Fast breeder reactors can breed more fissile material than they consume by using uranium-238 and plutonium-239. The largest fast breeder reactor, Superphenix in France, started in 1986 with a thermal power of 3000 MW and electrical power of 1180 MW. Fast breeder reactors have less than 1% of the world's total nuclear power. They use liquid sodium as a coolant instead of water since moderation is not needed. In a French reactor, 115 fissile nuclei were produced for every 100 fission reactions, showing these reactors can produce more fuel than they use.