Improved Assessment of Fire Spread over Horizontal Cable Trays Supported by Video Fire Analysis

Fire safety analyses in nuclear power plants need to assess the heat release rate (HRR) of potential cable fires. This study deals with the FLASH-CAT model which assesses the HRR of a fire spreading over horizontal ladder cable trays. As part of the OECD PRISME-2 project, fire tests which involved horizontal trays supported by a wall, highlighted fast fire growth and large HRR peak. This study investigated the ability of the FLASH-CAT model to predict the HRR for such configuration. The first assessments of the PRISME-2 tests with the FLASH-CAT model significantly delayed the ignition and under-estimated the fire growth rate and the HRR peak. A video fire analysis method was developed and contributed to propose updated input parameters, such as the ignition time and the horizontal spread rate, for cable tray configurations with a wall. In addition, modifications in the model which affect the burning cable tray area and the local fire duration are also discussed. The assessments of the PRISME-2 experiments with the modified FLASH-CAT model and the proposed input parameters are consistent with the measured HRR. In addition, the modified model also gives acceptable predictions of the HRR for numerous tests of the CHRISTIFIRE programme.