RESEARCH ON RISK-INFORMED CATEGORIZATION OF STRUCTURES, SYSTEMS AND COMPONENTS FOR NUCLEAR POWER PLANTS

抄録

The constructed Nuclear Power Plants in China have mainly adopted Deterministic analysis to implement categorization of structure, system and components. However, considering the balance of economy and safety, there are some inappropriate in the existing categorization of structures, systems and components. With the development of Probability Safety Assessment (PSA) and the application of Risk-Informed technology, a comprehensive approach which combines deterministic and probabilistic analysis and criteria has been proposed. According to 10.CFR 50.69 and RG 1.201, which are from the perspective of Probabilistic analysis, this paper categorizes systems and components into Safety Significant and Low Safety Significant by their safety degrees. Integrated with traditional deterministic categories, it has formed four different safety-classes which are RISC-1, RISC-2, RISC-3 and RISC-4 respectively. As for those RISC-3 components, the risk-informed categorization process determines that they are not significant contributors to plant safety. Therefore, special treatment requirements are removed for RISC-3 components and replaced with high-level requirements, to reduce unnecessary regulatory burden and budget cost and to improve economics of plants. In this paper, for instance, we will choose two typical systems of Fuqing NPP in China to implement the risk-informed categorization. And finally, conclusions can be drawn and optimization of existing categorization can be got.