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"Meltdown" SEE para 10 plus Telegraph article 12th May below yahoo post
New setbacks at Japan nuclear plant
http://uk.news.yahoo.com/water-leaks-japan-nuclear-plant-064619255.html
Japan's stricken Fukushima nuclear plant has been hit by new setbacks, its operator said Thursday, including a water leak from a reactor vessel and another spill of contaminated water into the ocean.
The government ordered the cull of thousands of cattle and other livestock roaming the 20-kilometre (20-mile) evacuation zone around the nuclear plant, which was abandoned when the disaster started two months ago.
Japan apologised to its neighbours about the toxic leak into the Pacific as food safety concerns widened, with Greenpeace reporting above-limit radiation in seaweed and a region south of Tokyo issuing a similar warning about tea.
The update from Tokyo Electric Power Company (TEPCO) came as emergency crews battle to bring the tsunami-hit and radiation-leaking atomic plant into stable "cold shutdown" some time between October and January.
The giant ocean wave triggered by the massive magnitude-9.0 seabed quake on March 11 knocked out the plant's water cooling systems, leading fuel rods inside several reactors to partially melt and sparking explosions.
Workers have since doused reactors and fuel rod pools with water to stop them from overheating and releasing far greater amounts of radiation.
TEPCO on Thursday said new measurements taken after workers in protective suits fixed gauges in the badly-hit reactor one building had indicated that the water pumped into the pressure vessel had quickly leaked out.
The water level had fallen below the bottom end of the four-metre (12 foot) long nuclear fuel rods, leaving them fully exposed to the air.
However, the vessel's relatively low outside temperature of 100-120 degrees Celsius (212-248 degrees Fahrenheit) indicated that the rods had now dropped to the bottom of the vessel and were submerged under water, TEPCO said.
Environmental group Greenpeace said the news showed that at least some earlier water level readings had been entirely wrong and that "the situation is clearly far more serious than previously reported".
"As the fuel rods were fully exposed and subsequently melted, it is highly likely that the core?s integrity is compromised and that there is a larger amount of melted fuel at the bottom of the reactor pressure vessel," said Jan Beranek, the group's international nuclear campaign leader.
TEPCO has been injecting around seven tons of water an hour into the reactor one pressure vessel and plans to flood the wider containment vessel around it.
The dousing operations -- in which tens of thousands of tons of water have been injected with fire trucks, concrete boom pumps and other systems -- have created massive amounts of highly contaminated runoff water.
After earlier ocean spills, TEPCO said runoff had again leaked into the sea from a concrete pit near reactor three, one of the plant's six units.
Samples of seawater taken near the plant contained caesium-134 at a concentration 18,000 times the permitted level, the utility said, adding that the spill had been stopped by filling the pit with concrete.
Top government spokesman Yukio Edano called the leak "deplorable" and apologised to the fishing industry and to neighbouring countries.
Greenpeace, which has sent its Rainbow Warrior flagship to take samples of marine life and water off the plant, called on the government to undertake comprehensive radiation testing of seaweed along the Fukushima coast.
Initial tests of 22 seaweed samples collected at distances up to 65 kilometres (40 miles) out to sea from the plant "registered significantly high levels of radioactive contamination," the group said.
Ten seaweed samples showed levels of over 10,000 becquerels per kilogramme, the group said. It did not specify whether the contamination was from iodine-131 or caesium-137 -- the official safety limits for which are 2,000 and 500 becquerels per kilogramme respectively.
Meanwhile, Kanagawa prefecture southwest of Tokyo said it was recalling its tea after measuring about 570 becquerels of caesium per kilogramme in leaves grown in Minamiashigara city -- compared to the legal limit of 500.
"We have not specified the source of the radiation," said Kangawa agriculture official Hideto Funahashi, "but we cannot imagine any other source than the nuclear power plant."
Daily Telegraph
Nuclear meltdown at Fukushima plant
One of the reactors at the crippled Fukushima Daiichi power plant did suffer a nuclear meltdown, Japanese officials admitted for the first time today, describing a pool of molten fuel at the bottom of the reactor's containment vessel.
Engineers from the Tokyo Electric Power company (Tepco) entered the No.1 reactor at the end of last week for the first time and saw the top five feet or so of the core's 13ft-long fuel rods had been exposed to the air and melted down.
Previously, Tepco believed that the core of the reactor was submerged in enough water to keep it stable and that only 55 per cent of the core had been damaged.
Now the company is worried that the molten pool of radioactive fuel may have burned a hole through the bottom of the containment vessel, causing water to leak.
"We will have to revise our plans," said Junichi Matsumoto, a spokesman for Tepco. "We cannot deny the possibility that a hole in the pressure vessel caused water to leak".
Tepco has not clarified what other barriers there are to stop radioactive fuel leaking if the steel containment vessel has been breached. Greenpeace said the situation could escalate rapidly if "the lava melts through the vessel".
However, an initial plan to flood the entire reactor core with water to keep its temperature from rising has now been abandoned because it might exacerbate the leak. Tepco said there was enough water at the bottom of the vessel to keep both the puddle of melted fuel and the remaining fuel rods cool.
Meanwhile, Tepco said on Wednesday that it had sealed a leak of radioactive water from the No.3 reactor after water was reportedly discovered to be flowing into the ocean. A similar leak had discharged radioactive water into the sea in April from the No.2 reactor.
Greenpeace said significant amounts of radioactive material had been released into the sea and that samples of seaweed taken from as far as 40 miles of the Fukushima plant had been found to contain radiation well above legal limits. Of the 22 samples tested, ten were contaminated with five times the legal limit of iodine 131 and 20 times of caesium 137.
Seaweed is a huge part of the Japanese diet and the average household almost 7lbs a year. Greenpeace's warning came as fishermen prepared to start the harvest of this season's seaweed on May 20.
Inland from the plant, there has been a huge cull of the livestock left inside the 18-mile mandatory exclusion zone with thousands of cows, horses and pigs being destroyed and some 260,000 chickens from the town of Minamisoma alone. The Environment ministry has announced, however, that it will attempt to rescue the thousands of pets that were left behind when residents were ordered to evacuate. At least 5,800 dogs were owned by the residents of the zone, although it is unclear how many remain alive, two months after the earthquake struck.
