Tokyo Electric Power Co., operator of the crisis-ridden Fukushima Dai-Ichi nuclear power plant, said it found a new leak near the tanks holding contaminated water at the disaster site.
The utility, which serves 29 million customers in the Tokyo metropolitan area, is collecting soil where the leak occurred and doesn’t believe any water reached the ocean, company executives said at a briefing in Tokyo. About 100 metric tons (26,400 gallons) of water may have escaped a concrete barrier, the company said.
“Such a water leak was found despite a variety of measures taken by the company,” Masayuki Ono, an official at the utility’s nuclear power and plant division, said. “We are sorry to have caused concern,” he said.
The finding is a reminder of the task still facing Tokyo Electric as the utility, known as Tepco, battles to manage the plant almost three years since the earthquake and tsunami.
Beta radiation readings of 230 million becquerels per liter were taken in a sample collected from a gutter on top of the leaked tank at the Fukushima Dai-Ichi plant, according to a statement from the Tokyo-based utility. Japan’s safety limit for radioactive materials in drinking water is 10 becquerels per liter, according to the health ministry.
Radioactive water overflowed from the 10-meter long tank after two valves -- which were supposed to be closed -- had been opened, Ono said today. The leak was found 700 meters (0.4 miles) from the ocean in an area isolated from any drainage ditch, he said.
Setback to Decommissioning
Japan’s nuclear regulator, which is planning to check the utility’s probe of the leak and planned preventative measures, said today that it has asked Tepco to ensure no more leaks from the same type of water storage tanks occur.
The leak highlights difficulties for the regulator as it seeks to force Tepco to limit radiation at the site without slowing down its decommissioning.
“We need a balance of the best regulation and also the quickest decommissioning at Fukushima Dai-Ichi because we really want to have the reduction of the risk at the site,” Nuclear Regulation Authority commissioner Toyoshi Fuketa said today in Tokyo.
Tepco has installed about a thousand tanks at Fukushima to store hundreds of thousands of tons of water used to cool fuel after the nuclear accident in March 2011.
Some 300 tons of contaminated groundwater seep into the ocean each day at the Dai-Ichi station 240 kilometers (150 miles) north of Tokyo, Japan’s government has said.
Between May 2011 and August 2013, as many as 20 trillion becquerels of cesium-137, 10 trillion becquerels of strontium-90 and 40 trillion becquerels of tritium entered the ocean via groundwater, according to past statements from Tepco.
Tepco’s shares closed down 7 yen, or 2.4 percent, at 455 yen in Tokyo trading after earlier declining as much as 2.8 percent. The Nikkei 225 Stock Average dropped 2.2 percent.