A Conceptual Validation Framework for Probabilistic Safety Assessment - presentation title (Demands to Extend Validation Elements for Probabilistic Risk Assessment)

Probabilistic Safety Assessment (PSA) emerged in the 1980s, as a complementing technique for the safety assessment of nuclear power plants (NPPs). In the late 1990s, the USNRC approved PSA as a technology complementary to Deterministic Safety Assessment (DSA) and proposed a series of regulatory guides for its adoption in practice, such as RG. 1.174. These guides provide a risk-informed framework for the combined use of PSA and DSA. However, PSA suffers from non-definite justification of its quantitative outcomes, because of the uncertainties involved and the lack of a solid framework of qualification. The present study seeks to define a framework for PSA validation and a procedure for qualification based on four elements: Initiating Event Validation (IV), Sequence Validation (SV), Consequence Validation (CV), and Probabilistic Process Validation (PV). The requirements for the development and the expectations for each validation element are provided.