Computation of consequence measures of piping component failures

In-service inspections are applied to safety important pipe components in nuclear power plants (NPPs) to ensure their structural reliability. In risk-informed in-service inspections (RI-ISI), these inspections are planned according to risk importance of piping components. The quantitatively computed risk of a piping component combines the probability of the failure and the associated consequences.

This report focuses on estimating the consequences of the piping component failures. Conditional core damage probability (CCDP) and conditional large early release probability (CLERP) are used as the consequence measures. It is demonstrated how CCDP and CLERP values of piping component failures can be calculated automatically using the RI-ISI feature of the probabilistic risk assessment (PRA) software FinPSA. The RI-ISI feature enables detailed modelling of the consequences of the piping component failures without complicating the PRA model itself. Special focus is on the computation of the CLERP values for piping failures affecting severe accident management.