Video: New radioactive water leak discovered at Fukushima plant The video was released by the Tokyo Electric Power Company (Tepco) as they continue their efforts to make safe the nuclear plant wrecked by Japan's 2011 earthquake and tsunami. Highly radioactive water was detected inside the No. 3 reactor building at the Fukushima Dai-Ichi nuclear plant, Tepco said. It is believed that the water may have leaked from within the reactor. The water was found to have high levels of radioactive cesium and cobalt, but Tepco claimed none of the water has leaked out of the building itself. A report in December suggested it would take five years to put an end to radioactive water leaks in and around the plant.