Spent Fuel Pool Risk Analysis for a CPR1000 Unit

Abstract

After the Fukushima nuclear accident, the safety level of the spent fuel pool has gradually attracted increasing attention. This paper develops a probabilistic safety assessment (PSA) model for the spent fuel pool of a CPR1000 unit, and quantitatively evaluates the frequency of fuel damage. Possible weaknesses of the spent fuel pool are identified, and suggestions are provided to optimize the operation and management of nuclear power plants, thereby further improving the accident prevention and mitigation capabilities of the spent fuel pool and enhancing the overall safety of nuclear power plants. Through the quantitative analysis of spent fuel pool PSA, SFP fuel damage frequency of 6.99E−09/reactor year is finally developed. Compared with the core damage risk, SFP fuel damage frequency is very low, less than 1% of the core damage frequency, and the risk level is far lower than the reactor core. From the quantitative results of the initiating events, PTR discharge piping breakup and loss of offsite power are the dominant contribution to fuel damage frequency, mainly due to 1) After PTR discharge piping breaks, the ruptures can’t be isolated, and the emergency make-up is not available, finally leading to fuel damage; 2) Under refueling state, the loss of offsite power, diesel generator failure, while the main transformer, RRI/SEC, LHP/LHQ is to carry out planned maintenance, and also the emergency water supply failure jointly lead to fuel damage.