The crippled nuclear plant at Fukushima is losing its two-year battle to contain radioactive water leaks and its owner emphasized for the first time it needs overseas expertise to help contain the disaster.
Tokyo Electric Power Co. is grappling with the worst spill of contaminated water since the March 2011 earthquake and tsunami caused a meltdown at the Fukushima Dai-Ichi plant. The call for help from Zengo Aizawa, a vice president at the utility, follows a leak of 300 metric tons of irradiated water. Japan’s nuclear regulator labeled the incident “serious” and questioned Tepco’s ability to deal with the crisis. Prime Minister Shinzo Abe made similar comments earlier this month.
“We will revamp contaminated-water management to tackle the issue at the Fukushima Dai-Ichi plant and seek expertise from within and outside of the country,” Aizawa said at a press conference last night in Tokyo. “There is much experience in decommissioning reactors outside of Japan. We need that knowledge and support.”
The International Atomic Energy Agency in Vienna and the U.S. Nuclear Regulatory Commission said they are prepared to help.
Tepco was storing 330,000 tons of radioactive water as of Aug. 13 in tanks covering an area equal to 37 football fields, according to the company. The utility is clearing forest to make room for more tanks as it adds to the stored water at a rate of 400 tons a day after pumping it out from under the plant’s reactors, which melted down as a result of the March 2011 earthquake and tsunami.
The water is treated to remove some of the cesium particles before it is stored, which has left 480 filters clogged with the radioactive material at the site. Each weigh 15 tons and are warehoused in what the utility calls temporary storage, though it will take hundreds of years for the radiation to decay. Other radioactive contaminants remain in the water even after treatment. That includes strontium, which has been linked to bone cancers.
Besides radiated water, the site north of Tokyo has more than 73,000 cubic meters of contaminated concrete, 58,000 cubic meters of irradiated trees and undergrowth, and 157,710 gallons of toxic sludge, according to the utility.
Japan’s nuclear watchdog has ratcheted up alarm over the potential for more leaks of highly radioactive water from the hundreds of storage tanks at the Fukushima atomic plant.
The possibility of leaks from other tanks “is the biggest concern,” said Nuclear Regulation Authority Chairman Shunichi Tanaka at a press conference yesterday. “This will need to be handled carefully on the assumption that one incident could bring another.”
Late last night, Tepco said water leaking from the storage tank probably ran into the ocean, citing high radiation readings in a drainage ditch.
As much as 20 trillion becquerels of cesium and 10 trillion becquerels of strontium leaked into the ocean since May 2011, Tepco spokeswoman Mayumi Yoshida said today. The total amount of cesium and strontium is equivalent to about 100 times the annual limit on radiation from the plant to the ocean under normal conditions, according to calculations based on Tepco data.
The release is about a million times less than the contaminants spilled into the world’s oceans after nuclear bomb tests in the 1950s and 60s, said Peter Burns, a radiation physicist based in Melbourne, who was formerly Australia’s representative on the United Nations’ committee on the effects of atomic radiation.
Radiation levels are rapidly diluted by the ocean and should pose few hazards outside of the harbor that is directly receiving the contaminants, said Kathryn Higley, a radiation health physicist at Oregon State University in Corvallis.
At least one commissioner at Japan’s nuclear regulator questioned the accuracy of data being released by Tepco and whether the incident had been fully reported. The leak, along with a separate spill of 300 tons of radioactive water a day into the Pacific Ocean, is raising doubts about the utility’s ability to handle the 40-year task to decommission the nuclear site.
Tepco is providing the regulator with information, company spokesman Yoshikazu Nagai said by phone, declining to comment further. The company’s shares fell as much as 15 percent in Tokyo yesterday, their biggest intraday slide since June 5, and were down 4.9 percent to 530 yen at 10:57 a.m. in Tokyo.
Japan’s government has ordered an investigation into the safety of hundreds of other tanks storing contaminated water in Fukushima, the site of the world’s worst civilian nuclear disaster since the Chernobyl reactor exploded in 1986.
There are 226 tanks of similar bolted design to the leaking unit with the same 1,000-ton capacity at the site, said Tatsuya Shinkawa, director of the nuclear accident response office in the government’s Agency for Natural Resources and Energy, which called for the probe.
Nuclear incidents and accidents are ranked by order of severity on the International Nuclear and Radiological Event Scale or INES, which has seven categories and was set up by the International Atomic Energy Agency.
On Aug. 19, Tepco said about 300 tons of highly radioactive water had leaked from a storage tank and was ranked as category one on INES, the lowest.
Japan’s NRA raised that to category three yesterday, or a “serious incident.” The 2011 meltdown of the three reactors at Fukushima is in the highest severity category of seven on the INES scale, the same as Chernobyl.
“This INES evaluation is based on the 300-ton leak, but I really wonder if we can trust data provided by Tepco,” Toyoshi Fuketa, a commissioner at the NRA, said at a meeting in Tokyo. “I really wonder if we should judge based on Tepco’s data.”
In two separate incidents this month, workers were exposed to radioactive releases at the plant.
Prime Minister Abe has said that Tepco alone isn’t able to handle the clean-up, promising more government funds without detailing how they’d be used.
Tepco needs “to stop going from crisis to crisis and have a systematic approach to water management,” Dale Klein, the chairman of an advisory panel to Tepco and a former head of the U.S. Nuclear Regulatory Commission, said yesterday in an interview.
INES is a means to measure nuclear accidents in terms of their effects on health and the environment, according to the International Atomic Energy Agency. Each of its seven steps represents a ten-fold increase in severity. The IAEA last night said it takes the leaks in Japan “seriously” and that it “remains ready to provide assistance on request,” according to a statement on its website. The U.S. Nuclear Regulatory Commission is also ready to provide assistance if requested, agency spokesman Scott Burnell said.
A seven rating means there has been a “major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures,” according to the INES fact sheet.
Japan’s regulator raised the INES rating on the water leak based on radiation levels reported by the utility this week and on an evaluation of measures at the plant to prevent such incidents. The IAEA will be the final arbiter of where the leak will sit on the severity scale.