Experiences and Insights in Development of Probabilistic Safety Assessment of Research Reactors in BARC

Abstract

Probabilistic Safety Assessment (PSA) techniques have become a standard tool in safety evaluation of nuclear power plant. For research reactors, experiment facilities aspects add a further dimension to application of PSA. Such experiments may increase the risk of damaging the reactor core. Sufficient experience is now available to suggest that current PSA methodology is a valuable tool for application to research reactor. Level 1 PSA of three research reactors i.e. 40 MWt Cirus, 100 MWt Dhruva, 2 MWt Upgraded Apsara Reactor Project in BARC, Trombay has been performed. The modelling for PSA of these research reactors has been carried out considering only with the internal initiating events for full power operational state and reactor core as the source of radioactive inventory. The special issues like common cause failure, uncertainty analysis and human reliability analysis have been addressed in the analysis. The specific purpose of these studies apart from normal application, i.e. to obtain safety insights, has been (a) design evaluation, (b) evaluation of scenario involving multiple failures, (c) regulatory support in decision making, (d) ageing assessment and (e) development of future applications like risk-monitor, risk-based ISI programme, and surveillance test interval optimization for safety systems. Further work is in progress on external event PSA e.g. Seismic PSA, and Aircraft Impact analysis and Fire PSA methodology. This paper discusses the experiences and insights in the development of PSA of Research Reactors at Bhabha Atomic Research Centre, Trombay.