Be0100020 Radiological Assessments and Enhanced
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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