation des effluents liquides et en suspension dans l'air proyenant des Laboratoires nuclgaires de Chalk River au cours des operations normales

par J.F. Palmer Rgsume

Des limites de liberation (DRL) fondles sur les limites de dose reglementaires ont £te calculees pour la dScharge routiniere de reactivity dans les effluents liquides et en suspension ians l'air provenant des Laboratoircs nucleaires de Chalk River. Trois types de sources d'effluents en suspension dans l'air ont ete consideres: la cheminee des reacteurs NRX/NRU, la "cheminSe de 61-m" (relive a 1'installation de production de molybdene 99) et un "eVent de toiture" (typique de ceux installes sur plusieurs batiments a Chalk River). Des sources d'effluents liquides se dirigeant vers la riviere des Outaouais ont et6 traitges comme une source unique provenant du centre dans son ensemble. On a considere dans les calculs divers itineraires d1exposition-des travailleurs du centre et du public en dehors du site de Chalk River.

Les DRL reprSsentent les limites maximales pour les Emissions routiniSres de radioactivity provenant de Chalk River et se dirigeant dans 1' environnement imme'diat. Les Emissions sont en fait assujetties S des niveaux rgglementaires inf^rieurs aux DRL et elles ont St§ confirmies par une observation r€guli§re. Cependant, les procedures adoptees pour rfigler ces aspects des operations de Chalk River sortent du cadre de ce rapport et ne font l'objet que de brefs commentaires. Les DRL sont fondSes sur le nouveau systSme de la limitation des doses recommandS par la Commission international de protection radiologique dans le document ICRP-26 qui est incorpor# S la derniSre Edition des r§glements de contr6le de l'gnergie atomique.

Laboratoires nucle'aires de Chalk River Chalk River, Ontario KOJ 1J0 Fgvrier 1981 AECL-7243 ATOMIC ENERGY OF CANADA LIMITED

DERIVED RELEASE LIMITS (DRL's) FOR AIRBORNE AND LIQUID EFFLUENTS FROM THE CHALK RIVER NUCLEAR LABORATORIES DURING NORMAL OPERATIONS

J.F. Palmer

ABSTRACT

Derived release ,;..--s (DRL's), based on regulatory dose limits, have been calculated for routine discharges of radioactivity in airborne and liquid effluents from the Chalk River Nuclear Laboratories (CRNL). Three types of sources of airborne effluents were considered: the NRX/NRU Stack, the "61-m Stack" (connected to the 99Mo Production Facility), and a "Roof Vent" (typical of those installed on several buildings on the site). Sources of liquid effluents to the Ottawa River were treated as a single source from the site as a whole. Various exposure pathways to workers on the site and to members o^ the public outside the CRNL boundary were considered in the calculations. The DRL's represent upper limits for routine emissions of radioactivity from CRNL to the surrounding environment. Actual releases are regulated by Administrative Levels, set lower than the DRL's, and are confirmed by monitoring. However, the procedures adopted to handle these compliance aspects of the CRNL operations are outside the scope of this report and are discussed only briefly. The DRL's are based on the new system of dose limitation recommended by the International Commission on Radiological Protection in ICRP-26, which is beinc incorporated in the latest revision of the Atomic Enemy Control Regulations.

Chalk Rix'er Nuclear Laboratories Chalk River, Ontario KOJ 1J0 1981 February

AECL-7243 - i -

TABLE OF CONTENTS

Page 1. INTRODUCTION 1-1 2. SITE AND POPULATION DATA 2-1 3. SOURCES OF RADIOACTIVE RELEASES 3-1 4. RADIOLOGICAL PROTECTION STANDARDS 4-1 4.1 Basic Standards - Individual Dose Limits 4-1 4.2 Derived Limits for Internal Exposures - Annual Limits of Intake (ALI) 4-4 4.3 Dose Conversion Factors for External 4-7 Exposures 4.3.1 Immersion 4-7 4.3.2 Standing on Contaminated Ground 4-8 4.4 Population Dose (Collective Dose) 4-9 Considerations 5. METHODOLOGY 5-1 5.1 General 5-1 5.2 Description of Environmental Transfer 5-3 Pathways, Exposed Groups, and Radio- nuclides Considered at CRNL 5.3 Formulation of Environmental Transfer 5-8 Pathways 5.4 Evaluation of Transfer Parameters 5-10 5.4.1 Transfer from Source of Airborne 5-10 Effluent to Atmosphere: (P ) 0/1 5.4.2 Transfer from Atmosphere to Ground/ 5-16 Soil: (P ) 1/ 3 5.4.3 Transfer from Atmosphere to Pasture 5-18 Grass and Leafy Vegetables: (P ) and (P ) 1'" 1/6 5.4.4 Transfer from Soil to Vegetation: 5-19 (P ), (P ) and (P ) 3/1 3/5 3/6 5.4.5 Transfer from Pasture Grass to 5-21 Milk: (P ) - ii - TABLE OF CONTENTS (Cont.) Page 5.4.6 Inhalation Rates and Ingestion Rates: 5-22 (P ), (P ), (P ), (P ), 1.9 2,10 5,10 6/10 (P ), and (P ) 7.10 8/10 5.4.7 External Exposure Due to Immersion in 5-24 a Radioactive Cloud: (P ), and {P ) 1,12 1 / 1 It 5.4.8 External Exposure Due to Radionuclides 5-26 Deposited on Ground: (P ) and (P ) 3 » 1 2 3,n 5.4.9 Transfer from Source of Liquid Effluent 5-27 to Ottawa River: (P } 0 , 2 5.4.10 Concentration Factors for Freshwater 5-28 Fish: (P ) 2/7 5.4.11 Transfer from Ottawa River to Garden Soil 5-29 Via Spray Irrigations (P ) 2/3 5.4.12 Transfer from Ottawa River to Leafy 5-31 Vegetables Via Spray Irrigation (P ) 2 > 6 • 5.4.13 Special Cases (Airborne Releases of 5-32 H-3 and C-14) 6. RESULTS OF CALCULATIONS 6-1 6.1 Maximum Permissible Release Rates (q ) for 6-1 Individual Pathways 6.2 Derived Release Limits (DRL's) for Critical 6-3 Groups 6.3 Derived Release Limits (DRL, ) Assuming Critical 6-6 Group is at the Boundary 6.4 Source Averaging Time 6-7 7. PRACTICAL CONSIDERATIONS 7-1 7.1 Uncertainties in Calculations 7-1 7.2 Multiple Sources 7-2 7.3 Mixtures of Unidentified Radionuclides 7-4 7.4 Management of Effluents (Setting Administrative 7-5 Levels, Monitoring and Reporting of Releases) 8. SUMMARY AND CONCLUSIONS 8-1

9. ACKNOWLEDGEMENTS 9-1 - iii -

TABLK OP CONTENTS (cont.)

Page

10. REFERENCES 10-1

APPENDIX A - The Atomic Energy Control Regulations

APPENDIX B - The Effects of Deposition/ Resuspension of Radionuclides

APPENDIX C - Nomenclature - IV -

LIST OF TABLES

2.1 Populations Within 80 km of CRNL 3.1 Major Sources of Airborne Effluents at CRNL 3.2 Sources of Liquid Effluents Discharging into Ottawa River at CRNL 4.1 Effective Dose Equivalent Limits Recommended in ICRP-26 4.2 Annual Limits of Intake, ALI, for Members of Public Based on ICRP-26 Dose Limits 4.3 Dose Conversion Factors (DCF ) for Continuous External Exposure Due to Immersion ina a Semi-Infinite Cloud of Noble-Gas Radionuclides

4.4 Dose Conversion Factors (DCF ) for Continuous External Exposure Due to Standing on ^ a Smooth Contaminated Plane Surface

5.1 Radionuclides, Pathways, and Exposed Groups Considered in Calculations 5.2 Factors for Decay, Occupancy, Usage and Shielding

5.3 Values of Transfer Parameter (P ) from Source of Airborne Effluent to Atmosphere0'1 5.4 Evaluation of Transfer Parameter (P ) (Transfer from Atmosphere to Ground/Soil) ''9

5.5 Evaluation of Transfer Parameters (P ) and (P ) (Transfer from Atmosphere to Pasturea' "* lr6 Grass and Leafy Vegetables) 5.6 Evaluation of Transfer Parameters (P ), (P ), (P ) (Transfer from Soil to Vegetation) 8/* 3'5 3'6 5.7 Evaluation of Transfer Parameter (P ) (Transfer from Pasture Grass to Milk) "'e 5.8 Assumed Maximum Intake Rates for Humans 5.9 Effective Energies of Noble-Gas Radionuclides for Use in Whole-Body Dose and Skin Dose Calculations 5.10 Assumed [5.2] Concentration (Bioaccumulation) Factors for Ottavra River Pish (Flesh) [Transfer Parameter (P )] 2,7 LIST OF TABLES (Cont.)

5.11 Evaluation of Transfer Parameter (P ) (Transfer from Ottawa River to Garden Soil 2'3 via Spray Irrigation) 5.12 Evaluation of Transfer Parameter (P ) (Transfer from Ottawa River to Leafy 2'6 Vegetables Via Spray Irrigation)

6.1 Maximum Permissible Release Rat-^s (<3M) in Pathways for Airborne Radionuclides (Other Than Nobla Gases) Released from NRX/NRU Stack

6.2 Maximum Permissible Release Rates (qM) in Pathways for Airborne Radionuclides (Other than Noble Gases) Released from 61-m Stack

6.3 Maximum Permissible Release Rates (qM) in Pathways for Airborne Radionuclides (Other than Noble Gases) Released from Roof Vents

6.4 Maximum Permissible Release Rates (<3M) in Immersion Pathway for Noble Gases Released from NRX/NRU Stack

6.5 Maximum Permissible Release Rates (qM) in Immersion Pathway for Noble Gases Released from 61-m Stack 6.6 Maximum Permissible Release Rates (q ) in Immersion Pathway for Noble Gases Released from Roof Vents

6.7 Maximum Permissible Release Rates (qM) in Pathways for Liquid Effluents Released from CRNL 6.8 Derived Release Limits (DRL's) for Airborne Effluents from CRNL 6.9 Derived Release Limits (DRL's) for Liquid Effluents from CRNL

6.10 Derived Released Limits (DRLb) for Airborne Effluents from CRNL Assuming Critical Group is at Boundary LIST OF FIGURES

2.1 Map of Ontario and Quebec Showing Location of CRNL 2.2 Restricted Area, Chalk River Nuclear Laboratories 2.3 Populations Within 80 km of CRNL

2.4 Cumulative Population Distribution Around CRNL 3.1 Major Sources of Airborne and Liquid Radioactive Effluents at CRNL

3.2 Aerial Photo of CRNL and Surroundings 5.1 Generalized Exposure Pathways to Man from Airborne and Liquid Effluents 5.2 Environmental Transfer Pathways for Airborne and Liquid Effluents at CRNL 5.2A Environmental Transfer Parameters for Pathway A (Immersion) 5.2B Environmental Transfer Parameters for Pathway B (Standing on Contaminated Ground) 5.2C Environmental Transfer Parameters for Pathway C (Inhalation) 5.2D Environmental Transfer Parameters for Pathway D (Milk Ingestion) 5.2E Environmental Transfer Parameters for Pathway E (Vegetable Ingestion Via Airborne Deposition) 5.2F Environmental Transfer Parameters for Pathway F (Vegetable Ingestion Via Spray Irrigation) 5.2G Environmental Transfer Parameters for Pathway G (Water Ingestion) 5.2H Environmental Transfer Parameters for Pathway H (Fish Ingestion) 5.3 Weighted Mean Dilution Factor (P ) for Continuous Release and Uniform Wind Rose °'1 - Vll -

RADIOLOGICAL UNITS

At the time of publication of this report, the nuclear industry in Canada (and indeed, other countries) is at various stages of conversion to the new radiological units [becquerel (Bq), gray (Gy), and sievert (Sv)] under the International System (SI* . Most published data at the time of preparing the report are in the older units [curie (Ci), rad,and rem]; few are in the new SI units. During this transitional period, the policy at CRNL has been to use the older units and to indicate the corresponding SI units by adding bracketed values in the text or by providing conversion factors as footnotes to tables, figures, etc. This policy has been adopted in this report. The apnropriate conversion factors are:

1 Ci = 3.7 x 10" Bq = 37 GBq 1 rad = 0.01 Gy 1 rem = 0.01 Sv. 1-1

1. INTRODUCTION

Operation of any nuclear facility usually involves releases of radioactive material in the form of airborne and 'liquid effluents to the environment. Such releases must be kept within certain limits in order to satisfy the following basic principles which have been accepted internationally [1.1] and which follow from recommendations [1.2,1.3] issued by the International Commission on Radiological Protection (ICRP):

(a) The radiation dose equivalent * to individuals — excluding natural background and medical exposures—shall not exceed the limits recommended for the appropriate circumstances by the ICRP.

(b) No practice shall be adopted unless its introduction produces a positive net benefit.

In Canada, the Atomic Energy Control Board (AECB) has issued regulations under the Atomic Energy Control Act that are consistent with the above principles. The current regulations (Appendix A) require that practically everyone involved with the development, production and use of atomic energy obtain a licence for such operations from the Board. In this regard, the AECB has issued a licence to Atomic Energy of Canada Limited (AECL) to operate its nuclear facilities at the two main research sites, Chalk River Nuclear Laboratories (CRNL) and Whiteshell Nuclear Research Establishment (WNRE). The licence stipulates certain conditions which must be met, some of which relate to

* See definition at end of this section. 1-2

releases of radioactive material and reflect the endorsement by the AECB of the above principles.

To meet the objectives of (a) above, it is necessary that models be available to calculate the release rates of radioactive effluents corresponding to the recommended dose limits. This report deals with such models and the calculation of so-called derived release limits (DRL's) for airborne and liquid effluents at CRNL, as defined at the end of this section. A companion document [1.4] deals with the similar calculation of DRL's at WNRE. Once the DRL's or the upper limits for releases have been established, it is a matter for internal AECL groups like the Nuclear Safety Advisory Committee (NSAC) to ensure that the actual releases are "as low as reasonably achievable"; in effect, to ensure that (b) and (c) above are met. However, such considerations are outside the scope of this report and will be discussed only briefly.

It should be noted that the models presented apply only to releases during normal operation of nuclear facilities. Accident conditions are not considered here but are usually considered in the safety analysis reports for each facility reviewed by the NSAC.

Finally, it should be noted that guidelines for releases of radioactivity to the environment have been in effect for many years at CRNL (and WNRE). The present report supplants the previous CRNL guidelines and provides a document that:

updates the methodology and the data to conform as far as possible with the latest national and international recommendations. 1-3

extends the methodology to include more radionuclides.

is consistent with other AECL site guideline reports with regard to the basis, format, and application of such reports.

Definitions

Derived Release Limit (DRL):

The upper limit for the release rate of a single radionuclide from a single source which is derived from the regulatory dose-equivalent limits by analytical models of all significant environmental pathways to an individual in the most heavily exposed group (i.e., the "critical group"). In deriving the DRL, the intention is to establish a release liir.it such that adherence to it will provide virtual certainty of compliance with the ICRP recommendations .

Dose Equivalent:

A quantity (in units of rems or Sv) which is equivalent to the absorbed dose (in units of rads or Gy) weighted by the quality factor of the type of radiation and other modifying factors. In the remainder of this report, the term "dose" means "dose equivalent" unless qualified otherwise.

Critical Group [1.5]

For a given radionuclide and source, a fairly homogeneous group of people whose age, habits, diet, etc. cause them to receive doses higher than the average received by typical people in all other groups in the population. It is recognized that there may be individuals within (or sometimes even 1-4

outside) the group whose behaviour is so extreme that they receive doses somewhat higher than those to the average of the group. However, for the setting of release rates, the limiting factor is the average dose to the critical group,i.e., to a person with habits representative of the group. 2-1

2. SITE AND POPULATION DATA

CRNL is located on the Ontario bank of the Ottawa River approximately 150 km upstream from Ottawa (see Fig. 2.1). The laboratories comprise four nuclear reactors and numerous other facilities directed at research into and development of peaceful uses of atomic energy, particularly the development of nuclear power to meet Canadian requirements. Approximately 25 km upstream from CRNL (see Fig. 2.1) the first Canadian power reactor (NPD-Nuclear Power Demonstration) was built and is also operating on the bank of the Ottawa River.

AECL has occupied the site since 1945 and the characteristics which made it an ideal site originally still apply some 35 years later, i.e.,

The land of the region is largely covered by forest of relatively small commercial value and is used very little for agriculture or dairy farming.

The site is remote from populated areas.

- The river provides an abundant and easily accessible supply of water for the research facilities.

Although the bulk of the research facilities are located in a relatively small fenced-in area close to the river, the CRNL property extends over a total area of approximately 37 km comprising the so-called "Outer Area" (see Fig. 2.2). The Outer Area is surrounded by a marked boundary and vehicular movements into and out of the area are controlled at a manned gate-house on the plant road. 2-2

The boundary is approximately 6 km from the main laboratories in the directions of the village of Chalk River and the town of Deep River and tho closest permanent residents outside the boundary are approximately 7 km from the main laboratories in these directions. In the southeast direction, the CRNL property is bounded by the Petawawa Military Reserve which is uninhabited for a distance of approximately 20 km. Across the Ottawa River from CRNL (in Quebec), the land is uninhabited for several kilometres upriver and downriver except during the summer months by a few cottage dwellers. The closest permanent residents on the Quebec side are about 20 km downriver in the small village of Fort William.

The majority of the population surrounding CRNL lives in Ontario in Renfrew County, which includes approximately 200 km of the Ottawa River shoreline and contains approximately 88,000 residents (1975/1976 census data). Table 2.1 and Fig. 2.3 show a break-down of the population distribution out to a radius of 80 km from CRNL. It can be seen that more than half of the total population resides in the southeast direction, which includes the largest population centre (Pembroke - 14,900 residents) at a distance of approximately 30 km from CRNL. It can also be seen from Table 2.1 that approximately 6% of the total population are "infants" (three years older and under). The cumulative population data as a function of radial distance from CRNL are plotted in Fig. 2.4.

The average population density within a radius of 20 km of CRNL is only 15 people/km? This is much lower than the population densities of large cities, e.g., the average population density in the generally suburban area of Toronto is about 250/km*. 2-3

TABLE 2.1 - POPULATIONS* WITHIN 80 km OF CRNL Radius(km) 0-20 20-40 40-60 60-80 Sub-Total i Totals i 1 1 Infantst 3* + 3 N 1 Others 20* + 20 23

Infants 3* • + + 3 NE 23 Others 20* + + 20 Infants : 3* 49 172 67 291 2861 ' Others i 20* 416 1566 568 2570 Infants ; 707 915 604 625 2851 SE • 47419 ' Others [ 9075 17907 9092 8494 44568

Infants 92 143 160 240 635 I 13775 I I Others 1510 2410 3515 5714 13140 I Infants 98 20 20 138 SW 2393 Others / 1439 408 408 2255 I Infants t 355 9 9 9 382 6373 ]Others 5616 125 125 125 5991 Infants 23 26 NW 252 ; Others j 20* 206 226

Total j Infants ,' 1264 ! 1139 965 961 Within ! • AnnulusI Others 17720 21055 14706 15309 Total = 73119 •Cumu- -. Infants 1264 2403 3368 4329 dative Total ,Others 17720 ! 38775 53481 68790 I

* Evaluated from 1975/1976 Census Data. t Ages 3 and Under. + Total of about 10 people in N and NE directions between 20-80 km and in NW direction between 40-80 km. i|i Assumes total population in N, NE, E and NW octants divided equally. FIG. 2.1: MAP OF ONTARIO AND QUEBEC SHOWING LOCATION OF CRNL 2-5

CRNL ACTIVE ARC* MID INNER AREA

FENCED AREAS)

TO TO WN OF

DEEP RIVER

A, B, C, D, E, F, - WASTE MANAGEMENT AREAS FIGURE 2.2 CHALK RIVER NUCLEAR LABORATORIES OUTER AREA 2-6

12.000 FIG. 2.3 POPULATIONS* WITHIN 80km OF CRNL

•1S76/7S C.n.ui 0«t. (Su Tabte 2.1) U^ 8.000 2-7

10' r FIG. 2.4: CUMULATIVE POPULATION DISTRIBUTION AROUND CRNL

10'

NON - INFANTS 10' (> 3 YEARS OLD)

103 20 30 40 50

RADIUS FROM CRNL (km) 3-1

3. SOURCES 01' RADIOACTIVE RELEASES

The major sources of airborne and liquid effluents at CRNL arise from operations within the so-called "active" area (Fig.3.1), which contains the NRX and NRU research reactors and various other facilities connected with the power reactor development program, the heavy water recovery program, and the commercial radioisotope business.

The major sources of airborne effluents are listed in Table 3.1. Although the locations and elevations of the various release points differ, they can be conveniently grouped into three main types for the purposes of calculations in this report, i.e., the "NRX/NRU Stack", the "61-m Stack", and "Roof Vents". Table 3.1 summarizes the facilities feeding these three types of sources and lists data for typical air flow rates and for common radionuclides, either detected or potentially present in the effluents.

There are essentially only five liquid effluent streams that discharge into the Ottawa River at CRNL (see Fig. 3.1) and only one of these (the "process sewer") can be considered as an important source of radioactivity. Data for the five liquid effluent streams are listed in Table 3.2.

Most of the radioactivity in the process sewer is due to tritium [as H-3 (oxide)] which results from various heavy-water handling operations. The remainder is due mainly to operation of the NRX reactor, which is cooled with untreated water that is returned to the river after a three-hour delay. Because of this substantial delay, releases of very shor: 1ived radionuclides via the process sewer are negligible and the main radionuclides present (see Table 3.2) are the longer-lived activation products (Na-24, Cr-51, etc.) and fission products (1-131, Cs-137, etc.) [3.1]. 3-2

It should also be noted that radioactive releases to the river via Perch Creek and the Maskinonge/Chalk Lakes system entail much longer delays. For example, the source of activity in the Perch Lake basin is seepage from liquid disposal pits and from contaminated ground in the vicinity of Waste Management Area "A" (and, to a lesser extent, Waste Management Area "B"). Figs. 2.2 and 3.2 show the geographical relation between the waste management areas, Perch Lake, and Perch Creek. All of the radioactive waste placed in the "B" Area after 1963 is stored in solid form in engineered structures below ground; however, liquid wastes having low radioactive and chemical concentrations are discharged to ground pits near the "A" Area via two 1.2-km long pipe-lines from the active area (see Fig. 3.2) . The Reactor Pits are reserved for water from various reactor systems and from the fuel rod storage bays. The Chemical Pit is used for disposal of water from laboratory drains and other potentially contaminated sources within the Active Area. The rate at which radionuclides dispersed in the waste management areas would move through the ground and the route they would follow were predicted more than a decade ago [3.2-3.4] and both were largely confirmed by subsequent observations. In practice, the limit on the amount of radioactivity discharged to the waste management areas is set so that the administrative control level on the amount of radioactivity in Perch Creek will not be exceeded. Thus far, only the long—lived radionuclides, including tritium have been detected (see Table 3.2) and their concentrations have not been significant.

Similarly, minor releases of tritium [3H(oxide)] to the Ottawa River via the Maskinonge/Chalk Lakes system (Figs. 2.2 and 3.1) have been detected. This was traced to dispersed radioactivity from the burials of low-level solid wastes in Waste Management Area "C", which was begun in 1963 but is gradually 4 3-3

being phased out. Thus far, tritium and small amounts of Co-60 are the only radionuclides that have been detected in ground- water and surface water moving away from this area.

Radioactivity released to the Ottawa River via the five main liquid effluent streams is diluted by the large river flow (about 750 m3/s averaged over the year) and is thoroughly mixsd [3.5] before reaching the nearest population centre (Petawawa, about 20 km downstream) that uses the river water for domestic purposes. It is convenient therefore to treat CRNL as a single source of liquid effluent for the purposes of calculating radiation exposures to people downstream and arriving at a release limit for the site as a whole. The CRNL water supply intake is located upstream of the discharge points so that exposure of the site workers via liquid effluents does not enter into the calculations. I 3-4

x'ABLE 3 . 1

MAJOR SOURCES OF AIRBORNE EFFLUENTS AT CRNL

Typical Source Flow Radionuclides Description (ra'/s) Presentf

NRX/NRU Stack 12 H-3(oxide) Exhaust air from (50-m high) C-14 NRX/NRU reactors Ar-41 in ^2:1 ratio of (Bldg. 163) Radioiodines flows Radiokryptons Radioxenons

61-m Stack 3.1 Radioiodines Exhaust air mainly Radiokryptons from Mo-99 Production (Bldg. 206) Radioxenons Facility in Bldg. 225 and 234.

Roof Vents:

- Bldg. 150 7.,8 H-3 (oxide) NRU Reactor Bldg.

- Bldg. 210 9..7 H-3 (oxide) Heavy Water Up- grading Plant

- Bldg. 221 5.1 Radioiodines Chemical Operations Radioxenons

- Bldg. 234 3.5 Participates Universal Cells Radioiodines

- Bldg. 250 0.4 H-3 (oxide) Che-nical Engineering

- Bldg. 375 4.7 Particulates Metallurgy Cells and Radioiodines Mixed Oxide Fuel Radioxenons Fabrication Facility

- Bldg. 468 1.1 H-3 (oxide) Decontamination Radioiodines

- Bldg. 558A 0.7 H-3 (oxide) Tritium Recovery Exp't

f Either confirmed by analysis or potentially present in significant quantities. Radionuclides considered in calculations are listed in Table 5.1. 3-5

TABLE 3.2

SOURCES OF LIQUID EFFLUENT DISCHARGING

INTO OTTAWA RIVER AT CRNL

Typical Source Flow Radionuclides Description (mVs) Presentt

Process Sewer 1.6 H-3 (oxide) ^80% of flow from NRU heat exchangers and normally Activation) (e.g., Na-24, inactive. Products / Cr-51, As-76) Remainder of flow mainly Fission \ (e.g., 1-131, from NRX cooling with Products • Cs-137, Ce-144) small additions from: - Heavy Water Recovery Plant - Decontamination Centre

Sanitary Sewer 0.012 H-3 (oxide) Toilets, showers, and floor drains Activation) (e.g., Cr-51, Products / Co-60, Cs-134)

Fission ) (e.g., 1-131, Products / Cs-137,Ce-144

04 Storm Sewer 0.05 H-3 (oxide) Contaminated ground water Co-60 Sr-90 Cs-137 Alpha*

Maskinonge/ 0.16 H-3 (oxide) Drainage f ran Waste Chalk Lake Co-60 Management Area "C" via System Duke stream

Perch Creek 0.06 H-3 (oxide) Drainage from Waste Co-60 Management Areas into Sr-90 Perch Lake Basin Alpha* t Either confirmed by analysis or potentially present in significant quantities. Radionuclides considered in calculations are listed in Table 5.1. * Includes natural radionuclides. FIG. 3.1 - MAJOR SOURCES OF AIRBORNE AND LIQUID > RADIOACTIVE EFFLUENTS AT CRNL AERIAL PHOTO OP CRNL AND SURROUNDINGS

WASTE MAN AREA 'A' 4-1

4. RADIOLOGICAL PROTECTION STANDARDS

4.1 Basic Standards - Individual Dose Limits

Releases of airborne and liquid effluents result in external and internal radiation exposures of man via various pathways, which are described in some detail in Section 5.1. In order to cet limits for the releases, it is necessary to first establish basic standards for radiation doses in body tissues that would limit the risk from radiation exposure to an acceptable level.

Basic standards for radiological protection have been developed over the years and have been kept continuously under review by the International Commission on Radiological Protection (ICRP). The last major change occurred in 1977 when the ICRP published new recommendations [1.3] which eliminated the former dose limits for individual organs and tissues contained in the 1959 and 1965 recommendations [4.1, 4.2]. The new system of dose limitation is generally more restrictive than the previous system because of the requirement to consider the total detriment from all irradiated tissues. Briefly, the new recommendations express the dose limits in terms of "effective-dose-equivalent" limits which, for stochastic effects*, are based on the total risk of all tissues irradiated. In other words, the system of dose limitation recommended incorporates "the setting of a single dose-equivalent limit for uniform irradiation of the whole body and a system designed to ensure that the total risk from irradiation of parts of the body does not exceed that from uniform irradiation of the whole body". [1.3]

See footnote on next page. 4-2

Weighting factors for individual organs and tissues are provided in the recommendations to perform the latter calculation. The recommendations further stipulate that "no single tissue should receive more than a specified dose-equivalent limit to prevent the occurrence of non-stochastic* damage"[1.3]. The recommended values of the dose-equivalent limits for atomic radiation workers and members of the public are summarized in Table 4.1.

