Japan's crippled Fukushima nuclear power plant has once again sprung a leak, releasing more than eight tonnes of potentially radioactive water.

However, officials at the Tokyo Electric Power Company , which operates the plant, said Wednesday none of the water has flowed outside the nuclear complex.

TEPCO says a pipe in the Number 4 reactor broke on Tuesday night, possibly because of the below-freezing temperatures. They said the leak was discovered quickly and stopped by closing a valve.

The Fukushima-Daiichi powerplant was crippled by a major earthquake and tsunami that struck Japan last March. The meltdown triggered was the world's worst nuclear crisis since the 1986 Chernobyl disaster, and eroded public confidence in Japan's nuclear power industry.

All but three of Japan's remaining 54 nuclear reactors have been shut down for safety checks, and the government has abandoned its plan to generate more than 50 percent of its energy from nuclear power by 2030.

The Japanese cabinet approved legislation Tuesday that would create a new nuclear watchdog agency and limit a nuclear reactor's operational lifespan to 40 years. One of the reactors at the crippled Fukushima reactor has been operating for 41 years.