Corium (nuclear reactor) Corium (nuclear reactor) Corium (also called fuel containing material (FCM) or lava-like fuel containing material (LFCM)) is the lava-like mixture of fissile material created in a nuclear reactor's core during a nuclear meltdown. It consists of nuclear fuel, fission products, control rods, structural materials from the affected parts of the reactor, products of their chemical reaction with air, water and steam, and, in the event that the reactor vessel is breached, molten concrete from the floor of the reactor room. The heat causing the melting of a reactor may originate from the nuclear chain reaction, but more commonly decay heat
Nuclear reactor safety system is frequently drawn from an adjacent river, the sea, or other large body of water, the system can be fouled by seaweed, marine organisms, oil pollution, ice and debris. In locations without a large body of water in which to dissipate the heat, water is recirculated via a cooling tower. The failure of half of the ESWS pumps was one of the factors that endangered safety in the 1999 Blayais Nuclear Power Plant flood, while a total loss occurred during the Fukushima I and Fukushima II nuclear accidents in 2011. Emergency core cooling systems (ECCS) are designed to safely shut