Stochastic effects are those for which the probability of the occurrence increases with increasing radiation dose, with zero probability only at zero dose. The severity of stochastic effects is riot dependent on the level of dose. Non-stochastic effects ,e.g., opacity of the lens of the eye, are those for which there is a threshold below which they will not occur, and whose severity increases with dose above the threshold. Two other categories of effects of ionizing radiation on human health are somatic and non-somatic effects. Somatic effects are those which manifest themselves in the exposed individual, while non-somatic effects are those which occur in the descendant(s) of the exposed individual. Any effects of radiation doses below the dose limits will be stochastic, with fatal cancer the main somatic effect, and genetic defects the non-somatic effect. 4-3

The ICRP recognized that the recommended weighting factors (Table 4.1) would vary with the age and sex of the individual. However, they felt that the total risk (expressed as effective dose equivalent) to an individual would be calculated with sufficient accuracy if these weighting factors were used for everybody, regardless of age and sex. The effective dose equivalent has also been criticized as it does not take into account the production of non-fatal cancers, nor genetic effects subsequent to the first two generations. The ICRP has recently reviewed the problem and has concluded [4.3] that the uncertainty in the estimates was large enough that any refinement in the numbers would be unjustified.

In Canada, the Atomic Energy Control Board (AECB) has set standards for maximum permissible doses in line with those recommended by the ICRP and has incorporated them into the Atomic Energy Control Regulations. The latest revision of the Regulations (Appendix A) will incorporate the new dose limits recommended by the ICRP and a similar move is expected in other countries [4.4, 4.5, 4.6]. The dose limits are presented in the Regulations (and in Table 4.1) for:

- members of the public, and an "atomic radiation worker", which is defined in the Regulations as "any person who in the course of his work, business or occupation is likely to receive a dose in excess of any dose specified (for members of the public)".

It can be seen in Table 4.1 that the dose limits for atomic radiation workers are ten times higher than those for members of the public. The more restrictive 4-4

dose limits for "members of the public" are used in the calculations of derived release limits not only for those individuals but also for the on-site workers. This conservative approach was adopted for several reasons, not the least of which was to allow a large margin for those workers actually engaged in the handling of radioactive materials so that they would be less restricted in per- forming the necessary work. Another important reason is included in the following recommendation from paragraph 161 of ICRP-26U.3] :

- "Where the exposure is unconnected with the work, and where the work is in premises not containing the radiation sources giving rise to the exposure, the working condition should be such that the limits applicable to members of the public are observed."

Workers at CRNL are felt to fall under this category for the purpose of release calculations.

4.2 Derived Limits for Internal Exposures - Annual Limits of Intake (ALI)

Since it is difficult to measure directly the basic standards (dose limits) described in the preceding section, derived limits referring to quantities that can be measured are required. For example, in the case of internal exposures resulting from the inhalation or ingestion of radioactivity, various body organs and tissues will become irradiated to different levels depending on the fractional uptake of the particular radionuclide in the organ, the mass of the organ, the radioactive decay properties of the radionuclide, etc. The "effective dose equivalent" must be less than the dose limits in Appendix A and Table 4.1. Obviously, there is a 4-5

need for the limits to be expressed in terms of derived but measurable quantities such as rates of intake of radioactivity or concentrations of radioactivity in air and water.

Recently, the ICRP has published data [4.7] on annual limits of intake (ALI) for inhalation and ingestion of a selected number of radionuclides in order to facilitate the implementation of the new ICRP-26 recommendations [1.3]. All of the ICRP data applies to adult radiation workers but the data can be adjusted with care to apply to the radiation exposure of adult members of the public. Derived limits for infant members of the public are not given in the ICRP recommendations .

To cover the cases of intake via inhalation and ingestion over a wide range of age groups (infants and adults) and for all the major radionuclides of interest, J.R. Johnson [4.8] of the CRNL Biomedical Research Branch has calculated effective dose equivalent conversion factors based on the new ICRP-26 recommendations. The results have been divided into the annual dose limits to give annual limits of intake for inhalation and ingestion (see Table 4.2).

Dr. Johnson's data [4.8] are used in this report as they represent the only known systematic calculation of dose conversion factors for both adults and infants that takes into account the differences in metabolic parameters between these age groups. The ICRP values [4.7] of ALI for adults are included in Table 4.2, where available, for comparison. It can be seen that the agreement between Johnson's values and the ICRP values is generally good (within a factor of about two). The differences result from two main considerations- 4-6

Firstly, the aerosol diameter used in his calculations for inhalation exposure was 0.3 pm, which is thought to be more appropriate for routine releases to the environment than the 1.0 ym used by the ICRP [4.7]. Secondly, Johnson has reviewed the value used for the fraction of a radionuclide ingested that is absorbed into the blood and has included calculations for absorption fractions more appropriate for use with environmentally incorporated radionuclides than the occupational factors used by the ICRP [4.7] . .* It should be noted that the ALI calculations are based on the concept of the 50-year committed dose equivalent [4.9], i.e., the integral to 50 years of the dose to a body organ following an intake of radioactive material. This ensures that if the committed dose due to an intake in any given year is within the dose limits, the maximum annual dose received after 50 years of chronic intake at the same annual rate will also be within the annual dose limits. It also means that for the intake of a radionuclide having a long residence time in the body (biological half-life of several years) at the level of the ALI, the actual annual dose received in the first few years of a chronic intake would be much less than the annual dose limit.

Finally, as indicated in the notes accompanying Table 4.2, the ALI's listed correspond to the minimum value of ALI if more than one chemical and physical form of the radionuclide is possible. This was done because the actual form of the released radionuclide is not usually known. If the form is known and is different to that listed, reference should be made to the original data [4.8] to determine the factor of conservatism introduced by this parameter in the final results. 4-7

4.3 Dose Conversion Factors for External Exposures

A person may be exposed by radiation outside the body by, for example, standing in a cloud of radioactive material (immersion) or standing on contaminated ground. The annual dose limits to be applied for such external exposures of the whole body or skin are listed in Appendix A and Table 4.1. As in Section 4.2, it is convenient to relate these limits to measurable quantities such as concentrations of the radioactive material in the air or on the ground. This may be done by means of the dose conversion factors described in the following sections.

ICRP-26[1.3] notes that the whole-body dose for external exposure may be calculated as the dose equivalent that would occur at a depth of 1 cm or more in a 30 cm diameter sphere (the "deep dose-equivalent index"). Similarly, the skin dose may be calculated as the dose equivalent in a shell, 0.07 mm to 10 mm deep, on the outside of the 30 cm diameter sphe^G (the "shallow dose-equivalent index"). Data are not yet available to relate these dose equivalents to radioactive concentrations. In the meantime, dose conversion factors based on data recommended by the U.S. NRC [4.11] have been used in this report. These data are based in turn on a whole-body dose from external radiation at a depth of 5 cm into the body and a skin dose at a depth of 0.07 mm of tissue.

4.3.1 Immersion

External dose conversion factors [4.11], DCF , relating whole-body and skin doses to concentrations of radioactive material in air are listed in Table 4.3. The factors are listed only for the radioactive noble gases (such as Ar-41 and various radionuclides of krypton and xenon) because, for these, one would expect the external radiation dose from the radioactive 4 -

atmosphere to deliver a much higher dose than that from the gas held in the lungs or other body organs [4.1]. For other radionuclides, the internal dose due to inhalation is more important and the annual limits of intake (Section 4.2) apply.

Besides the assumptions made in Section 4.3, the dose conversion factors for the noble gases are based on the usually conservative assumption that the body is irradiated from half the solid angle formed by a radioactive cloud of large volu:..e, i.e., by a semi-infinite cloud of radioactive gas [4,. 1] . The factors apply equally to adults or infants.

4.3.2 Standing on Contaminated Ground

External dose conversion factors, DCP /relating whole- s' body and skin doses to concentrations of radioactive material deposited on the ground are also available in reference [4.11]. Besides the assumptions made in Section 4.3, the dose conversion factors were derived for a height of 1 m above the surface. The results apply equally to adults or infants.

For the purposes of calculations in this report, the data in reference [4.11] have been multiplied by a factor of two to remove the "ground roughness factor" of 0.5 that was applied in the original calculations. The results, listed in Table 4.4, are therefore representative of dose conversion factors for a person standing on a smooth plane surface. The effects of ground roughness and other factors are then taken account of in Section 5.4.8.

4 4-9

4.4 Population Dose (Collective Dose) Considerations

The radiological protection standards discussed in the preceding sections (4.1, 4.2, and 4.3) are all related to limiting the doses received by individuals. This will in turn, limit the risk to individuals and their descendants (see Section 4.2). The question remains whether limits on total population dose (collective dose) should also be established to limit the total detriment to the exposed population to an acceptable level.

The AECB tackled the problem in the early stages of the Canadian nuclear power reactors by stipulating [4.12] the following population dose limits for routine operations:

- 101* man-rem/a (102 nan-Sv/a) - 101* man-thyroid-rem/a (102 man-thyroid-Sv/a) .

The integration extends over all areas outside the exclusion area in which the individual whole-body dose and the individual thyroid dose exceed 1? of the annual dose limits for members of the public. For the existing power-reactor locations in Canada, individual dose - not population dose - has usually been the limiting factor in determining release limits for normal operation [4.13].

Population dose limits for power reactors are not included in the current Atomic Energy Control Regulations (Appendix A). The AECB is reconsidering its policy towards population doses in light of the ALARA ("as low as reasonably achievable") principle with a view to basing the limits on a realistic cost-benefit analysis [4.4]. However, until the matter is clarified and a quantitative ALARA statement is included in the Regulations, it would be presumptuous to base the derivation of release limits at CRNL on anything other 4-10

than the individual dose limits. This seems to be in line with the approach being taken by the ICRP. For example, the recent review by the ICRP of its recommendations [4.3] states that:

- the effective dose equivalent, summed over the exposed population, should be used for collective dose calculations.

- these collective dose estimates should only be used for cost-benefit analyses (paragraphs 129 - 132 of ref. [1.3]).

- a limit on collective dose is inappropriate.

Another aspect of population dose that deserves special consideration is the concept of "collective dose commitment", which applies to the release of certain long-lived radionuclides* that can become distributed worldwide. For these radionuclides, the traditional method of calculating release limits by assessing the dose to individuals close to the nuclear facility is not applicable because:

- the radionuclides persist in the environment and hence the true dose delivered in any one year is the sum of the doses arising from that year's release and from all previous years' releases corrected for radioactive decay and for any other process which removes them from interaction with humans.

For example, 12.3-year H-3, 5730-year C-14, 10.8-year Kr-85, and 1.7 x 10 7-year 1-129. I 4-11

- the population affected by the release is not just that iii a limited area around the nuclear facility but could be the entire population of the world. In particular, whereas the dose limits for individuals recommended by the ICRP are based on the assumption that the population at risk is receiving some benefit (e.g., the electrical power produced), it is difficult to use similar arguments for the long-lived radionuclides in which the population receiving the benefit may only be a small fraction of the total population at risk.

It is obvious that an international consensus will have to be reached on a solution to the problem and numerous studies have been directed to this end [4.14, 4.15, 4.16, 4.17]. rTntil this is done, for the purposes of this document, release limits at CRNL will be based on the individual dose limits while recog- nizing that a problem exists for certain long-lived radionuclides. However, it snould bG realized that releases of some of the radionuclides of concern in the collective dose commitment concept (e.g.,Kr-85 and 1-129) are associated mainly with reprocessing of reactor fuel, an operation which is not now performed at CRNL. TRBLE 4.1 - Kbttri'lVE DOSE EQUIVBLENT LIMITg KEOCMffiaDED IN ICRP-26 [1.3]

Atomic Radiation Markers Matters of Public "type of Irradiation Limt for Limit for Limit for Limit for Stochastic Effectst Non-Stochastic Effects* Stochastic Effectst Non-Stochastic Effects*

Uhiforra Irradiation 5 rem/a 0.5 ren/a of Mole Body (0.05 Sv/a) (0.005 Sv/a)

Weighting Weighting Tissue (T) factor, Eactor

0.25 0.25 Breast 0.15 0.15 o — Red Bone Marrow 0.12 0.12 -Jl Lung 0.12 50 rem/a 0.12 5 ran/a Thyroid 0.03 (0.5 Sv/a) 0.03 (0.05 Sv/a) I Bone Surfaces 0.03 0.03 f—' Remainder^ 0.30 0.30 CO

Skin 50 rem/a (0.5 Sv/a) Lens of Eye 15 rem/a (0.15 Sv/a)

t Stochastic effects#e.g., malignant and hereditary disease, are those for which the probability of an effect occurring, rather than its severity, is regarded as a function of dose, without threshold. + Non-stochastic effects e.g., opacity of the lens of the eye, are those for which the severity of the effects varies with the dose, and for which there is a threshold. * Hj, = annual dose equivalent in tissue (T). ifi The ICRP raaannaHs that a value of weighting factor, W = 0.06,is applicable to each of the five organs or tissues of the remainder receiving the highest dose equivalents, and that the exposure of all other remaining tissues can be neglected. (When the gastro-intestinal tract is irradiated, the stomach, small intestine, upper large intestine and lower large intestine are treated as four separate organs.) 4-14

TABLE 4.2 - AMUUAL LIMITS OF IHTAKB, ALI, FOR MEMBERS OF PUBLIC BASED ON ICRP - 26 DOSE LIMITS

Inhalation Intake Ingeation intake

Radlo- Chuiical k 01 Chemical t, Nuclide Physical Form ^inhal.' '' Phyaical Fonr

Fi Clan Infanta Adulta Fi Infanta Adulta

B-3 (HTO) 1.0 B.5E-04b'C 2.5E-03C (4.0E-03;d 1.0 2.7E-O3 5.0E-03 (8.0E-03) Be-7 { .01 5.5E-Q4 1.1E-03 0.01 4.8E-02 4.2E-03 C-14(CO3> .0 B.9E-03 2.GE-02 C-14 (part. .0 1.3E-U6 6.1E-06 1.0 8.7E-0S 2.GE-04 Na-22 .0 3.4E-05 8.2E-D5 1.0 1.9E-05 4.2E-OS -24 .0 1.3E-Q4 G.lE-04 1.0 1.2E-04 5.6E-04 S-35 .0 5.4E-0S l.BE-04 0.1 4.5E-04 6.1E-04" Sc-46 .0001 B.1E-06 1.9E-05 o.oool 1.8E-04 1.3E-04e -47 D.0001 7.6E-0S 3.4E-04 o.oool 1.9E-04 1.9E-04 Cr-51 0.1 5.0E-04 1.6E-O3 0.1 3.6E-03 5.1E-03 Kn-S4 0 1 B.4E-05 1.3E-04 (8.IE-OS) 0.1 3,JE-04 4.1E-D4 (1.9E-04) Fe-59 0 1 1.IE-OS 4.4E-05 0.1 3.9E-05 9.BE-05 Co-SB 0.05 2.0E-05 5.5E-05 (8.IE-OS) O.B -GO 0.05 1.3E-06 2.7E-06 (2.7E-06J 0.B 5.3E-O6 1.IE-OS Zn-65 0.5 1.6E-05 3.5E-0S 0.5 1.BE-05 4.GE-05 Aa-76 0.03 2.6E-05 1.2E-04 0.03 2.6E-05 5.7E-05 Sr-89 0.3 2.1E-06 1.IE-OS 0.3 2.5E-05 5.1E-05 (5.4E-05) -90+ 0.3 e.6E-09 3.7E-07 0.3 9.OE-OT 3.4E-O6 <2.7E-Q6} Zr-95+ 0.002 B.3E-06 2.2E-0S {2.7E-05) 0.002 2.1E-04 2.OE-04 (1.4E-04) 3.7E-05 1.OE-04 U.1E-04) 0.5 7.3E-05 1.9E-04 Hb-95 0.01 f HO-99+ 0.8 2.BE-05 1.3E-04 {1.4E-04I O.B I.7E-05 7.4E-05 (1.6E-Q4) Hu-103 0.05 2.8E-05 8.6E-05 2.9E-Q4 3.3E-04 -106+ 0.05 2.SE-07 8.SE-07 o.os 1.1E-05 1.8E-05 0.05 Ag-10Bro+ 0.05 1.3E-07 2.5E-06 0.05 1.5E-Q4 2.7E-04 -110B 0.05 1.9E-0G 3.BE-06 0.05 5.4E-Q5 5.4E-0S Sb-124 0.2 9.7E-0G 2.0E-05 0.9 3.0E-QS 4.3E-05 -125 0.2 Z.1E-05. 4.5E-05. 0.9 9.9E-05a 1.3E-04. Te-132+ 0.2 6.2E-06* 2.7E-05 U.9E-05) 0.9 3.7E-06 2.1E-05 (5.4E-06) 1-125 1.0 6.2E-07* 3.BE-06" (5.4E-06]" .0 6.2E-07* 3.8E-06e (2.7E-06)* -129 1.0 I.SE-07* 5.5E-07I (8.2E-O7)f .0 1.5E-07e 5.5E-07e (5.4E-07) -131 1.0 3.2E-07 2.BE-06e |5.4E-06) .0 3.2E-07® 2.BE-06* (2.7E-06)^ -132 1.0 2.GE-05* 2.5E-04 {8.1E-04>e .0 2.6E-05 2.5E-04e (2.7E-04) -133 1.0 1.5E-06* 1.5E-05* (2.7E-05)f. .0 1.5E-06 1.5E-05 (1.4E-05) -134 1.0 1.1E-04* 1.2E-03* (5.4E-03)e .0 1.1E-04* 1.2E-03* (2.2E-0J)* -135 1.0 6.4E-066 6.5E-05e (1.6E-04)e .0 6.4E-D6B 6.5E-05 (8.IE-OS) Cm-134 1. 0 1.8E-05 1.6E-05 (1.IE-OS) 1.0 B.9E-0G 7.8E-06 <8.1E-06) -137 1. 2.0E-05 2.2E-05 U.6E-0S) 1.0 1.1E-O5 1.1E-05 (1.1E-05) Ba-140+ 0. 2.4E-0S 7.0E-05 0.1 B.5E-05 2.6E-04 La-140 0. 0003 1 3.7E-05 1.3E-04 0.0003 5.2E-05 7.4E-05B Ce-141 0. 0003 i 1.IE-OS 5.1E-05 (5.4B-05> -143+ 0. 0003 1 4.4E-05 1.9E-04 0.0003 6.2E-05 1.3E-04 -144+ 0. 0003 -i 3.4E-07 1.3E-06 (1.4E-06) 0.0003 1.7E-05 2.2E-05 12.2E-05) Eu-152 0.0001 t 3.4E-07 9.7E-O7 O.OODl -154 0.0001 V 3.3E-07 9.5E-07 0.0001 Hf-175 0.002 * 2.1E-05 6.0E-05 0.002 5.6E-04 4.5E-04 -181 0.002 i 1.6E-05 4.7E-05 0.002 2.3E-O4 2.1E-04 Hg-203 0.02 H 4.2E-05 B.7E-05 O.Z 1.3E-O4 i.8E-04 Ra-226+ 0.2 W 7.4E-09 2.7E-08 (E.4E-08) 0.2 1.1E-08 4.6E-O8D 11.9E-07) Th-22B+ 0.0002 Y 3.2E-10 1.3E-09. (l.GE-09) 0.03 8.3E-10 5.7E-09 -232+ 0.0002 Y 5.OE-10 1.1E-099 (2.7E-10) 0.03 PB-233+ 0.01 W 3.8E-05 1.2E-04 0.01 2.4E-04 3.OE-04 0-232+ 0.002 Y 1.5E-10 ?.SE-10 (8.1E-10) 0.05 2.8E-D8 .9E-08 (2.2E-07)"; -233 0.002 t S.7E-10 .2E-09 (2.7E-09) O.OS 1.1E-0G .8E-O6 (1.1E-O6)^ -234 0.002 t 6.7E-10 .2E-09 (3.7E-09) O.OS 1.1E-06 .BE-06 (1.1E-06I -235 0.002 t 7.1E-10 .4E-09 (S.4E-09) O.OS 1.1E-06 .9E-06 (1.4E-O6)g -230 0.002 Y 7.7E-10 .GE-09 (5.4E-09) 0.05 Hp-237 0.01 H 1.2E-10* .6E-10* 0.O1 -239 0.01 H 1.5E-04 .9E-04 0.01 2.7E-04 .9E-04 PU-238 0.0001 H 1.2E-108 1.0E-09* {5.4E-10)* 0.0001 1.3E-078 1.1E-O6B (8.1E-07)e -239 0.0001 H 1.1E-10* 9.1E-10* (5.4E-10)* 0.3001 I.2E-O7 1.OE-OGf (5.4B-07)^ •240 0.0001 H 1.1E-10 9.1E-10* {5.4E-10) O.OODl 1. 2E-078 1. OE-06 (5. 4E-O7) ** -241+ 0.0001 It G.BE-09,. 6.4E-08^ {2.7B-0B1® 0.0001 7.5E-06 6.9E-0S (2,78-05) A*-241 0.0005 H 2.Oe-10 B.8E-10* (5.4E-10) 0.0005 2.3E-0B8 1.9E-076 |1.4E-07)8 CM-242 O.OOOS H S.5E-D9 3.2E-08 (2.7E-0B) 0.0005 1. 3E-06 8. 7E-06,, {5. 4E-O6) * -244 0.0006 » 2.1E-10* 1.7E-09* (1.1E-09)* 0.0005 4 6E-08 • 3.8E-07 (2.4E-07)

1 Ci - 37 CBq Znclud*a contribution fro* daughter(a). 4-15

NOTES FOR TABLE 4.2

(a) The chemical and physical form of a particulate radionuclide may be tied to a value of Fi (the fraction reaching body fluids after entry into the gut) and, for the inhalation route, the lung retention class, i.e., the length of time the material is held in the lungs (D = relatively "soluble"; material remains in lungs for Days. W = "slightly soluble"; material remains in lungs for Weeks. Y = "insoluble"; material remains in lungs for Years). The values listed correspond to the minimum value of ALI if more than one form has been assumed in the calculations [4.8].Inorganic compounds corresponding to values of Fi and to classes D, W, Y may be found in Tables 6.3 and 6.5 of ref. [4.6] and in Table 3 of ref. [4.10]. Non-particulate gaseous forms are indicated by "G". (b) 8.5 E - 04 = 8.5 x 10~". (c) Includes factor of two decrease for absorption through skin. (d) Where available,- data from ECRF-30 [4.7] are included in brackets. (e) ALI reduced to meet non-stochastic limit of 5 rem/a (0.05 Sv/a). (f) Minimum ALI, corresponding to F: = 0.05, Class Y. (g) Minimum ALI, corresponding to Class W. 4-16

TABLE 4.3

DOSE CONVERSION FACTORS (DCF ) FOR CONTINUOUS EXTERNAL EXPOSURE DUE TO IMMERSTQN IN A SEMI-INFINITE CLOUD OF NOBLE-GAS RADIONUCLIDES [4.11]

Dose Conversion Factor, DCF cL (rem-a'^/tci Radionuciide

Whole-Body Dose* Skin Dose ** (DCFa)b (DCFa)s

Ar-41 8.84E+06t 1.30E+07 Kr-85m 1.17E+06 2.83E+06 -85 1.61E+04 1.36E+06 -87 5.92E+06 1.66E+07 -88 1.47E+07 1.93E+07 -89 1.66E+07 2.93E+07 -90 1.56E+07 2.54E+07 Xe-131m 9.15E+04 6.49E+05 -133m 2.51E+05 1.36E+06 -133 2.94E+05 6.98E+05 -135m 3.12E+06 4.43E+06 -135 1.81E+06 4.00E+06 -137 1.42E+06 1.39E+07 -138 8.83E+06 1.43E+07

I\I For {Sva~1)/teg«tn~3) , multiply by 2.7X10"1 3. 2 * At a depth of 5 an or 5 g/cm into the body. ** At a depth of 0.07 mm or 7 mg/cm into the skin. t 8.84E+06=8.84xl06. 4-17 TABLE 4.4 DOSE CONVERSION FACTORS (DCF ) FOR CONTINUOUS EXTERNAL EXPOSURE DUE TO STAMPING ON A SMOOTH CONTAMINATED PLANE SURFACE t

Dose Conversion Factor, DCF (rem-a"1)/Ci y Radionuclide • in ) ijj Whole Body Dose* Skin Dose** (DCFg)b (DCVs

Cr-51 3.86E+03+ 4.56E+03 Mn-54 1.02E+05 1.19E+05 Fe-59 1.40E+05 1.65E+05 Co-58 1.23E+05 1.44E+05 -60 2.98E+05 3.51E+05 Zn-65 7.01E+04 8.06E+04 Zr-95 8.77E+04 1.02E+05 Nb-95 8.94E+04 1.05E+05 Mo-99 3.33E+04 3.86E+04 Ru-103 6.31E+04 7.36E+04 -106 2.63E+04 3.16E+04 Sb-124 2.28E+05 2.63E+05 -125 5.43E+04 6.14E+04 Te-132 2.98E+04 3.51E+04 I -129 7.8 9E+03 1.31E+04 -131 4.91E+04 5.96E+04 -132 2.98E+05 3.51E+05 -133 6.49E+04 7.89E+04 -134 2.81E+05 3.33E+05 -135 2.10E+05 2.45E+05 Cs-134 2.10E+05 2.45E+05 -137 7.36E+04 8.5 9E+04 Ba-140 3.68E+04 4.21E+04 La-140 2.63E+05 2.98E+05 Ce-141 9.64E+03 1.09E+04 -143 3.86E+04 4.38E+04 -144 5.61E+03 6.49E+03 Hg-203 3.24E+04 3.77E+04 Ra-226 1.12E+05 1.30E+05 Np-229 1.67E+04 1.93E+04

From ref. [4.11], with "ground roughness factor"removed (see Sec. 4.3.2) For (Sva-M/teq-nr2) , multiply by 2.7xlO~13 * At a depth of 5 cm or 5 g/cm2 into the body j . , , , c ** •" lat 1 m above surface At a depth of 0.07 mm or 7 mg/cm2 into the skin) 3.86E+03 = 3.86xlO3 5-1

5. METHODOLOGY

5.1 General

As shown pictorially in Fig. 5.1, radionuclides in airborne and liquid effluents can result in radiation exposures to man in the environment via a number of routes or "pathways". Some pathways, such as ingestion of food, result in internal exposures; others, such as immersion in a radioactive cloud, result in external exposures. However, the total exposure to an individual via all significant pathways from an effluent source must be taken into account to ensure that the regulatory dose limits (Section 4.1) are not exceeded.

There are several international and national publications [1.1, 5.1, 5.2] giving guidance for calculating derived release limits (DRL's) to ensure that the above requirement is met and this report follows the same methods. Briefly, the methodology consists of,firstly, determining for each radionuclide released from each source the most important pathways with regard to radiation exposure of individuals in various localized groups; secondly, calculating the maximum release rate (<3M) corresponding to the individual dose-rate limits for each pathway; thirdly, for each exposed group, summing the qM~values in such a way (see Section 6.2) as to determine the maximum permissible release rate

(QM) for the radionuclide from the particular source; fourthly, identifying the smallest of the Q^-values. The minimum value of

QM will be the DRL for that radionuclide and source. The exposed group for which the minimum applies is the "critical group". 5-2

The DRL (as defined in this report) then represents an upper limit to the rate of release of a radionuclide from a single source. Releases from other sources and other radionuclides from the same source must be taken into account in an overall assessment of radiation exposure. This is usually taken care of when setting administrative levels to ensure that the actual releases are only a small fraction of the DRL's. Detailed consideration of the methods for establishing administrative levels to accomplish this are outside the scope of this report and will be discussed only briefly (see Section 7.4).

As will be clear in the following sections, numerous

parameters are used in the pathway calculations of qM- Values of the parameters pertaining to the local environmental conditions are used where available. However, in many cases, local values are not known accurately and in these cases, the value chosen will be on the conservative side. This is done to ensure that adherence to the DRL will provide "virtual certainty of compliance" with the ICRP recommendations (paragraph 82 of ref. [1.3]). At the same time, it should be realized that the trend towards conservatism means that "failure to adhere to the (DRL) will not necessarily imply a failure to achieve compliance with the (ICRP recommendations) and may require only a more careful study of the circumstances" (see same ICRP reference).

