Simulation-based dynamic probabilistic risk assessment of an internal flooding-initiated accident in nuclear power plant using THALES2 and RAPID

Abstract

Probabilistic risk assessment (PRA) is a method used to assess the risks associated with large and complex systems. However, the timing at which nuclear power plant structures, systems, and components are damaged is difficult to handle explicitly if the risk of an external event is evaluated using conventional PRA based on event trees and fault trees. A methodology coupling thermal-hydraulic analysis with external event simulations using Risk Assessment with Plant Interactive Dynamics (RAPID) is therefore proposed to overcome this limitation. A flood propagation model based on Bernoulli’s theorem was applied to represent internal flooding in the turbine building of the pressurized water reactor. Uncertainties were also taken into account, including the flow rate of the floodwater source and the failure criteria for the mitigation systems. The simulated recovery actions included the operator isolating the floodwater source and using a drainage pump; these actions were modeled using several simplifications. Overall, the results indicate that combining isolation and drainage can reduce the conditional core damage probability upon the occurrence of flooding by approximately 90%.

Application of quasi-Monte Carlo and importance sampling to Monte Carlo-based fault tree quantification for seismic probabilistic risk assessment of nuclear power plants

“…To perform this study, the authors partially used a supercomputer HPE SGI8600 in the JAEA. Additionally, the authors utilized some of the expertise gained from developing the JAEA's dynamic PRA tool named risk assessment with plant interactive dynamics (RAPID) (Zheng et al, 2022;Kubo et al, 2022c), which was conducted under the auspices of the NRA, J.…”

Quantification of risk dilution induced by correlation parameters in dynamic probabilistic risk assessment of nuclear power plants

“…Owing to the advancements in computer performance in recent years, various tools have been developed and applied to safety issues in nuclear power plants since then. [12][13][14][15][16][17][18] The Japan Atomic Energy Agency (JAEA) has developed a dynamic PRA methodology and tool called Risk Assessment with Plant Interactive Dynamics (RAPID) [19][20][21][22][23] to technically support NRA. RAPID has been used to evaluate nuclear-power-plant safety issues, including external event-induced risk.…”

“…The Japan Atomic Energy Agency (JAEA) has developed a dynamic PRA methodology and tool called Risk Assessment with Plant Interactive Dynamics (RAPID) 19–23 to technically support NRA. RAPID has been used to evaluate nuclear-power-plant safety issues, including external event-induced risk.…”

Accident Sequence Precursor Analysis of an Incident in a Japanese Nuclear Power Plant Based on Dynamic Probabilistic Risk Assessment

“…To realize this method, the author used RAPID (risk assessment with plant interactive dynamics) framework [27][28][29] and THALES-2 (thermal hydraulic analysis of loss of coolant, emergency core cooling, and severe core damage, version 2) T-H analysis code [30][31][32][33][34]. Risk assessments of the randomly-and seismically-induced internal fooding were conducted using these codes [35,36].…”