About 20 tons of radioactive coolant water leaked from an 8-centimeter-long crack in a pipe at a nuclear power plant in Tsuruga, Fukui Prefecture, Japan on Monday, officials of the Japan Atomic Power Co. said. No radiation leaked outside the No. 2 reactor building where the accident occurred, they said. It was the largest leak of coolant at a Japanese nuclear facility since 1979, when 95 tons spilled out at the No. 2 reactor of the Takahama nuclear power plant, also in Fukui Prefecture.