Cable tray fire tests with halogenated electric cables in a confined and mechanically ventilated facility

摘要

Cable fires are one of the main fire hazards present in nuclear power plants (NPPs). Therefore, as part of the Organisation for Economic Co-operation and Development (OECD) PRISME-2 project, cable tray fire tests were performed both in open atmosphere conditions and in a confined and mechanically ventilated facility, called DIVA. These tests aim at showing the effects of a confined and ventilated environment on fire characteristics and consequences. This study deals with five fire tests, which used halogenated (poly [vinyl chloride] or PVC) cable types. Two tests were carried out in open atmosphere and three tests in the DIVA facility. The latter used a ventilation renewal rate (VRR) of either 4 or 15 h(-1). The confined and ventilated conditions reduced the mass loss rate and heat release rate than did those obtained in open atmosphere. Furthermore, the three confined tests produced unburnt gases, which ignited in the fire room. Two explosions were highlighted for the tests that used a VRR of 4 h(-1). These explosions indeed led to fast flame propagations over the entire upper part of the fire room and steep overpressures of almost 150 hPa. The low-qualified PVC cables and the ventilation set-up used in this study strongly contributed to the occurrence of these explosions.