A final word of caution [5.1] must be added against the use of the estimates given here of the relationships between source emissions and doses for purposes other than those intended and stated above, e.g., for estimating the effect of known releases on the radiation doses and consequent health risks to the exposed populations[4.6]. To be meaningful, such analyses must be based only on locally derived environmental data and information. 5-3

5.2 Description of Environmental Transfer Pathways, Exposed Groups, and Radionuclides Considered at CRHL

Not all of the pathways shown in Fig. 5.1 are important in the CRNL environment and some may be excluded either because they are not applicable (e.g., consumption of seaweed) or their contribution to the exposure is insignificant compared with other pathways. Consideration of these various factors has resulted in the selection of the following eight pathways (five for airborne effluents and three for liquid effluents) for che CRNL calculations:

Pathway A (Immersion):

- external exposure while being immersed in a cloud of radioactive noble gases from airborne effluents.

Pathway B (Standing on Contaminated Ground):

- external exposure while standing on qround contaminated with radionuclides deposited from originally airborne material.

Pathway C (Inhalation):

- internal exposure due to direct inhalation of radionuclides in the plume from airborne effluents (with no depletion) . This pathway makes no allowance for inhalation of radionuclides that might be resuspended from ground deposits. It can readily be shown (see Appendix B) that the assumption of no allowance for the deposition-resuspension process is a conservative one. 5-4

Pathway D (Milk Ingestion): ^

- internal exposure due to ingestion of radionuclides via the grass-cow-milk pathway, in which the cow is assumed to graze at the CRNL upriver boundary (6 km from the main laboratory site) on grass contaminated with radionuclides from airborne effluents.

Pathway E (Vegetable Ingestion via Airborne Deposition):

- internal exposure due to ingestion of home-grown vegetables contaminated with radionuclides deposited from airborne effluents.

Pathway F (Vegetable Ingestion via Spray Irrigation):

- internal exposure due to ingestion of home-grown m vegetables that have been spray irrigated with river water contaminated with radionuclides in liquid effluents.

Pathway G (Water Ingestion);

- internal exposure due to drinking rivar water contaminated with radionuclides from liquid effluents.

Pathway H (Fish Ingestion);

- internal exposure due to eating fish reared in river water contaminated with radionuclides from liquid effluents. 5-5

The exposed groups of individuals considered in the calculations comprise adult workers on site and members of the public (adults and infants) outside the boundary. The workers are assumed to spend 2000 hours/year (40 hours/week, 50 weeks/year) on site and, during that time, are exposed via three of the airborne-effluent pathways (A, B, and C). Exposure via the other airborne-effluent pathways (D and E) and the liquid-effluent pathways (F, G, and H) is not applicable on site for obvious reasons and the fact that the site drinking- water supply is taken upstream of the discharge points for liquid effluents into the Ottawa River (see Section 3). Workers may be exposed via these other pathways during off-site hours but the effect would be less than that considered for members of the public who reside permanently outside the boundary or would he negligible in comparison to the pathways (A, B, and C) already considered.

The choice of exposed groups of members of the public considered in the calculations is narrowed for several reasons, e.g., the wind is channelled by ths Ottawa River valley and qenerally blows either upriver or downriver (see Figure. 3.2)/ the land across the river (in Quebec) is only occupied during the summer months by a few cottage dwellers (see Section 2), and the nearest population centre that uses the river water for domestic purposes is Petawawa, Ontario, about 20 km downstream of CRNL. This essentially limits the groups of interest to two locations on the Ontario side of the river, i.e., members of the public residing permanently near the upriver boundary (about 6 km from CRNL in the direction of Deep River)* and in Petawawa, about 20 km downriver.

* The closest permanent residents at present in this direction are about 7 km from CRNL (see Section 2). 5-6

Two age groups (adults and infants) are considered at both locations . However, because the upriver residents are so much closer to CRNL than the downriver residents and because the wind blows approximately equally in both directions, the derived release limits (DRL's) for airborne effluents will be based on the exposure of the upriver groups. On the other hand, the DRL's for liquid effluents will be based on the exposure of the downriver groups.

It may be argued that the application of the grass- cow-milk pathway (Pathway D) to the upriver groups is conservative because the dairy herds closest to CRNL are about 20 km downriver, rather than 6 km upriver. This conservative approximation was made, however, mainly because changes in milk production outside CRNL may occur without notice. In this regard, the following remarks by Dr. W.S. Snyder [5.3] are worth quoting: "Admittedly it is easy to criticise the assumption that a cow grazes at the boundary and that a child drinks the milk .... However, the critics generally do not suggest what alternative they would prefer. For example, one can easily assume that the cow is kept (a long way) from the boundary ... but the cost of the surveys to ascertain whsther or not the assumption is a reasonable one, not just now but also for the life of the reactor into the future, must be taken into account. Surely ... if it is feasible to produce power under these conservative assumptions at small cost to the con- sumer, it would seem sensible to make these conservative assumptions since allowances must be made for the uncertainties of realization of the design as well as for the future status of both the reactor and the population."

It is expected that groups in both locations (upriver and downriver) have home gardens which contribute a certain 5-7

amount of radiation exposure due to the vegetable-ingestion pathways, via either airborne deposition (Pathway E) for the upriver groups or spray irrigation (Pathway F) for the downriver groups. Fish, however, is not a major dietary source for infants so that for them, the fish-ingestion pathway (H) is not considered.

In summary, the characteristics of the five exposed groups of individuals considered in the calculations are:

Exposed Group No. 1 adults on site, exposed via Pathways A, B, and C.

Exposed Group No. 2 infants at the upriver boundary, exposed via Pathways A, B, C, D, and E.

Exposed Group No. 3 adults at the upriver boundary, exposed via Pathways A, B, C, D, and E.

Exposed Group No. 4 infants in Petawawa, exposed via Pathways F and G.

Exposed Group No. 5 adults in Petawawa, exposed via Pathways F, G, and H.

The major radionuclides or classes of radionuclides in airborne and liquid effluents from CRNL (either confirmed by analysis or potentially present) have already been summarized in Tables 3.1 and 3.2, respectively. The complete list of individual radionuclides of interest at CRNL is presented in Table 5.1 along with the eight pathways (A to H) and the five exposed groups considered in the calculations of DRL's. 5 -

It can be seen in Table 5.1 that certain combinations of radionuclide, pathway, and exposed group are not considered for reasons already discussed in this and previous sections (see, for example, Sections 4.3.1 and 4.3.2) or they have been excluded for various other reasons such as the following:

Certain activation products (e.g., Na-22, Na-24, Sc-46, Sc-47) are usually found only in liquid effluents (mainly from NRX).

External radiation exposures due to predominantly beta emitters (e.g., H-3, Sr-89, Sr-90) and alpha emitters (e.g., Th-232, U-235, Pu-239) deposited on the ground (Pathway B) are no+ important.

Some radionuclides (e.g., 1-132, 1-134) are too short-lived to contribute significantly to pathways associated with liquid effluents (Pathways F, G, and H).

Table 5.1 therefore summarizes those combinations (marked with an "X") that are considered in the detailed calculations that follow.

5.3 Formulation of Environmental Transfer Pathways

Barry [5.1] has suggested that, in deriving release limits, it is convenient to consider each exposure pathway made up of a series of systems or reservoirs with "transfer parameters" .connecting each system in the sequence. This is illustrated in Fig. 5.2 for the eight pathways (A to H) described in the preceding section. As an example, transfer parameter Pi,9 would describe the transfer of a radionuclide from the atmosphere to the lung. The overall transfer parameter P between the source and the "effective dose 0 ... 13 5-9

equivalent rate" would be given by the products of the individual transfer parameters applicable to each step along a particular sequence, e.g., for the inhalation pathway (Pathway C in Fig. 5.2):

P = P -P .P .P .P (1) 0 . • • 1 3 0,1 1,9 9,11 11,12 12rl3

and the dose rate, DR, is related to the release rate, Q, by the expression:

DR = P -Q (2) o ... i s

The maximum permissible release rate, qM, for the pathway would then be given by dividing the dose-rate limit (Section 4.1) by the overall transfer parameter:

_ Dose-Rate Limit M P (3) 0 ... 1 3

It can be seen in Fig. 5.2 that for internal exposures, certain transfer parameters in the sequence (P9,ii; Piorii; Pi 1,12; and Pi 2,13) can be eliminated if the intake rates due to inhalation or ingestion are related to the Annual Limits of Intake (ALI), described in Section 4.2 and listed in Table 4.2. This simplification has been used for calculations of qM for all internal-exposure pathways.

Figs. 5.2A to 5.2H illustrate the transfer parameters for pathways A to H, respectively, in more detail along with the definition of each parameter, the units used, and the equations for calculating q . It will be noted in Figs. 5.2A to 5.2H that certain multiplying factors in the pathways (depicted by circles) are included in the transfer parameters to take account of decays of radioactivity, periods of occupancy 5-10

in contaminated areas, periods of usage of contaminated material, and shielding protection inside buildings. Values of the factors assumed in the calculations are listed in Table 5.2 for people on site and off site. In many cases, the values chosen are based on conservative assumptions, e.g., it is assumed than an on-site worker spends his full working time (40h/week, 50 weeks/a) outdoors. The transfer parameters (including the multiplying factors where applicable) are evaluated in the following sections.

5.4 Evaluation of Transfer Parameters

5.4.1 Transfer from Source of Airborne Effluent to Atmosphere:(F

The concentration, C (Ci*/m3), of a radionuclide a in the air distant from a point source is proportional to the source emission rate, Q (Ci/s). Thus: C = K'Q (4) a where K = the atmosphere dispersion coefficient (s/m3), and is equivalent to P , the first transfer parameter in the sequence defined in equations (1) and (2). It follows that: Q Po,i = K = _f_ (s/m3) .-. Q [ '

Po is a function of the weather conditions existing at the time and of the vertical and horizontal position of the point of interest in the atmosphere relative to the source. The dispersion model of Pasquil [.'5.5] (and an exactly equivalent form of the model described by Sifford [5.6]) is widely used to estimate P. for six types of weather conditions, labelled 0/1 A to F and defined in the following table. P.J. Barry [5.1] has used the model to calculate long-term average values of

1 Ci = 37 GBq 5-11 I

P for each of the six different weather classes (categories o.i A to F) and has presented the results graphically as functions of distance from various source heights, assuming a uniform swing of the wind in which the wind blows 12.5% of the time in each 45° sector.

WEATHER CONDITIONS DEFINING DISPERSION CLASSFS

A. Extremely unstable conditions D. Neutral conditions* B. Moderately unstable conditions E. Sliqhtly stable conditions C. Slightly unstable conditions F. Moderately stable conditions

Surface wind Daytime conditions Nighttime Conditions speed Strong Moderate Cloudy Thin overcast or 3/8 cloudiness (m/s) Sun Light > 4/8 cloudinesst

<2 A A-B 2 A-B B 4 B B-C 6 C C-D >6 C D

* Applicable to heavy overcast, day or night. + The degree of cloudiness is defined as that fraction of the sky above the local apparent horizon which is covered by clouds. Barry 15.1] goes on to show that, in the absence of reliable local data on the occurrence freguencies for the six weather classes, a reasonable basis for calculating the long-term average value of P is to assume the following occurrence frequencies which 0 i 1 are typical of areas in the northern temperate latitudes:

A - 2% B - 8% C - 15% D - 45% E - 15% F - 15% 5-12

Barry's curves for this so-called "typical" weather distribution are shown in Fig. 5.3 as functions of distance from various source heights assuming a uniform wind rose.

For the present calculations, values of P are required for three sources (the 50-m high NRX/NRU Stack", the "61-m Stack", and a "Roof Vent")* and for people exposed at two locations (on the CRNL site and at the CRNL boundary, about 6 km from the main laboratory area in the direction of Deep River - see Section 5.2). It should be noted that the curves in Fig. 5.3 are based on atmospheric dispersion over open flat country and ideally should only be applied to such conditions. In particular, Barry [5.1] has noted that use of the data for close-in distances (within several kilometres of the source) causes some difficulty when clusters of large buildings are involved and recourse must be made to field studies or wind-tunnel studies if reasonably reliable estimates are required.

Fortunately, for the NRX/NRU Stack, Barry [5.7,5.8] has obtained field measurements of P with distance by 0,1 directly measuring concentrations of Ar-41 released from the stack over several years of study. For example, at a monitoring station located in a building on the CRNL site about 1 km from the stack, he found P = 6 x 10"' s/m3 and this was 0 i 1 assumed to be representative of the CRNL site generally. At another monitoring station, located approximately 4.8 km from the stack in the direction of Deep River, he found P = -e o,i 5 x 10 s/m3. Both these values have been plotted in Fig. 5.3 for comparison with Barry's calculated curves. However, it should

* See Section 3 and Table 3.1 5-13

be noted that a true comparison is not possible without taking account of the wind rose pattern at CRNL, e.g., the wind is channelled by the Ottawa River valley and generally blows either upriver or downriver and about 50% of the time in each direction (see Fig. 3.2). Therefore, at a distance of 1 km, one would predict a value of P (for a 50-m stack) of about — 7 cga 0 r 1 -7

2 x 10 x jp.9 = 8 x 10 s/m , in good agreement with Barry's measured value. The agreement at 4.8 km is not as good. Even so, since Barry's values represent a direct measurement of conditions at CRNL, they will be used for the dispersion model from the NRX/NRU Stack.

For low level releases from roof vents on buildings at the CRNL site, the dispersion model is much less reliable. While much has been written about dilution in the air in the lee of a building [5.1], this usually refers to an isolated building and there is little guidance for a cluster of buildings typical of CRNL. In some unpublished work, P.J. Barry made some measurements of tritium releases via an exhaust fan on the NRU building and found P = 3 x 10 s/m3 within about 70 m Ofl -5 of the base of the building, falling to 5 x 10 s/m3 by about 170 m. He assumed a value of 3 x 10 s/m3 as representative of the buildings at the CRNL site for determining maximum on-site exposures due to releases from roof vents. The same value will —

NRX/NRU Stack, i.e., P = 5 x 10 s/m3. o / l

To simplify the DRL calculations, the boundary value of 5 x 10 s/m3, based on measurements of the noble gas, Ar-41, is used for the releases of all radionuclides without taking account of the effects of plume depletion. This of course introduces some error if radionuclides other than Ar-41 are released from the source. For example, in the case of plume depletion of radionuclides due to deposition and washout processes, the error will obviously be on the conservative side, i.e., the plume concentration will be overestimated. The effect is not large, however, and can be ignored for distances less than about 10 km [5.1]. In the case of plume depletion due to radioactive decay in the time taken for the radionuclides to travel between the source and the receptor, it is important to note that the decay of Ar-41 — although not large — was not taken into account in the original measurements. Therefore, the error will be conservative for radionuclides shorter-lived than Ar-41 (1.8-hour half-life) and will be slightly non-conservative for longer-lived radionuclides.

It remains to choose a P value that would apply for 0 I 1 on-site exposures due to releases from the 61-m Stack, which is located amongst the buildings on site as distinct from the remote location of the NRX/NRU Stack (see Fig. 2.2 and 3.1). The matter has been discussed with Barry [5.9] and several complicating factors for close-in distances have been identified as follows:

(a) CRNL is .a built-up area which causes: -enhanced turbulence around and over buildings, -an increase in the frequence of occurrence of category A (and B) weather (high instability). 5-15

(b) CRNL may be considered as a "valley site" in which: - restricted winds may increase the incidence of category A (and B) weather. the ridge behind Bldg. 250 may cause downwash from stacks below the ridge height.

Factor (a) above would tend to increase the rate of dilution compared to that expected for the normal occurrence (about 2%) of category A weather; however, for areas close to the stack, the plume may be brought to the ground more rapidly so that the close-in concentration may be higher than that derived for the normal occurrence. With regard to the downwash effect in factor (b) due to the ridge and the topography of I buildings, Barry assumed that this would lead at most to a lowering of the effective stack height to 30 m under normal

weather conditions. He concluded [5.9] that the value of P applicable to the 61-m Stack at close-in distances lies 0 i 1 somewhere between curves (2) and (3) in Fig. 5.3 and may be close to the case he worked out for a 60-m stack and "enhanced A/B weather" (curve (5) in Fig. 5.3) . However, until more information becomes available, it has been decided to use the — 6 most conservative value, i.e., the maximum value of 10 s/m3, between curves (2) and (3) in Fig. 5.3. After correcting for the wind rose pattern at CRNL, the value becomes : P = 10 x 50% = 4 x 10 s/m3. Ofl 12.5% In summary, Table 5.3 lists the values of P used in o i l the calculations for the three sources and the two exposure locations considered for airborne releases. 5-16

5.4.2 Transfer from Atmosphere to Ground/Soil: (P )

— . . I f 2

With the exception of the noble gases, radionuclides released in airborne effluents will deposit on the ground to some extent as they travel down-wind. In the absence of rain, which would give rise to washout of a proportion of the radionuclides, deposition would occur by a so-called "dry deposition process", i.e., by sedimentation of the larger particles in the area closest to the release source and, at all distances, by diffusion and impaction of the smaller particles and by diffusion and chemical reaction of vapours.

Washout by rain is considered to be a relatively unimportant effect for the calculations of derived release limits and it is therefore neglected for this report. For example, Barry [5.1] concluded from a review of experimental studies of dry deposition and washout that the latter effect was insignificant for radioiodines and small particles (less than a few urn diameter) at distances less than about 10 km. Similarly, a recent U.S. NRC Regulatory Guide [5.10] concluded that, "for long-term averages, dose calculations considering dry deposition only are not usually changed significantly by the consideration of wet deposition".

For dry deposition, the rate of deposition, D (Ci*-m"a•s-1), 3 may be related to the air concentration, C (Ci/m3), by the "velocity of deposition", V (m/s), which was introduced by Chamberlain and Chadwick [5.11] in the following form:

Da = Ca*Vg (6)

V depends upon the physical and chemical form of the radionuclide released, the nature of the surface of deposition,

* 1 Ci = 37 GBq 5-17

the wind speed, and the amount of precipitation. Experimental data on deposition have been reviewed and it has been recommended [5.2] that, for purposes of hazards calculations, a value of V of 2 x 10""2m/s be used for radioiodines and 3 x 10~3m/s for radioactive particulates.

If the conservative assumption is then made that the radionuclides deposited on the ground are removed only be radioactive decay and are not affected by weathering or ground water processes, it can easily be shown that the buildup of radioactivity on the ground, C (Ci/m2), is given by: -A .t, C = 86,400 a (1-e r ft) 9 Ar -A .t (7) = 86,400 Ca'Vg (1-e r b)

where 86,400 = number of seconds in one day A = radioactive decay cconstant (d-1) of the radionuclide

tb = period (d) of buildup of the radionuclide on the ground.

Since by definition the transfer parameter P is the ratio of the ground concentration, C , to the air concentration, C g a (see Fig. 5.2B), it follows from equation (7) that the transfer parameter is given by: P = 86,400 Vg (l-e"X r-tb) (m) (8) 1 • 3 y2— Ar Values of P used in the calculations for those radionuclides 1 / 3 of concern in Pathways B, D, and E (see Table 5.1) are listed in Table 5.4. It is assumed in the calculations, again conservatively, 5-18

that the period of buildup of the radionuclide on the ground (t^) is 50 years or about 1.8 x 10* days.

5.4.3 Transfer from Atmosphere to Pasture Grass and Leafy Veqetables:(P ) and (P ) 1 i U 1/6

An expression similar to equation (8) can be derived readily for the transfer parameters for airborne deposition on pasture grass and leafy vegetables. By considering the additional factors for initial retention of the radionuclide on the vegetation and the physical loss of the radionuclide due to weathering during the growing seasons, one obtains:

-A .t g (1-e e" e) (m3Ag for the transfer parameter to pasture grass where r = fraction of the deposited radioactivity retained on pasture grass (dimensionless) 1 Ag = effective removal rate constant (d" ) for the radionuclide from pasture grass + = ^r *w' where A is the radioactive decay : constant (d~ ) and Aw is the removal rate constant (d**1) for physical loss by weathering

tg = time period (d) in which the pasture grass is exposed to radionuclide deposition during the growing season Y = agricultural yield (wet weight) of pasture grass (kg/m2).

Assuming that the effective removal rate constant (A ) is the same for pasture grass and leafy vegetables, one obtains for the transfer parameter to leafy vegetables:

r' • V iA *.t i 3 P = 86,400 2 (1_e- e- e) (m Ag) (10) »'6 v' -A 5-19

where the primed parameters (r1, t' , Y') are defined as above but for leafy vegetables. Ideally, site-specific values for the above parameters should be used to evaluate P and P but, thus far, measurements for the Chalk River region 1 I 6 have not been obtained. Therefore, the following conservative values obtainable in the literature were assumed to apply;

r = 0.5, for radioiodines or particulates [5.2] r1 = 0.2, for radioiodines or particulates [4.11] X = 0.05 d~2, which corresponds to a removal half- life of about 14 days [4.111

te = 30 d [4. 11]

t'e = 60 d [4.11] Y = 0.7 kg/m2 [4.11] Y' = 2.0 kg/m2 [4.11]

From these values and the recommended values of deposition velocity (V ) from the preceding section, the transfer parameters P and P have been evaluated in Table 5.5 for each of the radionuclides of interest in the milk-ingestion and vegetable-ingestion pathways (Pathways D and E in Table 5.1)

5.4.4 Transfer from Soil to Vegetation: (P ), (P ) and (P ) 3 I •> 3 r 5 3 t 6

Besides the transfer of radioactivity to vegetation via airborne deposition (preceding section), there is also the uptake of radioactivity deposited on the ground via the plant roots. If C is the concentration (Ci*/m2) on the ground, the concentration, C (Ci/kg), in the edible parts of the vegetation is given by [4.11]:

C B . c (Ci/kg) (11) v r> "

* 1 Ci = 37 GBq 5-20

where B = concentration factor for uptake of a radionuclide from the soil by edible parts of the vegetation, in Ciykg (wet weight) vegetation per Ci/kg dry soil. P = effective "surface density" of the soil, in kg (dry soil)/m2.

It follows from the definitions in Figs, 5.2 D, E, and F that the transfer parameters for uptake by pasture grass and vegetables are given by the ratio, v , i.e., cg P = p = p = B (m2Ag) . (12) 3,i> 3/5 3 » 6 P Site-specific values for the concentration factor, B, are not available for all the radionuclides of interest in the calculations. However, a study of the data from various experimenters has resulted in certain recommended values being proposed for the CSA standard [5.2]. These values have been adopted where available and are listed in Table 5.6. The remaining values in Table 5.6 have been taken from U.S. references [4.11 and 5.17].

For the choice of value of effective soil density (P), it seems reasonable to assume that the pasture grass and vegetables are grown in cultivated land so that the activity deposited on the ground is mixed fairly uniformly over a certain ploughed depth. In line with the recommendation of the U.S. NRC [4.11], a depth of 15 cm is assumed and this corresponds to a value of P = 240 kg/m2.

Table 5.6 lists the transfer parameters for the radionuclides of interest, based on expression (12) above.

1 Ci =37 GBq 5-21

5.4.5 Transfer from Pasture Grass to Milk: (P.,,8)

The concentration of a radionuclide in milk, C (Ci*/L), is related to the concentration of the radionuclide on pasture

grass, Cp (Ci/kg), by the following expression [4.11]:

CM = WCPG

where F,, = average fraction of the cow's daily intake of the radionuclide which appears in each litre of milk, i.e., Ci/L per Ci/d

Q = cow's daily feed (wet weight) of pasture grass (kg/d).

Since by definition the transfer parameter P is the ratio of •^k the milk concentration to the pasture grass concentration (see Fig. 5.2D), it follows from equation (13) that the transfer parameter is given by F^-Qp. However, the transfer parameter must also take into account the fact that cows in the area can only graze on pasture grass for part of the year and must eat pasture grass as stored feed for the rest of the time. Further, there is a delay between the time the cow ingests the feed and the time the milk is consumed. These "usage factors" and decay factors are applied as shown in Fig. 5.2D and result in the following expression for the transfer parameter: P = F • Q_ (OF + UF • DE- ) DF (kg/1) (14) til M F 1 2 12 Although there do not seem to be any experimental

estimates of FM in Canada, the parameter has been studied in other countries. The U.S. NRC [4.11] and Barry [5.1] have recommended values for various radionuclides (see Table 5.7).

Canadian data for Qp is similarly lacking; however, a value of

§) QF = 50 kg/d has been suggested in the U.S. [4.11].

* 1 Ci = 37 GBq 5-22

Until more site specific data become available, the recommended values have been used to calculate P from equation 1 I 8 (14) in Table 5.7. Values of the usage and decay factors assumed for the Chalk River region were taken from Table 5.2.

5.4.6 Inhalation Rates and Ingestion Rates; (P ) , (P ) , (P ) , (P ) , (P ) , and (P ) 1/9 2,10 5/10 6 f 1 0 7 / 1 0 IrH

Typical values for inhalation rates and ingestion rates (for milk, water, fish, and vegetables) of people in the Chalk River region are not known accurately. Therefore, recourse was rade to conservative {" default") values recommended in various references (see Table 5.8).

As shown in Figs.5.2 C, D, G and H, the intake rates must be modified by the appropriate occupancy and usage factors in Table 5.2. Using the symbols in Table 5.8, the transfer parameters for inhalation, water ingestion, fish ingestion, and milk ingestion are, respectively:

p := BR-OFj (fflVa) (15) 1 , 9

p I UP (L/a) (16) 2 / 1 0 V *

P IR," UF (kg/a) (17) 7 , 1 0 r s

P _ IR »UF (L/a) (18)

The transfer parameters for vegetable ingestion (P and P ) 5/10 6/10 require some explanation. For example, it has already been pointed out (Section 2) that the Chalk River region is not a major farming area so that only a fraction of the dietary intake of vegetables 5-23

listed in Table 5.8 would be grown locally. In the home gardens that are known to exist, there would be a period of about a month near the end of the summer growing period when a gardener might consume fresh leafy vegetables (e.g., lettuce, cabbage, spinach), root vegetables (e.g., potatoes, carrots, onions, beets), other above-ground vegetables (e.g., peas, beans, corn) and fruit (mainly apples). It is unlikely that a large fraction of the leafy vegetables would be stored for winter use but it is not uncommon for a gardening family to subsist 'over the winter on a variety of home-grown root vegetables, other vegetables, and apples kept in cold storage. It is expected that much of the external contamination on leafy vegetables, other above-ground vegetables and fruit would be removed before consumption by washing or by removal of the outer protective layers [4.6] .

In summary, "'t is assumed conservatively that 10% of a person's total annual intake of vegetables and fruit (IR , IR , and IR. in Table 5.8) is derived from contaminated home gardens and the produce is consumed soon after harvesting with no allowance fcr a reduction of the radioactivity due to decay or washing (in the case of leafy vegetables). In the case of other above-ground vegetables and fruit, however, it is assumed that the external contamination is removed so that the consumption of these products can be combined realistically with the consumption of root vegetables. It is further assumed, again conservatively, that half of the person's total annual intake of non-leafy vegetables and fruit (IRrv and IR in Table 5.8) is derived from contaminated home gardens and is consumed over a six-month period (average decay period of 90 days). In terms of the symbols in Tables 5.2 and 5.8 and Figs. 5.2E and F, the transfer parameters for vegetable ingestion are then given by: 5-24

P = (IR + IR ) (UF + UF-DF ) (kg/a) (19) 5,10 TV ^ 6 7 ! P = IR, 'UF (kg/a). (20) 6,io lv e

5.4.7 External Exposure Due to Immersion in a Radioactive Cloud: (P ) and (P ) 1 I 1 2 1 , 1 •< —

It should be clear from Section 4.3.1 that the dose rate, DR (rem*/a), received by the whole body of a person immersed continuously in a semi-infinite cloud of radioactive gas is related to the concentration, C_ (Ci /m3), of the gas by the expression: a

D^ = (DCFa)b'Ca (rem/a) (21)

where (DCF ), is the dose conversion factor (Table 4.3) expressed a a —1 —3 in units of (rem-a )/(Ci«m ). Similarly, the skin dose rate, DR_, would be given by the expression:

DR = (DCF )'C_ (rem/a) (22) S a 5 cl where (DCF )s is the dose conversion factor for skin exposure a expressed in the same units.

