Pilot application of risk informed safety margin characterization to a total loss of feedwater event

• We apply a risk-informed approach to characterize safety margins.
• This approach was applied to of a loss of feedwater event at a pressurized water reactor.
• Probability distributions for the important parameter values were constructed.
• These distributions were sampled to generate MAAP4 code simulation cases.
• Simulation results were evaluated to determine the safety margins.

In this paper we present the results of application of a risk-informed safety margin characterization (RISMC) approach to the analysis of a loss of feedwater (LOFW) event at a pressurized water reactor (PWR). This application considered a LOFW event with the failure of auxiliary feedwater (AFW) for which feed and bleed cooling would be required to prevent core damage. For this analysis the main parameters which impact core damage for the scenario were identified and probability distributions were constructed to represent the uncertainties associated with the parameter values. These distributions were sampled using a Latin Hypercube Sampling (LHS) technique to generate sets of sample cases to simulate using the MAAP4 code. Simulation results were evaluated to determine the safety margins relative to those obtained using typical probabilistic risk assessment (PRA) modeling (success criteria) assumptions.