BE0100020

THEO ZEEVAERT, HANS VANMARCKE AND JOHAN PARIDAENS

RADIOLOGICAL ASSESSMENTS AND ENHANCED NATURAL RADIOACTIVITY

Scientific staff Background ical impact assessments for radioactive waste dispos- SAM GEUENS, al. In the second theme we are leading the working The observance of the basic principles of radiation DIRK MALLANTS, group on remediation assessment with a test scenario protection (justification, optimisation and limitation JAN RONSYN, about the site of Olen, around the Bankloop brook. of individual dose) requires that the radiological LIEVE SWEECK, doses from practices or dose savings from counter- JOHAN PARIDAENS, We perform radiological impact assessment and opti- measures be assessed. The group is addressing radi- HANS VANMARCKE, misation studies in the frame of restoration of ological optimisation in important issues such as GEERT VOLCKAERT, radioactively contaminated sites and land disposal of radioactive waste disposal and remediation of THEO ZEEVAERT radioactive waste, as a support to the competent radioactively contaminated environments. authorities and other clients. On behalf of Union Supporting staff An important aspect in the growing concern amongst Miniere, we carry out a comprehensive impact RENE BUBBE, the population about the quality of their living envi- assessment study with respect to the radium storage JEAN-PIERRE ALZETTA, ronment is the occurrence of enhanced levels of nat- facility at the Olen plant of UM, with the support of PAUL WHXEBORTS ural radioactive isotopes such as radium. Mapping the department of Waste and Disposal. On behalf of such contamination, evaluating the seriousness and EdF (contract from ANTEA), we assessed the radio- 22 proposing possible and feasible solutions is becom- logical impact of envisaged liquid Na discharges ing an important aspect of health physics measure- into the Rhone at Creys-Malville, in consequence of ments. the dismantling of the Superphenix reactor. A PhD thesis is going on, aiming at the development Objectives of a transport model for small rivers of the Nete- to elaborate and improve methods and guidelines basin, contaminated with NORM (naturally occur- 226 for the evaluation of restoration options for ring radioactive material), in particular Ra. radioactively contaminated sites; Support is also provided to the R&D project on envi- B to develop, test and improve biosphere models for ronmental restoration (4 year programme) co-ordi- the performance assessment of radioactive waste nated by the section of radioecology. The contribu- disposal in near-surface or deep geological repos- tion consists in an adaptation of the dynamic bios- itories; phere model (DOSDIM) and the development of a S to assess the impact of releases from nuclear or vegetation model. industrial installations; 2 to apply new techniques for retrospective radon measurements in real field conditions and to Enhanced natural radioactivity assess radon decay product exposure by combin- ing these techniques; The database of retrospective radon data, collected in 3 to increase our capabilities in mapping and sur- various villages of Yugoslavia, will be further veying sites possibly or likely contaminated with analysed. The final aim is to obtain a valid image of enhanced levels of natural radiation. the radon exposures of these populations. A new sampling campaign is foreseen in Russia, as a sup- port for epidemiological studies. The expected radon Programme 3 concentrations here are between 100 and 200 Bq/m . Radiological assessments The radiological impact of the installation of a flue In the field of radiological impact assessment our gas purification system of a coal-fired power station department is in charge of optimising models for was partially studied for Electrabel. The programme evaluating biospheric concentrations and doses to foresees in the completion of this study as soon as the humans. To keep in touch with the international flue gas scrubbing system is fully operational. developments in that field and to upgrade our assess- ment models, we participate in the IAEA programme We conducted two measuring campaigns, for the BIOMASS (Biosphere Modelling and ASSessment VLM (Vlaamse Landmaatschappij) to accurately methods). The three themes in BIOMASS are map the 226Ra contamination of the farmland in the radioactive waste disposal, environmental releases whole of the former flooding zone of the Bankloop, and biosphere processes. In the first and in the third as a result of the historic Union Miniere activities. theme we are participating on behalf of The programme foresees a follow up of the situation ONDRAF/NIRAS in the framework of our radiolog- here.

