There must be a large leak," Junichi Matsumoto, a general manager at the utility also known as Tepco, told a news conference on Thursday. "The fuel pellets likely melted and fell, and in the process may have damaged ... the pressure vessel itself and created a hole," he added. Since the surface temperature of the pressure vessel has been holding steady between 100 and 120 degrees Celsius, Matsumoto said the effort to cool the melted uranium fuel by pumping in water was working and would continue. He said the utility would study whether to increase the amount of water it is injecting to overcome the leak and raise the level of water covering the fuel, at the risk of allowing more radioactive water to leak out of the facility. Nearly 10,400 tonnes of water has been pumped into the reactor so far, but it is unclear where the leaked water has been going. The high radiation makes it difficult for workers to check the site, Matsumoto said. Fukushima reactor water leak risks delaying crisis plan | Reuters P.S I think one thing is clear where ever the water is going it will not be good for the environment .