Level-l PSA for KAPS-1&2 — An overview of plant specific improvements

Abstract

Plant Specific PSA study is the most potent tool to analyze Risk due to Nuclear Power Plant, considering design aspects, operating practices and past operating experience. It requires an optimal mixture of the critical approach of an analyst and the practical approach of an operator to develop a comprehensive and realistic Plant Specific PSA. KAPS Level-I PSA was the first comprehensive PSA carried out for Standard Indian PHWR. KAPS PSA Level-I is revised to make it Plant Specific, to include latest developments in PSA and to incorporate insights of past operating experience. This Paper covers various improvements aimed to develop a detailed and plant specific KAPS PSA Level-I study. Major improvements carried out includes: Consideration of all possible Initiating Events (IE) from operating experience and support system failures, Initiating Event frequency calculation using detailed Fault Tree method, Refinement of Consequence Categorization, Plant Specific component failure data and estimation of Reliability parameters Bayesian Updation of generic data with plant specific inputs, Improvements in Reliability Analyses of systems, Systematic Event Trees development with inclusion of detailed plant specific aspects, Analysis of Human Error Probability (HEP) for various latent and dynamic human error using Human Cognitive Resource (HCR) model after carrying out control room walk down, plant walk down and operator interviews and incorporation of Engineering modifications carried out in plant systems. Collection of component failure data and Initiating Frequency data, from Computerized Maintenance Management System (CMMS), Event Reports, Significant Event Reports, Monthly Performance Reports, Maintenance Reports and Plant Outage Reports are also included.