Defences against fire hazards in AGR and PWR cabling installations

The nuclear safety requirements for a nuclear power station have a considerable impact on the site layout and in particular the cable installation. An important aspect of nuclear safety principles deal with the consideration of internal and external hazards including fire. Due to the large numbers of power and control cables utilised in a large power station (40-50,000) and the volume of combustible material associated with the insulation and sheathing of these cables, the fire and smoke hazard-requires very careful consideration. The paper considers the philosophy behind the separation and segregation of redundant systems and cable routes which are important to safety in a nuclear power station and some of the provisions made to prevent, detect and minimise the spread of fire in their cable installations. Fire barriers, cable types and construction, used in the most modern advanced gas cooled reactor (AGR) and pressurised water reactor (PWR) designs, are briefly described