* Experts warn the situation 'could turn grave'
Japan has declared a state of emergency at a nuclear power plant after its cooling system failed following today's massive earthquake.
So far officials have said there is no leak of deadly radiation from the crippled facility in Onahama city, about 170 miles north-east of Tokyo in the Fukushima prefecture. But around 2,800 residents within a two-mile radius of the plant have been ordered to evacuate the area.
Chief Cabinet Secretary Yukio Edano said the nuclear power plant developed a mechanical failure in the system which cools the reactor after it was shut down in the earthquake.
He said the measure was a precaution, there was no radiation leak and the facility was not in immediate danger.
Plant workers are now scrambling to restore cooling water supplies, but warned there was no prospect for an immediate success.
It is understood that water levels at the facility have not reached critical levels.
But while workers at the nuclear facility battled to restore normal function, a huge fire engulfed a natural gas facility in Chiba Prefecture near Tokyo
Flames soared hundreds of feet into the air from the terminal which is based in the sea and felt the full force of the earthquake.
The nuclear plant's owners confirmed that water levels inside the reactors at its Fukushima-Daiichi nuclear plant were falling but it was working to maintain water levels to avert the exposure of nuclear fuel rods.
Tomoko Murakami, leader of the nuclear energy group at Japan's Institute of Energy Economics, said there did not appear to be an imminent danger of a radiation leak.
'Even if fuel rods are exposed, it does not mean they would start melting right away,' she said.
'Even if fuel rods melt and the pressure inside the reactor builds up, radiation would not leak as long as the reactor container functions well.'
But Mark Hibbs, a nuclear expert at the Carnegie Endowment for International Peace, warned that the situation could turn grave.
'This is no laughing matter,'he said, referring to unconfirmed reports that one or more of the emergency diesel generators for the cooling system were not working.
He said there was serious concern in Japan whether the cooling of the core and removal of residual heat could be assured.
'If that does not happen, if heat is not removed, there is a definite danger of a core melt ... fuel will overheat, become damaged and melt down.'
A spokesman for Tokyo Electric Power, which operates the facility, confirmed that water levels inside the reactors were on a falling trend, but added it was working to maintain water levels to avert the exposure of nuclear fuel rods.
The company has been trying to restore power to its emergency power system so that it can add water to the inside of the reactors, the spokesman added.
The Onahama plant is one of ten nuclear power plants in the Fukushima district.
The quake also started a fire in a turbine building at another nuclear power plant in Onagawa in the neighbouring Miyagi prefecture, but the reactor building was reported to be secure.
Tohoku Electric Power said smoke was observed coming out of the building, which is separate from the reactor, and the cause was under investigation.
The company also said there have been no reports of radioactive leaks or injuries.
The International Atomic Energy Agency, the world’s nuclear watchdog, said today that it was seeking further details about the situation at a Japan’s Fukushima Daiichi nuclear power plant.
'The IAEA is seeking further details on the situation at Fukushima Daiichi and other nuclear power plants and research reactors, including information on off-site and on-site electrical power supplies, cooling systems and the condition of the reactor buildings,' the IAEA said in a statement.
Professor Tim Abram, a nuclear fuel technology expert at Manchester University, said that as long as a reactor is shut down, it is considered 'benign' until bosses decide it is safe to be turned back on.
He said: 'All nuclear facilities are designed to withstand seismic events.
'The magnitude of the seismic event that they are designed to withstand varies from country to country.
'It’s not done on a case of a particular point on the Richter scale, but instead on the basis of probability of earthquakes in particular countries. In somewhere like Japan, the probability will be much, much higher.'
The professor said although a failure in the cooling system of a nuclear power plant was 'unexpected', once a reactor is shut down, the heat levels plummet anyway.
He said: 'Reactors shut themselves down automatically when something called "ground acceleration" is registered at a certain point, which is usually quite small. It will instantly drop control rods into the core.'
At that stage, he said, the heat of a nuclear station drops dramatically in a matter of seconds, and within a couple of minutes, it is down to under five per cent of its normal temperature.
He added: 'That’s a tiny, tiny percentage of the usual power output of the core.
'You still need to get rid of the decay heat, but the system is very capable of doing that.
'It’s a bit like a braking system on a car failing when it is travelling at 3mph, when it is designed to slow it down from 120.'
1 comments:
What is the pressure reading?
Do they have circulation?
Is the core covered?
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