Japan feared three months after the Fukushima nuclear power plant was hit by a tsunami that aftershocks could further damage one of its fuel storage pools, causing rods inside to melt and spew radiation within hours, according to a newly released document.
The Japan Nuclear Energy Safety Organization said it carried out a simulation that showed some 1,500 mostly used fuel rods at the plant’s No. 4 reactor building could start breaking in two hours if aftershocks further damaged the pool and caused cooling water to escape. The fuel rods could start melting within eight hours, the organization said in a report dated June 30 and published Friday.
The report shows that the pool remained vulnerable for nearly four months until its operator completed reinforcement work in July. Tokyo Electric Power Co. had said before then that the building could withstand major aftershocks without reinforcement, but made repairs after acknowledging structural damage and water leaks from the pool area.
We do not know their names, their faces, their families or their personal stories. Nobody really does. They are strangers, in a faraway land, doing the unthinkable.
In Japan they have a name: The Fukushima 50. A coterie of nuclear plant employees — some reports indicate 50, others suggest four working rotations of 50 — who stayed behind while 700 of their co-workers were evacuated from the stricken Fukushima-Daiichi facility on the Japanese coast.
Five have been killed. Two are missing. Twenty-one have been injured in a struggle where, in the words of Japan’s Prime Minister Naoto Kan, “retreat is unthinkable.”
The men understand the stakes. They know there is no turning back. One worker told a departing colleague he was prepared to die — that it was his job. Another informed his wife he wouldn’t be coming home anytime soon.
Amid widening alarm in the United States and elsewhere about Japan’s nuclear crisis, military fire trucks began spraying cooling water on spent fuel rods at the country’s stricken nuclear power station late Thursday after earlier efforts to cool the rods failed, Japanese officials said.
The United States’ top nuclear official followed up his bleak appraisal of the grave situation at the plant the day before with a caution that it would “take some time, possibly weeks,” to resolve.
The developments came as the authorities reached for ever more desperate and unconventional methods to cool damaged reactors, deploying helicopters and water cannons in a race to prevent perilous overheating in the spent rods of the No. 3 reactor.
Moments before the military trucks began spraying, police officers in water cannon trucks were forced back by high levels of radiation in the same area. The police had been trying to get within 50 yards of the reactor, one of six at the plant.The five specially fitted military trucks sprayed water for about an hour, but the full impact of the tactic was not immediately clear.
The chairman of the United States Nuclear Regulatory Commission gave a far bleaker appraisal on Wednesday of the threat posed by Japan’s nuclear crisis than the Japanese government had offered. He said American officials believed that the damage to at least one crippled reactor was much more serious than Tokyo had acknowledged, and he advised Americans to stay much farther away from the plant than the perimeter established by Japanese authorities.
The announcement opened a new and ominous chapter in the five-day-long effort by Japanese engineers to bring the six side-by-side reactors under control after their cooling systems were knocked out by an earthquake and a tsunami last Friday. It also suggested a serious split between Washington and its closest Asian ally at an especially delicate moment.
The Congressional testimony by Gregory Jaczko, the chairman of the commission, was the first time the Obama administration had given its own assessment of the condition of the plant, apparently mixing information it had received from Japan with data it had collected independently.
Helicopters dumped water Thursday on and near the Nos. 3 and 4 units at Japan’s Fukushima Daiichi nuclear plant in the latest attempt to halt the nuclear accident that appeared to be spinning out of control. The helicopters belong to the nation’s self-defense forces, public broadcaster NHK reported.
Initially, just a few drops were carried out before the operation was suspended. An NHK commentator said about 100 would be needed for the operation to succeed.
During the afternoon, engineers were planning to begin the process of restoring power to the stricken nuclear complex, a government official said. The complex lost its power Friday, when a 9.0 earthquake followed by a tsunami hammered northeastern Japan.
"Today, we are trying to restore the power supply using the power lines from outside," said the official with the Nuclear and Industrial Safety Agency. "This is one of the high-priority issues that we have to address."
