Condition-based probabilistic safety assessment for maintenance decision making regarding a nuclear power plant steam generator undergoing multiple degradation mechanisms

Seyed Mojtaba Hoseyni (1) , Francesco Di Maio (1) , Enrico Zio (2)

1 Dipartimento di Energia [Milano]
2 CRC - Centre de recherche sur les Risques et les Crises

Condition-Based Probabilistic Safety Assessment (CB-PSA) makes use of inspections and monitoring information on Systems, Structures, and Components (SSCs) to update risk quantities. In this paper, we show the benefits of exploiting the condition-based estimates for taking maintenance decisions on a SSC undergoing multiple degradation mechanisms. To develop the method, we make reference to a spontaneous Steam Generator Tube Rupture (SGTR) Accident Scenario in a Nuclear Power Plant (NPP). The SG is susceptible to multiple degradation mechanisms, i.e., Stress Corrosion Cracking (SCC) and pitting. Tube plugging and Water Lancing and Chemical Cleaning (WL-CC) can be performed, before leading to a SGTR accident. Decisions must be taken on the maintenance strategy to perform at each inspection cycle. Results of a case study regarding SGTR show that the decisions based on the risk estimates provided by a CB-PSA approach allow controlling the SGTR risk at minimum maintenance cost.

Mots clés: Probabilistic Safety Assessment (PSA); Condition-Based PSA (CB-PSA); Maintenance Nuclear Power Plant (NPP); Steam Generator (SG); SG Tube Rupture (SGTR); Pitting Stress Corrosion Cracking (SCC)

Domaines: Sciences de l'ingénieur [physics]; Gestion des risques et des crises

Seyed Mojtaba Hoseyni, Francesco Di Maio, Enrico Zio. Condition-based probabilistic safety assessment for maintenance decision making regarding a nuclear power plant steam generator undergoing multiple degradation mechanisms. Reliability Engineering and System Safety, 2019, 191, pp.106583. ⟨10.1016/j.ress.2019.106583⟩. ⟨hal-02432537⟩