124 Radiation Protection Achievements dose Ra mSv/y) Radiological assessments 1.00E+02

International validation studies - BIOMASS l.OOE+01 In BIOMASS Theme 1, Radioactive waste disposal, we participate in three task groups: 1.00E+00 si TGI, dealing with guidance on the definition of I exposed groups; 1,00 E-01 I 1 B TG2, providing guidance on the application of data to assessment models; a TG6, dealing with the elaboration of models for CLRP - CLRP - Olenrad B - Olenrad B - Veszp DOSDIM - DOSDIM- RESRAD, indoors outdoors indoors outdoors indu ors outdoors indoors outdoors Yu - in & example reference biospheres. The emphasis in outdoors this task group during the last year, has been on (Ra&Pb) changes in the biosphere with time. In a first We compared various models for the calculation of the indoor and outdoor Radon approach a generic description of biosphere inhalation dose of the radium-contaminated farmland without remediation at year 1. changes is considered. The changes may be due The graph shows that results were comparable, but 95% confidence intervals were to volcanism, seismic events, meteorite impact, large. orogeny, climate change (from a natural origin or man-induced), social/institutional developments. In BIOMASS Theme 3, Biosphere processes, we In a second approach the methodology is applied participate in the working group on iiuit modelling. to real example sites, namely Aspo in Sweden and In this working group testing scenarios were set up Harwell in England. The changes in these cases concerning the contamination of soil, fruit and leaves are considered to be due essentially to climate of strawberries, apples and black currents due to changes. releases of 137Cs, 90Sr, ml. Two typus of scenarios were applied: hypothetical and real cnes. The hypo- In BIOMASS Theme 2, Environmental releases, the thetical scenarios, including continuous and spike working group on remediation assessment, of which releases, permitted the models and modelling results SCK»CEN is group leader, has achieved the task rel- only to be compared. The real ones, based on pot ative to the second approach which is related to the experiments with strawberries, contaminated assessment of the effectiveness of potential remedial through soil and foliar deposition, allowed for the actions (removal of contaminated soil and capping) accuracy of the model predictions to be verified. The at the Bankloop riverine site. Deterministic and prob- comparison of the modelling results among them- abilistic model calculations have been carried out, selves and with the experimental results, showed a including uncertainty and sensitivity analyses. With good performance of the SCK'CEN model (DOS- respect to the probabilistic assessments, 95% confi- DIM). dence intervals have been calculated and most influ- ential parameters identified. The figure shows the results of five participating models (among which the Modelling of the transport of radium in small SCK-CEN model DOSDIM) for the exposure path- rivers way radon inhalation before remediation. The reduc- tion of the dose through the remediation measures The PhD thesis concerning the modelling of the fate considered were shown to be rather restricted. The and transport of NORM, in particular radium, in 95% confidence intervals ranged from less than 1 small rivers, started in September 1999. Most of the order of magnitude up to two orders of magnitude. year 2000 has been devoted to the preparation of The parameters related to this exposure pathway measuring campaigns at the river and the examina- were shown to be the most influential ones for the tion of possibly relevant surface water models. total dose. The results of the model calculations have Laboratory experiments for the investigation of sorp- been compared and the reasons for differences tion phenomena of radium on river sediments were analysed. A first draft of a TECDOC (IAEA) report carried out by a student on work placement. concerning the work of this working group has been elaborated. In the beginning of following year it has to be finalised.

