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

Abstract

Summary 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.

Horizontal cable tray fire in a well‐confined and mechanically ventilated enclosure using a two‐zone model

“…Table gives the expanded relative uncertainty evaluated or assessed for some measurements and assessments carried out as part of the PRISME‐2 CFS test campaign . The evaluation of the uncertainty for the HRR is detailed in Zavaleta and Audouin for the CFS‐3 and 4 fire tests and in Zavaleta for the CFS‐1 and CFS‐2 fire tests.…”

“…About 250 sensors were used to measure heat flux, gas temperature, pressure, gas, and soot concentrations mainly in the fire room and the adjacent room, as well as gas velocity through the doorway between the two rooms. Experimental results of CFS 1 to 4 tests are reported in Zavaleta and Audouin and Zavaleta . In support of CFS tests, CFSS tests were carried out in open atmosphere, under the SATURNE calorimetric hood, and involved the same fire sources as the ones used in the CFS 1 to 4 tests.…”

“…Since the investigation of cable tray fires in confined and mechanically ventilated compartments has been scarce up to now, IRSN conducted, in the framework of the OECD PRISME‐2 program, more than a dozen fire tests involving horizontal cable trays burning either under a calorimetric hood in open atmosphere (CFSS tests campaign) or inside a mechanically ventilated facility (CFS tests campaign) to investigate this topic. These tests aimed at investigating the effects of confined and mechanically ventilated conditions on real‐scale cable tray fires.…”

“…Given the multitude of parameters involved in the definition of this fire source (orientation of cables, length of cables, number of cable trays, spacing between trays, cables loading, flame retardant compounds …), no theory to date has been put forward on how to model all aspects of the problem, even for only open atmosphere conditions. Some approaches, in the form of experimental studies, have nevertheless been carried out, and an empirical model (FLASH‐CAT) was developed for horizontal cable tray fires in an open atmosphere. Recently, the experiments carried out at IRSN improved the knowledge on this topic.…”

On the Relation between Strength and Stiffness of Cable Tray

“…For flame retardant capability of cable tray, there have been growing interests in understanding and predicting the fire development since the cable tray fire in 1975 at Browns Ferry Nuclear Power Plant. Most of the work were concentrated on experimental and numerical analyses of cable tray fires, in either open atmosphere or in confined and mechanically ventilated compartments [19][20][21][22], as well as the fire behavior of the cable tray arrangements [23,24]. e models for flame spread behavior were developed to estimate the heat release rate for the vertical cable tray fire [25] and to predict the fire development of the cable tray based on the computational fluid dynamics [26].…”