Experimental Investigation of Cable Arrangement on the Cable Burning Behavior in a Cone Calorimeter

Cables are one of the main fire hazards in nuclear power plants (NPPs). Cable arrangement, especially cable spacing in an electrical cable tray has a significant effect on cable tray fire. Predicting cable fire behavior in NPPs is necessary for the nuclear safety analysis. In this work, cable fire experiments with halogen-free flame retardant cable (XLPE cable with a diameter of 8.55mm) were carried out in a cone calorimeter. Cable spacing was changed from 0 mm to triple of cable diameter, including 7 different spacing arrangements under 3 different external heat fluxes. Besides, the experimental data of two other halogen-free flame retardant cables in the literature available are used. With the increase of cable spacing, the heat release rate per unit area (HRRPUA) was significantly increased and the fire duration was considerably decreased, while the time to ignition (TTI) of the cable was basically invariable with different cable spacings. Furthermore, the effects of the cable spacing on the cable burning become constant when the cable spacing was larger than a critical cable spacing. This work provides experimental support for industrial cable fire risk assessment, and the above findings are beneficial for fire prevention in the design stage of NPPs.