Estimation of probability distribution depending on magnitude of sodium leak event postulated in PSA, 2

Kurisaka, Kenichi ; Takamatsu, Misao ; Martin, L.*

This study aims to quantify the probability distribution of the leak flow rate when a sodium leak event takes place, in terms of the effectiveness evaluation of accident management measures using probabilistic safety assessment. For this purpose, sodium leak instances that were experienced in domestic and foreign sodium-cooled fast reactor systems were investigated and analyzed. In most of these leak instances, individual total leak amount is known, but the leak duration time is unknown. Therefore, the previous study needed to assume the leak duration time as a probability distribution to estimate the leak flow rate. In this study, for more realistic evaluation, we investigated both total leak amount and leak duration time of sodium leak instances that were experienced in the Phenix reactor system. For 12 instances where total leak amount was already known, leak duration time became clear. Five leak instances were newly added. The probability distribution of the leak duration time was statistically analyzed by using these data. As a result, it became possible to quantify more realistically the probability distribution of the leak flow rate.