Preliminary Calculations of Radionuclide Release From Near-Field to Biosphere Using Computer Code Goldsim

This paper presents preliminary calculations for the performance assessment of the hypothetical disposal facility for spent nuclear fuel in the Slovak Republic. In the concept of geological disposal, two host rock formations are under consideration: granite and clay. Slovakia is now in site selection phase therefore the lack of input data for calculations is compensated from the international reports [1, 2]. The calculations of radionuclide release were made for the spent nuclear fuel disposed in a hypothetical underground repository situated in clay host formation. One-dimensional mathematical model of the radionuclide release through the engineered and natural barrier system up to one million years was simulated using a flexible compartment model tool Goldsim. Both deterministic and probabilistic calculations have been applied. The input parameters for probabilistic calculations are selected from the probability density functions (PDF) using Monte Carlo method. Radionuclide release to the biosphere is considered via contaminated groundwater supply taken from a deep well. Three different exposure pathways were considered: consumption of the root vegetables, consumption of meat and drinking of water from well. The results of preliminary assessment of radiological consequences are expressed in terms of release rates on the aquifer-well interface together with the corresponding individual annual doses for average member of the critical group of adults living in the vicinity of the repository. The regulatory limits regarding the annual doses for the concept of geological disposal in Slovakia are under preparation.