Adapted FLASHCAT methodology to model horizontal cable tray fires using computational fluid dynamics

Abstract

Nuclear power plants (NPPs) have an extensive network of electrical cables and associated trays to support daily operations. As electrical cables have combustible mass, their presence adds to the fire load in such plants. Thermal stress from cable fires can cause cable failures and spread fire to other redundant cables or other equipment, jeopardizing the safe operation of NPPs. Assessing the heat release rates (HRR) of cable fires is critical for the nuclear industry as HRR regulates the thermal stress in the surrounding of a fire and other fire products that can damage the facility. This paper presents a computational fluid dynamics-based method to model the HRR of such cable fire. The method is partly based on the FLASHCAT model (modified and adapted here) and the surface temperature ignition model of the Fire Dynamics Simulator (FDS) software. The simulation set up with validation objective replicates an experiment of OECD PRISME 3 program in which cables arranged over two horizontal trays are burnt. HRR obtained from the simulation had peak HRR underestimated by 4%, and the time to reach peak HRR overestimated by 5%. The result is encouraging as it provides confidence in using the method outlined in the paper.