Comparison of event tree/fault tree and convolution approaches in calculating station blackout risk in a nuclear power plant

Autor: Man Cheol Kim
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Nuclear Engineering and Technology, Vol 56, Iss 1, Pp 141-146 (2024)
Druh dokumentu: article
ISSN: 1738-5733
DOI: 10.1016/j.net.2023.09.018
Popis: Station blackout (SBO) risk is one of the most significant contributors to nuclear power plant risk. In this paper, the sequence probability formulas derived by the convolution approach are compared with those derived by the conventional event tree/fault tree (ET/FT) approach for the SBO situation in which emergency diesel generators fail to start. The comparison identifies what makes the ET/FT approach more conservative and raises the issue regarding the mission time of a turbine-driven auxiliary feedwater pump (TDP), which suggests a possible modeling improvement in the ET/FT approach. Monte Carlo simulations with up-to-date component reliability data validate the convolution approach. The sequence probability of an alternative alternating current diesel generator (AAC DG) failing to start and the TDP failing to operate owing to battery depletion contributes most to the SBO risk. The probability overestimation of the scenario in which the AAC DG fails to run and the TDP fails to operate owing to battery depletion contributes most to the SBO risk overestimation determined by the ET/FT approach. The modification of the TDP mission time renders the sequence probabilities determined by the ET/FT approach more consistent with those determined by the convolution approach.
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