An Establishment of a Calculation Framework For the Operational Safety Assessment of KRS -11267

ABSTRACT In this study, we established the methodology and a calculation framework for the safety assessment of a radioactive waste repository in South Korea. The most important factor in the construction and operation of a radioactive waste repository is to ensure safety and to protect the public and environment. The procedures required for safety assessment are an identification of initiating events, performance assessment of safety systems, an identification of accident scenarios, an exposure dose assessment for the workers and the public resulting from the release of radioactive material. In order to identify initiating events, we adopted a qualitative hazard identification method. We suggested a PSA (Probabilistic Safety Assessment) method to assess the performance of safety systems and to identify accident scenarios. We established methodologies for the exposure dose assessment by selecting exposure pathways and establishing methodologies for the estimation of exposure doses for each pathway. Then we established a SSAT (Systematic Safety Analysis Tool) for the operational safety assessment of the disposal facilities for radioactive waste. This systematic safety analysis tool will enable a safety analysis of a potential interim spent nuclear fuel storage facility. The systematic safety analysis tool provides an integrated framework that streamlines the propagation of design modifications and alternatives into the safety analysis. For the event tree and fault tree analysis in the systematic safety analysis tool, the AIMS-PSA (Advanced Information Management System for Probabilistic Safety Assessment) Manager and the submodules CONPAS (CONtainment Performance Analysis System) and KwTree (KIRAP window Tree) will be used. The RSAC (Radiological Safety Analysis Computer) program will be used in the estimation of exposure doses. We made sample calculation for the drop accident at the surface facilities of the KRS (Korean Reference disposal System) in order to check the applicability of the operational safety assessment framework. This paper focuses on the development of the event tree and fault tree analysis module and the identification of the applicability of the CONPAS and KwTree. The methodologies and the tool for the operational safety assessment of a radioactive waste repository established in this study will be used in the design modification as well as the safety assessment