Development of Severe Accident Evaluation Technology (Level 2 PSA) for Sodium-cooled Fast Reactors (1) Overview of Evaluation Methodology Development

摘要

To consolidate the Probabilistic Safety Assessment (Level 2 PSA) for sodium-cooled fast reactors, the analytical methodologies in the core-material relocation phase and the ex-vessel accident sequence should be established. In addition, a technical basis for Level 2 PSA should also be built up to construct the phenomenological event trees and to determine the branch probabilities in them. In the present study, the analytical methodologies above have been developed with the aim of establishing a severe accident evaluation technology for sodium-cooled fast reactors, and the dominant factors in each phase have been identified through sensitivity analyses. The information obtained from these analyses will be effectively reflected on the technical basis which is indispensable for the construction of phenomenological event trees.