Probabilistic Safety Analysis in Risk Informed and Performance Based Safety Management

Abstract

The integration of Probabilistic Safety Analysis (PSA) in Risk-Informed and Performance-Based Safety Management marks a significant advancement in nuclear safety. PSA is crucial for supplementing deterministic safety designs, ensuring the reliability of vital safety functions. It balances design features from a safety standpoint and identifies areas needing reinforcement. A comprehensive plant-specific PSA, encompassing both Level 1 and Level 2, covers internal initiating events and external hazards such as fires, floods, extreme weather, and seismic events in various operational modes. Plant staff are encouraged to conduct much of the PSA internally for effective decision-making. Regulatory guidelines mandate specific quality standards for PSA, requiring advanced methods including human factor analysis, thermal hydraulic analyses, and detailed uncertainty and sensitivity analyses. Acceptance criteria set by regulatory bodies, like total core damage frequency and conditional containment failure probability, form part of this analysis. The recommended risk-informed and performance-based regulatory enhancements aim to focus on significant activities, set risk-based performance evaluation criteria, develop measurable parameters for system and licensee performance monitoring, and prioritize results in regulatory decision-making. This approach not only aligns the objectives of licensees and regulators towards common safety performance indicators but also addresses stagnation in nuclear technology development and improves safety records by promoting licensee initiatives. It clearly assigns the responsibility for safety to the plant’s owner and operator, with regulatory bodies overseeing safety objectives implementation and performance monitoring. This shift in safety management underscores the vital role of PSA in contemporary nuclear safety practices, ensuring a balanced, thorough, and responsible approach to nuclear safety.