It follows from the formulation in Sections 5.3 and 5.4.1 and Fig. 5.2A that the transfer parameters, P and P , 1,12 1,1* are simply the dose conversion factors modified by the appropriate factors (Table 5.2) for the periods of occupancy outdoors and for the shielding effect of buildings for occupancy indoors. The transfer parameters are then given by:

P = (DCF ) (OF + OF -SF ) (rem-a"1)/ (Ci'm~3) (23) iiit as it 5 2

= (DCF h (OF + OF »SF ) (rem»a -1)/(Ci«m~3) (24)

* 1 rem = 0.01 Sv t 1 Ci = 37 GBq 5-25

Because it is relatively easy to measure source emission rates in units of Ci- MeV/s without regard to the amounts of individual radionucl ide.? in the source, it is often convenient to express the derived release limits in the same units. To do this, it is important to note that the dose conversion factors in Table 4.3 are closely related to the disintegration energies of the radionuclides. Also, the dose rate to a small mass of air on the plane surface of a semi-infinite cloud of radioactive gas is givea by [4.1]:

DR (air) = 0.25E-C rad/s (2.5E-C mGy/s) 3 a 6 7 = 7.9xlO E«C a rad/a (7.9xlO E«Ca mGy/a) (25) where E is the average energy per disintegration of the radionuclide in MeV. Hence, from the dimensional similarity of expressions (21), (22), and (25), one can define an effective energy (E, for whole body dose, E_ for skin dose) such that: D S

(DCF ) Eb = a b (MeV) (26) 7.9xlO6

(DCF ) Es = a s (MeV) (27) 7.9xlO6 For whole-body dose, the effective energy, E,. will be approximately the average y disintegration energy; for skin dose, Eg will be approximately the average 6+Y disintegration energy. Therefore, if the release limit of a radionuclide is derived in units of Ci/s, the limit can be expressed in units of Ci-MeV /s or Ci>MeV_ /s by multiplying by E^ or E, respectively. The same result would be obtained by using, for the dose conversion factor in the whole-body or skin dose calculations, the value of 7.9xlO6 (rem-a^1)/(Ci'MeV *m~3)* or

* 2.1xlO~6 (Sva-M/tB 5-26

6 1 3 7.9 x 10 (rem-a" )/(Ci'MeVg+ •m' )* respectively.

Values of 1!^ and Es, derived from Table 4.3 and expressions (26) and (27), are listed in Table 5.9 and are used later in the report for conversions of units as described above. It should be noted that the assumption of a semi- infinite cloud of uniform concentration in the calculations tends to overestimate the exposure dose rates at close-in distances (between about 1 km and 10 km from the source) because the cloud has not developed sufficiently and because the effect of radioactive decay is ignored (see Section 5.4.1). The discrepancy is more pronounced for the short-lived, strongly gamma-emitting noble gases such as 3.1-minute Kr-89 released close to the ground,but the degree of conservatism is difficult to predict with any certainty [5.1], For releases of strong gamma emitters from tall stacks, the semi- infinite cloud model may substantially underestimate the dose to a person on the ground within about 1 km of the stack because the concentration at ground level is low yet the direct radiation from the high concentration in the plume may be significant. This effect is only important for unusually tall stacks at very short distances. However, for the stack heights and distances in this study on which the dispersion coefficient (Pfl ; in Section 5.4.1) was based, the semi-infinite cloud model is expected to be conservative (overestimate the doses) for all noble-gas radionuclides.

5.4.8 External Exposure Due to Radionuclides Deposited on Ground:(P ),and(P ) 3/12 3 jit

From the formulation in the preceding sections and in Fig. 5.2B, it is clear that the transfer parameters, P

* 2.lxlO-6(Sv-a"1)/(Bq.MeV 5-27

and P relate the external skin and whole-body dose rates 3 i 1 h ' (DR and DR. , respectively) of a person standing on ground contaminated with a concentration, C , of a radionuclide. In units of (rera»a~')/(Ci«m~'), the transfer parameters for exposure on an infinite plane surface are equivalent to the dose conversion factors (DCF in Table 4.4) modified by the appropriate occupancy and shielding factors (Table 5.2) as follows:

P = (DCF ) (OF + OF • SF )SF (rem-a-1)/(Ci-m"2) (28) 3 , 1 2 g S 2 3 1 3

P , = (DCF ), (OF + OF • SF ) SF (rem «a-1) / (Ci«m~z) (29) 311 IJD 2 313

The shielding factor SF takes account of the fact that the ground on which the radionuclide is deposited will not always be smooth and flat so that some allowance must be made for the effect of shielding provided by ground roughness, vegetation, snow cover, etc. Experimental data and calculations [5.13, 5.14] indicate that the external dose would be reduced by a factor of about two for most practical applications. A value of 0.5 for the dose reduction multiplying factor (SF in Fig. 5.2B and Table 5.2) has therefore been chosen. Values for the other factors (listed in Table 5.2) account for the periods of occupancy outdoors and for the shielding effect of buildings for occupancy indoors.

5.4.9 Transfer from Source of Liquid Effluent to Ottawa River: (P )

Although radioactivity is released to the Ottawa River via five main liquid effluent streams, it was decided for these calculations (see Sections .3 and 5.1) to treat CRNL as a single source and assume that the total release (Ci/s) of a particular radionuclide is diluted by the average flow of the river (about 750 m3/s) [3.1] before becoming a source of 5-28

radiation exposure to people downstream. The derived release limit (DRL) would then represent an upper limit to the rate; of release of that radionuclide from the site as a whole, independent of the presence of other radionuclides in the CRNL effluent or other effluent sources (e.g., NPD) along the river. These factors would be taken into account when establishing administrative levels for the actual releases from the individual effluent streams (see Section 7.4).

In light of the above description and the formulation in Figs. 5.2F, G, and H, the "dilution factor" (P ) or the 0 i 2 multiplier of the release (Ci/s) to give the equilibrium concentration (Ci/L) in the river is given by:

Po,2 = 1 = 1.3 x 10~6 s/L (30) 750 m'-s-'x 103L-m-3

5.4.10 Concentration Factors for Freshwater Fish: (P ) 2 f 7

The transfer parameter, P (see Fig. 5.2H), relates 2/7 the concentration of a radionuclide in water (Ci*/L) to the concentration (Ci/kg) of the radionuclide in fish (flesh). This so-called concentration factor (or bioaccumulation factor) is a complex function of many factors such as the mineral content, the pH, and the salinity of the water as well as the feeding habits of the fish species. The mineral content of the water has an overriding importance in the determination of equilibrium concentration factors and, for the "low mineral content" of the Ottawa River (about 70 yg/mL total dissolved solids), the values listed in Table 5.10 and based on experimental studies in numerous references are recommended [5.2].

1 Ci = 37 GBq 5-29

It is assumed in the calculations that the concentration in the water in which the fish matures is the concentration after full dilution by the river flow (see preceding section). While it might be argued that this underestimates the concentration in fish flesh if the fish spends most of its time near the outfall, such an argument is not supported by measurements. For example, in the long-term study by the Federal Department of National Health and Welfare [5.15] of water and fish samples taken downstream of CRML, it was found that the concentration factor for Cs-137 averaged about 5,000, in good agreement with the value (Table 5.10) of 5,000 assumed on the basis of the potassium content of the river. A much higher value than 5,000 might be expected if the above effect was significant. Although similar experimental data are not available for most of the other radionuclides of interest, the concentration factors listed in Table 5.10 are thought to be conservative.

5.4.11 Transfer from Ottawa River to Garden Soil Via Spray Irrigation: (P ) 2 , 3

An expression analogous to that for atmospheric deposition on the ground (Section 5.4.2) may be developed to describe deposition on garden soil due to spray irrigation in Pathway F (Fig. 5.2F). For example, if I (L-m ~1»d~1) is the average spray irrigation rate during the growing season and C (Ci*/L) is the water concentration, the rate of deposition, D , of water-borne radionuclides on the soil is given by:

and the buildup of radioactivity on the soil, C , is given 5

* 1 Ci = 37 GBg 5 - 3Q

by [4.11]:

D Cs = fx. w (l-e'VS) A r = f . fw'1 (l-e"Ar#tb) (Ci-nT2) (32) 1 X where fj = the fraction of the year that the garden is irrigated (dimensionless) X = radioactive decay constant (d"1) of the radionuclide

tb = period (d) of buildup of the radionuclide on the soil.

Since by definition the transfer parameter P is tha ratio 2 i 3 of the soil concentration to the water concentration (see Fig.5.2F), it follows from equation (32) that the transfer parameter is given by:

P = fI*X (l-e^r^b)

irriqated for a few months during the growing season (fI=20%) . Based on these values in expression (33) , the transfer parameter P is evaluated in Table 5.11 for the radionuclides of interest 2 I 3 in the spray-irrigated vegetable-ingestion pathway (Pathway F in Table 5.1) . 5-31

5.4.12 Transfer from Ottawa River to Leafy Vegetables Via Spray Irrigation: (P ) 2 , 6

The transfer parameter for deposition on the surface of leafy vegetables due to spray irrigation can be derived in the same way as that for airborne deposition in expression (10) to give:

P = ^-^ (l-e"Aet<:'e) (L.kg-1) (34) 2 6 ' Y'-Ae where Y', A , and t1 are as defined in Section 5.4.3, and

r" = fraction of the deposited radioactivity retained on leafy vegetables during spray irrigation (dimensionless)

I = average spray irrigation rate (L'm~2'd"M during the growing season = 2 L'm"~2> d"1 , assumed from preceding section.

One would expect that the fraction deposited during spray irrigation r" would be much less than the value (r'=0.2) assumed in Section 5.4.3 for airborne deposition. There is experimental evidence [4.6] to support a value of r" = 0.05 and the same value will be assumed here.

Using the above values of I and r" and the values of Y', e, and t' from Section 5.4.3, the transfer parameter P is c 2,6 evaluated in Table 5.12 for the radionuclides of interest in Pathway F (Table 5.1). 5-32

5.4.13 Special Cases (Airborne Releases of H-3 and C-14 )

Airborne tritium (released in the form of tritiated water vapour, HTO) and C-14 (released in the form of * ""COj) offer special characteristics that make it convenient to calculate release limits for these radionuclides in ways other than those discussed above. Briefly, the approach uses a specific- activity model [4.17, 5.1, 5.18] which assumes that the specific activity* of the radionuclide in the body reaches an equilibrium level equivalent to the specific activity of the radionuclide in the air after intake by the various airborne pathways ( e.g., inhalation, milk and food ingestion, etc.). The approach is a reasonable one because HTO and l*C02 will not become concen- trated significantly during passage through environmental systems and they will gradually reach an equilibrium, in a time short compared to the lifetime of a nuclear facility, with the water and carbon in the constituents of a person's local diet of water, milk, vegetables, etc. The approach is assumed to apply equally to people of all ages. Of course, the approach is overly conservative if locally contaminated food and water does not form a major part of a person's total intake of hydrogen and carbon. For example, the approach would not be realistic for exposure of on-site workers to HTO and '''COz since they are exposed mainly via the inhalation pathway and the usual type of calculation (see Fig. 5.2C) would apply. For exposure of members of the public at the upriver boundary, who are closest to the sources of airborne releases (see Section 5.2), the highly conservative approach will be used in line with the conservative assumptions that have

"Specific activity" in this sense means the radioactivity of a nuclide per unit mass of all the isotopes of the element present; e.g., curies of C-14 per gram of carbon, not per gram of C-14. 5-33

already been made for milk and vegetable ingestion (see Sections 5.2 and 5.4.6).

As an example of the specific-activity approach for airborne tritium released as HTO, the average concentration of tritium (curies per gram of water vapour) in air at the CRNL boundary is given by:

8 3 Q (5xlO- s»m- ) = lxl0-aQ (ciVg) (35) 5 g«m~3 where Q = the average release rate (Ci/s)

5xlO~8 s-m~3 = the average dilution factor (P ) at the 0/1 CRNL boundary (see Table 5.3) 5g»m~3 = the mean concentration of water vapour in air (corresponds to 50% relative humidity at about 10°C)

Assuming that the concentration in the body fluids is in equilibrium with this air concentration and knowing [4.17] that the dose equivalent rate per unit concentration in the whole body is about lxlO8 (rem -a"1) / (Ci-g"1 water) [2 . 7xlO~5 (Sva"')/ (Bq^g"1) ] , then the maximum permissible release rate of HTO corresponding to the whole-body dose limit of 0.5 rem^a*"1 (0.005 Sva"1) is given by:

q = M — = 0.5 Ci/s (36) (lxlO"8)(lxlO8) (19 GBq/s) A similar calculation for the maximum permissible release rate in of CO2,assuming that the stable carbon content of air is about 0.16 g.m""3 and the dose equivalent rate per unit specific activity of carbon in the whole body is about 2.1xlO8 (Ci-g"1 carbon) [5.7xlO"5(Sv.a"1)/(Bq-g"1)] [4.17], results in:

q = 0J> = 7.6xlO~3 Ci/s. M (0.28 GBq/s) (37) (5xlQ-B) (2.1x10" > 6.16

* 1 Ci = 37 GBg 5-34

It should be noted that the specific-activity approach does not apply if the airborne C-14 is released in particulate form. Therefore, since the annual limit of intake by inhalation for particulate C-14 is so much more restrictive than for 1'*C02 (see Table 4.2) and since the form of C-14 released is not always known, the cases for C-14 released in particulate form will be worked out separately by the usual types of calculations described in the preceding sections. 5-35

TWtt£ 5.1 - RADICHUCLIIIS, PATHftYS, AND EXP0SH3 GROUPS CCKSIDERED IN CaiOJIATlaS* Airborne Effluents liquid Effluents

Patnwoy (mx Fig. 5.3) ttadicnuclide Half-Life A B c D E F G H (daya) (inner 3 ton (cent -grwjnt ) (inhalation) {milk ing. (veg.ing. - (veq. ing. - (water Ing.) ifiah i«g.> airborne dqa. spray irrig

Expoeed 1 LJ 2 3 4 S 4 5 5

H-31HI0) 4.47E+O3 X | X X X X X X j + X X X X x ; Be-7 5.33E+O1 . X X X X X C-14 2.09E+O6 c-14 (part.) X X X X X Na-22 9.50E+O2 X X X X X -24 5.26E-O1 X X X X X S-35 1.72B*61 X X X X X Sc-46 • 37Et01 X X X X X J -47 .40E+00 X X X X X Cr-51 X X XXX X X X X X X X X X Wi-54 .O3E+O2 X X XXX X X X X X X X X X Ete-59 .51E+01 X X XXX X X X X X X X X X Co-5B .lOE+Ol X X XXX X X X X X X X X X -60 X X XXX X X X X X X X X X Zn-65 .44E+O2 X X XXX X X X X X X X X X Aa-76 .1OE+0& X X X X Sr-B9 ,05E*Ol XXX X X X X X X X X X ! -90 i.03E+O4 XXX X X X X X X X X X ; 6.50E+O1 X X X < X X (t>-95 3.5IE+01 X X XXX X X X X X X X X X [ W>-99 2.75E+OO X X XXX X X X X X X X X x 1 Ru-103 3.96E4O1 X X XXX X X X X X X X X X 1 -106 3.67E+O2 X X XXX X X X X A X X X X 4.75E+O4 -110m 2.52E402 X X X X X I Sb-124 6.02E+01 X X XXX X X X X X X X X -125 X ' TB-132 3.'25E+OQ X X XXX X X X X X X X X x ; i=I35 XXX X X X X X X X X -1J9 6.21B*09 X X XXX X X X X X X X X -X J- -131 6.06B*00 X X -X XX X X X X X X X X X -132 9.54E-02 X X XXX • -133 8.70E-01 X X XXX X X X X X X X X X -134 3.65E-02 X X XXX -135 2.74E-01 X X XXX X X X X X X X X X X X X X X >t -337 l!lOB*04 X X XXX X X X X X X X X X Ba-140 1.28B+01 X X XXX X X X X X X X X X Ia-340 1.67B+00 X X XXX X X X X X X X X X Ot-141 3.30E+O1 X X XXX X X X X X X X X X j -143 1.36E+O0 X X XXX X X X X X X X X X 1 - 44 2.B5E+O2 X X XXX X X X X X X X X X it JI Jt it X -154 5.84E+03 X X X X X Hf-175 X X X X X -1B1 X X X X X HJ-20J X X XXX X X X X X X X X X RB-226 S,84B*05 X X XXX X X X X X X X X X Th-228 6,9flRHl? XXX X X X X X X X X X

P.-M3 2.'7«*02 X X X X X U-232 2.S7V6I X X X -233 XXX X X X X X X X X X -234 9!02B*07 XXX X X X X X X X X X -235 2.59»*11 XXX X X X X X X X X X -238 1.6519*12 XXX X X X X X X X X X Np-237 7.B1&0U XXX X X X X X X X X X -239 2.35»*O0 X X XXX X X X X X X X X 11 Pu-238 Si T^TL 5t Si 5! x x Si it -239 XXX X X X X X X X X X -240 2.400*06 XXX X X X X X X X X X -241 5.112+03 XXX X X X X X X X X X Mn-241 l.S9SfO5 XXX X X X X X X X X X Cte-242 1.63B*O2 XXX X I it— Kr-85m 1.B3E-01 X -85 3-93B+03 X -87 5.27E-02 X -88 1.17E-01 X -B9 2.22E-O3 X -M 3.822-04 X to-131» l.lflBfOl X -133B 2.26B+O0 X -133 5.27D*00 X -135m 1.0BE-02 X -135 3.B3E-O1 X -137 2.71E-O3 X -131 l.ltt-02 x CUM ccnaidarad a i atrfcad with "X- t 4.47E+03-4.47X10' 4 BpmsUl CUM (in Sactitxt 5.4.13) - Mult* on Bit* • Infant* at ($rlutr Boundary - MolU it Uprivmr Bcuriuy - In£anta In TMaMw • Mult* In I 5-36

7ABI£ 5.2 - FACTORS FDR DECAY, OCCUPANCY, USAGE, AND SHIELDING

Value Assumed

Factor for radioactive decay in stored feed and vegetables = e r n where *_.= radioactive [4.111 & decay constant *d~') and t_ = (Table 5.7) Sec.5.A,5 tine delay between harvest and ingestion (assumed=90d)

Factor for radioactive decay in mil* = erf where Xr=_radio- active decay constant (d ') and N/A e r [4.11] tf = transport time between cow (Table 5.7) ingestion and milk, consumption {assumed=2d)

Occupancy by humans of contaminated atmosphere (outdoors or 1.0 indoors), fraction of time at location

Occupancy by humans of contaminated ground outdoors, fraction of year

Occupancy by humans of buildings on contaminated ground, fraction of year

Occupancy by hiirans of contaminated atmosphere outdoors, fraction of year

.Occupancv bv htmans nf buijri in xmtaminated atmosphere, fraction o£ year

Shielding factor for occupancy inside buildings on contaminated ground

Shielding factor for occupancy inside buildings in contaminated atmosphere

Dose reduction factor to account for ground roughness and some Sec.5,4.8 shielding by snow in winter

Usage by cow of contaminated N/A pasture grass, fraction of year

Usage by cow of contaminated N/A [5.1] stored feed, fraction of year

Usage by humans of contaminated milk, fraction of year

Usage by humans of contaminated drinking water, fraction of year

UF Usage by hwnans of contaminated s 1.0 15.1] fish, fraction of year (adults only)

UF Usage by humans of contaminated fresh root and other vegetables, fraction of year

Usage by humans of contaminated stored root and other vegetables, fraction of year

Usage by hunans of contaminated leafy vegetables, fraction of year

N/A * Not applicable 8 n/d, 365 A/a * 40 h/weekr 50 weeks/a 16 h/d, 365 d/a 5-37

TABLE 5.3 VALUES OF TRANSFER PARAMETER (Pp,i) FROM SOURCE OF AIRBORNE EFFLUENT TO ATMOSPHERE

P (s/m3) 0 i 1 Source On Site At Upriver Boundary

NRX/NRU Stack 6xlO~7 5x10"6

61-m Stack 4xI0~6 5xlO"8

Roof Vent 3x10"" 5xlO"e 5-38

TABLE 5.4

EVALUATION OF TRANSFER PARAMETER IP )

(TRANSFER FROM ATMOSPHERE TO GROUND/SOIL)

P] s = B6,400 \ (l-e'V'b) (m) V r where g = deposition velocity (see Section 5.4.2) = 2xlO~2 m/s for radioiodines = 3xlO™3 m/s for particulates r = radioactive decay constant {d"1) b = buildup period (see Section 5.4.2) = 1.8x10" d (50a) Decay Constant, A p r Radionuclide (a-') 1 r 3 (It!)

C-14 (part.) 3.3E-07+ 4.7E+O6 Cr-51 2.5E-02 1.0E+04 Mn-54 2.3E-O3 1.1E+05 Fe-59 1.5E-02 1.7E+04 Co-58 9.8E-03 2-6E+04 -60 3.6E-04 7.2E+05 Zn-65 2.8E-03 9.3E+O4 Sr-89 1.4E-02 1.9E+O4 -90 6.7E-05 2.7E+06 Zr-95 1.1E-02 2.4E+04 Nb-95 2.0E-02 1.3E+04 Mo-99 2.5E-01 1.0E+03 Ru-103 1.8E-02 1.4E+04 1.9E-03 1.4E+05 Sb-124 1.2E-02 2.2E+04 -125 7.0E-04 3.7E+05 Te-132 2.1E-01 1.2E+0 3 1-125 1.1E-02 1.6E+05 -129 1.1E-10 4.7E+06 -131 B.6E-02 2.0E+04 -132 7.3E+00 2.4E+02 -133 8.0E-01 2.2E+03 -134 1.9E+01 9.1E+01 -115 2.5E+00 6.9E+02 Cs-134 9.3E-04 2.8E+05 -137 6.3E-05 2.BE+06 Ba-140 5.4E-02 4.8E+03 La-140 4.1E-01 6.3E+02 Ce-l'.l 2.1E-02 1.2E+0 4 -143 9.3E-04 2.8E+05 -144 2.4E-03 1.1E+05 Hg-203 1.5E-02 1.7E+O4 Ra-226 1.2E-Q6 4.6E+06 Th-22B 9.9E-04 2.6E+05 -232 1.3E-13 4.7E+06 0-232 2.6E-05 3.7E+06 -233 1.2E-08 4.7E+06 -234 7.7E-09 4.7E+06 -235 2.7E-12 4.7E+06 -238 4.2E-13 4.7E+06 Np-237 8.9E-10 4.7E+06 -239 2.9E-01 8.9E+02 Pu-238 2.2E-05 3.9E+06 -239 7.8E-08 4.7E+06 -240 2.9E-07 4.7E+06 -241 1.4E-04 1.7E+06 Am-241 4.4E-06 4.5E+06 Cm-242 4.3E-03 6.0E+04 -2ii l.OE-04 2.2E+D6

t 3.3 E-07 - 3.3x10" 5-39

EVALUATION OF TRANSFER PARAMETERS (P ) and (P ! lit i< s (TRANSFER FROM ATMOSPHERE TO PASTURE GRASS AND LEAFY VEGETABLES)

P = 86,400 r (l-e^e-S) (mVkq) y. P •V ) (mVkg) = 86,400 r'

(See Section 5.4.2 and 5.4.3 for values of parameters used in above equations.)

Padionuclide Decay"Constant,A \ = X +0.05 p P (d"1) e (d"M (mVkg) (mVkg)

c-14tpart.) 3.3E-07t 5.0E-02 2.9E+03 4.9E+02 Cr-51 2.5E-02 7.5E-02 2.2E+03 3.4E+02 Mn-54 2.3E-03 5.2E-02 2.8E+03 4.8E+02 Fe-59 1.5E-02 6.5E-02 2.4E+03 3.9E+02 Co-5 8 9.8E-03 6.0E-02 2.6E+03 4.2E+02 -60 3.6E-04 S.OE-02 2.9E+03 4.9EJ-02 Zn-65 2.8E-03 5.3E-02 2.8E+O3 4.7E+02 Sr-89 1.4E-02 6.4E-02 2.5E+03 4.0E+02 -90 6.7E-05 5.0E-02 2.9E+03 4.9E+02 Zr-95 i.lE-02 6.1E-02 2.5E+03 4.1E+02 Nb-95 2.0E-02 7.UE-02 2.3E+03 .' 6E+02 Mo-9 9 2.5E-01 3.0E-01 6.2E+02 'S+01 Ru-103 1.8E-02 6.8E-02 2.4E+03 j /C+02 -106 1.9E-03 5.2E-02 2.6E+03 J.',E+02 Sb-124 1.2E-02 6.2E-02 2.5E+03 4.1E+02 -125 7.0E-04 S.1E-02 2.BE+03 4.8E+02 Te-132 2.1E-01 2.6E-01 7.1E+02 1.0E+02 1-125 1.1E-02 6.1E-02 1.7E+04 2.8E+03 -129 1.1E-10 S.OE-02 1.9E+04 3.3E+03 -131 8.6E-02 1.4E-01 8.7E+03 1.2E+03 -133 8.0E-01 8.5E-01 1.5E+03 2.0E+02 -135 2.5E+00 2.6E+OO 4.7E+02 6.6E+01 CB-134 9.3E-O4 5.1E-02 2.8E+03 4.8E+02 -137 6.3E-05 5.0E-02 2.9E+03 4.9E+02 Ba-140 5.4E-OS 1.0E-01 l.BE+03 2.6E+02 La-140 4.1E-01 4.6E-01 4.0E+02 5.6E+01 Ce-141 2.1E-02 7.1E-O2 2.3E+03 3.6E+02 -143 9.3E-04 5.1E-02 2.8E+03 4.8E+02 -144 2.4E-O3 5.2E-02 2.8E+O3 4.8E+02 Hg-203 1.5E-02 6.5E-02 2.4E+03 3.9E+02 Ra-226 1.2E-06 5.0E-02 2.9E+03 4.9E+02 Th-228 9.9E-04 5.1E-02 2.BE+03 4.8E+02 -232 1.3F <3 S.OE-02 2.9E+03 4.9E+02 U-232 2.6i2-US S.OE-02 2.9E+03 4.9E+02 -233 1.2E-08 5.0E-02 2.9E+03 4.9E+02 -234 7.7E-09 5.0E-02 2.9E+03 <.9E+02 -235 2.7E-12 S.OE-02 2.9E+03 4.9E+02 -23B 4.2E-13 S.OE-02 2.9E+03 4.9E+02 NP-237 8.9E-10 5.0E-02 2.9E+03 4.9E+02 -239 2.9E-01 3.4E-01 5.4E+02 7.6E+01 Pu-238 2.2E-05 S.OE-02 2.9E+03 4.9E+02 -239 7.8E-08 5.0E-02 2.9E+03 4.9E+02 -240 2.9E-07 S.UE-02 2.9E+03 4.9E+02 -241 1.4E-04 S.OE-02 2.9E+O3 4.9E+02 Am-241 4.4E-06 S.OE-02 2.9E+03 4.9E+02 Cn-242 4.3E-03 5.4E-02 2.7E+03 4.6E+02 -244 1.0E-04 S.OE-02 2.9E+03 4.9E+02

t 3.3E-07-3.3X10" 5-40

TABLE 5.6

EVALUATION OF TRANSFER PARAMETERS (P ), (P ), (P )

(TRANSFER FROM SOIL TO VEGETATION)

p = p = p a j^_ (m'/kg)

where B = concentration factor for uptake of radionuclide from soil .jy edible parts of vegetation, in Ci*/kg (wet we:ght) vege'-.ation per Ci/kg dry soil P = effective "surface density" of soil = 240 kg (dry soil)/m2 (see Section 5.4.4)

H-3(HTO) 4.8E+00t [4.11] 2.OE-02 Be-7 4.2E-04 1.8E-06 C-14(part.) 5.5E+00 2.3E-02 Na-22 2.2E-04 -24 I 5.2E-02 S-35 6.0E-01 [5.21 Z.bE-JJ Sc~f6 -47 [ 1.1E-03 4.6E-06 Cr-51 2.5E-04 1.0E-06 •tln-54 3.UE-02 1.3E-04 Fe-59 4.0E-04 1.7E-06 Co-SB 3.9E-05 -60 . 9.4E-03 Zn-65 4.0E-01 •• 1.7E-03 As-76 1.OE-02 4.2E-05 Sr-89 -90 . 2.0E-01 8.'E-04 Zr-95 1.7E-04 7.1E-07 Nb-95 9.4E-03 3.9E-05 Mo-99 1.3E-01 5.4E-04 Ru-103 \ 1.OE-02 : 4.2E-05 • ^106 Ag-lOBm 6.3E-O4 -lxOm :..5E-01 Sb-124 1.1E-02 • 4.6E-05 -125 Te-132 1.3E+00 5.4E-03 1-125 -129 -131 5.5E-O2 2.3E-04 -133 -135 Cs-134 8.3E-05 -137 2.OE-02 Ba-140 5.0E-03 2.1E-05 La-140 2.5E-03 • l.OE-05 Ce-141 -143 2.5E-O3 l.OE-05 -144 Eu-152 l.OE-05 -154 2.5E-03 Hf-175 1.7E-04 [4.11] 7.1E-07 -181 Hg-203 4.0E-01 15.21 l.VE-03 Ra-226 1.3E-02 [5.171 5.4E-05 Th-228 -232 4.2E-03 1.8E-05 E>a-233 2.5E-O3 l.OE-05 0-232 -233 1.2E-06 -234 2.9E-04 [5.21 -235 -236 ' Mp-237 l.OE-05 -239 2.5E-O3 14.111 PU-L3S -239 2.0E-04 [5.21 B.3E-07 -240 -241 Mi-241 1.0E-03 4.2E-06 Ca-242 1.0E-03 4.2E-06 -244

