Identification of Significant Scenarios for Accident Management Based on PSA Studies of PHWR

Indian regulatory requirement (AERB Safety Guide, AERB/NPP-WCR/SG/D-26, 2020 Accident Management Programmes for Nuclear Power Plants) calls for event/accident scenarios shall be comprehensive while developing Accident Management Guidelines (AMG) document. Probabilistic Safety Assessment (PSA) provides insights into significant accident sequences which are identified to contribute to the core damage frequency, threat to the containment and release of radioactivity to the public. These accident sequences could arise from internal or external events, multiple failure of systems or components and human errors etc. From the cluster of events, the accident sequences which eminently contribute to the core damage frequencies are identified as the accident sequences which needs to be analyzed in detail for developing accident management guidelines. The purpose of present paper is to identify the dominant accident sequences for developing AMG. This is based on inputs from PSA and plant vulnerabilities that needs to be addressed by providing necessary accident management provisions and related operator actions.