Tokyo Electric Power Co. found unsafe levels of radioactivity in groundwater at its crippled Fukushima station, even as Japan’s nuclear regulator set the clock ticking on the restart of the nation’s idled reactors.
The utility, known as Tepco, detected tritium levels of 500,000 becquerels per liter and strontium levels of 1,000 becquerels per liter at a monitoring well in its turbine complex at the Dai-ichi plant, it said in a statement today.
Japan’s nuclear safety guidelines require tritium levels at nuclear plants to remain below 60,000 becquerels per liter and strontium levels below 30 becquerels per liter. Japan’s safety limit for radioactive materials in drinking water is 10 becquerels per liter.
The new findings by the utility, which has struggled with the handling of contaminated water at Fukushima, came as Japan’s Nuclear Regulation Authority finalized its new safety guidelines required for any nuclear plant restarts. All but two of Japan’s 50 reactors are idled for safety assessments after the earthquake and subsequent tsunami of March 11, 2011 caused meltdowns and radiation leaks at the Fukushima plant. The NRA was set up after the disaster to independently review Japan’s nuclear power.
The Fukushima contamination’s spread seemed limited, with a separate monitoring well about 70 meters away showing tritium levels of 380 becquerels per liter and strontium levels of 28 becquerels per liter, according to the statement by the company.
There was no apparent affect on the ocean water adjacent to the seaside plant, Toshihiko Fukuda, general manager for Tepco’s nuclear power and plant siting division, said at a press conference today.
“Tritium concentrations in the sea water remain in the same range as before,” he said.
The company suspects the contamination stems from an April 2011 accident that resulted in the spill of radioactive water, which is now being detected in the water table, according to the statement.
Tepco shares fell 3.9 percent to close at 517 yen on the Tokyo Stock Exchange, the worst performance among Japan’s 10 regional power companies. The TOPIX Electric Power & Gas Index gained 0.3 percent while the benchmark Nikkei 225 Stock Average rose 1.9 percent.
The nuclear regulator’s guidelines, which will take effect from July 8, still require Cabinet approval, Chairman Shunichi Tanaka said at a meeting in Tokyo today. Under the rules, nuclear power plants will need to build secondary control centers at least 100 meters from reactor buildings to manage emergency cooling systems and radiation filter vents. They also stipulate tsunami defenses must be based on the largest estimated waves from the most recent scientific assessments.
“This will enhance the stability and reliability of our nuclear plants’ operations,” Makoto Yagi, chairman of Japan’s Federation of Electric Power Cos. and president of Kansai Electric Power Co., said in a statement. “We ask the NRA to work efficiently in confirming compliance with the new standards so that decisions on restarts can be made.”
Kansai Electric plans to file to restart the No. 3 and No. 4 units at its Takahama plant as soon as the new rules take effect, spokesman Akihiro Aoki said today by phone. The company will also seek the regulators’ endorsement for the No. 3 and No. 4 units at its Ohi plant, now the nation’s only operating reactors, he said.
Hokkaido Electric Power Co. plans to file for unit Nos. 1-3 at its Tomari plant, according to spokesman Shota Okada. Shikoku Electric Power Co. is considering filing for the No. 3 unit at its Ikata plant after the rules take effect, spokesman Tomoaki Yasuoka said.
Kyushu Electric Power Co. is preparing to file for unit Nos. 3 and 4 at its Genkai plant and for unit Nos. 1 and 2 at its Sendai plant, according to spokeswoman Naoko Iguchi.
While Tepco hasn’t announced specific restart proposals, the resumption of four of seven reactors at its Kashiwazaki Kariwa plant is cited as part of a turnaround plan released in May 2012 that would return it to profit this fiscal year.
The tritium and strontium detections at Tepco’s Fukushima plant followed a government order last month to build an underground wall to prevent groundwater from flowing into the basements of reactor buildings. The plant site, 220 kilometers (137 miles) northeast of Tokyo, is running out of space to store radioactive water, raising concerns the operator will be forced to dump it into the ocean.