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

Electrical cable trays are used in large quantities in nuclear power plants (NPPs) and are one of the main potential sources of fire. A malfunction of electrical equipment due to thermal stress for instance may lead to the loss of important safety functions of the NPPs. The investigation of such fires in a confined and mechanically ventilated enclosure has been scarce up to now and limited to nuclear industry. In the scope of the OECD PRISME-2 project, the Institut de Radioprotection et de Surete Nucleaire (IRSN) conducted more than a dozen fire tests involving horizontal electrical cable trays burning either in open atmosphere or inside mechanically ventilated compartments to investigate this topic. A semi-empirical model of horizontal cable tray fires in a well-confined and mechanically ventilated enclosure was developed. This model is partly based on the approach used in FLASH-CAT and on experimental findings from IRSN cables fire tests. It was implemented in the two-zone model SYLVIA. The major features of the compartment fire experiments could then be reproduced with acceptable error, except for combustion of unburned gases. The development of such a semi-empirical model is a common practice in fire safety engineering concerned with complex solid fuels.