Analysis of site operating state contributions for multi-unit PSA with Korean NPP Sites

摘要

? 2023Multi-unit probabilistic safety assessment (PSA) projects targeting nuclear power plants are focusing on the risk of multi-unit sites as an expansion from single unit PSA projects. The evaluation of PSA projects requires the duration of states, while the duration of site operating states (SOSs) used for multi-unit PSA are based on assumptions or operation history data, which have high variance and need improvement. In this paper, a simulation model calculating the contribution for each SOS is proposed based on the operation history data. Input data is the operation state for each unit in unit days, where length of components for each SOSs gained by the input data is processed with Bayesian information criterion to gain the most well-fitting probability distribution. The output provides the portion of all SOSs, and case studies cover all sites in Korea and investigate sensitivity analysis of unit type and trip considerations. The result shows that full-operation SOS is around 30 percent, and more than one unit is down for around 70 percent. The usage of these data is able to show alternative point-of-views of declaring the importance of each SOS in multi-unit PSA projects as well as leading the overall risk of the site.