[4/5/11] The leakage of highly radioactive water from a cracked concrete pit at Tokyo Electric Power Co.'s Fukushima Daiichi reactor No. 2 has stopped, the Japanese utility said early Wednesday.
The leakage stopped after workers poured 1,560 gallons of "water glass" — a sodium silicate compound—through holes around the pit and at the bottom of the pit, a Tepco spokesman said.
The radiation level of the water in the pit was 1,000 millisieverts an hour, and has been regarded as the most dangerous water flowing into the ocean.
Workers had tried a variety of methods to reduce the flow from the heavily damaged No. 2 reactor, put at several tons of water an hour, since it was discovered coming from a crack in a concrete container near the shoreline Saturday.
The steady flow from the crack had been blamed for a surge in the level of contamination in seawater near the complex. A water sample taken just outside the water intake for the No. 2 unit showed the level of radioactive iodine-131 at 7.5 million times the allowable limit, the most dangerous level of radiation so far detected.
[4/4/11] TOKYO >> Workers used a milky bathwater dye Monday as they frantically tried to trace the path of radioactive water seeping into the ocean from Japan's tsunami-damaged nuclear plant.
The crack in a maintenance pit discovered over the weekend was the latest confirmation that radioactivity continues to spill into the environment. The leak is a symptom of the primary difficulty at the Fukushima Dai-ichi complex: Radioactive water is pooling around the plant and preventing workers from powering up cooling systems needed to stabilize dangerously vulnerable fuel rods.
The plant operators also deliberately dumped 10,000 tons of tainted water — measuring about 500 times above the legal limit for radiactivity — into the ocean Monday to make space at a storage site for water that is even more highly radiactive.
Engineers have turned to a host of improvised and sometimes bizarre methods to tame the nuclear plant after it was crippled in Japan's magnitude 9.0 quake and tsunami on March 11.
Efforts over the weekend to clog the leak with a special polymer, sawdust and even shredded newspapers failed to halt the flow at a cracked concrete maintenance pit near the shoreline. The water in that leak contains radioactive iodine at rates 10,000 times the legal limit.
Suspecting they might be targeting the wrong channel to the pit, workers tried to confirm the leak's pathway by dumping several pounds (kilograms) of salts used to give bathwater a milky hue into the system, plant operator Tokyo Electric Power Co. said Monday.
"There could be other possible passages that the water may be traveling. We must watch carefully and contain it as quickly as possible," said Hidehiko Nishiyama, a spokesman for the Nuclear Safety and Industrial Agency.
Radioactive water has pooled throughout the plant because the operator has been forced to rely on makeshift ways of pumping water into the reactors — and allowing it to gush out wherever it can — to bring down temperatures and pressure in the cores.
Government officials conceded Sunday that it will likely be several months before the cooling systems are completely restored. And even after that happens, there will be years of work ahead to clean up the area around the complex and figure out what to do with it.
[3/27/11] TOKYO >> Highly radioactive iodine seeping from Japan's damaged nuclear complex may be making its way into seawater farther north of the plant than previously thought, officials said Monday, adding to radiation concerns as the crisis stretches into a third week.
Mounting problems, including badly miscalculated radiation figures and no place to store dangerously contaminated water, have stymied emergency workers struggling to cool down the overheating plant and avert a disaster with global implications.
The coastal Fukushima Dai-ichi power plant, located 140 miles (220 kilometers) northeast of Tokyo, has been leaking radiation since a magnitude-9.0 quake on March 11 triggered a tsunami that engulfed the complex. The wave knocked out power to the system that cools the dangerously hot nuclear fuel rods.
On Monday, workers resumed the laborious yet urgent task of pumping out the hundreds of tons of radioactive water inside several buildings at the six-unit plant. The water must be removed and safely stored before work can continue to power up the plant's cooling system, nuclear safety officials said.
The contaminated water, discovered last Thursday, has been emitting radiation that measured more than 1,000 millisieverts per hour in a recent reading at Unit 2 — some 100,000 times normal amounts, plant operator Tokyo Electric Power Co. said.
As officials scrambled to determine the source of the radioactive water, chief Cabinet Secretary Yukio Edano repeated Monday that the contaminated water in Unit 2 appeared to be due to a temporary partial meltdown of the reactor core.
He called it "very unfortunate" but said the spike in radiation appeared limited to the unit.
