Assessment approach for a safety margin of parameters on the high-level radioactive waste disposal

Ebashi, Takeshi; Koo, Shigeru*; Oi, Takao 

In order to demonstrate the robustness of the design of a high-level waste (HLW) disposal system, an important measure is to preliminarily set parameter values, which take into account safety margins for an acceptable dose. In evaluating the safety margin, it is necessary to estimate a range of parameters for an acceptable dose by a sensitivity analysis based on the appropriate conditions for each scenario. In this study, the comprehensive sensitivity analysis method was applied to performance assessment of a HLW disposal system. This paper presents the approach to assess a safety margin for parameters. As a result, safety margins for the parameters of the engineered barrier system (glass dissolution rate, overpack failure time, buffer thickness) were illustrated under conservative conditions of the natural barrier. Such an approach will provide useful information for scenario analysis and offer insights into the design and construction of a robust system for HLW disposal concept.