UK | Japan: Crippled nation on nuclear knife-edge

Posted on March 14, 2011

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UK | THE SCOTSMAN | 14 March 2011

JAPAN’S unstable nuclear reactors are at serious risk of another major explosion as the Fukushima plant threatens to send radioactive material spewing well beyond the current exclusion zone, a leading nuclear expert has warned.

Further fears have been raised over the safety of two other nuclear power plants following the devastating earthquake and tsunami which hit Japan three days ago.A state of emergency was declared by the International Atomic Energy Agency (IAEA) at the Onagawa site in northern Japan after high levels of radiation were recorded in the area.A cooling pump also failed at a third nuclear plant in Tokai, 120km north of Tokyo.Last-ditch attempts to cool down two of the three nuclear reactors at the Fukushima-Daiichi plant were ongoing last night. Earlier bids to prevent overheating of the Number 3 reactor failed.Masashi Goto, a former nuclear power plant designer, told a press conference in Tokyo that the consequences of a serious meltdown “would be tremendous”, adding that he believed such a scenario was highly likely.The Japanese government yesterday admitted another explosion at Fukushima-Daiichi – this time at Reactor 3 – was a possibility but tried to play down that likelihood. If nuclear reactors overheat, the containers that house the core could melt, or explode, sending enormous quantities of radioactive material into the atmosphere.

Mr Goto said the reactors at Fukushima-Daiichi were suffering pressure build-ups way beyond that for which they were designed, creating a severe risk of a second explosion.

The first explosion occurred in the early hours of Saturday morning, UK time, destroying a building that housed a nuclear reactor.

The Japanese authorities, who have come under attack for failing to provide enough information to the public, yesterday confirmed there had been a fuel melt in one of the reactors at the troubled plant.

It has emerged that the third reactor to suffer a failure in its cooling mechanism contained the controversial Mox fuel, which is in part made of plutonium and is thought to be more dangerous in the event of a serious meltdown.

Radiation of up to 700 times the normal level has been found at the Onagawa power plant north of Fukushima – although the government insisted that it was fallout from the radiation leak at Fukushima, rather than a separate incident at Onagawa, which was engulfed by a 21-foot wave when the tsunami hit the area on Friday.

“First I was worried about the quake,” said Kenji Koshiba, a construction worker who lives near the Fukushima plant. “Now I’m worried about radiation.”

He spoke at an emergency centre in Koriyama town located near the site.

Around 190 people, including 60 elderly patients and medical staff who had been waiting for evacuation in the nearby town of Futabe, and 100 others evacuating by bus, might have been exposed to radiation, said Ryo Miyake, a spokesman from Japan’s nuclear agency.

The severity of their exposure, or if it had reached dangerous levels, was not clear. Radiation sickness can cause symptoms including vomiting, diarrhoea, headaches and fever, while at higher levels of radiation, people suffer damage to organs, which can usually be fatal.

Tokyo Electric Power Company, which owns the plant, said radiation levels at Fukushima-Daiichi, 150 miles north of Tokyo, have risen above the safety limit but posed no “immediate threat” to human health.A small amount of potentially toxic iodine and caesium were detected outside the blast site over the weekend, prompting authorities to set up a 12-mile exclusion zone around Fukushima-Daiichi and a six-mile zone around another nuclear facility close by in a bid to reduce the risk of radiation to the public.Officials said one of two pumps being used to cool the water of a suppression pool for the nuclear reactor at Tokai, in Ibaraki prefecture, had failed but that the back-up pump was working.”Japanese authorities have informed the IAEA that the first, or lowest, state of emergency at the Onagawa nuclear power plant, more then 100km north, has been reported by Tohoku Electric Power Company,” said a spokesman for the IAEA.Mr Goto said a worst-case scenario for Japan would be an explosion of Fukushima-Daiichi’s nuclear core.”It is difficult to say (exactly what would happen], but that would be a core meltdown,” he said. “If the rods fall and mix with water, the result would be an explosion of solid material like a volcano spreading radioactive material.”Steam or a hydrogen explosion caused by the mix would spread radioactive waste more than 50km. Also, this would be multiplied. There are many reactors in the area so there would be many Chernobyls.”The incident, the worst since that at Chernobyl in 1986, has been rated a “4” on the International Nuclear and Radiological Event Scale, compared to the disaster in the Ukraine which was ranked the highest level of “7”, and the nuclear meltdown at Three Mile Island in Pennsylvania in 1979, which was said to be a “5”.

He added that the government should have issued more information about the “venting” it had carried out at Fukushima-Daiichi to reduce pressure. “There has not been enough information about the hydrogen being vented,” he said. “We don’t know how much was vented and how radioactive it was.”

Mr Goto warned that the reactors at Fukushima-Daiichi were suffering pressure build-ups far beyond that for which they were designed.

The third reactor, where the authorities were yesterday battling to control the building pressure inside the container, contains a fuel called Mox – a mixture of plutonium oxide and uranium oxide – which was long opposed in Japan as it is thought to be more dangerous than conventional nuclear fuel and could deliver twice the radioactive fallout from any meltdown.

The fuel was unused at the reactor for ten years following a legal dispute with local residents and campaigners – and was only brought into use last summer.

“You have a very serious situation,” said Scottish nuclear expert Shaun Burnie, adding that there were also signs of problems at Fukushima-Daiina, around 10km away from the other plant.

“You have a situation now where there is a very controversial fuel in a reactor which is now going through an early stage of meltdown. It is a very bad scenario. In the event of an accident, particularly a loss of coolant, as we have here, it is harder to control the reactions in the vessel as plutonium burns at a higher temperature.

“In the worst-case scenario, if they are not able to sustain the cooling operations, you would have fuel melt and at a certain point the potential of plutonium and uranium melted fuel dropping down into the base of the reactor and exploding. At which point, you have a large amount of the radioactive inventory in the reactor.”Japan’s meteorological agency has said the wind that was yesterday blowing over the Fukushima plant was due to blow from the west last night, pushing any radioactivity towards the Pacific Ocean.Earlier, the wind was blowing from the south, raising concerns radioactivity could affect residential areas.”Radiation levels are higher around Onagawa, but it is still not clear why,” added Mr Burnie.

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