Behaviour of electrical cables under fire conditions

A Fire Probabilistic Safety Assessment - called the Fire PSA -is being carried out by the French Institute of Radiological Protection and Nuclear Safety (IRSN) to be used in the framework of the safety assessment of operating 900 MWe PWRs. The aim of this study is to evaluate the core damage conditional probability which could result from a fire. A fire can induce unavailability of safety equipment, notably damaging electrical cables introducing a significant risk contributor. The purpose of this paper is to present the electrical cable fire tests carried out by IRSN to identify the failure modes and to determine the cable damage criteria. The impact of each kind of cable failure mode and the methodology used to estimate the conditional probability of a failure mode when cable damage occurred is also discussed.