Verification of Validity of Isotope-Specific Exemption Levels for Surface Contamination Using Monte Carlo Calculation

Current surface contamination density standards are conservatively determined not for each nuclide but by the type of emitter. In the previous studies, isotope-specific exemption levels for surface contamination for representative nuclides were originally derived by developing a deterministic dose assessment model that can be applied throughout radiation, transport and waste safety fields. In this study, the effects of uncertainty in assumed parameters on the derived exemption levels were examined by developing a probabilistic dose assessment model using the Monte Carlo calculation. The criteria for the judgment of validities of the derived exemption levels were decided applying the concept of the representative person given by the International Commission on Radiological Protection (ICRP), the set of minimum dose constraint for the optimization of the radiological protection of the public revealed in a recent study and the probabilistic dose assessment model developed by the Nuclear Safety Commission (NSC) of Japan. Moreover, the effects of correlation in parameters on the results of probabilistic dose assessment are probabilistically examined by developing the function of specifying the random seeds independently for each parameter in the Monte Carlo calculation. These results verify the validity of the deterministically derived isotopespecific exemption levels for surface contamination.