* 1 Ci • 37 GBq t 4.8E+00 • 4.8x10' - 4.8 5-41

TABLE 5.7

EVALUATION OF TRANSFEH PARAMETER (P )

(TRANSFER FROM PASTURE GRASS TO HILK1

P^ •= Fm- QF (UF + UF -DP )DF

QF - cow's daily feed (wet weight) of pas1

UF(- 0.5 UF - 0.5 see Table 5.2 DF - e"9oXi: or'- .""r

Radionuclide Decay Constant, X DF DP (d~l) r (d/U m Ref. (*g/Li

C-14 (part.) 3.3E-07+ 1.0E+00 i..OE+QO 1.2E-02 (4.11] 6.OE-01 Cr-51 2.5E-02 1.1E-01 9. J,«-01 2.2E-03 5.3E-02 Mn-54 3.3E-03 B.1E-01 l.OE-t-00 2.5E-04 1.1E-02 Fe-59 1.5E-02 2.6E-01 9.7E-01 1.2E-03 3.7E-02

-60 3.6B-O* .7E-0. 1. T+OO 4.9E-02 1 Zn-65 2.8E-03 . 8F.-f 1 9.,£-01 3.9E-02 1.7E+00 Sr-89 1.4E-02 .C» 01 9.7E-01 1.0E-03 (5.1J 3.1E-02 -90 6.7E-05 .9E-01 1.0E+00 3.0K-6. Zr-95 1.1B-02 .7E-01 9.8E-01 5.0E-06 H.ll] 1.7E-04 Kb-9 5 2.0E-02 -7E-01 J.6E-01 2.5E-03 7.0E-02 Mo-9 9 2.5E-01 .7E-1D 5.1E-01 7.5E-03 1.1E-01 Ru-103 1.8E-02 .OE-01 9.6E-O1 1.0E-06 2.9E-05 -106 1.9E-03 .4E-01 1.0E+00 4.6E-0S sb~124 1.iE-62 3.4E-O1 9.BE-01 1.5E-03 4.9E-Q2 I -125 7.0E-O4 9.4E-01 1.0E+00 7.3E-02 Te-132 2.1E-01 6.2W-09 6.6E-01 1.0U-03 1.7E-02 (5.H -129 1.1E-1D l.OE-t-00 1.0E+00 5.OE-01 -131 8.6E-02 4.4E-O4 8.4E-01 2.1E-01 -133 8.0E-O1 5.4E-32 2.OE-01 5.0E-02 '. -135 2.5E+00 1.9E-9B 6.7E-03 1.7E-03 9.3E-04 9.2E-01 , (JE+OO 1.0E-02 -137 6.3E-05 9.HE-O1 .OE+00 5.OE-01 Da-HO 5.4E-02 7.BE-O3 ,OE-01 4.OE-O4 [4.11] 9.1E-03 La-140 4.1E-01 9.4E-17 .4E-01 S.OE-06 5.5E-05 Ce-1* 2.1E-02 1.5E-01 ,6E-0l l.OE-04 2.8E-03 -1 9.3E-04 9.2E-01 ,QE+00 4.8E-03 -14A 2.4E-03 8 1E-01 •OE+00 4.5E-O3 1.5E-02 2.6E-01 ,7E-01 3.BE-O2 1.2E+00 Ra-226 1.2E-06 1.0E+00 .OE+00 S.OE-03 4.OE-01 i Th-220 9.9E-04 9.1E-01 .0E+00 S.OE-06 2.4E-04 -232 1.3E-13 1.QE+00 ,OB+QO 3.SE-O4 ' U-232 2.6E-0S I.AE+OO .OE+QO 3.0E-04 3.5E-02 1 -233 1.2E-0B 1.0E+00 .0E+00 3.SE-02 -234 7.7E-09 l.OE+DO .OE+00 2.5E-02 -235 2.7E-12 1.0E+00 :.OE+00 3.5E-02 i -23fl 4.2E-13 1.0E+00 I.OE+00 3.5E-02 Np-237 l.tE-10 1.0E+00 i .as+oo S.OE-OS 3.SE-04 -239 2.9E-01 4. CE-12 .6E-01 7.0E-03 i.iii~v* -239 7.fE-OI l.OZ+00 'OE+00 1.01-04 j -240 2.9E-O7 1.01+00 l.OE+00 l.OE-04 • -241 1.4E-O4 9.9E-01 i.OE+00 1.01-04 j A*-241 4.4E-0« 1.0E+00 i.OE+00 5.0E-0C a.51-04 < CT-242 4.31-03 «.IE-01 4 -IE-01 5.0E-0« 2.11-04 [ -344 l.OE-04 t.«e-oi 1 OE+00 2.if-04 '

I Ci - 37 O*q

3.3B-O7»?.3)il0": TABLE 5.8

ASSUMED MAXIMUM INTAKE PATES FOR HUMANS

Value Assumed

Synbol Description On Site (Workers) Off Site (Members of Public)

Adults Ref. Infants Ref. Adults Fief.

BR Inhalation (Breathing) Rate 2400 m3/a [5.12] 1400 m'/a [5.12] 8330 m3/a [5.12] en Milk Ingestion I Rate N.A.t Sec.5.2 365 L/a [5.2] 290 L/a [5.2] (1 L/d) (0.8 L/d)

Drinking-water N.A. Sec.5.2 90 L/a [5.2] 600 L/a [5.2] *** Ingestion Rate

IRf Fish Ingestion N.A. Sec.5.2 N.A. Sec.5.2 18 kg/a [5.1] Rate (0.05 kg/d)

»*, Ingestion Rate of N.A. Sec.5.2 40 kg/a [5.2] 180 kg/a [5.2] Root Vegetables

^av Ingestion Rate of N.A Sec.5.2 60 kg/a [5.2] 250 kg/a [5.2] Above-Ground Vegetables & Fruit

N.A. Sec.5.2 10 kg/a [5.2] 30 kg/a [5.2] IRlv Ingestion Rate of Leafy Vegetables

t N.A. - Not Applicable 5-43

TABLE 5.9 EFFECTIVE ENERGIES OF NOBLE-GAS RADIONUCLIDES FOR USE IN WHOLE-BODY DOSE AND

SKIN DOSE CALCULATIONS

Effective Energies (MeV) * Radionuclide Whole-Body Dose Skin Dose fs

Ar-41 1.12E+00t 1.64E+00 Kr-85m 1.48E-01 3.58E-01 -85 2.04E-03 1.72E-01 -87 7.50E-01 2.10E+00 -8P 1.87E+00 2.44E+00 -89 2.10E+00 3.71E+00 -90 1.98E+00 3.21E+00 Xe-131m 1.16E-02 8.22E-02 -133m 3.18E-02 1.72E-01 -133 3.72E-02 8.84E-02 -135m 3.96E-01 5.61E-01 -135 2.29E-01 5.07E-01 -137 1.80E-01 1.76E+00 -138 1.12E+00 1.81E+00

* Obtained by dividing values in Table 4.3 by 7.9xlO6 (see Section 5.4.7) t 1.12E+00 « 1.12x10° - 1.12 5-44

TABLE 5.10

ASSUMED 15.2] CONCENTRATION (BIOACCUMULAriON) FACTORS FOR

OTTAWA RIVER FISH (FLESHI

ITRANSFEH PAflAMETER(P )J

p Radionuclide (Ci*•kg"1ifiah/fCi'L"1)water = L/kg

H-3(HTO) l.OE+00 Be-7 l.OE+01 C-14(part.) 5.0E+04t Na-22 24 (1.0E+0 31+ S-35 l.OE+03 Sc-46 -47 / (l.OE+02) Cr-51 2.OE+02 Mn-54 5.OE+02 Fe-59 l.OE+02 Co-5 8 1 l.OE+03 . -60 Zn-65 2.0E+03 AS-76 l.OE+03 Sr-89 -90 | 2.3E+01** Zr-95 l.OE+02 Nb-95 l.OE+02 Mo-99 (l.OE+03) RU-103 | (l.OE+02) -106 Ag-108m I l.OE+01 -110m . Si-124 -125 } (2.OE+02) Te-132 (4.OE+02) 1-125 -129 -131 5.0E+01 -133 -135 CS-134 -13/ i 5.0E+03+t Ba-140 2.OE+02 La-140 (2.5E+01) Ce-141 -143 l.OE+02 -144 Eu-152 1 (l.OE+02) -154 Hf-'.75 \ (l.OE+02) -181 Hg-203 1.0E+04 Ra-226 l.OE+02 Th-228 -232 i ll.OE+02) Pa-233 (2.0E+01I U-23J -233 -234 2.0E+01 -235 -238 Np-237 2.0E+01 -239 Pu-238 -23» 5.0E+01 -240 -241 Ml-241 {1.OE+02) ca-242 -244 } (l.OE+03)

1 Ci - 37 G*rt S.0X*04 - S.0x>0* Values shown in brackets ar« lass well •fltablishad. x Bassd on average calciuai content of Ottawa River, ICa) >^7 ug/«L •as«d on avsraqs potassii •i cont«'i? of Ottawa Hivat, |K) • 0.7 ug/ 5-45

TABLE 5.11

EVALUATION OF TRANSFER PARAMETER (P^ ()

(TRANSFER FROM OTTAWA RJVER TO GARDEH SOIL VIA SPRAY IRRIGATION)

(L/m2)

A = radioactive decay constant (d ') 11 tb = buildup period = l.BxlO d (50a) I « irrigation rate = 2Lnn~2-d~1 see Sec.5.4.11 f - fraction of year for irrigation =

Decay constant,X p Radionuclide Id"1) (L/m2)

H-3IHTO) 1.6E-04t 2.4E+03 Be-7 1.3E 02 3.1E+01 C-14(part.) 3.3E-07 7.2E+03 Na-22 7.3E-04 5.5E+02 -24 1.1E+00 3.6F.-01 S-35 7.9E-0J 5.1E+0? Sc-46 B.3E-03 4.8E+01 -47 2.0E-01 2.0E+00 Cr-51 2.5E-02 1.6E+01 Hn-54 :..3E-O3 1.7E+02 Fe-59 1.5E-02 2.7E+01 Co-5 8 y.8E-03 4.1E+01 -60 3.6E-04 1.1E+03 Zn-65 2.8E-03 1. 4E+02 A3-76 6.3E-01 6.3E-01 Sr-89 1.4E-02 2.9E-M11 -90 6.7E-05 4.2E+03 Zr-95 1.1E-02 3.6E+01 Nb-95 2.0E-02 2.0E+01 HO-99 2.5E-01 1.6E+00 RU-103 1.8E-02 2.2E+01 -106 1.9E-03 2.1E+02 Ag-108m 1.5E-05 6.3E+03 -110m 2.8E-03 1.4E+02 Sb-124 1.2E-02 3.3E+01 -125 7.0E-04 5.7E*02 Te-132 2.1E-01 1.9E*00 1-125 1.1E-02 3.6E+01 -129 1.1E-10 7.2E+03 -131 8.6E-02 4.7E+00 -133 8.0E-01 5.0E-01 -135 2.5E+00 1.6E-01 O-134 9.3E-04 4.3E402 -137 6.3E-05 4.3E403 BB-140 5.4E-02 7.4E*00 La-140 4.1E-01 9.8E-01 Ctt-141 2.1E-02 1.9E+01 -143 9.3E-04 4.3E+02 -144 2.4E-O3 " 7S+0j Eu-152 l.SE-04 " t'K+C5 -154 1.2E-04 i.3E+03 Hf-175 9.9r-03 4.0H+01 -111 1.6E-02 2.3E+01 Hg-203 1.5E-02 2.7E+01 M-226 1.2E-0C 7.1E*03 Tn-221 9.91-04 1.0C*0i -232 1.31-13 7.211*03 rm-Z33 2 SI-02 l.«I*01 U-232 -233 12.CI-0.2E-0t3 1 7.21*0S.TI*SS3 -234 7.71-0* -235 2.7E-12 7!21*01 -231 4.2E-13 J.2X*03 Np-217 l.tt-10 7.21*03 -2M VU-2JI 2,it-05 Si 1B+ f)3 -23» 7.U-0I 7.21* 11 -240 2.H-07 7.21*13 -241 1.41-04 2.»«>3 Aa-241 4.4I-0t 4.11403 Cm-Ill 4.11-01 t.ll*b!l -244 1.01-04 ].](*S1 t 1.(1-04-1.(•!•* 5-46

TABLE 5.12

(TRANSFER PROM OTTAWA RIVER TO LEAFY VEGETABLES VrA SPRAV IRRIGATION)

1 = Ar + 0.05 (d" )

-1 Ar = radioactive decay constant (d )

t'e = exposure time = 60 d Y" = yield (wet weight) of vegetables = 2 Jcg/m'

c" = retention factor = 0.05 see Seccion 5,4.12

Decay Constant, X X = X + 0.05 p r Radiomiclide e r »i * (d"1) (d-'l (LAg)

H-3(HTO) 1.6E-04+ 5.0E-02 9.5E-01 Be-7 1.3E-02 6.3E-02 7.8E-01 C-I4(part.) 3.3E-07 S.OE-02 9.5E-01 Na-22 7.3E-04 S.1E-02 9.3E-01 -24 1.1E+00 1.2E+00 4.2E-02 S-35 7".9E^03 5-BE~62 8.4E-01 Sc-46 B.3E-03 5.8E-02 a.4E-01 -41 2.0E-01 2.5E-01 2.0E-01 Cr-51 2.5B-02 7.5E-02 C.6E-01 Mn-5 , 2.3E-03 5.2E-02 9.2E-01 Fe-S9 2.5E-02 6.5E-02 7.5E-01 1 C6-58 5.&E-03 6.0E-02 8.1E-01 -60 3.6E-04 5.OE-O2 9.5E-01 Zn-65 2.8E-03 5.3E-02 9.0E-01 As-76 6.3E-01 6.8E-01 7.4E-02 Sr-89 1.4E-02 6.4E-O2 7.6E-01 -90 6.7E-05 5.0E-02 9.5E-01 Zr-95 i.iE-02 b.lK-02 8.0E-01 Hb-95 2.0E-02 7.0E-02 7.0E-01 Mo-9 9 2.5E-01 3.0E-01 1.7E-01 Ru-103 1.8E-02 6.6£-02 7.2E-01 -106 1.9E-03 5.2E-02 9.2E-01 Ag-10am 1.5B-OS b.OK-02 9.5E-01 -110* 2.BE-O3 5.3E-02 9.0E-01 Sb-124 1.2E-02 S.2E-02 7.9E-01 -125 7.0E-04 5.1E-02 9.3E-01 T.-132 2.1E-D1 2.6E-01 1.9E-01 1-125 1.1E-02 6.1E-02 8.0E-01 -129 1.1E-10 5.0E-02 9.5E-01 -131 8.6E-02 1.4E-01 3.6E-01 -133 8.0E-01 9.5E-01 5.9E-D2 -135 2.5E+O0 2.6E+0Q 1.9E-02 r~ 9.3E-O4 "" "5.1E-02" "* "" " "" 9.3E-01 -13? 6.3E-OS 5.0E-Q2 9.5E-01 Va-140 5.4E-02 1.0E-01 5.0E-01 Lti-140 4.1E-01 <.«E-01 1.1E-01 Ce-141 2.1E-O2 7.1E-02 6.9E-01 -143 9.3E-O4 5.IB-02 9.3E-01 -144 2.4E-03 5.2E-02 9.2E-01 Eu-152 1.5B-d4* 5TOE-05 -154 1.2E-04 5.0E-02 9!5E-0l H1T-175 9.9E-03 6.0E-02 a.lE-01 -ltl 1.6E-02 6.6E-02 7.4E-QI Hg-203 l.SE-02 6.SE-02 7.5E-01 Ha-226 1.2B-06 5.0E-02 9.5E-01 Th-221 9.9E-04 5.1E-Q2 9.3E-01 -232 1.3E-13 5.OC-O2 9.5E-01 Pft-233 2.5E-02 7.5E-0i! 6.6E-01 0-232 2.CE-O5 9.5E-01 -233 l.VE-08 " "5.o^-isr5.0E-02 ' " 9.5E-01 -234 7.7B-O* 5.OE-02 9.5E-01 -235 2.7E-12 5.0K-02 9.5E-01 '238 4.2E-13 5.0C-02 9.5E-01 Mp-23? •.IE-10 5.0E-02 9.5E-01 -23* 2.»E-01 3.4E-01 1.SE-D1 PU-231 2.2E-05 !>.0K-02 9.5E-01 -23* 7.IE-0I 5.0E-02 9.5E-01 •240 2.W-07 5.0B-02 9.5E-01 -241 L.4E-04 5.0E-02 9.5E-0I ta-241 4.4Z-Ok 5.0E-02 9.5E-01 C»-242 4.3B-O3 S.4K-0^ t,*f.-01 -244 1.DC-O4 s.oe-02 9.5E-01

1.H-I4-1.K10- 5-47

FIG 5.1: GENERALIZED EXPOSURE PATHWAYS TO MAN FROM AIRBORNE AND LIQUID EFFLUENTS

LIQUID EFFLUENTS

EXTERNAL EXPOSURE INTERNAL EXPOSURE

NOTE- DASHED PATHWAYS CONSIDERED UNIMPORTANT IN CRNL ENVIRONMENT PATHWAY 6 - IMMERSION

WHOLE BODY EXTERNAL - EXPOSURE PATHWAYS PATHWAY 8 - STANDING ON CONTAMINATED GROUND

WHOLE BODY

INTAKE"!

PATHWAY C - INHALATION

INTERNAL - EXPOSURE 9.M 1.12 1 F i ^3, 12

PATHWAYS PATHWAY D - MILK INGESTION TI3SJE Ot ORUKS III) BUT (10) MUST BE LE5S THAN MAXIMUM PERMISSIBLE ROOT I OTHEII L°-" !_D_lJ I ANNUAL DOSE LIMITS (SEE SEC. 4.1) I «E6ET<8ltS m- 2-Y, J I '»> I PATHWAYS E 4 F oHl.3 ! ~ IEUT -VEGETABLE INGESTION/I CO VEGETABLES INTAKE RATES - MUST BE LESS THAN ANNUAL LIMIT OF INTAKE (ALI - SEE SEC. 1.2) PATHWAYG-WATER INGEST ION NOTES: (1) HEAVY LINES INDICATE MAIN

PATHWAY H- FISH INGESTION^ ROUTES FOLLOWED IN CALCULATIONS

AIRBORNE - EFFLUENT PATHWAYS LIOUID - EFFLUENT PATHWAYS

FICURE 5.2: ENVIRONMENTAL TRANSFER PATHWAYS FOR AIRBORNE AND LIQUID EFFLUENTS AT CRNL Fin. 5.2A - ENVIRONMENTAL TRANSFER PARAMETERS FOR

PATHWAY A (IHHFRSION) £ Source Atmosphere Skin Dose Rate whole-Body p (rem/a) Uose-Rate 0 i 1 .(rem/a) (0) tlc)

Units values

P = atmospheric dispersion,(ci*/m3) per (Ci/s) released s/m3 Table 5.3

p = skin dose rate from external exposure to 1(12 contaminated atmosphere includes occupancy and shielding factors Sec. 5.4.7 P = whole-body dose rate from external exposure to shown 1'lh contaminated atmosphere

OF = occupancy by humans of contaminated atmosphere outdoors, dimensionless * fraction of year

OP = occupancy by humans of buildings in contaminated s atmosphere, fraction of year

SF = shielding factor for occupancy inside buildings in dimensionless s contaminated atmosphere Max. Permissible Annual Skin Dose+ Maximum Permissible Release Rate for Skin Exposure, (Ci/s)

Max. Permissible Annual Whole-Body Dose+ (Ci/s) Maximum Permissible Release Rate for Whole-Body Exposure, q =

* 1 Ci = 37 GBq 41 1 (rem-a*1 J/(Ci-i 2.7x10"'3 (Sv-a"1 )/(Bq-m~!) 1 ! + 5 rem-a' (0.05 Sv.a~ J [ see Table 4.1 + 0.5 rem.a"1 (0.005 Sv-a"1) 5-50

FIG. 5.?fi - EiwtRowtf-HTAL TRANSFER PARAMETERS FOR

PATHWAY B (STANDING ON CONTAMINATED GROUNn)

P Source P Atmosphere Ground

(0) (1) (3)

Values

P • atmospheric dispersion, (Ci'/m ) per (Ci/s) released Table 5.3

P = airborne deposition or ground, (Ci/tn2) per Ici/m1) Table 5.4

includes occupancy

P « whole-body i

OF = occupancy by humans of contaminated ground outdoors, 2 fraction of year

OF = occupancy by humans of buildii dimensionlesB 1 fraction of year

d linen si on less

SF - dose reduction factor to account for ground roughness and dimensionlesB 1 some shielding by snow in winter

Max. PetmiBaiole Annual Skin Dose + |Ci/«) Maximum Permissible Release Rate for Skin Exposure. qH

P p p e i" ,,,' 1(1,

Max. Permissible Annual Who^e-Body Dose •* jgi^j H»,l»u» P.r»i..lble ne. for Whol.-Body Expo.u

t 5 «».«-• (0.05 4 0.5 r«.a~l (0.0 FIG. 5.2C - ENVIRONMENTAL TRANSFER PARAMFTFRS FOR

PATHWAY C (INHALATION)

Source Atmosphere Intake Rate (Ci*/a)

ID) (1)

Units Values I = atmospheric dispersion, (Ci*/m3) per (Ci/s) released s/m3 Table 5.3 I-1 = transfer from atmosphere to lung by inhalation (includes occupancy Sec.5.4.6 factor OP ) j

OF - occupancy by humans of contaminate^ atmosphere (outdoors or 1 indoors), fraction of time at loc-Lion dimension less Table 5.2

Annual Limit of Intake (ALI._.inhal.'=1 )t1 (Ci/s) Maximum Permissible Release Rate, q.'M P - P 0 F 1 1,9

* 1 Ci = 37 GBq + Values in Table 4.2 FIG. 5.2D - ENVIRONMENTAL TRANSFER PARAMFTFRS FOR

PATHWAY D (MILK INGESTION)

Soil

(3) ri I.* Source Atmosphere 1 -Intake Rate p P (CiVa) (0) (1) (4)

Units Values

atmospheric dispersion, (Ci*/m3) per (Ci/s) released s/m3 Table 5.3 0 , 1 p airborne deposition on soil, (Ci/m2) per (Ci/mJ) m Table 5.4 1' 1 I uptake by roots of pasture grass, (Ci/kg) per (Ci/m2) m2/kg Table 5.6

airborne deposition on pasture grass, (Ci/kg) per (Ci/m3) m'/kg Table 5-5

transfer from pasture grass to milk (includes usage and decay kg/L Table 5.7 factors shown), (Ci/L) per (Ci/kg)

transfer from milk to human gut by ingestion ( includes usage L/a Sec.5.4.6 factor UF )

UF = usage by cow of contaminated pasture grass, fraction of year dimensionless

UF = usage by cow of contaminated "iiored feed, fraction of year dimensionless

UF^ = usage by humans of contaminated milk, fraction of year dimensionless

DF = factor for radioactive decay in stored feed dimensionless

DF = factor for r-idioactive decay during period between dimensionless 2 ingestion ^ feed by cow and ingestion of milk by receptor Annual Limit of Intake (ALI- Maximum Permissible Release Rate, q =

1 Ci = 37 GBc

Values in Table 4.2 FIG. 5.2E - ENVIRONMENTAL TRANSFER PARAMETERS FOR PATHWAY E

(VEGETABLE INGESTIOK VIA AIRBORNE DEPOSITION?

-Intake Bate (Ci*/a)

Atmosphere

:o)

values

atmospheric dispersion, (Ci*/m3) per (Ci/s) released Table 5. 3 2 1 airborne deposition on soil, (Ci/m ) per (ci/m ) Table 5.4 I P = uptake by roots of vegetables, (Ci/kg) per (Ci/m2) m!/kg Table 5.6 U1 airborne deposition on leafy vegetables, (Ci/kg) per (Ci/m3) m'/kg Table 5.5 transfer from root vegetables to human gut by ingestion kg/a Sec.5 .4.6 (includes usage and decay factors shown) transfer from leafy vegetables to human gut by ingestion kg/a (includes usage factor UF ) UF = usage by humans of contaminated fresh root and other cimensionless 6 vegetables, fraction of year UF = usage by humans of contaminated stored root and other dimensionless 7 vegetables, fraction of year UF = usage by humans of contaminated fresh leafy vegetables dimensionless * fraction of year DF « factor for radioactive decay in stored vegetables dimensionless Table

Annual Limit of Intake (ALIing.'1" (Ci/s) Maximum Permissible Release Hate, qM =

* 1 Ci = 37 GBq t Values in Table 4.2 FIG. 5.2F - ENVIRONMENTAL TRANSFER PARAMETERS FOR PATHWAY F

(VEGETABLE INSESTION VIA SPRAY IRRIGATION)

Units Values

= "dilution factor" in Ottawa River, (Ci*/L) per (Ci/s) released s/L Sec.5.A.9

= deposition via spray irrigation on soil, (Ci/mz) per (Ci/L) L/m2 Table 5.11

= P^ = uptake by roots of vegetables, (Ci/kg) per (Ci/m3) ir.Vkg Table 5.6

= deposition via spray irrigation on leafy vegetables, (Ci/kg) L/kg Table 5.12 per (Ci/L) it- = transfer from root vegetables to human gut by ingestion kg/a Sec.5.A.6 (includes usage and decay factors shown)

= transfer from leafy vegetables to human gut by ingestion kg/a Sec.5.4.6 ' [includes usage factor UF )

UF = usage by humans of contaminated fresh root and other dimensionless 6 vegetables, fraction of year

UF = usage by humans of contaminated stored root and dimensionless * other vegetables, fraction of year

UF = usage by humans of contaminated leafy vegetables, dimensionless B fraction of year

DF = factor for radioactive decay in stored vegetables dimensionless

Annual Limit of Intake (ALI. „ )+ (Ci.'s) Maximum Permissible Release Rate, g. 'M

* 1 Ci = 37 GBq t Values in Table 4.2 FIR. S.2G - ENVIRONMENTAL TRANSFER PARAMETERS FOR PATHWAY G (WATER INGESTION)

Intake Rate (Ci*/a)

Units Values Ul P = "dilution factor" in Ottawa River, ICi*/L) per (Ci/s) released S/L Sec. 5 .4.9 0, 2 p = transfer from water to human out by ingestion (includes usage factor UF ) L/a Sec. 5 .4.6 i» 1 o » UF = usage by humans of contaminated drinking water, fraction of year dimensionless Table 5.2

_ Annu. Limit of Intake (ALL )t (ci/s) Maximum Permissible Release Rate, q,, = p , P 0,2 2, 1 0

* 1 Ci = 37 GBq

+ Values in Table 4.2 FIG. 5.2H - ENVIRONMENTAL TRANSFER PARAMETERS FHR

PATHWAY H (FISH INGESTION)

Ottawa River Intake Rate (Ci*/a) (O) (21 (7)

Units Values

"dilution factor" in Ottawa River,(Ci*/L) per ICi/s) released s/L Sec.5.4.9

concentration factor in fish, (Ci/kq) per (Ci/L) L/kg Table 5.10

transfer from fish to human gut by ingecion (includes usane factor UP ) kq/a Sec.5.4.6 5 UF = usage by humans of contaminated fish, fraction of year dimensionless Table 5.2

A-nnual Limit of Intake (ALI. ) Maximum Permissible Release Rate, C{ = ing. (Ci/s)

• 1 Ci = 37 GBq t Values in Table 4.2 3 WEIGHTED MEAN DILUTION FACTOR, Po , (s/m )

o O

EFFECTIVE STACK HEIGHT J CURV E © © © 0 I EFFECTIV E HEIGH T STAC K CO O3 •= 73 a "TYPICAL " "ENHANCE D a; 33 O O r»i = m Cn = =£ m

= =

— m o as < o c = O3 sg m —i z 3) — O 3C Z O 1= s z, =O m

= = til = —t m 00 O m 33 s z = en m s = —^ ra

3 = = CJl 6-1

6. RESULTS OF CALCULATIONS

6.1 Maximum Permissible Release Rates for Individual Pathways

The maximum permissible release rates, qM, in Ci*/s, for each of the cases marked in Table 5.1 have been evaluated by the methods described in Section 5 and tue results are listed in the following tables:

Table Source Pathways

6.1 NRX/NRU Stack airborne radionuclides 6.2 61-m Stack B,C,D,E (other than noble gases) 6.3 Roof Vents

6.4 NRX/NRU Stnck 6.5 61-m Stack noble gases 6.6 Roof Vents fi . 7 Whole Site radionuclides in liquid F,G,H effluents

As an example, consider the evaluation of the case for release of Nb-95 from the NRX/NRU Stack and exposure via the inhalation pathway (Pathway C) of infants at the upriver boundary (Exposed Group No. 2). From Fig. 5.2C, the maximum permissible release rate is given by:

ALI inhal. (Ci*/s) (38) P . P 0/1 1,9

1 Ci = 37 GBq 6-2

where ALI = 3.7X1G*"5 Ci* (from Table 4.2) P = 5x10~8 s/m3 (from Table 5.3) n , 1 P = (1400 m3/a)(1.0) (from Sec.5.4.6 and 1 r 9 Tables 5.2 and 5.8)

3-7*10~S = 0.53 CiVs (39) . q n (5xlO~8)(1400)

for the combination of Pathway C and Exposed Group No.2 in the case of airborne releases of Nb-95 from the MRX/NRU Stack.

