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International Atomic Energy Agency says radioactivity released into atmosphere from Japan

March 15, 2011

Nuke plant blasts raise radiation threat


The Japanese government says radiation levels near a quake-stricken nuclear power plant are now harmful to human health, after a further two explosions and a fires at the facility.

“There is no doubt that unlike in the past, the figures are the level at which human health can be affected,” said chief government spokesman Yukio Edano.

The International Atomic Energy Agency (IAEA) says it has been informed by Japanese authorities the spent-fuel storage pond at the No. 4 reactor is on fire and radioactivity is being released directly into the atmosphere.

It is unclear whether this is a new fire, or a report of the fire which started earlier today but was extinguished. Japanese authorities say there is a possibility the fire was caused by a hydrogen explosion.

Mr Edano says radiation levels at the nuclear plant have reached as high as 400 milisieverts an hour, thousands of times higher than readings taken before the latest blasts.

Mr Edano says radiation levels as at 10.22am (local time) were 30 millisieverts between the No. 2 and the No. 3 reactors, 400 millisieverts near No. 3 and 100 millisieverts near No. 4.

Earlier prime minister Naoto Kan warned the risk of more radioactive leakage was rising and urged people living within 30 kilometres of the plant to take safety precautions.

“Depending on what happens at the power plant we would like to ask you to remain indoors at your home or in your offices,” he said.

“We would like to ask you to remain indoors and avoid going outside.”

Kyodo says “minute levels” of radiation have been detected in Tokyo, quoting the metropolitan government, and radiation levels in Saitama, near Tokyo, were 40 times normal levels, quoting the local government.

“We don’t consider it to be at a level where the human body is affected,” said Sairi Koga, an official of the Tokyo Metropolitan Government.

Radiation levels in Kanagawa prefecture, west of Tokyo, were also briefly up to nine times the normal level, Kyodo reported, quoting the prefecture government.

But the news agency says it is not immediately clear if the detections are related to the quake-damaged nuclear plant.

A single dose of 1,000 millisieverts – or one sievert – causes temporary radiation sickness such as nausea and vomiting, according to the World Nuclear Association.

A dose of 5,000 millisieverts would kill about half those receiving it within a month.

Tens of thousands have already been evacuated within a 20 kilometre radius around the Fukushima No. 1 plant, 250 kilometres north-east of Tokyo.

Mr Edano says an explosion at the No. 4 reactor, which contains spent fuel rods, was caused by a build-up of hydrogen.

“Spent nuclear fuel in the reactor heated up, creating hydrogen and triggered a hydrogen explosion,” he said.

Mr Edano says radioactive substances were leaked along with the hydrogen.

Prior to the explosion the reactor was on fire but Kyodo and other local media are reporting the blaze has been extinguished.

The government also reported apparent damage to part of the container shielding the No. 2 reactor, but it was unclear whether this resulted from the blast.

Mr Edano says “damage appears on the suppression pool” – the bottom part of the container that contains water used to cool the reactor and control air pressure inside.

Similar hydrogen blasts had hit the No. 1 and No. 3 reactors on Saturday and Monday.

Buildings housing four of the six reactors at the plant, which opened in 1971, have now been hit by explosions.

Mr Edano says sea water is currently being pumped into reactors 1, 2 and 3 – all of which have experienced overheating – and pressure levels at these reactors were stable.

Officials have not reported the kind of radiation leakage that would accompany a major meltdown.

The French embassy in the capital warned in an advisory that a low level of radioactive wind could reach Tokyo within 10 hours.

However, a Japanese Meteorological Agency official says winds over the nuclear plant are blowing slowly in a south-westerly direction that includes Tokyo, but will shift westerly later on Tuesday.

Japan has already asked the UN atomic watchdog to send a team of experts to help stave off a nuclear emergency following the massive quake and tsunami.

The nuclear crisis comes as Japan struggles to deal with the aftermath of the earthquake and tsunami, which are feared to have killed more than 10,000 people.

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