Generic and adaptive probabilistic safety assessment models: Precursor analysis and multi-purpose utilization

TL;DR

This paper presents lightweight, adaptable probabilistic safety assessment models for nuclear reactors that incorporate comprehensive factors and uncertainties, enabling risk comparison and precursor analysis without detailed plant-specific PSAs.

Contribution

The authors develop generic, transparent PSA models for nuclear reactors that are easily adaptable, incorporate diverse factors, and support large-scale precursor analysis and inter-plant risk comparison.

Findings

Models show good agreement with detailed PSAs in literature

Effective for initial risk screening and precursor analysis

Facilitate inter-plant risk comparisons

Abstract

Motivated by learning from experience and exploiting existing knowledge in civil nuclear operations, we have developed in-house generic PSA models for pressurized and boiling water reactors. The models are computationally light, handy, transparent, user-friendly, and easily adaptable to account for major plant-specific differences. They cover the common internal initiating events, frontline and support systems reliability and dependencies, human-factors, common-cause failures, and account for new factors typically overlooked in many developed PSAs. For quantification, the models use generic US reliability data, precursor analysis reports and studies, the ETHZ Curated Nuclear Events Database, and experts' opinions. Moreover, uncertainties in the most influential basic events are addressed. The generated results show good agreement with assessments available in the literature with detailed PSAs. We envision the models as an unbiased framework to measure nuclear operational risk with the same "ruler", and hence support inter-plant risk comparisons that are usually not possible due to differences in plant-specific PSA assumptions and scopes. The models can be used for initial risk screening, order-of-magnitude precursor analysis, and other research and pedagogic applications especially when no plant-specific PSAs are available. Finally, we are using the generic models for large-scale precursor analysis that will generate big picture trends, lessons, and insights.