25 Application of CENS Concept for International Peer Review to Probabilistic Safety Assessment (Level 1) of Swiss Gösgen Nuclear Power Plant (PSAM-0248)
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Published:2006
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This paper deals with the new concept for peer reviews developed by Centre for Nuclear Safety (CENS) - Concept for International Peer Review for PSA Level 1, the independent systematic examination and assessment of the quality of the PSA-study and performed Peer review of Swiss Gösgen Nuclear Power Plant PSA Level 1.
The analysis of overall scope, methodology, results, findings, of Gösgen NPP's and recommendations for the Gösgen NPP future development in the area of plant-specific PSA are summarized in the paper.
CENS employed a team of PSA and system analysts to provide an objective review of the Gösgen PSA (GPSA). This assessment included reviews to determine the technical adequacy of the GPSA analysis methods, the maintenance and update processes to ensure that the PSA continues to reflect the as-built, as-operated Gösgen plant configuration for analyzed plant operating states, and applications using generally accepted industry PSA practices. The PSA Peer Review provided both an objective review of the PSA technical elements and a subjective assessment, based on experts' PSA experience, regarding the acceptability of the PSA technical elements. The PSA Peer Review Team consisted of experts from Belgium, Germany, Russia , Switzerland and USA in the areas of accident sequence analysis, systems analysis, human reliability analysis, external events analysis (seismic, fire). The team used a set of review criteria and guidelines as a framework within which to evaluate the scope, comprehensiveness, completeness, and fidelity of the PSA products available.
There were three main objectives for the assessment of the level of safety of the plant:
1. Identification of important risk contributors and the most effective areas for improvement;
2. Comparison of the PSA results with explicit or implicit international standards; and
3. Assisting plant management and operation by determining the risk significance of plant components, configurations, and operator actions.
The Gösgen PSA review was primarily directed to determine the degree or extent to which the Gösgen PSA achieved the above objectives. Additionally, the peer review served to provide recommendations for focusing future PSA activities and to provide suggestions for enhancing the use of risk information at the Gösgen nuclear power plant.
The 2003 Gösgen PSA model (GPSA 2003) was the designator used for the current model reviewed by the peer review team. Planned or partial update results were considered, if appropriate, however, the results and conclusions were based on the current model.
The special interaction process between the review team and the plant project manager will be discussed, as well as recommendations for improvements based on experiences will be given in the paper.