Probabilistic Safety Assessment of Newly Added Auxiliary Transformers In Fangjiashan Nuclear Power Plant

In order to further improve the safety of the nuclear power plant, China nuclear power Fangjiashan nuclear power plant plans to add an auxiliary standby transformer, which is used for the redundancy of the original auxiliary transformer. This permanent change will improve the reliability of external power supply of nuclear power plant and reduce the frequency of loss of external power supply, so as to improve the safety level of Fangjiashan nuclear power plant. In this paper, the probabilistic safety assessment method is applied to analyze Fangjiashan unit, and the level-1 PSA model of internal events under power operation conditions, level-1 PSA model of internal events under low power and shutdown conditions and spent fuel pool model are modeled respectively. After the permanent change of auxiliary standby transformer is added during Fangjiashan power operation, low power and shutdown, The quantitative safety analysis results are given for the improvement of safety and reliability of Fangjiashan nuclear power plant. This evaluation provides an idea for the application of PSA in the permanent change of nuclear power plant. Before the permanent change of power plant plan, through the analysis of probabilistic safety evaluation, we can get how much benefit this change brings to the nuclear safety of power plant.