Radiation Protection 125 Radiological impact assessment for industrial Enhanced natural radioactivity clients A first analysis of the retrospective database from The impact assessment study of the radium storage several rural Yugoslavian villages, containing com- facility of Union Miniere in Olen, ordered by UM, is bined radon volume trap and surface trap retrospec- being carried out. Various evolution scenarios, iden- tive radon data, together with contemporary radon tified in a preceding scenario study, are being con- data has shown some interesting results. It appears sidered, including the normal as well as altered evo- that often radon concentrations in the same house lution scenarios. We executed a first part of the study, may vary a lot between different rooms. This should consisting in the examination and measuring of the be taken into account for radon exposure assess- physical and chemical data of the site, the waste and ments. Another striking fact was that contemporary the technical barriers and the calculation of the leach- radon concentrations, even if they are based on 12 ing and transport of the contaminants from the stor- month measuring campaigns, are often not represen- age facility to the groundwater. We prepared also the tative for the long-term radon concentrations. This is formulation of the concentrations of the radionu- demonstrated in the figure. Extrapolating contempo- clides in the biosphere media and the resulting annu- rary radon concentrations to assess long-term radon al individual doses to the critical group for the vari- exposures is therefore to be considered a question- ous scenarios. For the modelling of the groundwater able practice. transport of the contaminants (by the Department of Waste and Disposal) and the assessment of the doses, For Electrabel, we performed a radiological impact we have to wait for the results of the modelling of the assessment of a coal-fired power. The plant had been groundwater flow (to be carried out by Prof. Van equipped with a flue gas purification system, desul-

Autenboer, LUC). phurisation (SOX) and denitrification (NOX), the so- called DENOX and DESOX installations. Only the The contract obtained from EdF (co-ordinator DESOX installation worked properly at the time of ANTEA) for a radiological impact assessment of liq- the study, so only the effects of this one could be uid 22Na discharges into the Rhone at Creys Malville, studied so far. We made a radiological mass balance, in consequence of the dismantling of the considering incoming products (coal, limestone) and Superphenix reactor, has been carried out. Because the outgoing products such as fly ash, bottom ash and of the low radioactive half-life of 22Na (2.6 a) and the gypsum. The naturally occurring radioactive materi- delayed discharge of the most contaminated efflu- als concentrate in the fly ash and bottom ash, as ents, the annual individual doses to the critical group could be expected, but due to the low radioactivity turned out to be negligible (much less than 1 mSv/y). contents of the utilised coal, this does not pose any problems from a radiation protection point of view. The gypsum produced during the wet scrubbing pro- cedure with lime in the DESOX installation showed . 10.00 - no increased NORM concentrations and is in this 5 f 5.2 a ; i : 36 J : ; ; ;i respect comparable to natural gypsum.

For the VLM (Vlaamse Landmaatschappij), we tcmpo t 1 measured the 226Ra contamination of the whole of the 1.00 4. area of farmland in the former flooding zones of the •'0.85 ; ..•_•.• .::::: Bankloop. About 45 hectares of land were investi- r o / co n 0.41 ; gated, the most contaminated 25 ha of which is now 9 : ilVT/CONTl • available in grid points indicating the surface gamma ; I:.'. ST / CONT I ; dose rates every 10 m. The figure shows these 25 ha oi 0.10 - of land. We found that about 16 ha had to be cata- 123456789 10 11 12 13 14 logued as radioactively contaminated of which about Uzice house number 1 ha quite heavily. For these contaminated areas, another type of land use was suggested.

Ratio of the long-term retro radon concentrations to the contemporary (CONT) ones, for volume traps (VT) and surface traps (ST) respectively, from the Perspectives Yugoslavian village Uzice. The dashed lines delimit the area where the deviation between retro and contemporary is less than 100 %. Less than half of the cases fall Next to the execution of the present impact assess- within these limits, urging for caution in extrapolating contemporary radon data for retrospective purposes. ment study on behalf of Union Miniere, a new study

126 Radiation Protection Kleine Nete

-500 -400 -300 -200 -100 100 200 300 Distance (m)