In each of the Tables 6.1 to 6.7, the minimum value of

qM for each radionuclide is marked with an asterisk (*). The corresponding pathway in which the minimum occurs is the "dominant pathway" for that radionuclide from the particular source.

It can be seen in Tables 6.1 to 6.6 that most of the dominant pathways for airborne effluents involve exposure of the adult workers on site, either due to inhalation, immersion, or standing on contaminated ground. In a few cases, e.g., certain radioiodines released from the NRX/NRU Stack and the 61-m Stack, the infant drinking milk which may be produced at the upriver boundary is on the dominant pathway. The adult at the upriver boundary enters into a dominant pathway only for H-3(HTO) released from the NRX/NRU Stack, C-14(CO2) released from all sources, and Sr-90 released from the NRX/NRU Stack. In fact, the case of C-14(CO2) released from roof vents is the only case for releases from roof vents in which the on-site worker is not on the dominant pathway (see Table 6.3).

1 Ci = 37 GBq 6-3

As will be shown in the next section, exposure of an individual via all significant pathways must be taken into account in calculating the derived release limit (DRL) for a specific radionuclide from a specific source. In many cases, however (e.g., exposure of the infant at the boundary due to 1-131 released from the MRX/NRU Stack), the effect of one pathway (milk ingestion) is so much greater than the others (inhalation, vegetable ingestion, and standing on contaminated ground) that the minimum value of q,, (marked with an asterisk in Table 6.1) also corresponds to the DRL for that combination of radionuclide and source. In short, the DRL's are either equivalent to or less than the asterisked q -values in Tables 6.1 to 6.7.

6.2 Derived Release Limits (DRL's) for Critical Groups

As noted in Section 5.1, the derived release limit JDRL) as defined in this report represents an upper limit to the rate of release of a radionuclide from a single source. As such, the DRL for the rcidionuclide must take into account the radiation exposure of an individual via all significant pathways

from the source. If (Q.J .k is the maximum permissible release rate of the i'th radionuclide from the k'th source to individuals in the n'th exposed group, the following summation must hold:

"Vikn

P (ViknV iknpp (40) =z—^— kuM' ikn p 'Hw' iknp

wh^re (qM> ^. is the maximum permissible release rate (in Tables 5.1 to 6.7) via the p'th pathway for that radionuclide, 6-4

source, and exposad group. The DRL for that radionuclide and ^

source is then the minimum value of (QM)-k The exposed group for which this minimum occurs is the "critical group" and the pathway along which the largest fraction of the dose is received is the "dominant pathway". As noted in the preceding section, the dominant pathways have already been identified in Tables 6.1 to 6.7 as the pathways in which the asterisked values of q appear.

As an example of the use of expression (4 0), consider the release of Nb-95 from the NRX/NRU Stack. If we let:

(QM) = the maximum permissible release rate for exposure of the on-site worker

(QM) = the maximum permissible release rate for exposure of the infant at the upriver boundary

(QM) = the maximum permissible release rate for exposure of the adult at the upriver boundary, one obtains, UEing expression (40) and the values in Table 6.1:

,„ , 1 1 1 > 0.0062 0.069

0.026 0.53 0.025 3.9

«v 3 = = 0.018 Ci/s 1 1 : i (- • - + 0.026 0.24 0.081 3.5

1 Ci = 37 GEq 6-5

The DKL is then 0.0057 Ci/s, the critical group consists of the on-site workers, and the dominant pathway is "B" (external exposure due to standing on contaminated ground). This is summarized i/ Table 6.8 along with the DRL's, critical groups, and dominant pathways for the other airborne radionuclides and sources calculated in a similar manner. The DRL's and similar parameters for radionuclides in liquid effluents are listed in Table 6.9.

It should be clear from expression (40) that if, for example, three pathways are involved in the calculation of the values of (Q )., , the minimum value (or the DRL) is less than the value of q,, in the dominant pathway by a factor of no more than three. In many cases, the value of q in the dominant path. \y (marked with an asterisk in Tables 6.1 to 6.7) is so much lower ti n the values in other pathways for the same individual that the DRL is essentially equivalent to the asterisked q., value.

It is possible that the individual in the critical group for whom the DRL applies is not the same individual as the one in the dominant pathway. For example, in the case of airborne Sr-90 releases from the NRX/NRU Stack, the critical group consists of the infants at the upriver boundary (Table 6.8) whereas the adults at the upriver boundary are in the dominant pathway (Table 6.1). Similarly, in the cases of 1-135 and Nu-237 released in liquid effluents, the critical group consists of the adults in Petawawa (Table 6.9) whereas the infants in Petawawa are in the dominant pathway (Table 6.7). However, in all other cases, again because the value of q,, in the dominant pathway is usually so much lower than the value in other pathways, the critical groups listed in Tables 6.8 and 6.9 are the same groups as those found in the dominant pathways marked in Tables 6.1 to 6.7.

Finally, it should be recalled (see Section 4.2) that the DRL's in Tables 6.8 and 6.9 apply to the most restrictive chemical and physical form of the radionuclide if more than one form is possible and if th:? exposure pathways involve inhalation (Pathway C) or ingestion (Pathw-^s D,E,F,G,H). The forms assumed in the 6-6

calculations are listed in Table 4.2. If the radionuclxde is released in a known form other than that listed., reference should be made to the original data [4.8] to determine the factor of conservatism introduced into the DRL calculation.

6.3 Derived Release Limits (DRL. ) Assuming Critical Group is at the Boundary

As noted in Sections 6.1 and 6.2, the critical group for airborne releases of most radionuclides consists of the on-site workers and., as can be seen in Table 6.8, the DRL for the workers is highly dependent on whether the release is from the NRX/NRU Stack, the 61-m Stack, or a Roof Vent. Naturally, this effect has to be taken into account in determining the administrative control levels for the actual releases from the sources (see Section 7.4). However, it has been found convenient to also have a set of DRL's for airborne releases in which the critical group (either an infant or an adult) is situated at the boundary. In this case, the individual is situated far enough from the source that the dilution factor (P in Table 5.3) is independent of the type of source and there- 0/1 fore the DRL will be representative of airborne releases from the site as a whole. In other words, the actual releases from the separate sources are additive and the total release can be expressed nsetully as a percentage of the DRL to give a measure of the maximum radiation hazard to members of the public.

The boundary DRL's (designated DRL, ) have been calculated by the method described in the preceding section using the q,, values in Tables 6.1 to 6.6 for an infant (individual "2") and an adult (individual "3") at the upriver boundary. The DRL, results along with the critical parameters are listed for the airborne radionuclides in Table 6.10. 6-7

For radionuclides in liquid effluents, it has already been explained that the critical group is always outside the boundary, downstream of the site. The corresponding DRL's are listed in Table 6.9 and, in all cases, the adults downstream turned out to be in the critical group.

6.4 Source Averaging Time

Barry [5.1] has given a good introduction to the subject of "source averaging time" for airborne releases and it is well to quote the following pertinent paragraphs from his report (with some clarifying comments by the present author inserted in parentheses) :

" In using atmospheric dispersion formulae (of the type described in Section 5.4.1), the source emission rate is usually expressed in units per second. Averaging over so short a time, however, is operationally inconvenient unless a source is continuous at a uniform strength. In most practical situations, radionuclides are released to the atmosphere from nuclear facilities intermittently rather than continuously and it becomes important to consider over what time interval the strength of a discontinuous source may be averaged. For example, if the maximum release rate is calculated to be, say, 1 pCi*/s, then during the course of one day, one week, and one year the amount released from a steady 4 S 7 continuous source could be 8.64x10 , 6. 05x10 , and S.15x10 pCi*, respectively. The question then is could such amount be released during a relatively short interval, say one or two hours once on average per day, per week and per year? "It has been shown (in an earlier section of Barry's report) that during an interval of an hour or so, atmospheric diffusivity may be less than the average by a factor of at least 10 to 15 (at a distance of 1 km from the source) with a 10% oocurrenae frequency. Thus, if the total allowable annual release were to occur during an hour or so, it follows that under certain transfer conditions the annual dose resulting from such a release might exceed the

* 1 pCi = 37 mBq 6-8

long-term average annual dose by a factor of 10 to 15 and we should expect, again on average, that these doses would occur during one year out of every 10. If the mean annual dose is equal to the dose limit, it is clear that during the one year in 10 the dose would also exceed the dose limit by a factor of 10 to IS. This is so even though over many years the average dose would not exceed the limit. If the basic averaging period for dose is taken to be one year such a situation would be unacceptable and the allowable time of averaging the strength of an intermittent source must in consequence be less than one year.

"For occupational workers intermittently exposed to a radionuclide, the ICRP recommends that, for internal exposure, a dose commitment resulting from an intake of a radio?iuclide equivalent in amount to the intake for one-half yearf at the Maximum Permissible Concentration may be accumulated as a single dose. This means that the total intake at the continuous maximum rate during six months may be taken in as a single dose."

Barry [5.1] goes on to show that, if the maximum allowed discharge rate averaged over time t is to be equal to the maximum discharge rate allowed for one year (the DRL) then, for a source- receptor distance of 1 km:

15 (DRL)-t: < 0.5•(DRL)•(time exposed in years) which gives t = 0.033 years or 12 days for continuous exposure. Barry also points out that the ratio of the short-term peak value of the diffusion coefficient for a given averaging time to its long-term mean increases with distance from the source. If, for example, the distance was 5 km instead of 1 km, the ratio

Changed to one year in the new ICRP-26 recommendations [paragraph (35) of ref. (1.3)], except in the case of occupational exposure of women of reproductive capacity and pregnant women. 6-9

would be nearly 40 for a 10% occurrence frequency and the allowable source averaging time would be reduced to about five days for continuous exposure.

The above arguments would apply mainly for continuous exposure to an airborne release of relatively short-lived material that would reach equilibrium (in the body and in the environment) in times less than a year. Considerations of some other factors (e.g., releases of extremely long-lived radionuclides, exposures at shorter distances) would tend to increase the source averaging times calculated above while others (e.g., exposures for a fraction of the year) would tend to decrease it. A source averaging time of one week would appear to be appropriate (and operationally convenient) for releases of all airborne radionuclides considered here. Further, it would appear that a more detailed analysis of the situation is not warranted when one considers the other uncertainties in the DRL calculations.

The source averaging time of one week for airborne releases has been taken into account in Tables 6.8 and 6.10 by listing the DRL's as "Maximum Curies in One Week". Intermittent releases during a week may occur as long as the total allowable release for the week is not exceeded. Provided intermittent releases occur randomly in time, there is no need to restrict the number of such releases in a year as long as the annual dose limits are not exceeded.

The situation regarding source averaging time for liquid effluents is quite different. In this case, the discharge is to the Ottawa River and the dilution, unlike that for atmospheric releases, is relatively unaffected by random environmental processes. Hence, there is little concern that peak discharge rates might coincide with abnormally low dilution rates and the source averaging time could be one-half year (or one year 6 - 10

in the case of the new ICRP-26 recommendations [1.3]). A source averaging time of one month has been chosen for operational convenience. This is taken into account in Table 6.9 by listing the DRL's for radionuclides in liquid effluents as "Maximum Curies in One Month". 6-11

TABLE 6.1 - MAXIMUM PERHISI IN PATHWAYS FOR

AIRBORHE HADIOHUCLIDES (OTHEB THAN HOBLE GASES) RELEASED FROM

HRX/HHO STACK

Radionuclide (Contain. Ground) (Milfc Ingeation) (Veg. Ingestion)

Expoaed Group*

H-3(HTQ) 1.7E+00 5.0E-01 C-l4(OOt> 1.8E+01 7.6E-03 O14(part.) 4.2E-0, I.5E-02 •7.2F-O5 2.7E-04 2.6E-04 1.9E-Q4 Cr-51 3.8E+O0 1.SE+O0 2.8E+00 2.1E+O2 1.0E+02 3.1E-01 5.9E-01 9.2E-O1 5.5E+00 1.9E+00 4E-Q2 6E-02 !,OE+I ..6E+00 2.6E-02 1.1E-01 1.9E+00 2.2E+00 2.0E-0 5.3E-03 4.6E-02 2.5E-02 B.4B-02 *1.SE-I 6.2E-04 4-3E-02 2.6E-02 3.OE-63 2. 9 2.6E- 1.2E-O3 B.9E-04 9.2E-04 1.4E-04 2r-95 I.4E-03 , 1.4E-02 1.5E-0: 1.2E-D1 5.3E-02 Kb-95 1.2E-03 2.6E-02 .1E-02 3.9E+00 3.5E+DG Mo-99 '.2E-01 9.0E-01 7.SE-02 3.7E+00 5.3E05.3E+00 ftu-103 3.4"E-02 6.0E-Q: I3.5E+02 l.fiE+61 5.&E+05&E+00 -106 8.2E-D3 *6.lE-Qi 9.6E+00 1.3E-01 Sb-124 J2.4E-02 6.6E-01 -12S 1.5E-03 4.6E-01 Te-132 8.4E-01 U-2E-01 1-125 •5.9E-06 4.5E-05 3.2E-03 5.6E-03 -129 •8.2E-07 13.BE-06 4.3E-0S 3.BE-05 -131 *9.6E-06 [1.1E-04 5.3E-03 1.5E-02 -132 » 9 9 -133 9 5.1E-02 2.1E-01 j 1.0 2.1E-02 •1.1B-03 1.4B-O2 1.4E-01 4.BE-01 -134 *2.8E-01 , 1.ZE+00 : 6.3 9 0 -135 9 0 5.0E-Q2 ! 2.1E-01 j »4.5E-Q: 9.1E-02 l 1.9E+00 6.2E-VOQ 5.1E-O4 l.lE-i 15.6E+Q0 9.3E-02 -137 3.9E-04 1.5E-D2 3.5E-03 BB-140 l!7E-01 4!9E-i 2.BE-01 6.5E+O0 6.7E400 La-140 1.3E+0 2 8.7E+OD CB-141 -143 .2E+00 -144 1.2E-02 4.9E-02 .8E-01 Hq-203 1.3E-D25.5E-02 •2.5E-03 J4.3E-03 2741+00 .6E-01 Ra-226 •4.7E-07 I2.5E-06 1.4E-05 .4E-05 Th-228 6.BE-D5 >5.BE-04 2.2E-O5 .6E-05 232 1.1E-0I I3.7E-D4 S.3E-06 .3E-06 2.1E-06 l.aE-06 ME-05 -233 .2E-06 9.6E-06 7.7E-O6 B.3E-04 1.7E-03 2.7E-02 .2E-02 -234 .2E-06 9.6E-06 7.7E-06 8.3E-04 1.7E-03 2.7E-02 .2E-02 -235 .4E-06 1.0E-05 a.22-06 8.3E-04 1.8E-03 2.7E-O2 .3E-O2 -238 .5E- 1.1E-05 3.6E-06 2.0E-03 Np-23? •6.7E-67 .06 2.3E-0« 9.6E-O5 jlioi-oi -239 *4.lE-01 .1E+00 . 4E+D0 3.9E+02 •7.1E+02 7.1E+O1 3.4E+01 PU-238 *6.9E-07 .7E-06 . 4E-06 2.5E-02 2.6E-01 3.8E-03 9.6E-03 -239 *6.3E-07 .6E-06 . 2E-06 2.3E-02 2.4E-01 3.3E-O3 8.0E-03 -240 •6.3E-07 -6E-06 i.ZE-06 2.3E-D2 2.4E-01 3.3E-03 B.OE-03 -241 '4.4E-05 •7E-O5 1.4E+D0 2.6E-O1 7.3E-01 Am-241 •6.1E-D 4E-06 -06 7E-03 9E-O4 5.8E-04 Crn-242 •2.2E-0S 9E-05 1.3E-01 S.5E-02 1.2E-01 -244 •1.2E-06 .OE-06 3.5E-03 9.2E-04 1.9E-03

( 1 - Adults on Site t j 2 - rnfanta at opriver Boundary * 3 - Adults at Upriver Boundary * Dominant pathway,i.«,, tha pathway f«julting in the minimum of q^. •• Included in specific-activity Model for pathways D and E (see section 5.4.131. 0 Effect insignificant compared to other pathways! case not evaluated. » 1 Ci - 37 Gflq 6-12

TABLE 6.2 - HAXIHUH PERMISSIBLE RELEASE HATES (q^Ci^/al IN PATHWAYS FOR

AIRBORNE RADIOHUCLIDES (OTHER THAU BOBLE GflSES) RELEASED FROM

61 - W STACK

Pathway (see Fig. 5.2)

(Milk ingeBtion) (Veg. ingeatlon)

•2.6E-01 5.0E-01 i 2.7E+00 *7.SE-03 C-14(part.) 6.4E-O4 2.7E-04 2.6E-04 Cr-51 1.7E-01 2.BE+00 ' 2.1E+C2 Mn-54 9.2E-Q1 5.5E+00 Fe-59 I.3E-02 4.6E-O3 l.eE-fll l.lE-61 .4E-62 Co-5 8 M.4E-04 9.4E-0: 5.7E-03 2.9E-01 1.3E-0J .6E-02 1.1E-01 1.9E+00 -60 Zn-65 i^p -90 9.2E-04 1.4E-04 Zr-95 1.OE+01 3.3E+00 Nb-95 B.1E-02 3.9E+00 3.5E+00 Ho-9 9 3.7E+00 5.3E+00 -106 1.3E-D1 Sb-124 6.6E-D1 -125 4.6E-01 Te-132 7.0E-D1 S.ee-63 -129 3.BE-O5 -131 1.5E-02 -132 t -133 4.8E-Q1 -134 0 -135 6.2E+00 1.7E-O3 2.6E-O! 3.9E-02 9.9E-02 2.2E-03 -137 1.5E-0' 2.3E-03 2.9E-0! 5.3E-O2 3.SE-04 4.9E-04 1.5E-02 3.5E-O3 Ba-140 2.8E-01 1.1E+00 6.5E+00 6.7E+00 La-14Q •6.6E-03 1.8E-0: 1.3E+02 2.3E+02 1.9E+01 S.7E+OO 9.4E-03 1.7E+00 7.8E+00 «!.9E+00 •1.0E-04 1.2E+00 l.BE-03 6.3E-01 2.SE-01 fia-226 Th-226 6.8E-05 2.2E-05 t -232 5.3E-06 ! 1.&E-66 7.4E-04 3.0E-A4 -233 •3.3E-07 9.6E-06 7.7E-06 8.3E-04 1.7E-O3 2.7E-0Z l.ZE-02 -234 9.6B-06 7.7E-D6 B.3E-O4 1.7E-03 2.7E-O2 1.2E-02 -235 •315E-07 1.0E-05 8.2E-O6 8.3E-04 l.BE-03 2.7E-02 1.3E-D2 -23B J.1E-05 E-06 2.OE-O3 J.9E-02 1.4E-O2 Np-237 2.3E-06 1-06 -239 PU-23B -239 -240 -241 •9.2E-08 1.4E-06 1.7E-03 •3.3E-06 7.9E-05 1.3E-01 •1.8E-07 3.DE-06 3.5E-O3

i1 * Adults on Site t j 2 » Infants «t Upriver Boundary (3 • Adults at Upriver Boundary

* Dominant pathway, i.e., the pathway resulting in the mininum value of qM

** Included in tpeclfic-activity model for pathways D and E (see Section 5.4,13) t Effect insignificant compared to other pathway*! c*ee not evaluated + 1 Ci • 37 GBq + 2.8E-02-2.flxlO"f 6-13

TABLE 5.3 - HflXIMUH PERMISSIBLE RELEASE HATES (q^-Ciys) IN PftTHWhY!

AIRBORNE RADIOHUCLIDES (OTHER THAU HOBLE GflSES) RELEASED FROM

ROOF VEHTS

Pathway see Fig. 5.2 ]

B C D E Radionuclide

Expose d Groupt

1 2/3 1 3 2 3 2 3

H-3(HTO) 9 9 '3.5E-03 C-14 (COj) 3.6E-02 i C-14 (port.) 0 Cr-51 *3.fl 7. E-01 2.2E-03 : 7.1E+0 3.BE+00 1.5E+0 3 2.8E+00 2.1B+O2 1.0E+02 Hn-54 + 1. E-04+ 1.8E+00 Fe-59 1. E-Ob -GO •2.2E-06 1 IFfi H.5E-05 I ' 2.6E-62 " 1.BE-0 4.5E-* 6.3E-61 -90 9 9 Zr-95 1.0E+01 3.3E+00 ' Nb-95 •1.2E-05 3.5E+00 Ho-99 4.4E-04 •1.6E-0S 3.4E-02 -106 Sb-124 -125 4.4E-0 2 ' 1.3E+00 4.6E-O1 Te-132 4.1E-04 8.4E-Q1 • •3.8E-05 8.9E-O! 6.5E-02 1.7E-'' 1.T--01 4.4E-O1 7.0E-01 i-lis 9 i •5.3E-05 8.9E-C3 9.1E-03 4.6E-O5 ' 3.2E-O3 S.8E-63 •3.9E--07 -129 8.1E-O4 -131 1.5E-05 -132 3.7E-01 0 1 IE-03 -13* 0 0 -135 l.DE-04 Cs-134 S.lE-04 2.2E-0S J:£8j —3I8E-63—' 1 4.6E-A4 ' 9.9E-O2 Z.2E-6S ! -137 •7.0E-08 Ba-140 •8.2E-05 La-140 •8.7E-05 t.BE-Ql 1.8B-04 S.3E-01 3.1E-D1 1.3E+02 2.3E+02 1.9E+01 B.7E+00 Ce-141 -14 j -14J 2.8E-O1 *2.6E-6S ' 5.5E-Q2 1.2E-04 '1 6.0E-01 "—S.IE-61—^ 5.SE-03 i . 3E-63 ' S.4E+00 B.6E-01 Trt- 228 9 •1.8B-09 4.6E-06 3.1E-06 6.8E-05 5.BE-04 2.2E-O5 4.6E-05 232 0 •J..5E-09 7.1E-06 2.6E-06 1.1E-04 3.7E-04 5.3E-06 3.3E-06 U-i 12 t •l.OE-09 2.1E-06 l.HE-06 2.1E-05 3.7E-O5 7.4E-04 3.6E-6-* 3 9.6E-06 7.7E-06 B.3E-04 1.7E-03 2.7E-O2 1.2E-02 -2 4 •4.4E-OS 9.6E-06 7.7E-06 B.3E-04 1.7E-03 2.7E-02 1.2E-02 8 •S.OE-09 1.1E-05 8.6E-06 9.1E-04 2.0E-O3 2.9E-02 1.4E-02 Np- •1.3E-09 39 9.8] -04 PU- 36 39 i '1.3E-09 8.0E-03 40 8.0E-03 41 "B.9E-08 Am-I 41 ' 1.4E-06 2.1E-06 1.7E-03 tH -244 1 •2,*E-09 3.0E-06 4.1E-06 3.5E-03 3.6E-02 9.2E-04 1.9E-03

Adulta on Site ts at Uprive r Boundary * 11Adul =t• at LJprivei Boundary

** Included in specific-activity model for pathways D and E (see Section S.4.13) 6-14

TABLE 6.4 - MAXIMUM PERMISSIBLE RELEASE RATES (qM-CiVs) IN IMMERSION PATHWAY FOR NOBLE .JASES RELEASED FROM NRX/KRO STACK

Pathway (see Fig. 5.2) A (Immersion) Radionuclide Exposed Individualt 1 2/3

Ar-41 *4. 1E-01+ 1.7E+00 Kr-85m *3.1E+00 1.3E+01 85 *2. 7E+01(a) l.lE+02Ca) 87 *6. 2E-01 2.6E+00 88 *2. 5E-01 1.OE+00 89 *2. 2E-01 9.1E-01 90 *2. 3E-01 9.7E-01

Xe-131nT '•4. 0E+01 1.7E+02 -133m *1. 5E+01 6.0E+01 -133 *1. 2E+01 5.1E+01 -135m *1. 2E+00 4.8E+00 -135 *2. OE+00 8.4E+00 -137 *2. 6E+00 1.1E+01 -138 *4. IE-01 1.7E+00 (*A.6E-01 Ci-MeV /s(b) 1 9E+00 Ci-MeV /s

(I = Adults on Site 1>1 Ci = 37 GBq t J 2 = Infants at Upriver Boundary (3 = Adults at Upriver Boundary 4.1E-01=4.1xl0~'=0.41 * Dominant pathway, i.e., the pathway resulting in the minimum value of qM. (a) Corresponds to non-stochastic limit of 5 rem/a (0.05 Sv/a) to the skin. All other values correspond to effective dose equivalent limit of 0.5 rem/a (0.005 Sv/a). (b) Applies if mixture contains; small proportion of noble gases (e.g., 8SKr) having ratio E /E. (see Table 5.9) greater than 10. (c) Applies if mixture contain£ large proportion of noble gases (e.g., *sKr) having ratio E /E. (see Table 5.9) greater than 10. 6-15

TABLE 6.5 - MAXIMUM PERMISSIBLE RELEASE RATES (q,,-Ci^/s) IN IMMERSION PATHWAY FOR NOBLE GASES RELEASED FROM 61-m STACK

Pathway (see Fig. 5.2) A (Immersion) Radionuclide Exposed Individual! 1 2/3

Ar-41 *6 2E-024 1.7E+00 Kr-85m *4. 7E-01 1.3E+01 -85 *4. 0E+00(a) 1.1E+O2(a) -87 *9. 3E-02 2.6E+00 -88 *3. 7E-02 1.0E+00 -89 *3. 3E-02 9.1E-01 -90 *3. 5E-02 9.7E-01 Xe-131m *6. 0E+00 1.7E+02 -133m *2. 2E+00 6.0E+01 -133 *1. 9E+00 5.1E+01 1 -135m *1. 8E-01 4.8E+00 -135 *3. 0E-01 8.4E+00 -137 *3. 9E-01 1.1E+01 -138 *6. 2E-02 1.7E+00 | *6. 9E-02 Ci-MeV /s(b) 1.9E+00 Ci-MeV /s(b) Mixed Noble Gases Y I -a) (c) *6. 9E-01 Ci-MeVe+y/s(a) (c) 1.9E+01 Ci-MeV /s *

j 1 = Adults on Site i> 1 Ci = 37 GBq t { 2 = Infants at Upriver Boundary , K , „, , ,vln-2 (3 = Adults at Upriver Boundary * b.tE-ut-b.txxu * Dominant pathway, i.e., the pathway resulting in the minimum value of q,,. M (a) Corresponds to non-stochastic limit of 5 rem/a (0.05 Sv/a) to the skin. All other values correspond to effective dose equivalent limit of 0.5 rem/a (0.005 Sv/a). (b) Applies if mixture contains small proportion of noble gases 85 (e.g., Kr) having ratio Eg/Eb (see Table 5.9) greater than 10. (c) Applies if mixture contains large t>icportiop n of noble ggases _ (e.g., 8S Kr) having ratio E (see Table 5.9) greater than 10. 6-16

