Complementary safety indicators (endpoint) for the best analysis of the radiological impacts during the safety assessment to radioactive waste disposal facilities

The paper shows the implementation of the concentrations and fluxes of naturally occurring radioactive materials (NORM) as new safety indicators on risk assessment (safety assessment) to radioactive waste environmental management. These obtained endpoint, allow the best analysis of the radiological impact associated to radioactive waste isolation system. The common safety indicators for safety assessment purpose, dose and risk, are very time dependent, increasing the uncertainties in the results for long term assessment. The complementary and new proposed endpoints are more stable and they are not affected by changes in the critical group, pathways, etc. Therefore, it could be the basis to enhance the safety assessment results. The NORM values on facility site were obtained as result of national surveys, the natural concentrations of U, Ra, Th, K has been associated with the variation of the lithologies in 3 geographical areas of the Country (Occidental, Central and Oriental). The results obtained are related with the safety assessment topics and allowed to apply the new complementary safety indicators, by comparisons between the natural concentrations and fluxes on site and its calculated values for the conceptual repository design. In order to normalize the concentration results, the analysis was realized adopting the criteria of the Repository Equivalent Rock Volume (RERV). The preliminary comparison showed that the calculated concentrations and fluxes in the Cuban conceptual radioactive waste repository are not higher than the natural values in the host rock. According to the application of new safety indicators, the reference disposal facility does not increase the natural activity concentration and fluxes in the environment. In order to implement these new safety indicator it has been used the current 226Ra inventory of the Repository and the 226Ra as natural concentration on the site. In Cuba, it is the first application of other safety indicators for safety assessment of radioactive waste disposal facilities, evidencing that those endpoints are very useful tool to support all study about the risk and safety analysis of the radioactive waste disposal System. (author)