Generic Accident Progression Event Tree for Belgian Level 2 PSA

摘要

Within the framework of the Western European Nuclear Regulators Association (WENRA) reference levels and the periodic safety review process an updated level 2 PSA study is performed by Tractebel Engineering S.A. (GDF SUEZ) (TE) for the seven Belgian Nuclear Power plants (NPP), which are all of Pressurized Water Reactor type. Therefore a generic Accident Progression Event Tree (APET) is developed divided into two successive parts treating respectively the Containment Performance (CP-APET) and the source term or the release of fission products (FP-APET) for a representative range of severe accidents. The main improvements compared to previous level 2 PSA studies are the development of a generic APET instead of a specific one for each plant, including both power states and shutdown states in one APET and taking into account accident management actions, namely the Emergency Operating Procedures and the Severe Accident Management Guidelines. Additionally, the FP-APET consists of eight general user functions, which are modified volume-based XSOR-algorithms, each evaluating the amount and timing of the release of one of the radionuclides' classes from NUREG-1465, resulting in a schematic approach and an increased number of sequences evaluated during ST assessment.