TABLE 6.6 - MAXIMUM PERMISSIBLE RELEASE RATES

IN IMMERSION PATHWAY FOR NOBLE GASES RELEASED FROM

ROOF VENTS

Pathway (see Fig. 5.2) A (Immersion) Radionuclide Exposed Individualf 1 2/3

Ar-41 *8.3E-04+ 1.7E-:-00 Kr-85m ! *6.3E-03 1.3E+01 -85 ! *5.4E-02(a) 1.1E+02(a) -87 *1.2E-03 2.6E+00 -88 *5.0E-04 1.0E+00 -89 *4.4E-04 9.1E-01 -90 j *4.7E-04 9.7E-01 Xe-131m *8.0E-02 1.7E+02 -133m *2.9E-02 6.0E+01 -133 *2.5E-02 5.1E+01 -135m *2.3E-03 4.8E+00 -135 *4.0E-03 8.4E+00 -137 *5.1E-03 1.1E+01 -138 *8.3E-04 1.7E+00

»*9. 3E-04 Ci-MeV /s

= Adults on Site 1 Ci = 37 GBq Infants at Upriver Boundary ill Adults at Upriver Boundary 8.3E-04=8.3xl0~* * Dominant pathway,i.e., the pathway resulting in the minimum value of q . (a) Corresponds to non-stochastic limit of 5 rem/a (0.05 Sv/a) to the skin. All other values correspond to effective dose equivalent limit of 0.5 rem/a (0.005 Sv/a) (b) Applies if mixture contain£ small proportion of noble gases (e.g., 85Kr) having ratio E /E, (see Table 5.9) greater than 10. (c) Applies if mixture contain^ ]^arge proportion of noble gases (e.g., 85Kr) having ratio E /E, (see Table 5.9) greater than 10. 6-17

TABLE 6.7 - MAXIMUM PERMISSIBLE RELEASE RATES(q^-Ci^/a) IN PATHWAYS FOR

LIQUID EFFLUEMTS RELEASED FROM CRNL

Pathway (see Fig. 5.2) I

Radionuclide F G H 1 (Vfeg. Ingestion - Spray irrigation) (Water Ingestion) (Fish Ingesticn)

Exposed Groupt

4 5 4 5 5

H-3(HTOJ 4.5E-01+ •3.2E-01 1.5E+01 6.4E+0Q 2.1E+02 Be-7 4.7E+04 1.4E+0S 4.1E+02 •5.4E+00 1.8E+01 C-14(part.) ! 6.7E-03 4.5E-03 7.4E-01 3.3E-01 *2.2E-04 Na-22 l.BE+OO 9.8E-01 1.6E-01 5.4E-02 *1.8E-03 -24 2.1E+03 3.3E+03 1.0E+00 7.2E-01 •2.48-02 S-35 6.3E+01 2.1E+01 3.8E+00 7.HE-01 *2.6E-02 SC-46 1.6E+02 4.OE+01 I.5E+00 1.7E-01 •5.6E-02 -47 7.3E+02 2.4E+02 1.6E4-00 2.4E-01 *8.1E-O2 Cr-51 4.2E+O3 2.OE+03 3.1E+01 6.5E+00 *1.1E+00 Hn-54 1.3E+02 4.OE+01 2.8E+00 5.3E-O1 '3.5E-02 Fe-59 4.OE+01 3.3E+01 3.3E-01 1.3E-0X *4.2E-02 Co-5 fl 3.8E+01 4.IE+01 1 3.7E-01 l.is-bl 1 *fTT>E-7J3 -60 1.1E+00 6.0E-01 4.4E-0 2 1.4E-02 •4.7E-04 Zn-65 1.1E+00 6.7E-01 1.5E-01 5.9E-02 *9.8E-04 As-7 6 2.7E+02 2.0E+02 2.2E-01 7.3E-02 •2.4E-0 3 sr-ag I.4E+O1 8.0E+00 2.1E-01 •6.5E-02 1.1E-01 -90 3.3E-03 •2.8E-03 7.7E-03 4.4E-03 7.3E-03 Zr-95 2.OE+0I 6.4E+01 1.8E+00 2.6E-01 *8.5E-02 Nb-9 5 7.9E+01 6.6E+01 6.2E-01 2.4E-01 •8.1E-02 HO-9 9 7.7E+01 1.0E+02 1.5E-01 9.5E-02 *:.2E-03 Ru-10 3 3.0E+02 1.1E+02 2.5E+00 4.2E-01 *1.4E-01 -106 6.0E+00 2.9E+00 9.4E-02 2.3E-02 *7.7E-C3 Ag-lOflra 4.UE-Ol *2.JE-O1 1.3E+00 3.5E-01 1.2E+0 0 -llOn 8.0E+0Q 1.9E+00 4.6E-01 *6.9E-02 2.?3-01 Sb-124 2.8E+01 1.3E+01 2.6E-01 5.5E-O2 *9.2E-03 -125 3.OE+01 1.1E+01 e.5E-fll 1 1.7E-01 •2.8E-02 Te-132 9.5E+00 1.6E+01 3.2E-02 2.7E-02 •2.2E-03 1-125 4.8E-01 8.fiE-0i 5.3E-03 4.9E-03 *3.2E-03 -129 1.2E-03 9.6E-04 l.?E-03 7.1E-04 *4.7E-04 -131 6.7E-01 2.0E+00 2.7E-03 3.6E-03 "2.4E-03 -133 1.9E+01 6.4E+01 1.3E-02 1.9E-02 •l.iE-02 -135 2.6E+02 B.5E+02 *5.5E-02 ; B.3E-02 5.6E-02 Cs- "*" 2. 3E+O0 5.0E-01 7.6E-O2 i l-OE-02 *6.7E-05 3.8E-01 B.7E-02 9.4E-02 1.4E-02 •9.4E-05 1.3E+02 2.3E+02 7.3E-01 3.3E-11 *5.6E-02 L J 3.6E+02 1.7E+02 4.4E-01 *9.5E-02 1.3E-O1 C r-141 1.6E+O2 5.9E+01 1.2E+00 • 2.1E-01 *6.8E-02 -143 5.3E+01 2.6EU1 7.0E-01 1.7B-01 *5.6E-0i -144 1.3E+01 5.3E+00 1.5E-01 2.8E-02 *9.4E-02 Eu-152 i 2.3E+01 6.0E+CC 6.7E-01 1.0E-01 *3.3E-02 -154 2.2E+01 4.9E+00 7.2E-01 9.9E-02 •3.3E-02 Hf-175 ;' 5.3E+02 1.4E+02 4.BE+00 S.8E-01 •1.9E-01 -181 2.4E+02 7.3E+01 2.0E+00 : 2.7E-01 *9.OE-02 Hg-203 : 5.3E+01 2.OE+01 1.1E+00 I 2.3E-01 •7.7E-04 Ra-226 ! 3.5E-04 3.5E-O4 i 9.4E-OS : S.9E-05 *2.0E-05 Th~22B 4.9E-04 9.7E-04 j 7.1E-06 i 7.3E-06 •2.4E-06 -232 1.3E-04 ' 8.3E-O5 1.3E-05 5.1E-06 •i.7E-oe Pa-233 2.8E+02 1.2S+02 ' 2.1E+00 ! «3.8E-01 6.4E-01 U-232 1.5E-02 6.4E-03 2.4E-04 i *5.0E-05 8.3E-05 -233 5.6E-01 ' 2.7E-01 9.4E-03 •2.3E-03 3.BE-03 -234 ! 5.6E-01 ' 2.7E-01 : 9.4E-03 •2.3E-03 3.BE-03 -235 5.6E-01 1 2.9E-01 9.4E-03 •2.4E-03 4.1E-03 -238 | 6.2E-01 1 3.2E-01 ' 1.0E-02 *2.7E-03 4.5E-03 Np-237 6.7E-04 3.8E-04 *1.1S-O5 1.4E-05 2.4E-05 -239 1.4E+03 6.7E+02 2.3E+00 •5.0E-01 e.3E-01 Pu-23fl 8.3E-fl2 2.0E-01 ' l.lE-OS 1.4E-03 45.4E-"14 -239 1 7.1E-02 1.7E-01 1.0E-03 1.3E-03 *B.5E-04 -240 7.1E-02 i 1.7E-01 ' 1.0E-03 1.3E-03 •9.5E-04 -241 5.2E+00 '• 1. 5E+01 6. 4E-02 '. B. BE-0 2 *5.9E-02 Am-24l 6.6E-03 1.5E-02 • 2.0E-04 2.4E-04 *8.1E-a5 Cm-242 1.1E+00 ( 2.4E+00 1.1E-02 1.1E-02 *3.7E-03 -244 2.0E-02 4.SE-02 : 3.9E-04 4.9E-04 *1.6B-04

4 - Infant9 in Petawawa 5 - Adult* in Petawawa Dominant pathway,i.e. the pathway resulting in ^he minimum value of 1 Ci - 37 GBq 6-18

- IBttVH) KHBftSE LWTS (EBL's) KB MBBCRSE

NRVNHI stadt it. Jtof 1fents

Radirvnxrli^ Daninant ^^^ DHL ndnanfc s^ DBL Dopant ^/ DBL

./"'critical Ci*/5 HaxinunCi* •^Critical ci/s WjUJmnCi Ci/s ItadflUB Ci in Ore; Week y^ Qxxp' in One He* /^ Grc^- in Qe Heek

H-30no) D-E/2-3 5.0E-01t 3.0E405 CA 2.6E-O1 1.6M5 CA 3.5E-03 2.1E4O3 C-14!COi) D-E/2-3 7.6E-03 4.6E-H13 D-E/2-3 7.6E-O3 4.GE403 D-fi/2-3 7.6E-03 4.6E403 0-14 (part.) D/2 5.6E-05 3.4E401 D/2 5.6E-05 3.4EW1 CA B.5E-06 S.1&O0 Cr-51 BA 1.6E-01 9.7E+04 BA 2.4E-02 1.5EHI4 BA 3.2E-O4 1.9E*O2 tb-54 BA 6.5E-04 3.9E4O2 BA 9.EE-O5 5.BE-K11 BA 1.3Z-06 7.9E-01 571 2.7E-03 1.6E403 B/l 4.2E-O4 2.5EM2 BA 5.5E-0G 3.3E-99 D/2 1.3E-02 7.9E«3 CA 9.8E-03 5.9E4O3 CA 1.3Z-04 7.9E101 BU-103 B/l 7.2E-O3 4.4E4O3 BA 1.1E-03 6.7E4O2 B/l 1.4E-O5 B.5E4O0 -106 CA 4.7E-04 2.8E4O2 QA 7.0E-05 4.2E4O1 CA 9.2E-07 5.6E-01 Sb-124 BA 1.3E-03 7.9E+O2 BA 2.OE-O4 1.2£^02 BA 2.EE-06 1.6EMK) -125 .BA 3.GE-04 2.2E-HJ2 EA 5.3E-C5 J.2E401 BA 7.1E-07 4.3E-01 Tfe-132 * D/2 1.4E-02 8.5E-MJ3 CA 2.GE-03 1.6EW3 CA 3.5E-O5 2.1EW1 1-125 D/2 5.9E-06 3.6EHH] D/2 S.9E-0G 3.GEHW C/l 5.3E-O6 -129 D/2 8.OE-O7 4.BE-01 D/2 8.0E-07 4.BE-01 a/i 2.6E-07 1.6E-01 -131 D/2 9.6E-06 5.BEHX1 D/2 9.GE-O6 5.8EHW CA 3.1E-O6 1.9E4O0 -132 BA 6.3E-02 3.8EHI4 SA 9.5E-O3 5.7E»03 BA 1.3E-04 7.9EW1 -133 D/2 l.OE-03 6.0E4O2 D/2 l.OE-03 6.QEH12 CA 1.7E-05 l.OE+fll -134 BA 2.1E-01 1.3EtO5 BA 3.2E-02 1.9E«4 BA 4.3E-O4 2.6E4O2 -135 CA 2.4E-02 1.5E4O4 - CA 3.6E-O3 2.2E«3 CA 4.7E-05 2.SE401 Cs-134 B/l 1.2E-O4 7.3EH}1 B/l 1.8E-O5 1 ip*m B/l 2.SE-07 1.5E-01 -137 BA 3.5E-05 2.1Z-H11 BA 5.3E-06 3-2E-*O0 BA 7.0E-0B 4.2E-02 Ba-140 BA 2.2E-02 1.3EM1 BA 3.4E-03 2.1E4O3 BA 4.4E-05 2.7E«1 La-140 BA 3.0E-O2 1.8EW4 B/l 4.5E-03 2.7EM3 BA 5.9E-05 3.6E«01 Ce-141 CA 2.2E-02 1.3E-HH CA 3.4E-03 2.1EW3 QA 4.6Z-05 2.BE-K11 -143 BA 6.7E-O4 4>l£+O2 B/l l.QE-04 6.0EH11 BA 1.3E-06 7.9E-O1 -144 - CA 8.4E-04 5.1E+O2 CA 1.3E-04 7.9E»01 CA 1.7E-06 1.0EW0 BF2ST D/2 2.4E-O5 1.5EM3 BA 1.6E-O3 S.7EM2 WI 2.1E-05 1.3B*O1 BH-22G D/2 4.5E-07 2.7E-01 D/2 4.5E-07 2.7E-01 BA 1.6E-O8 9.7E-03 •D1-22B QA 9.0E-07 5.4E-01 CA 1.4E-07 B.5E-02 QA l.SE-09 1.1E-O3 -232 CA 7.6E-07 4.6E-01 C/l 1.1E-O7 6.7E-02 CA 1.5E-O9 9.1E-04 l>-232 CA 5.2E-O7 3-lE-Ol CA 7.8E-08 4.7E-02 E7I LOE-09 6.0E-O4 -233 CA 2.2E-06 1.3EM0 • CA 3.3E-O7 2.0E-O1 CA 4.4E-09 2.7E-03 -234 QA 2.2E-06 1.3E4O0 QA 3.3E-07 2.0E-01 CA 4.4E-O9 2.7E-03 -235 CA 2.4E-O6 1.5E-HJ0 CA 3.5E-07 2.1E-01 CA 4.7E-09 2.8E-03 -23B CA 2.5E-06 1.5E»O0 CA 3.BE-07 2.3E-01 CA 5.0E-09 3-0E-03 Np-237 CA 6.7E-0? 4.1E-O1 C/l 1.OE-O7 6.OE-O2 CA 1.3E-09 7.9E-04 -239 QA 2.2B-01 1.3E«5 QA 3.3E-02 2.CE-MM CA 4.5E-O4 2.7E-H12 Pu-238 CA 6.9E-07 4.2E-01 CA 1.0E-07 6.0E-02 CA 1.4E-O9 8.5E-04 -239 CA 6.3E-07 3.8E-01 CA 9.5E-OB 5.7E-O2 CA 1.3E-09 7.9E-04 -240 CA 6.3E-O7 3.BE-01 CA 9.5E-O8 5.7E-02 CA 1.3E-09 7.9E-04 -241 CA 4.4E-05 2.7E«1 CA 6.7E-06 4.1EW0 CA 8.9E-08 5.4E-02 Jto-241 CA S.lE-05 3.TE-01 c/1 9.2E-O8 5.6E-02 C7I 1.2E-09 7.3E-44 00-242 CA 2.2E-05 c/l 3.3E-M 2.0EMM CA 4.4E-0B 2.7E-02 -244 CA 1.2E-06 7i3E-01 CA l.BE-07 1.1E-O1 CA J.4E-0S l.SE-01 Br-41 VI 4.1E-01 2.5E*O5 AA E.2E-02 3.7EW4 AA 8.3E-O4 S.QEHI2 KE-85m AA 3.1E+O0 1.9E*O6 AA 4.7E-C1 2.BE«5 AA 6.3E-03 3.8EMI3 -85 AA 2I7EWI I.CH07 AA 4.DE4O0 2.4EH)E AA 5.4E-02 3.3BHH -87 AA 6.2E-01 3.7E4O5 AA 9.3E-O2 5.6E+M AA 1.2E-03 7.3BKI2 -88 AA 2.5E-01 1.5E4O5 AA 3.7E-02 2.2E4O4 AA 5.0E-04 3.OEW2 -89 AA 2.2E-01 1.3E4O5 AA 3.3B-02 2.IE4O4 AA 4.4E-O4 2.7B02 \ -90 AA 2.3E-O1 1.4E+05 AA 3.5E-02 2.1£H)4 AA 4.7E-04 2.8E«2 S te-131» AA 4.0EI01 2.4E«7 «A 6.0EMK) 3.6EM6 AA 8.0E-02 4.BE404 | -131n AA 1.5E401 9.1EtO6 VI 2.2EKK) 1.3E«6 AA 2.9E-02 1.8E404 -133 AA 1.2E+01 7.3E+O6 AA 1.9EKK) 1.IEHW AA 2.5E-02 l.SKH S -135m AA 1.2E+O0 7.3E4O5 AA 1.8E-01 1.1E4O5 AA 2.3E-03 1.4EHB -135 AA 2.OE+O0 1.2E+O6 AA 3.0E-01 1.8E4O5 VI 4.0E-C3 2.4E403 i -137 AA 2.6E-HW l.ffi+06 AA 3.9E-01 2.4E»O5 AA 5.1E-03 3.1EW3 -138 AA 4.1E-01 2.5E4O5 AA 6.2E-02 3.7E<04 AA 8.3E-O4 5.0EM2 1 M AA 4.6E-011"1 2.BEtO5li" VI 6.9E-02 (a) , jErtw'" AA 9.3E-O4 W 5.6E«2

HUCBD Nob, bl 01 AA 2.BBO6 VI 6.9E-01 AA 9.3E-03

„ Ci = 37 (»J 1 •= at 3 = Adults at D • Hilk Ingesticn - E - Vegetable Ir^estion t 5.0E-01-5.0X10-1 (a) ?ln'H'Mf if T"*tim* mrrtwin*? «»'»i inrnywiifm of nlile «jaw« (e.g., '*Kr) having ratio *L^L (BBC Table 5.9) tjnwtw tton 10 (b) «K>lies if mixture cxntains liige prcpart±cn of n*0e gssea (e.g., tsKr) having ratio ^^% (eee Table 5.9) greattr titan 10. 6-19

TABLE 6.9 - DERIVED RELEASE LIMITS |DB,'»)

LIQUID EFFLUEHTS FROM CRNL

DRL Radianuclide Dominant ^—"""^ Pathway* _^^*^^^ "^~-^ critical Group* Ci*/S Maximum Ci* in One Month

H-31HT0) F/5 3.0E-01t 7.9E+05 Be-7 G/5 4.1E+00 1.1E+07 C-14 (part.) H/5 2. IE-04 5.5E+02 Na-22 H/5 1.7E-03 4. 5E*-03 -24 H/5 2.3E-02' 6.0E+04 S-35 H/5 2;5E-02 6.6E+04 Sc-46 H/5 4.2E-02 1.1E+05 -47 H/5 6.1E-02 1.6E+05 Cr-51 H/5 9.4E-01 2.5E+06 • Mn-54 H/5 3.3E-02 8.7E+04 Fe-59 H/5 3.2E-02 8.4E+04 CO-5& H/5 5.8E-03 1.5E+04 -60 H/5 4.5E-04 1.2E+03 Zn-65 H/5 9.6E-04 2.5E+03 So-7 6 H/5 2.3E-03 6.0E+O3 Sr-89 G/5 4.1E-02 1.1E+0S -90 F/5 1.4E-03 3.7E+03 zr-95 H/5 6.4E-02 1.7E+05 Nb-95 H/5 6.1E-02 1.6E+05 MO-99 H/5 3.1E-03 8.1E+03 HU-103 H/5 1.0E-01 2.6E+05 -106 H/5 5.8E-03 1.5E+04 Ag-108m F/5 1.2E-01 3.2E+05 -110m G/5 5.2E-02 1.4E+05 Sb-124 H/5 7.9E-03 2.1E+04 -125 H/5 2.4E-02 6.3E+04 Te-132 K/5 2.0E-03 5.3E+03 1-125 H/5 1.9E-03 5.0E+03 -129 H/5 2.2E-04 5.8E+02 -131 K/S 1.4E-03 3.7E+O3 -133 H/5 7.7E-03 2.0E+04 -135 G/5 3.3E-02 8.7E+O4 Ce-134 H/5 6.7E-05 1.8E+02 -137 H/5 9.3E-05 2.4E+02 BO-140 H/5 4.8E-02 1.3E+05 La-140 G/S 5.5E-02 1.4E+05 Ce-141 H/S 5.1E-02 1.3E+05 -143 H/5 4.2E-02 1.1E+05 -144 H/5 7.0E-03 1.8E+04 EU-152 H/5 2.5E-02 6. 6E+ 04 -154 H/5 2.5E-02 6.6E+04 Hf-175 H/5 1.4E-01 3.7E+05 -181 H/5 6.7E-02 l.BE+05 Hg-203 H/5 7.7E-04 2.0E+03 Ra-226 H/5 1.4E-05 3.7E+O1 Til-228 H/5 l.BE-06 4.7E+00 -232 H/5 1.3E-06 3.4E+00 Po-233 G/5 2.4E-01 6.3E+05 U-232 G/5 3.1E-05 8.1E+01 i -233 G/5 1.4E-03 3.7E+03 -234 G/5 1.4E-03 3.7E+03 -235 G/5 1.5E-03 3.9E+03 -23S G/5 1.7E-03 4.5E+03 Np-237 G/5 B.6E-06 2.3E+01 -239 G/5 3.1E-01 8.1E+05 PU-238 H/5 5.6E-04 1.5E-t-03 -239 H/5 5.1E-04 1.3E+03 -240 ; H/5 5.1E-04 1.3E+03 ! -241 j H/5 3.5E-02 9.2E+04 Am-241 H/5 6.0E-05 1.6E+02 On-242 H/5 2.8E-03 7.4E+03 -244 H/5 1.2E-04 3.2E+02 1 1 1 d - 37 GBg

F - Vegetable Xngsstion 4 - Infants in Petawawa G - Wat«r Ingeation 5 • Adult* in Petawawa H - Plan Ingeation

3.0E-0X-3.0xl0-'-0.3 6-20

TABLE 6.10 - DERIVED RELEASE LIMITS (DRI^) FOR

MRBOSKE EFFLOEWTS FROM CRHL ASSUMIMG

CRITICAL GROUP IS AT BOUHDARY

Radionuclide Dominant ^^

Maximum Ci*1 in ^^ Group* Ci*/a One Week

H-3 (BTO) D-E/2-3 5.0E-01+1C) 3.0E+05 C-U(CQa) D-E/2-3 C-14

A/2-3 1.9E+OQ [B) 1.1F+06 (S) Mixed Noble j Cl-MeVY/s Cl-Me\nr

A/2-3 1.9E+CH (bj J.2E+07 (b} ci woV /B , - S+v 7-1

7. PRACTICAL CONSIDERATIONS

7.1 Uncertainties in Calculations

It should be clear at this stage that numerous parameters have entered into the calculations of DRL's described in the preceding sections. Site-specific values of the parameters have been used where available. However, in many cases, local values are not known accurately so that default (conservative) values have been chosen. Some of these and other obvious conservatisms introduced into the calculations have already been noted as follows:

- the use of the 50-year dose commitment concept for chronic intakes of long-lived radionuclides in the first few years of exposure (Section 4.2).

- the assumption that the radionuclides released are in their most restrictive chemical and physical forms (Section 4.2).

- the assumption that cows graze at the CRNL upriver boundary (Section 5.2).

- the assumption that an on-site worker spends his full working time outdoors (Section 5.3).

- the assumption that radionucludes in the plume are not depleted due to deposition and washout processes (Section 5.4.1). 7-2

- the assumption that radionuclides deposited on the ground build up over a period of 50 years with no loss due to weathering or ground water processes (Sections 5.4.2 and 5.4.11).

- the use of maximum intake rates for inhalation and ingestion (Section 5.4.6).

- the use of the specific-activity approach for airborne H-3 and C-14 in which it is assumed that locally contaminated food and water provide the bulk of a person's intake of hydrogen and carbon (Section 5.4.13) .

The end result of combining the various transfer parameters is that many of the DHL's are conservative (overestimate the doses) by large factors, the magnitude of which could be determined by a parametric analysis like that done in the U.S. [7.1]. However, the important point is that the DRL's should not be used for estimating the effect of known releases on the radiation doses and consequent health risks to the exposed populations. Rather, the DRL for each radionuclide simply represents an upper limit to the release which, if adhered to, will provide a virtual certainty of compliance with the ICRP recommendations (see Section 5.1). Failure to adhere to the DRL for a particular radionuclide will not necessarily imply a failure to achieve compliance but will require a more careful study of the situation (by environmental monitoring, measuring actual doses, etc.) to ensure that the dose limits were not exceeded.-

7.2 Multiple Sources

^s noted in Section 3, there are several sources of airborne and liquid effluents at CRNL and each of them is 7-3

likely to release several radionuclides. As a result, individuals are exposed to radiation doses from more than one source and/or more than one radionuclide and the effect of them all must be taken into account when setting allowable release limits. In mathematical terms, the following criterion must be satisfied for each of the exposed groups of individuals of interest (the site worker, the infant and the adult at the boundary):

< 1 (41) W ikn

s where (QM) ••L. i- maximum permissible release rate for the i'th radionuclide from the k'th source, based on the dose to the individual in the n'th exposed group

Q., is the actual emission rate of the i'th radionuclide from the k'th source.

The criterion will be met (and a slight degree of conservatism will be introduced) if:

V V Qik < 1 (42) i k (DRL) ik where (DRL)^. is the derived release limit given in Table 6.8 or 6.9 for the i'th radionuclide, k'th source, and the critical group.

Consideration of the multiple source effect is of concern primarily when setting administrative levels for th:e actual releases from the facilities (see Section 7.4). Suffice it to say that as long as the actual release from each source is controlled 7-4

to a very small fraction of the DRL, criterion (42) is almost certainly satisfied.

7.3 Mixtures of Unidentified Radionuclides

Analysis of effluents to determine the concentrations of each of the radionuclides present is not usually done on a routine basis. A practical assessment of the monitoring requirements usually indicates that a measure of the bulk activity of an effluent sample or an analysis of the more important radionuclides that might be present is adequate. In the case of airborne releases of noble gases, for example, it is convenient to measure the source emission rate in units of Ci-MeV/s (or Bq-MeV/s) and relate the measurement to a DRL expressed in the same units (see Section 5.4.7), thus avoiding the unnecessary complexity and additional cost of a detailed analysis of the individual radionuclides that may be present.

Similarly, it may be convenient to monitor the release of aerosols of gamma-emitting radionuclides by collecting a sample of the effluent on a particulate filte-. and measuring the sample for gross gamma activity in units of Ci*MeV (or Bq«MeV ). It would then be necessary to specify the DRL in the same units, as was done for the noble gases. As an example, consider the case in which an airborne effluent contains a mixture of gamma emitters other than radioiodines and alpha/ gamma emitters. From the DRL's in Table 6.8 for gamma-emitting Particulates (other than radioiodines and alpha/gcimma emitters), one can show that the most restrictive DRL (in Ci*MeV /s) applies for Cs-137, which has a gamma energy of 0.66 MeV. For releases from the NRX/NRU Stack, the DRL would be about 2.3xlO"5 Ci-MeV /s (0.85 MBq.MeV /s). Such a DRL expressed in this way may be overly restrictive if the sample contained a large 7-5

proportion of short-lived gamma emitters that contributed much less than Cs-137 to the radiation dose received by the exposed individuals. Consideration might then be given to allowing the sample filter to decay for a certain period before counting.

Arguments similar to those above might be used for monitoring airborne effluents for the actinides (predominantly alpha emitters) or for monitoring liquid effluents. Similarly, it might be convenient to monitor an effluent specifically for the more restrictive component(s) and assign to the remainder of the activity or the gross activity the smallest DRL of the unidentified radionuclides that may be present.

7.4 Management of Effluents (Setting Administrative Levels, Monitoring and .teporting of Releases)

A considerable amount of effort is expended at CRNL to keep the radioactivity in effluents well below the DRL's, in effect, to ensure that the ALARA ("as low as reasonably achievable") principle of the ICRP is met (see Section 1). This is done primarily by establishing, for each release point, an administrative level set at a fraction of the DRL (usually less than 1%) and close to the normal operating level. Any release exceeding the administrative level would be investigated promptly to determine whether the release was indicative of an operational upset or a deterioration that should be corrected.

The procedures for managing the effluents involve essentially four main groups, which are described in reference [7.2] and the duties of which in this regard may be summarized as follows:

AECL Nuclear Safety Advisory Committee (NSAC):

- reviews the safety analysis report for each nuclear facility and ensures that all release points are 7-6

monitored sufficiently.

reviews (and if satisfied, approves) the calculation of DRL's for the facility. - in consultation with the EA* and after taking into account the effect of other sources (Section 7.2), sets an administrative level for each release point and records it in the licence for the facility. if necessary, revises the administrative levels either upwards or downwards as operating experience is obtained. reviews any unusual occurrence in which the DRL is exceeded.