50 100 150 200 300 400 500 1000 1500 nSv/h

Overview of the most contaminated areas of the former flooding zone of the Bankloop, receiving the liquid effluents of the Olen radium facility. About 16 hectares of land had to be catalogued as radioactively contami- nated (>100 nSv/h), of which about 1 ha quite heavily (>500 nSv/h). For certain areas a change of land use was recommended. concerning the elimination of the radium sources from the storage facility has been asked for by UM Mouchel & Partners Ltd. and will be carried out in the year 2001, with support (Weybridge, United Kingdom) of the department of Waste and Disposal. Risoe National Laboratories (Roskilde, Denmark) SCK'CEN took part in two project proposals for the Studsvik EcoSafe (Nykoping, 2nd call for key actions in the 5th Framework pro- Sweden) gramme of the European Commission. The first proj- ect is called BIOMOSA: Biosphere Models for the University College of Dublin Safety Assessment of radioactive waste disposal (Dublin, Ireland) based on the application of the Reference Biosphere University of Lund (Lund, methodology. The intention is to apply the Reference Sweden) Biosphere methodology, developed in the BIO- University of Veszprem MASS programme of the IAEA, to several actual (Veszprem, Hungfry) sites in Europe, belonging to different climatic regions, and to contribute in this way to the confi- inca Institute of Nuclear Sciences dence building in biosphere models for application in (Belgrade, Yugoslavia) performance assessment of nuclear waste disposal. Westlakes Research Ltd. The second project is called HELIMENT: Health and (Cumbria, United Kingdom) Social Impacts from contamination of aquatic and terrestrial environments. The purpose is to develop a ANL Argonne National Laboratory methodology to assess the health and social impacts (Argonne, USA) and risks to populations and environments being CIEMAT Centra de Investigaciones exposed to radioactive as well as non-radioactive Energetical, Medioambientales y contaminants. Technologicas (Madrid, Spain)

Radiation Protection 127 CLRP Central Laboratory for VLM Vlaamse Landmaatschappij Radiological Protection (Warsow, (Brussels, Belgium) Poland). VMM Vlaamse Milieumaatschappij ENRESA Empresa Nacional de Residuos (Erembodegem, Belgium) Radioactivos SA (Madrid, Spain) EPRI Electric Power Research Institute (Palo Alto, USA) Publications FZR Forschungszentrum Rossendorf J. Paridaens, H. Vanmarcke, K. Jacobs, Z. Zunic, (Dresden, Germany) "Retrospective Radon Assessment by means of 210Po GSF Gesellschaft fur Strahlen- und Activity Measurements", Applied Radiation and Isotopes, Umwelforschung (Neuherberg, Vol. 53, Issue 1-2, pp. 361-364, 2000. Germany) IPSN Institut de Protection et de Surete Presentations Nucleaire (Fontenay-aux-Roses, France) T. Zeevaert, A. Bousher, V. Brendler, P. Hedemann Jensen, S. Nordlinder, "Restoration strategies for radioactively NRI Nuclear Research Institute (Rez, contaminated sites and their close surroundings", IRPA-10, Czech) 10'" International Congress of The International Radiation NRPA Norwegian Radiation Protection Protection Association, Hiroshima, Japan, May 14-19, Authority (0steras, Norway) 2000. NRPB National Radiological Protection T. Zeevaert, A. Bousher, V. Brendler, P. Hedemann Jensen, Board (Didcot, United Kingdom) S. Nordlinder, "A ranking methodology of restoration PSI Paul Sherrer Institute (Villingen, strategies for radioactively contaminated sites", Switserland) International Conference on "Radiation legacy of the 20* century: Environmental restoration", Moscow, Russian RUG University of Ghent (Ghent, Federation, October 30 - November 2, 2000. Belgium) T. Zeevaert, "Radiologische impact van een bergingssite SENES Senes Oak Ridge Inc. (Oak Ridge, voor laagactief afval", Presentation for: "STOLA - USA) Werkgroep Milieu en Gezondheid", Dessel, June 28, 2000. SPA Typhoon Scientific Production Association H. Vanmarcke, J. Paridaens, "Radium Contamination Of Typhoon (Obnisk, Russia). The Banks Of A Small River Receiving The Liquid SSI Swedish Radiation Protection Effluents Of A Large Phosphate Plant", IRPA-10, Institute (Stockholm, Sweden) Hiroshima, Japan, P4a-225, May 14-19, 2000. VTT Technical Research Centre of J. Paridaens, H. Vanmarcke, "Correlation between radon Finland (Espoo, Finland) exposure and 210Po in surface and volume traps in dwellings : a field study in stable rural communities in Yugoslavia", 5th Int. Conf. on High Levels of Natural Radiation and Radon areas, Munich, Germany, September ANTEA (Orleans, France) 4-7, 2000. EC European Commission, Radiation J. Paridaens, H. Vanmarcke, "Environmental Radiological Protection Programme Impact of Phosphate ore Processing using Hydrochloric (Luxemburg, Grand duchy of acid for Acidulation", 5th Int. Conf. on High Levels of Luxemburg and Brussels, Natural Radiation and Radon areas, Munich, Germany, Belgium) September 4-7, 2000. Electrabel (Brussels, Belgium) H. Vanmarcke, J. Paridaens, "Contamination of the brook Gemeentebestuur Laakdal receiving the liquid effluents of the Olen radium facility ", (Laakdal, Belgium) 5th Int. Conf. on High Levels of Natural Radiation and ONDRAF/NIRAS Belgian Agency for Radioactive Radon areas, Munich, Germany, September 4-7, 2000. Waste and Enriched Fissile Z.S. Zunic, J.P. Me Laughlin, K. Fujimoto, Materials (Brussels, Belgium) I.V.Yarmoshenko, F.Trotti, J. Paridaens, H. Vanmarcke, A. UM Union Miniere (Olen, Belgium) Birovljev, C. Walsh, F. Bissolo, R. Falk, B. Jakupi, M.

