WWER plant probabilistic safety assessment

This paper addresses the ways of probabilistic safety assessment for WWER-1000 reactors in operation. Probabilistic analysis is supposed to be used to optimize operational documentation, to assess weaknesses and enhance safety and efficiency of the operating plants. Probabilistic safety assessment (PSA) is a necessary part of safety justification for NPPs both operating and under design. To practically implement the task much effort is needed to process information, prepare computers codes, to do calculations and adopt the results. Operational experience shows that WWER plants can be improved by improving stability, reducing the number of shutdowns, labour consumption as well as improving operational documentation and taking account of all hypothetical transients. The best possible way to achieve this goal is to use PSA. In this paper PSA performance programme adopted in VNIIAES is described. (author). 6 figs, 1 tab