Level-1 Probabilistic Safety Analysis of Prototype Fast Breeder Reactor

This paper summarizes the results from the level-1 Probabilistic Safety Analysis of Prototype Fast Breeder Reactor (PFBR) which is under construction at Kalpakkam. The scope of this study is limited to internal events at full power. The regulatory requirement in India is risk informed and the required target value for overall core damage frequency (CDF) <; le-6 / ry. The salient feature of this study is the inclusion of functional failure of natural convection based system in event tree development. For this study three categories of end states namely, pin failures, sub-assembly failures and whole core accident were identified. With conservative assumptions the estimated core damage frequency is about 0.9 1.3E-6 /ry. This includes the contribution from sub-assembly failures and whole core accident. Loss of Steam Water System (Heat Sink) is the dominant contributor. Modeling Sub-Assembly flow blockage event tree is found to have large uncertainties.