Fukushima’s operator TEPCO said the water seeping into a trench outside the Number two reactor at Fukushima Daiichi nuclear plant in northeast Japan had a radiation level of more than 1,000 millisieverts per hour.
Up until now, pools of water with extremely high levels of radiation have only been detected within the Fukushima Nuclear reactor buildings themselves. And now the water was found in an underground maintenance tunnel, with one end located about 55m (180ft) from the shore.
Such a high level can cause temporary radiation sickness including nausea and vomiting and far exceeds the 100 millisievert per hour which is generally regarded the lowest amount at which cancer risks are apparent.
Three plutonium isotopes – Pu-238, Pu-239 and Pu-240 – has also been detected in soil at five locations near the crippled plant, but Officials at Tokyo Electric Power Co (TEPCO) says the radioactive metal is not harmful to humans.
Plutonium was used in the fuel mix for only one of the six reactors, number three. The twin discoveries came hours after the government criticised Tepco for issuing incorrect readings from the plant.
TEPCO are now attempting to locate the source of the leak, which is near the turbine building of the Number 2 reactor and around 180 feet from the sea.
“The trench is located outside the building and the water contains radioactive materials,” said Hiro Hasegawa, a spokesman for TEPCO. “”There is normally no water found in this area so it is difficult to compare this to normal levels.”
“But we do not believe it is leaking into the ocean. We are now working out where the cause of the leak is and finding ways to remove the water as soon as possible.”
The discovery of the contaminated trench came one day after officials evacuated the turbine building of the Number 2 reactor when puddles of water inside were found to contain 1,000 millisieverts per hour of radioactivity – 100,000 times the normal level.
A temporary meltdown inside the core of the Number 2 reactor was possibly the cause of the building’s contaminated water, according to Yukio Edano, the chief government spokesman.
“The radiation seems to have come from the fuel rods that were partially melted down and came into contact with the water used to cool the reactor,” he said. He also added that the efforts to prevent the reactors from overheating “must be given priority.”
“If we need to increase water injection, this is what we need to do. If we stop water injection, fuel rod temperatures may increase and that may result in overheating,” Edano said. “But fundamentally we need to drain the water as soon as possible.”
Confusion and unease have been growing in Japan surrounding the nuclear situation due to a string of conflicting reports, alleged safety blunders and miscalculated figures.
Two nuclear plant workers suffered burns last week after stepping in toxic water but were released on Monday from a specialist radiation medical unit.
Speculation surrounding the extent to which the radiation may be leaking into the Pacific Ocean was also mounting after tests last weekend found nearby seawater contaminated 1,850 above legal limits.
More recent tests showed that this figure has dropped, although Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Agency said that he suspects radioactive water from the plant is leaking into the ocean.
However, nuclear experts said that any radiation leaking into the ocean would most likely pose little threat as it would swiftly dissipate.
“In terms of radiation leaking into the sea, this would be diluted very quickly and there would be no particular risk to fish for example, ” said Yoshiaki Oka, a professor at Tokyo’s Waseda University.
Meanwhile, there were calls for an extension to the official evacuation zone on Monday following Greenpeace reports of wider radiation contamination (see the photo above.)
Greenpeace tests in Iitate village, located 25 miles from the nuclear plant and 12 miles outside the evacuation zone, showed radiation levels of up to ten microsieverts per hour.
Referring to the yearly recommended limit of 1,000 microsieverts, Jan van de Putte, a radiation safety expert at Greenpeace, said: “It is clearly not safe for people to remain in Iitate, especially children and pregnant women, when it could mean receiving the maximum allowed annual dose of radiation in only a few days.”
With the spectre of a potential nuclear meltdown 150 miles away, the official blossoming of Tokyo’s cherry trees was met with muted celebrations yesterday.
The normally joyous occasion, which marks the blossom appearing at the capital’s Yasukuni shrine, was overwhelmed by the news that the death toll from the 11 March disaster has climbed above 11,000, with more than 17,339 missing and 170,000 people living in temporary shelters.
Recovery efforts along the 90 miles of blighted coast were further hampered by a strong aftershock yesterday morning registering 6.5 on the Richter scale and prompting a short-lived tsunami warning. [via The Telegraph (UK), CNN and Daily Mail (UK)]