Probabilistic Safety Assessment - Risk Informed approach

Over the past few years NPCIL has performed comprehensive Level-l Probabilistic Safety Assessment for all the Pressurized Heavy Water Reactors and Boiling Water Reactor. The results are extensively used for the Risk Informed approach whereby risk insights derived from these PSA´s are considered together with information obtained from Deterministic safety analysis, for modifying the existsing operator training, testing and maintenance practices. An estimated CDF is not a ≪magic cut-off≫ value, its insights Le, Qualitative results are equally valuable. Though Quantitative CDF values are useful to prioritize needed safety improvements when used as relative values, Qualitative insights of PSA studies are extensively being utilized in NPCIL for upgrading the Simulator training programmes for operators by including multiple component failures in event sequence progression, Design finalization in Project stage, Tech Spec modifications etc. This paper brings out a detailed description of simulator exercises carried out to improve upon the dynamic operator performances identified as major contributors to CDF along with brief description of modifications achieved in testing and maintenance practices of the components appearing as the dominant contributors to CDF.