The COFUN development for evaluating containment failure frequency using Stress-Strength analysis

When applied stress exceeds strength, containment failure may occur.The probability of leakage or rupture equals the probability that stress exceeds strength.Based on this stress-strength analysis, the COFUN code was developed to quantify ECF and LCF in the CET.The containment event tree (CET) models the progression of possible severe accident scenarios in the containment building.It is detailed to reflect various accident phenomena, progression, and damage.Each CET heading has a corresponding decomposition event tree (DET), which branches the PDS LD according to logical rules, with calculated branching probabilities.Each DET addresses key phenomena affecting these probabilities.Variables with probabilistic or discrete distributions are included due to phenomenological uncertainty.Containment failure frequencies for both ECF and LCF are evaluated using this analysis.Sensitivity analysis identifies variables impacting integrity, and statistical propagation with sampling is used to quantify uncertainty.