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Once the power supply has been re-established, the cooling system will be operated using seawater, he said. But he warned that the process will not be immediate.
Japanese Prime Minister Naoto Kan said Tuesday the risk of further releases of radioactive material remains "very high," as crews struggle to contain an increasingly critical crisis at a damaged nuclear plant.
Radiation levels at the Fukushima Daiichi nuclear power plant have increased to "levels that can impact human health," and anyone within a 30-kilometer radius of the plant should remain indoors, Chief Cabinet Secretary Yukio Edano said soon after Kan spoke.
Nearly all of the plant’s staff — some 800 people — have left, Edano said. Just 50 remain to carry out crucial cooling work.
"There is still a very high risk of further radioactive material coming out," the prime minister said, calling on people to remain calm. "We are making every effort possible so that no further explosion or no further leakage … would happen."
Kan spoke as a new fire burned at the No. 4 reactor at the damaged Fukushima Daiichi nuclear power plant in northeastern Japan.
Japan’s nuclear crisis verged toward catastrophe on Tuesday after an explosion damaged the vessel containing the nuclear core at one reactor and a fire at another spewed large amounts of radioactive material into the air, according to the statements of Japanese government and industry officials.
In a brief address to the nation at 11 a.m. Tokyo time, Prime Minister Naoto Kan pleaded for calm, but warned that radiation had already spread from the crippled reactors and there was “a very high risk” of further leakage. Fortunately, the prevailing winds were sweeping most of the plume of radioactivity out into the Pacific Ocean, rather than over populated areas.
The sudden turn of events, after an explosion Monday at one reactor and then an early-morning explosion Tuesday at yet another — the third in four days at the plant — already made the crisis at the Fukushima Daiichi Nuclear Power Station the worst nuclear accident since the Chernobyl reactor disaster a quarter century ago.
It diminished hopes earlier in the day that engineers at the plant, working at tremendous personal risk, might yet succeed in cooling down the most damaged of the reactors, No. 2, by pumping in sea water. According to government statements, most of the 800 workers at the plant had been withdrawn, leaving 50 or so workers in a desperate effort to keep the cores of three stricken reactors cooled with seawater pumped by firefighting equipment, while the same crews battled to put out the fire at No. 4 reactor, which they claimed to have done just after noon on Tuesday.
A fresh explosion rocked Japan’s quake-stricken nuclear power complex on Tuesday, around its overheating No.2 reactor, but there was no immediate word of any damage to the reactor itself, the country’s nuclear safety agency said.
Jiji news agency quoted authorities as saying radiation levels around the complex immediately after the blast, the third in as many days, were still relatively low, but it added that some workers had been told to leave the plant.
Authorities at the Fukushima Daiichi complex, damaged in Friday’s massive earthquake and tsunami, are trying to prevent meltdowns in all three of the plant’s nuclear reactors.
A crisis continued Tuesday at the troubled No. 2 reactor at the quake-hit Fukushima No. 1 nuclear power plant, as fuel rods became fully exposed again after workers recovered water levels to cover half of them in a bid to prevent overheating. The plant operator, Tokyo Electric Power Co., said steam vents of the pressure container of the reactor that houses the rods were closed probably due to the battery problem, raising fears that its core will melt at a faster pace.The firm said it will first lower the pressure of the reactor by releasing radioactive steam and open the vents with new batteries to resume the operation to inject seawater to cool down the reactor.Earlier, cooling functions of the reactor failed, causing water levels to sharply fall and fully exposing the fuel rods for about 140 minutes. TEPCO said they could not pour water into the reactor soon as it took time for workers to release steam from the reactor to lower its pressure, the governments nuclear safety agency said.As TEPCO began pouring coolant water into the reactor, water levels went up at one point to cover more than half of the rods that measure about 4 meters.Prior to the second full exposure of the rods around 11 p.m. Monday, radiation was detected at 9:37 p.m. at a level twice the maximum seen so far— 3,130 micro sievert per hour — near the main gate of the No. 1 plant, according to TEPCO.