Full Scope SLP PSA Models

The first full-scope Shutdown PSA studies performed were French studies for 900 MW and 1300 MW series NPPs. The results of those studies were widely published and have shown that actual risk during shutdown is in the same order of magnitude as the risk during the full-power operation. The results of French studies prompted a broad interest in application of shutdown PSAs, primarily in Europe. 

Most of the studies completed to-date identified the areas of particular concerns like Mid-loop operation for PWRs or Cold Over-pressurisation for BWRs. Many of the SLP PSAs found that simple modifications like change in procedures or additional instrumentation could significantly reduce the risk during plant outage. Additionally, many studies highlighted the possibility for other cost effective solutions. 

The general objective of a SLP PSA is broadly similar to the power PSA. This includes a comprehensive overview of the plant risk (defined as a Core Damage Frequency if Level 1 is concerned). Additionally, the objective may include identification of design and operational weaknesses, propose modifications, evaluate Technical Specifications, etc. 

A detailed discussion of the methods and approaches used in SLP PSA is presented in Chapter 3 of this document. 

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