Chalk River Environmental Authority (EA)

investigates a]1 reports of releases exceeding the administrative levels;. informs the Site Head and the NSAC of significant releases. recommends to the NSAC any changes in the administrative levels.

CRNL Radiation and Industrial Safety (RSIS) Branch:

- monitors the sources of airborne effluents and reports the releases to the EA at monthly intervals. reports any airborne release exceeding its administrative level to the EA promptly.

* EA - the Chalk River Environmental Authority 7-7

CRNL Environmental Research Branch

monitors the sources of liquid effluents and reports the releases to the EA at monthly intervals.

reports any liquid release exceeding its administrative level to the EA promptly.

In addition, the Environmental Research Branch conducts extensive surveys of activity in the surrounding environment (land, water, and air) to ensure that the releases do in fact represent a negligible radiation hazard to people at large.

Confirmatory evidence that the ALARA principle is effective in the CRNL operations is given in the annual reports of the actual releases from the site. For example, in the most recent report [7.3], the releases of all radionuclides in airborne and liquid effluents were shown to be a small fraction of the respective DRL's. Results of the environmental survey sub- stantiated that the releases represented a negligible radiation hazard to people outside the CRNL property. 8-1

8. SUMMARY AND CONCLUSIONS

(1) Derived release limits (DRL's) have been calculated for radionuclides in airborne and liquid effluents at CRNL that meet the definition prescribed originally (see Section 1), i.e., the upper limit for the release rate of a single radionuclide from a single source which is derived from the regulatory dose-equivalent limits by analytical models of all significant environmental pathways to an individual in the most heavily exposed group (i.e., the "critical group"). In deriving the DRL, the intention is to establish a release limit such that adherence to it will provide virtual certainty of compliance with the ICRP recommendations.

(2) Actual releases of radionuclides in airborne and liquid effluents at CRNL are regulated at a fraction of the DRL's in line with the ALARA ("as low as reasonably achievable") recommendation of the ICRP.

(3) In the DRL calculations the dose limits for radiation exposure of the on-site workers due to effluent releases were taken to be the same as the limits stipulated in the Atomic Energy Control Regulations for members of the public.

(4) The DRL's for airborne effluents (in Table 6.8) were calculated for the three types of sources existing at CRNL, i.e., the NRX/NRU Stack (Bldg. 163), the 61-m Stack (Bldg. 206) , and a Roof Vent (typical of those installed on several buildings on the site). The DRL's for liquid effluents (in Table 6.9) were calculated assuming a single source from the site as a whole. - 2

(5) The individual in the critical group for airborne releases of most radionuclides is the on-site worker. If the on-site workers are excluded, the critical group for airborne releases is made up of individuals at the upriver boundary. DRL's have also been calculated for this critical group. These boundary DRL's (designated DRL. and listed in Table 6.10) are independent of the origin of the airborne release and are therefore representative of the upper limits of airborne releases from the site as a whole.

(6) The individual in the critical group for releases of all radionuclides in liquid effluents is an adult member of the public living downriver from the CRNL site,

(7) The DRL's have been calculated in units of Ci*/s. However, to take account of the practical situations in which the source is usually not continuous at a steady rate, a source averaging time of one week for airborne releases appears appropriate. The DRL's are therefore also expressed in "Maximum Curies in One Week". For liquid effluents, a source averaging time of one month has been chosen and the DRL's have also been expressed in "Maximum Curies in One Month".

(8) Because of the many conservative factors used in the DRL calculations, a release of a particular radionuclide that exceeds the DRL will not necessarily mean that the dose limits have been exceeded but will require a more careful study of the situation (by environmental monitoring, measuring actual doses, etc.). Similarly, because many of the DRL's are conservative (overestimate the doses) by large factors, they should not be used for estimating the effect of known releases on the radiation doses and consequent health risks of the exposed populations.

* 1 Ci = 37 GBq - 3

(9) Monitoring of each of the individual radionuclides in airborne and liquid effluents need not be done as long as one has some prior knowledge of the constituents. Guidance is presented for determining a DRL for gross counting of a mixture based on the individual DRL data. 9-1

ACKNOWLEDGEMENTS

Preparation of this report has extended over a long period requiring extensive clarification and interpretation of the new ICRP-26 recommendations. During this period, the author has been encouraged by the advice and assistance of others carry- ing out similar studies in parallel. In particular, the efforts of P.J. Barry (who is authoring a general AECL report on the subject of calculating DRL's), R.W. Pollock and P.M. Wuschke (who are preparing a similar report for the AECL-Whiteshell site), and K.Y. Wong of Ontario Hydro (who is heading up a working group preparing a CSA standard on the subject) are gratefully acknow- ledged. Special thanks, however, go to J.R. Johnson for Appendix B and for the development of dose conversion factors for the ICRP-26 approach, the latter of which provided the major break- through in the work.

Smaller but nevertheless important contributions were made by many others and the author would particularly like to single out:

R.K. Elliott and G.G. Hooper, CRNL Plant Design Division - for preparation of Fig. 2.3 using the Computer Aided Design system. M. Measures, Dept. of National Health and Welfare - for permission to reference her unpublished report on radioactivity in the Ottawa River.

I.L. Ophel, CRNL Health Sciences Division - for data on fish concentration factors. M. Osborne, Statistics Canada, and the Renfrew County Office, Pembroke - for the census data in Table 2.1. R.V. Osborne, CRNL Health Sciences Division - for clarification of the external dose calculation for the immersion pathway (Sec. 5.4.7). 9-2

Finally, the author expresses his appreciation for the helpful comments from CPNL experts* charged with reviewing the report through various draft stages.

Members of the Reviewing Group were: P.J. Barry, D.H. Charlesworth, E.L. Cooper, G. Cowper, W.E. Grummitt (since retired), J.R. Johnson, A.M. Marko, J.A. Morrison (since retired), W.F. Merritt, I.L. Ophel, C.G. Stewart (since retired), L.C. Watson (since retired), and J.M. White. 10-1

10. REFERENCES

[1.1]* International Atomic Energy Agency, "Principles for Establishing Limits for the Release of Radioactive Materials into the Environment", IAEA Safety Series No. 45, STI/PUB/477 (1978).

[1.2] International Commission on Radiological Protection, "Report of Committee IV on Implications of Commission Recommendations that Doses be Kept as Low as Readily Achievable", ICRP Publication 22 (1973).

[1.3] International Commission on Radiological Protection, "Recommendations", ICRP Publication 26 (1977)

[1.4] Wuschke, D.M. and Dunford, W.E., "Calculation of Derived Release Limits of Radionuclides in Airborne and Aqueous Effluents for the Whiteshell Nuclear Research Establishment" (AECL-WNRE report in preparation).

[1.5] International Commission for Radiological Protection, "Principles of Environmental Monitoring Related to the Handling of Radioactive Materials: A Report Prepared by a Task Group of ICRP Committee 4", ICRP Publication 7 (1966).

[3.1] Grummitt, W.E. and Lahaie, G., "Environmental Monitoring &•_ Chalk River Nuclear Laboratories: Part 1. Gamma Ray Spectrometric Analysis of the NRX and Process Effluents", AECL-5698 (1977).

* The first numeral corresponds to the main section of this report in which the reference first appears. 10-2

[3.2] Parsons, P.J., "Movement of Radioactive Wastes Thru the Soil; Part 3 - Investigating the Migration of Fission Products from High Ionic Liquid Wastes Deposited in Soil", AECL-1325 (1961).

[3.3] Parsons, P.J., "Movement of Radioactive Wastes Thru the Soil; Part 4 - Migration from a Single Sourer- of Liquid Waste Deposited in a Porous Media", AECL-1485 (1962) .

[3.4] Parsons, P.J., "Movement of Radioactive Wastes Thru the Soil; Part 5 - The Liquid Disposal Area", AECL-1561 (1962) .

[3.5] Merritt, W.F., "Studies of Dilution in the Ottawa River Using Rhodamine B - CRNL to Pembroke", AECL-2030 (1964).

[4.1] International Commission on Radiological Protection, "Report of Committee II on Permissible Dose from Internal Radiation", ICRP Publication 2 (1959).

[4.2] International Commission on Radiological Protection, "Recommendations", ICRP Publication 9 (1965).

[4.3] Sowby, F.D., "Statement and Recommendations of the ICRP from its 1980 Meeting", Health Physics 39, pp. 377-387 (1980) .

[4.4] Bush, W.R., "Basis for Limiting Exposure to Ionizing Radiation", A Presentation to the Select Committee on Ontario Hydro Affairs, AECB-1180-2 (1979). 10-3

[4.5] Harrison, N.T., Bryant, P.M., Clarke, R.H., and Morley, F., "The Estimation of Derived Limits", NRPB-DLl (1979) .

[4.6] Commission of the European Communities, "Methodology for Evaluating the Radiological Consequences of Radioactive Effluents Released in Normal Operations", Doc. No. V/3865 (1979).

[4.7] International Commission on Radiological Protection, "Limits for Intake of Radionuclides by Workers", ICRP Publication 30, Part 1 (1978).

[4.8] Johnson, J.R., Stewart, D.G., and Carver, M.B., "Committed Effective Dose Equivalent Conversion Factors for Intake of Selected Radionuclides by Infants and Adults", AECL-6540 (1979).

[4.9] International Commission on Radiological Protection, "Report of Committee 4 on Evaluation of Radiation Doses to Body Tissues from Internal Contamination Due to Occupational Exposure", ICRP Publication 10 (1968).

[4.10] Task Group on Lung Dynamics, "Deposition and Retention Models for Internal Dosimetry of the Human Respiratory Tract", Health Physics 12, p. 173 (1966).

[4.11J U.S. Nuclear Regulatory Commission Guide 1.109, "Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I" (Rev. 1, 1977 Oct.).

[4.12] Hurst, D.G. and Boyd, F.C., "Reactor Licensing and Safety Requirements", paper presented at CNA Annual Conference, 1972 June 11-14. 10-4

[4.13] Beare, J.W. and Duncan, R.M., "Siting - The Means by Which Nuclear Facilities Are Integrated into A Canadian Community", paper presented at IAEA Symposium on the Siting of Nuclear Facilities, Vienna, 1974 Dec. 9-13.

[4.14] Environmental Protection Agency, "Proposed Standards for Environmental Radiation Protection for Nuclear Power Operations", U.S. Federal Register, Vol. 40, No. 104 (1975 May 29).

[4.15] "Ionizing Radiation: Levels and Effects", A Report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) to the General Assembly (1972).

[4.16] Beninson, D., "Population Doses Resulting from Radio- nuclides of Worldwide Distribution", paper presented at IAEA Seminar on "Population Dose Evaluation and Standards for Man and His Environment", Portoroz, Yugoslavia, 1974 May 20-24.

[4.17] OECD - Nuclear Energy Agency, "Radiological Significance and Management of Tritium, Carbon-14, Krypton-85, and Iodine-129 Arising from the Nuclear Fuel Cycle", report by an NEA Group of Experts, SEN(80)l (19 80).

[5.1]. Barry, P.J., "Methods for Calculating Upper Limits to the Rates of Discharge of Radionuclides to the Environment from Nuclear Generating Stations" (AECL report in preparation).

[5.2] Canadian Standards Association, "Guidelines for Calculating Derived Release Limits for Radioactivity in Gaseous and Liquid Effluents for Normal Operation", CSA Standard N288.1 (in preparation). 10-5

™ [5.3] Snyder, W.S., "Review of Final Environmental Statement Concerning the 'As Low As Practicable1 Hearing", Nuclear Safety 15, No. 4, p. 441 (1974).

[5.4] Kocher, D.C., "Effects of Indoor Residence on Radiation Doses from Routine Releases of Radionuclides to the Atmosphere", Huclear Technology, Vol. 48, pp. 171-179 (1980) .

[5.5] Pasquill, F., "The Estimate of the Dispersion of Wind- borne Material", Meteorological Magazine 90, pp.33-49 (1961).

[5.6] Gifford, F.A., "Use of Routine Meteorological Observations for Estimating Atmospheric Dispersion", Muclear Safety, Vol. 2 No. 4, pp. 47-57 (1961) .

* [5.7] Barry, P.J., "Concept of a Standard Site", AECL-2682 (1967)

[5.8] Barry, P.J., "Use of Argon-41 to Study the Dispersion of Effluent from Stacks", AECL-3731 (1970).

[5.91 Barry, P.J., private communication, 1977 January 17.

[5.10] U.S. Nuclear Regulatory Commission Guide 1.111, "Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from LightwWater-Cooled Reactors" (1976 March).

[5.11] Chambtrlain, A.C. and Chadwick, R.C., "Deposition of Airborne Radioiodine Vapor", Nucleonics 11, No. 8, pp. 22-35 U953) . 10-6

[5.12] International Commission on Radiological Protection, "Report of the Task Group on Reference Man", ICRP Publication 23 (1975).

[5.13] Huddleston, CM., Burson, Z.G., Kinkaid, R.M. , and Klingler, Q.G., "Ground Roughness Effects on the Energy and Angular Distribution of Gamma Radiation from Fallout", Civil Effects Study Report CEX 62.81, EG&G Inc. (1963).

[5.14] Clifford, C.E. , "Effects of Ground Roughness on the Gamma Doses from 3;Cs Contamination", Canadian Defense Research Chemical Laboratory, Report No. 401 (1963).

[5.15] Measures, M., and Taniguchi, H., "9°Sr and 137Cs in Ottawa River Water and Fish", unpublished report of Dept. of National Health and Welfare (1979) .

[5.16] Bayer, A., "The Radiological Exposure of the Population in the Rhine-Meuse Region by Nuclear Installations During Normal Operation", CEC Doc. No. V/1647 (1978).

[5.17] Miller, C.W., Baes, C.F, Dunning, D.E., Etnier, E.L., Kanak, K.K., Kocher, D.C., Little, C.A., McDowell- Boyer, L.M., Meyer, H.R., Rupp, E.M., and Shor, R.W., "Recommendations Concerning Models and Parameters Best Suited to Breeder Reactor Environmental Radiological Assessments" ORNL-5529 (1979).

[5.18] Veluri, V.R., Boone, F.W., and Palms, J.M., "The Environmental Impact of lkC Released by a Nuclear Fuel Reprocessing Plant", Nuclear Safety 17, No. 5, pp. 580-590 (1976). 10-7

[7.1] Little, C.A. and Miller, C.W., "The Uncertainty Associated with Selected Environmental Transport Models", ORNL-5528 (1979).

[7.2] "Organization of AECL As Regards the Control of Health, Safety and Environmental Aspects of Nuclear Energy", AECL-MISC-163, Rev. 1 (1980). Unpublished report.

[7.3} Watson, h.C., "Annual Safety Report 1979", ASRA-2 (1981). Atomic Energy of Canada Limited, unpublished report. A - 1

APPENDIX A

THE ATOMIC ENERGY CONTROL REGULATIONS

At the time of writing this report, the Atomic Control Regulations* were being revised to incorporate the new system of dose limitation recommended in ICRP-26 [1.3] and summarized in Table 4.1. A copy of the revised Regulations will be included in this appendix when they are issued.

* "Atomic Energy Control Regulations", Canada Gazette Part II, Vol. 108, No. 12, SOR/74-334 (1974 June 4). B - 1 AECL-7243

APPENDIX B

THE EFFECTS OF DEPOSITION/RESUSPENSION OF RADIONUCLIDES

It has been suggested that, under equilibrium conditions, resuspension of activity must be much less important than the activity in air from the initial plume, as the resuspended activity must have come from '-.he initial plume originally. The following simple mathematical model was constructed to investigate this "intuitively obvious" conclusion.

The model is :

with differential equations

(B-l)

~ = (B-2) r - 2

where A = Activity in cubic volume VB with sides of length d, A one side in contact with ground surface, and one perpendicular to wind direction. G = Activity in a thin layer of ground area d2 that is available for resuspension.

I = rate of input of activity into V = C -v-d2, where C is the concentration on the s s windward site of VA, and v is the wind velocity. A X, = rate constant for deposition = V »d2«V "', where V is the deposition velocity.

X = rate constant for activity leaving V in air

X = radioactive decay constant.

X = rate constant for resuspension of activity G.

Xs = rate constant for removal of activity G from being available for resuspension.

At equilibrium, dA _ dG Q dt dt and A= vw I1 - (w»'"Wvl B - 3

If resuspension were ignored the activity in V would be A A- = V'WV (B~4)

If deposition were also ignored then the activity in V would be A

A" = Io/U0+V (B-5)

If the condition that X and X are negligibly small is imposed, which will result in the largest values of A at equilibrium, then equation (B-3) becomes. ^ L1" v^-l = VXo (B~6) which is identical to equation (B-5) (with X =0) which was the result when both deposition and resuspension were ignored.

If only resuspension were ignored, then the activity 1 in vft (A ) would be smaller than the "true" activity (A) by a factor

Of course, X is not usually small compared to X and its inclusion would decrease A below the value obtained when deposition and resuspension were ignored.

The resu .ts obtained from the above simple model leads one to the conclusion that, for the inhalation exposure pathway, a conservative value for the Derived Release Limit will be obtained if both deposition and resuspension are ignored. B - 4

The above analysis and conclusion were provided by J.R. Johnson of the CRNL Health Sciences Division. A much more detailed study of the problem has been published by T.W. Horst*, who drew much the same conclusion as follows (underlining has been provided for what is thought to be the most important statement):

"The surfaae flux model is lastly used to investigate the importance of resuspension to the impaot of environmental releases of hazardous materials. It is shown that resuspension can make an important contribution to the total air concentration, especially at large distances downwind of the source where the direct plume has been almost entirely depleted by deposition. However, the net effect of the deposition-resuspension process is, in general,a reduction in the annual-average total surface air concentration. Thus a conservavive estimate of the annual exposure to this material can be made by ignoring both processes. This net reduction is shown to be a direct consequence of the climatological mix of wind speeds and atmospheric stabilities, the contaminant being preferen- tially deposited during periods of limited vertical mixing and high surfaae air concentrations and resuspended during periods of greater average mixing and lower surface air concentrations".

PNL-2426, "The Estimation of Air Concentrations Due to the Diffusion, Deposition and Resuspension of Contaminants by the Wind" by T.W. Horst (1977). APPENDIX C

NOMENCLATURE

Symbol Description Units Ref.

A to H Environmental exposure pathways are symbolized Sec. 5.2 by a letter as follows: A - immersion in a semi-infinite cloud B - standing on contaminated ground C - inhalation D - milk ingestion E - vegetable ingestion via airborne deposition F - vegetable ingestion via spray irrigation G - water ingestion H - fish ingestion

ALI Annual Limit of Intake of radioactive material Ci*/a Sec. 4.2 by inhalation (Ak^nhai' or ingestion Table 4.2 n Concentration factor for uptake of a radio- Ci/kg (wet weight) Sec. 5.4.4 I nuclide from the soil by edible parts of of vegetation per Table 5.6 vegetation Ci/kg dry soil BR Human inhalation (breathing) rate m3/a Sec. 5.4.6 Table 5.8 Concentration of a radionuclide in air Ci/m3 Sec. 5.4.1 Concentration of a radionuclide on the ground Ci/m2 Sec. 5.4.2

Concentration of a radionuclide in milk Ci/L Sec. 5.4.5 Concentration of a radionuclide on pasture Ci/kg PG grass Concentration of a radionuclide on the soil Ci/m2 Sec. 5.4.11

* 1 Ci = 37 GBq Symbol Description Ref.

C Concentration of a radionuclide in edible parts Sec. 5.4.4 of vegetation

Concentration of a radionuclide in water Sec. 5.4.11 Rate of deposition from the atmosphere to the Ci-m"2-s Sec. 5.4.2 ground/soil

Rate of deposition of a radionuclide on soil due Sec. 5.4.11 to spray irrigation Dose conversion factor for external whole-body (rem*-a 'M/lCi-m'3) exposure in a semi-infinite cloud Table 4. 3 Dose conversion factor for external skin exposure in a semi-infinite cloud n DCF Dose conversion factor for external whole-body < g>b exposure due to standing on a smooth contaminated i plane surface Table 4. 4

(DCF ) Dose conversion factor for external skin exposure (rem.a'M/lCi-m*2) g s due to standing on a smooth contaminated plane surface

DF Factor for radioactive decay in stored feed and dimensionless Sec. 5.4.5, i vegetables = e~ r" h where X = radioactive decay 5.4.6 constant (d"1) and t. = timer delay between harvest Table 5.7 and ingestion (assumed=90d) DF Factor for radioactive decay in milk = e r f dimensionless Sec. 5.4.5 z where X = radioactive decay constant (d~M and Table 5.7 t_ = transport time between cow ingestion and milk consumption (assumed=2d)

* 1 rem = 0.01 Sv Description Units Ref.

DR Effective dose equivalent rate received by rem/a Sec. 5.3 an individual exposed to internal or external radiation Dose rate for external whole-body exposure rem/a Sec. 5.4.7 Dose rate for external skin exposure rem/a DRs DRL The upper limit for the release rate of a Ci/s Averaged Over Sec. 1 single radionuclide from a single source One Week (Airborne which is derived from the regulatory dose- Effluents) or One equivalent limits by analytical models of Month (Liquid all significant environmental pathways to Effluents) an individual in the most heavily exposed group (i.e., the "critical group").

Average energy per disintegration of a MeV Sec. 5.4.7 n radionuclide i

Eb Effective energy of noble-gas radionuclide MeV for whole-body dose calculation Sec. 5.4.7 Table 5.9 Effective energy of noble-gas radionuclide MeV for skin dose calculation Fraction of year that garden is irrigated dimensionless Sec. 5.4.11 Sec. 5.4.5 M Average fraction of the cow's daily intake Ci/L per Ci/d of a radionuclide which appears in each litre of milk The fraction of a particulate radionuclide dimensionless Table 4.2 reaching body fluids after entry into the gut Average spray irrigation rate during the L-m"2-d-1 Sec. 5.4.11 growing season IR Human ingestion rate of above-ground kg/a Sec. 5.4.6 av vegetables and fruit Table 5.8 Description Units Ref.

Human ingestion rate of fish kg/a Human ingestion rate of leafy vegetables kg/a IRlv IR Human ingestion rate of milk L/a Sec. 5.4.6 m Table 5.8 Human ingestion rate of root vegetables kg/a IRrv Human ingestion rate of water IRw L/a K Atmospheric dispersion coefficient s/m3 Sec. 5.4.1 OP Occupancy by humans of contaminated atmosphere dimensionless Sec. 5.4.6 (outdoors or indoors), fraction of time at Table 5.2 location n i OP Occupancy by humans of contaminated ground dimensionless 2 outdoors, fraction of year Sec. 5.4.8 Table 5.2 OF Occupancy by humans of buildings on conta- dimensionless 3 minated ground, fraction of year Occupancy by humans of contaminated atmosphere dimensionless OP outdoors, fraction of year Sec. 5.4.7 Table 5.2 Occupancy by humans of buildings in conta- dimensionless OF minated atmosphere, fraction of year 5 P Effective "surface density" of soil kg(dry soil)/m2 Sec. 5.4.4

P Transfer parameter from airborne source s/m3 Sec. 5.4.1 0 I 1 to atmosphere Table 5.3 p Transfer parameter from liquid-effluent source s/L Sec. 5.4.9 0 I 2 to Ottawa River Sv Description Units Ref.

P Transfer parameter from atmosphere to ground/ m Sec. 5.4.2 soil Table 5.4

Transfer parameter from atmosphere to pasture m'/kg Sec. 5.4.3 grass Table 5.5

Transfer parameter from atmosphere to leafy m3/kg Sec. 5.4.3 1' 6 vegetables Table 5.5 Transfer parameter from atmosphere to lungs m'/a Sec. 5.4.6 I r 9 Transfer parameter from atmosphere to external (rem-a~1)/(Ci-m"3) 1/12 skin exposure Sec. 5.4.7 Transfer parameter from atmosphere to external (rem-a~I)/(Ci*m"'3) lr lit whole-body exposure n i Transfer parameter from Ottawa River to soil via L/m2 Sec. 5.4.11 spray irrigation Table 5.11

Transfer parameter from Ottawa River to fish Ci/kg per Ci/L Sec. 5.4.10 (flesh) Table 5.10 Transfer parameter from water to human gut L/a Sec. 5.4.6 Transfer parameter from soil to pasture grass mz/kg Sec. 5.4.4 Transfer parameter from soil to root vegetables mVkg Table 5.6 3/ S Transfer parameter from soil to leafy vegetables rnVkg 3 r 6 Transfer parameter from ground to external skin (rem-a"1)/(Ci-m~2) exposure Sec. 5.4.8 Transfer parameter from ground to external whole- (rem.a"')/(Ci-m'2) body exposure Description Units Ref.

Transfer parameter from pasture grass to milk kg/L Sec. 5.4.5 Table 5.7 Transfer parameter from root vegetables to kg/a 51 1 0 human gut Transfer parameter from leafy vegetables to kg/a human gut Sec. 5.4.6

Transfer parameter from fish to human gut kg/a Transfer parameter from milk to human gut L/a 8 I 1 0 Maximum permissible release rate for a radio- Ci/s Sec. 5.1, 6.1 nuclide in a single pathway from a single source to a single exposed group n Actual release rate of a radionuclide in an Ci/s Sec. 5.3 airborne or liquid effluent i

Cow's daily feed (wet weight) of pasture grass kg/d Sec. 5.4.5 Maximum permissible release rate for a radio- Ci/s Sec. 5.1, 6.2 nuclide from a single source to a single exposed group considering all pathways

Fraction of airborne radioactivity deposited dimensionless and retained on pasture grass Sec. 5.4.3 r' Fraction of airborne radioactivity deposited dimensionless and retained on leafy vegetables r" Fraction of radioactivity in irrigation spray dimensionless Sec. 5.4.12 deposited and retained on leafy vegetables

SF Shielding factor for occupancy inside buildings dimensionless Sec. 5.4.8 on contaminated ground Table 5.2 Symbol Description Units Ref. SF Shielding factor for occupancy inside buildings dimensionless Sec. 5.4.7 in contaminated atmosphere Table 5.2

SF Dose reduction factor to account for ground dimensionless Sec. 5.4.8 roughness and some shielding by snow in winter Table 5.2 Period of time over which release from source d Sec. 6.4 may be averaged to comply with derived release limit (DKL) Period of buildup of a radionuclide on the Sec. 5.4.2 ground/soil Period in vhich pasture grass is exposed to radionuclj.de deposition during the growing season Sec. 5.4.3 o tr Period in which leafy vegetables are exposed to radionuclide deposition during the growing season Transport time between ingestion by cow of pasture grass and consumption by humans of milk Table 5.2 Time delay between harvest (of pasture grass or vegetables) and ingestion UF Usage by cow of contaminated pasture grass, dimensionless fraction of year Sec. 5.4.5 Table 5.2 UF Usage by cow of contaminated stored feed, dimensionless fraction of year UF Usage by humans of contaminated milk, dimensionless Sec. 5.4.6 fraction of year Table 5.2 Symbol Description Units Ref.

UF Usage by humans of contaminated drinking water, dimensionless * fraction of year UF Usage by humans of contaminated fish, fraction dimensionless 5 of year UF Usage by humans of contaminated fresh root and dimensionless Sec. 5 4 6 6 other vegetables, fraction of year Table > UF Usage by humans of contaminated stored root and dimensionless 7 other vegetables, fraction of year UF Usage by humans of contaminated leafy vegetables, dimensionless _ 8 fraction of year V Velocity of deposition of an airborne radio- m/s Sec. 5.4.2 ^ nuclide on the ground/soil Y Agricultural yield (wet weight) of pasture grass kg/m2 > Sec. 5.4.3 O 2 Y' Agricultural yield (wet weight) of leafy kg/m 1 vegetables oo X Effective removal rate constant for a radio- d" Sec. 5 .4.3 e nuclide from pasture grass or leafy vegetables Table 5.5 X Radioactive decay constant d'1 Sec. 5 .4.2 Table 5.7, 5.11 0.693 Half-Life

Xw Removal rate constant for physical loss of a d" Sec. 5.4.3 radionuclide from pasture grass or leafy vegetables by weathering 1 to 5 Exposed groups are symbolized by a numeral as Sec. 5.2 follows: 1 - adults on site 2 - infants at the upriver boundary 3 - adults at the upriver boundary 4 - infants in Petawawa 5 - adults in Petawawa ISSN 0067 - 0367 ISSN 0067 - 0367

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