128 Radiation Protection Demajo, S.E. Simopoulos, "Results of Field Work Studies on Natural Indoor Radiation Population Exposures in Yugoslavia", 3rd Int. Yugoslav Nuclear Society Conference (YUNSC-2000), Belgrade, Yugoslavia October 2-5, 2000.

Reports T. Zeevaert, L. Sweeck, "Biosfeer modellering in de per- formantie van een geologische afvalberging", SCK'CEN Report for NIRAS/ONDRAF, R-3437, SCK'CEN, Mol, Belgium, April 2000. E. Schulte, G. Desmet, J. Gutierrez, C. Vazquez, C. Salt, H. Vandenhove, G. Voigt, T. Zeevaert, Eds., "Euratom-Ciemat Association Contract on Techniques and Management Strategies for Environmental Restoration. Final Report", Ciemat Report, Madrid, March 2000. D. Mallants, A. Dierckx, L. Hardy, G. Volckaert, L. Wang, T. Zeevaert, "Impact assessment of uranium mill tailings for the Olen site. Pt.l: Safety data and migration study", SCK'CEN Report R-3478, November 2000. I. Paridaens, H. Vanmarcke, "Onderzoek naar de radiolo- gische impact van het installeren van een rookgas zuiver- ingsinstallatie op de Electrabel site te Langerlo", SCK-CEN Internal Report BLG-846, May 2000. J. Paridaens, H. Vanmarcke, "Gamma dosistempometing op een stuk landbouwgrond gelegen aan de Roerdompstraat ten westen van de huidige Bankloop", grondgebied Olen, SCK-CEN Internal Report R-3457, June 2000.

J. Paridaens, H. Vanmarcke, "Overzicht van de besmetting met 226Ra van de voormalige overstromingsgebieden van de Bankloop gelegen ten noorden van de Roerdompstraat en ten zuiden van de Kleine Nete", SCK'CEN Internal Report R-3475, November 2000. H. Vanmarcke, G. Eggermont, H. Mol, "Ioniserende stral- ing", hoofdstuk 4.6 van het boek "MIRA-S 2000 : Milieu- en natuurrapport Vlaanderen : scenario's", Vlaamse Milieumaatschappij, ISBN 90-441-1048-9, pp.293-307.

Radiation Protection 129