A comparative radiological assessment of five European biosphere systems in the context ofpotential contamination of well water from the hypothetical disposal of radioactivewaste

Abstract

In the framework of the BioMoSA project for the development of biosphere assessmentmodels for radioactive waste disposal the Reference Biosphere Methodology developedin the IAEA programme BIOMASS was applied to five locations, situated indifferent European countries. Specific biosphere models were applied to assess thehypothetical contamination of a range of agricultural and environmental pathways andthe dose to individuals, following contamination of well water. The results ofthese site-specific models developed by the different BioMoSA partners, and theindividual normalised dose to the exposure groups were compared against each other.Ingestion of drinking water, fruit and vegetables were found to be among the mostimportant pathways for almost all radionuclides. Stochastic calculations revealed thatconsumption habits, transfer factors, irrigation rates and distribution coefficients(Kds) were the most important parameters that influence the end results. Variationsin the confidence intervals were found to be higher for sorbing elements(e.g. 36Cl, 237Np,99Tc,238U,129I) than for mobileelements (e.g. 226Ra, 79Se, 135Cs, 231Pa, 239Pu). The influence of daughter products, for which the distribution into the biospherewas calculated individually, was also shown to be important. This paper givesa brief overview of the deterministic and stochastic modelling results and theparameter sensitivity. A screening methodology was introduced to identify the mostimportant pathways, simplify a generic biosphere tool and refine the existing models.