Application of the Level-1 PSA Model in Various Regulatory Processes and Challenges Faced during their Execution

The Technical Support Organization (TSO) of Pakistan Nuclear Regulatory Authority (PNRA), has developed independent regulatory Level-1 PSA Models for 300MWe and 1100MWe PWR Nuclear Power Plants (NPP) to support the regulatory oversight process. PSA model development was carried out by the regulatory body as a tool for ensuring the safety of the nuclear power plants in relation to potential initiating events caused by random component failure and human errors. The PSA model for 300MWe NPP was developed under IAEA TC Project where IAEA experts provided support through periodic reviews and the PSA model for 1100MWe NPP was developed independently by PNRA. The PSA models provided many useful insights into plants' systems and components including independent assessment of the probabilities of occurrence of core damage states resulting from various initiating events and adequacy of plant emergency procedures. The Level-1 PSA models are being utilized at PNRA for various regulatory applications e.g. review and assessment of SARs (PSAR, FSAR), review of design modifications and technical specifications modifications, risk-informed inspection plans, PSA-based analysis of operational events, etc. In this paper, the applications of the regulator's Level-1 PSA models have been discussed. The challenges faced during the development of regulatory PSA models and implementation of PSA applications are described and potential future applications at PNRA are also highlighted. (author)