TOKYO—The operator of the troubled Fukushima Daiichi nuclear complex said over the weekend that its struggles to control highly radioactive water had suffered new setbacks.
The company announced the discovery of contaminated spots in new parts of the compound where the water is stored, while radiation levels jumped to highly dangerous levels in another part of that area where readings were previously lower.
The leakage water from the Fukushima Daiichi Nuclear Power Plant has been declared a level 3 "serious incident" by regulators. The WSJ's Deborah Kan speaks with Kathryn Higley, Head of Nuclear Engineering at Oregon State University.
Tokyo Electric Power Co. said it found on Saturday and Sunday high radiation levels in five locations near storage tanks installed to collect the 400 tons of contaminated water pumped out daily from the radioactive reactor buildings, indicating the possibility of new leaks from the tanks, or some other unexplained difficulties in containing the water.
Three of the measurements came in spots where contamination hadn't previously been detected. The other two hot spots registered sharp increases from previous measurements.
Two of the readings showed extremely high levels of radiation, one as high as 1,800 millisieverts per hour, another nearby at 1,700. Those are among the highest levels reported at the plant since the early days after a tsunami knocked out power on March 11, 2011, triggering one of the world's worst nuclear disasters. Exposure to such a level of radiation would kill a person within four hours, Tepco said.
Fukushima Daiichi: The Battle for Containment
More than two years after suffering one of the world's worst nuclear accidents, the compound remains a challenge for the operator and regulators.
Tepco has increased patrols and radiation readings after finding last month that 300 metric tons, or 79,000 gallons, of highly radioactive water had leaked from a hastily built storage tank. The Japanese government recently stepped in to take a more direct role in stemming the crisis at Fukushima Daiichi, which suffered triple meltdowns after the 2011 earthquake and tsunami knocked out backup power at the site.
The continuing reports of new radiation readings at Fukushima Daiichi underscore the difficulties Tepco and the government have in bringing the stricken compound under control.
For nearly two years, they say they have minimized the biggest danger of the crippled complex, the possibility of a new meltdown. But they have fallen behind on dealing with the hundreds of tons of groundwater coming into contact daily with the radioactive reactor buildings, sticking the bulk of it in storage tanks on the compound. Storage tanks hastily set up during plant emergencies have started springing leaks, and Tepco can't replace them with sturdier ones fast enough.
While disclosing the new findings over the weekend, Tepco officials played down the significance of any new risks.
"We're not taking the latest findings lightly and we understand that it's a critical challenge," Tepco spokesman Yoshikazu Nagai said Sunday. "But we're not in a situation where the 300 tons of leaked water [detected so far from the storage tanks] will increase to 600 or 900 tons."
At Fukushima, the Battle Continues
Reuters
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Workers move radiation-contaminated waste at a storage site in Naraha town, which is inside the former no-go zone within a 20-kilometer (12-mile) radius of the crippled nuclear-power plant. Currently, it is a designated evacuation zone.
Tepco said water levels of tanks nearby the five contaminated spots haven't fallen, suggesting the water hasn't leaked. Mr. Nagai said drain valves connected to the storage tanks are closed and that the tanks are built atop a concrete foundation, which the company says is waterproof, suggesting not much water has leaked outside the complex and into the ocean nearby. In the case of the 79,000-gallon leak, Tepco suspects the water leaked from a tank's drain valve that was open.
Regarding one of the new hot spots reported Saturday, Tepco said Sunday that it appeared to be caused by the fact that one drop of contaminated water is leaking every 90 seconds from a pipe linking two storage tanks. Late Sunday, Tepco said it appeared that the leak had stopped after it tightened bolts.
Reuters
An aerial view of Tokyo Electric Power Co.'s Fukushima Daiichi nuclear power plant.
As for the sharp rise in the radioactivity at one of the hot spots, Tepco said that while workers measured 1,800 mSv/h at a spot that was around five centimeters from the tank's base, the reading dropped sharply to 15 mSv/h when moving 50 centimeters away from the base, a level considered much less dangerous.
By wearing special gloves or using aluminum sheets, the radiation can be blocked, according to the operator. Still, the level is incredibly high since 100 mSv is the level at which cancer risks are seen as rising and equivalent to double the maximum dosage that workers at the plant are allowed in an entire year.
The continuous water problems have prompted Tepco and the government to continue seeking new solutions. The Japanese government is now studying an expensive, untested proposal to install a subterranean ring of ice to stem the spread of radioactive water. Prime Minister Shinzo Abe has said the government would now take the lead from Tepco after Japan's nuclear watchdog recently assessed the leak to be a "serious incident" or level 3 on an international nuclear accident scale of zero to seven.
