PREDICTION OF LONG-TERM NEGATIVE IMPACTS OF URANIUM PRODUCTION LEGACY SITES ON THE HYDROGEOLOGICAL ENVIRONMENT

Abstract

Using the IAEA ISAM (International Safety Assessment Methodology) methodology, information on the habits of the local population and statistical data on food consumption, dose coefficients for uranium-238 radionuclides were calculated for several scenarios of use of groundwater and surface water by the local population in the zone of influence of the uranium production legacy site - Prydniprovsky Chemical Plant, Kamianske City (PChP). These scenarios consider the following exposure pathways: drinking water consumption, crop irrigation, fishing and use of the river beach for recreation. Dose calculations were made with NORMALYSA software with use of mathematical models and radioecological parameters recommended by the IAEA. The dose coefficients obtained as a result of the modelling (which have the dimension of (Sv year)/(Bq m3)) allow calculating radiation doses by scaling them with actual radionuclide concentrations measured in groundwater and surface waters during monitoring or determined by modelling of of radionuclide transport processes in groundwater. The described approach to dose calculation can be applied for assessment of uranium legasy sites located in similar anthropogenic conditions. The described methodology was used to substantiate remediation measures that involve isolation of radioactively contaminated soils located at the PChP Northern Industrial Site using protective soil screens. According to the IAEA recommendations, an annual effective dose of 1 mSv/year was used as a radiological safety criterion for “existing exposure situations”. According to the results of predictive modelling, isolation and storage of contaminated soils within the PChP Northern Industrial Site does not pose unacceptable risks of radioactive contamination of groundwater.