However, new readings show contamination in the ocean has spread about a mile (1.6 kilometers) farther north of the nuclear site than before. Radioactive iodine-131 was discovered just offshore from Unit 5 and Unit 6 at a level 1,150 times higher than normal, Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency, told reporters Monday.
He had said earlier there was no link between the radioactive water leaking inside the plant and the radiation in the sea. On Monday, though, he reversed that position, saying he does suspect that radioactive water from the plant may indeed be leaking into the ocean.
Closer to the plant, radioactivity in seawater tested about 1,250 times higher than normal last week and climbed to 1,850 times normal over the weekend. Nishiyama said the increase was a concern, but also said the area is not a source of seafood and that the contamination posed no immediate threat to human health.
Up to 600 people are working inside the plant in shifts. Nuclear safety officials say workers' time inside the crippled units is closely monitored to minimize their exposure to radioactivity, but two workers were hospitalized Thursday when they suffered burns after stepping into contaminated water. They were to be released from the hospital Monday.
Meanwhile, a strong earthquake shook the region and prompted a brief tsunami alert early Monday, adding to the sense of unease across Japan. The quake off the battered Miyagi prefecture coast in the northeast measured magnitude-6.5, the Japan Meteorological Agency said.
[3/27/11] TOKYO >>Japanese officials reported a huge jump in radioactivity — levels 10 million times the norm — in water in one reactor unit at a tsunami-damaged nuclear plant Sunday, forcing workers to evacuate and again delaying efforts to control the leaking complex.
Radiation in the air, meanwhile, measured 1,000 millisieverts per hour — four times the limit deemed safe by the government, Tokyo Electric Power Co. spokesman Takashi Kurita said.
Word of the startling jump in radioactivity in Unit 2 came as TEPCO struggled to pump contaminated water from four troubled reactor units at the overheated Fukushima Dai-ichi plant, 140 miles (220 kilometers) northeast of Tokyo. The reading was so high that the worker measuring the levels fled before taking a second reading, officials said.
[3/23/11] TOKYO >> A spike in radiation levels in Tokyo tap water spurred new fears about food safety Wednesday as rising black smoke forced another evacuation of workers trying to stabilize Japan's radiation-leaking nuclear plant.
Radiation has seeped into vegetables, raw milk, the water supply and seawater since a magnitude-9 quake and killer tsunami crippled the Fukushima Dai-ichi power plant nearly two weeks ago. Broccoli was added to a list of tainted vegetables, and U.S. and Hong Kong officials announced a block on Japanese dairy and some produce from the region.
The crisis is emerging as the world's most expensive natural disaster on record, likely to cost up to $309 billion, according to a new government estimate. The death toll continued to rise, with more than 9,400 bodies counted and more than 15,600 people listed as missing.
[3/18/11] As General Electric defends the reactors it designed for Japan's Fukushima Daiichi nuclear power plant, independent nuclear specialists are also coming to the company's defense amid the nuclear crisis.
"I think GE should really be saluted for their design of the reactors," says Najmedin Meshkati of the University of Southern California, Los Angeles, a nuclear safety expert who has studied power plants worldwide, including at Chernobyl and in Japan. "[The crisis] really hasn't been a problem with the reactor design."
The most pressing issue now at the plant is a possible crack in a spent fuel pool, which sits above the reactor containment vessel and was damaged during explosions earlier this week. The containment vessels that hold the actual nuclear reactors, meanwhile, appear to have largely withstood a 9.0-magnitude earthquake, a 30-foot tsunami, explosions, and fires.
"I think GE is a hero in this," says Dr. Meshkati.
Dr. Meshkati says a root-cause analysis traces the current crisis back to the failed diesel generators. The March 11 earthquake and tsunami knocked out electricity to the plant, which triggered the activation of diesel generators that stopped operating within hours. At that point, cooling water was no longer pumped into the reactors to prevent the fuel rods from overheating.
As to why the generators failed to withstand the earthquake and tsunami, Meshkati says that's a question for plant operator Tokyo Electric Power Co. (TEPCO) and the Japanese regulatory body. "Had the diesel generators worked, we wouldn’t be talking today," he says.
