Efforts to cool reactors at Tokyo Electric Power Co.’s crippled nuclear station were disrupted after a 6.6-magnitude earthquake briefly cut power supply and forced workers to move to higher ground.
Japan’s government earlier extended the evacuation zone around the Fukushima Dai-Ichi plant after radiation levels rose in areas outside the 20 kilometer radius, Chief Cabinet Secretary Yukio Edano said today.
External power supply for three of the station’s six reactors was cut after today’s temblor, halting injection of water into units No. 1, 2 and 3, a spokesman for the utility known as Tepco said at a televised briefing. Cooling operations resumed after a 50 minutes, Japan’s nuclear safety agency said.
Japan’s biggest utility is battling radiation leaks from the atomic station at the center of Japan’s worst civilian nuclear disaster after it was crippled one month ago by a 9- magnitude quake and devastating tsunami. The latest temblor struck at 5:16 p.m. local time, U.S. Geological Survey said, and triggered a warning of a possible surge in sea levels.
Prime Minister Naoto Kan said the government is checking whether the quake, that struck 163 kilometers (100 miles) north- northeast of Tokyo, caused any further damage to the station. He postponed a press conference scheduled for 5:50 p.m. to mark the one-month anniversary of the March 11 earthquake and tsunami, the Cabinet press club said.
Sirens wailed across Japan and residents in cities and towns along the devastated northeastern coast held a minutes silence at 14:46 p.m., the time the quake struck last month.
Last month’s earthquake, Japan’s strongest on record, and tsunami left about 27,500 dead or missing, according to Japan’s National Police Agency. The government has estimated the damage at 25 trillion yen ($295 billion). Tepco may face claims of as much as 11 trillion yen, according to one estimate.
Water injection at reactors No. 1, 2 and 3 resumed after after external power supply was restored, Hidehiko Nishiyama, deputy director-general of Japan’s Nuclear and Industrial Safety Agency, said in a televised briefing. No abnormalities were observed at the other three reactors, he said.
Tepco is using emergency equipment to cool reactors damaged at the atomic station after backup generators were knocked out by the tsunami.
The utility is trying to remove highly contaminated water that’s holding up efforts to get the cooling pumps working and prevent further explosions after blasts damaged reactor containment vessels, releasing radiation into the air and sea and tainting food.
The latest earthquake halted the pumping of contaminated water from the No. 2 reactor, Tepco said today
Steam, Nitrogen Leak
Radioactive steam and nitrogen escaped from the containment vessel at the No. 1 reactor and the company is checking radiation levels around the reactor, spokeswoman Megumi Iwashita said by telephone before today’s quake.
Tepco started injecting nitrogen into the vessel to reduce the risk of a hydrogen explosion. The pressure inside the vessel is rising more slowly than expected, indicating a leak, Iwashita said.
Earlier today, the company said a hydrogen explosion was unlikely at the No. 1 unit.
“The situation is getting messier, especially at reactor No. 1,” Lauri Myllyvirta, a campaigner for Greenpeace told reporters in Tokyo today. “It seems likely that re-criticality or chain reactions in the fuel are taking place in there. Water isn’t going to be a solution for cooling the extra heat that generates.”
The environment group urged the government to extend the exclusion zone and said pregnant woman and children should be evacuated from “high risk areas” in Fukushima city, which is about 61 kilometers from the plant, and nearby Koriyama.
Tepco has sought to cool reactors by dousing them with millions of liters of water. The utility delayed discharging water with low levels of radioactivity into the sea, Nakagawa said today, holding up plans to transfer more contaminated fluids from a trench at the station’s No. 2 reactor to a condenser.
About 60,000 metric tons of contaminated water lies in the basements of turbine buildings and trenches around the No. 1, 2 and 3 reactors, the company said last week. Tepco needs to drain the water to restore reactor cooling systems in the turbine buildings.
Tepco said on April 8 that the station, which is about 220 kilometers north of Tokyo, wasn’t further damaged by a magnitude-7.1 aftershock on April 7.
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