[3/16/11] ZAO, Japan >> Japanese military helicopters dumped loads of seawater onto a stricken nuclear reactor Thursday, trying to avoid full meltdowns as plant operators said they were close to finishing a new power line that could restore cooling systems and ease the crisis.
U.S. officials in Washington, meanwhile, warned that the Fukushima Dai-ichi plant in northeastern Japan may be on the verge of spewing more radioactive material because water was gone from a storage pool for spent nuclear fuel rods.
The troubles at several of the plant's reactors were set off when last week's earthquake and tsunami knocked out power and ruined backup generators needed for their cooling systems, adding a major nuclear crisis for Japan as it dealt with twin natural disasters that killed more than 10,000 people and left hundreds of thousands homeless.
A Japanese military CH-47 Chinook helicopter began dumping seawater on the damaged reactor of Unit 3 at the Fukushima complex at Thursday morning (Wednesday afternoon in Hawaii), said defense ministry spokeswoman Kazumi Toyama. The aircraft dumped at least four loads on the reactor, though much of the water appeared to be dispersed in the air.
The dumping was intended both to help cool the reactor and to replenish water in a pool holding spent fuel rods, Toyama said. The plant's owner, Tokyo Electric Power Co., said earlier that the pool was nearly empty, which might cause the rods to overheat.
The comments from U.S. officials indicated there were similar problems at another unit of the Dai-ichi complex.
[3/16/11] FUKUSHIMA, Japan >> Nuclear plant operators trying to avoid complete reactor meltdowns said Thursday that they were close to finishing a new power line that could end Japan's crisis, but several ominous signs have also emerged: a surge in radiation levels, unexplained white smoke and spent fuel rods that U.S. officials said might be on the verge of spewing more radioactive material.
As fear, confusion and unanswered questions swirled around the Fukushima Dai-ichi complex, and Japan suffered myriad other trials from last week's earthquake and tsunami believed to have killed more than 10,000, its emperor took the unprecedented step of directly addressing his country on camera, urging his people not to give up.
"It is important that each of us shares the difficult days that lie ahead," Akihito said Wednesday (Tuesday in Hawaii). "I pray that we will all take care of each other and overcome this tragedy."
The 77-year-old emperor expressed his own deep concern about the "unpredictable" nuclear crisis. "With the help of those involved I hope things will not get worse," he said.
U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko said at a congressional hearing in Washington that all the water is gone from the spent fuel storage pond of Fukushima Dai-ichi's Unit 4 reactor, but Japanese officials denied it. Hajime Motojuku, a spokesman for plant operator Tokyo Electric Power Co., said the "condition is stable" at Unit 4.
Earlier, however, another utility spokesman said officials' greatest concerns were the spent fuel pools, which lack the protective shells that reactors have.
"We haven't been able to get any of the latest data at any spent fuel pools. We don't have the latest water levels, temperatures, none of the latest information for any of the four reactors," Masahisa Otsuki said.
If Jaczko is correct, it would mean there's nothing to stop the used fuel rods from getting hotter and ultimately melting down. The outer shells of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area.
"My understanding is there is no water in the spent fuel pool," Jaczko told reporters after the hearing. "I hope my information is wrong. It's a terrible tragedy for Japan."
He said the information was coming from NRC staff in Tokyo who are working with the utility in Japan. He said the staffers continue to believe the spent fuel pool is dry.
[3/16/11] The emergency at Japan's wrecked nuclear plant appears to be worsening after surging radiation levels forced engineers to temporarily withdraw, losing time in a desperate operation to cool the overheating reactors.
The technicians were dousing the nuclear reactors at the Fukushima Dai-ichi plant with seawater in an effort to cool them when they had to retreat late Wednesday morning local time. They returned in the evening after radiation levels subsided but in the hours between it was not clear what, if any, operations continued.
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High levels of radiation leaked from a crippled nuclear plant in tsunami-ravaged northeastern Japan after a third reactor was rocked by an explosion today and a fourth caught fire in a dramatic escalation of the 4-day-old catastrophe.
Workers were striving to stabilize three reactors at the Fukushima Dai-ichi nuclear plant in Fukushima state that exploded in the wake of Friday's quake and tsunami. Officials said 50 workers, all of them wearing protective radiation gear and working at great personal risk, were still trying to put water into the reactors to cool them.
The crisis at the complex is already the worst nuclear accident since the Chernobyl reactor disaster a quarter-century ago.
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