本帖最後由 peter236 於 2011-3-15 20:05 編輯
http://www.bbc.co.uk/news/world-asia-pacific-12755739
15 March 2011
Fukushima workers withdraw after radiation spikes
A spike in radiation levels at Japan's stricken Fukushima nuclear plant has forced workers to suspend their operation, a government spokesman says.
He was speaking after smoke was seen rising from reactor three. Earlier, a blaze struck reactor four for the second time in two days.
Friday's 9.0-magnitude earthquake and tsunami, which killed thousands, damaged the plant's cooling functions.
The site has also been hit by four explosions, triggering radiation leaks.
'On standby'
On Wednesday, Japanese Cabinet Secretary Yukio Edano said at a news briefing that workers at Fukushima had been withdrawn following the rise in radiation levels. It is believed that about 50 employees had been working at the plant to try to stabilise its four reactors.
Mr Edano also said that the radiation levels were now falling: from 1,000 millisieverts on Wednesday morning to 600-800.
But that was still more than average, Mr Edano said, adding that "the workers cannot carry out even minimal work at the plant now. Because of the radiation risk, we are on standby."
Map of exclusion zone around Fukushima Daiichi nuclear power plant - 15 March 2011
Officials had earlier warned people within 20-30km (12-19 miles) of the site to either leave the area or stay indoors. But they now say that that there are no plans to extend the evacuation zone.
The new fire at reactor four was reported early on Wednesday. Three hours later, Japan's nuclear safety agency said flames could no longer be seen.
But white smoke was later seen rising from reactor three. Officials are investigating the cause of both incidents and the damage done, with Mr Edano saying the smoke was probably steam from the evaporation of water, which caused the higher radiation.
"A part of the containment vessel is broken and it seems like the vapour is coming out from there. So... [it] appears to be that vapour is coming out from the broken part.
"And I'm not saying this with absolute certainty, but I'm saying this with an assumption. There's a high probability of such a phenomenon going on," Mr Edano said.
'Boiling pool'
Twenty-four hours earlier, on Tuesday morning, another fire broke out in the spent fuel storage pond at reactor four.
The reactor had been shut down before the quake for maintenance, but its spent fuel rods were still stored on the site.
Kyodo news agency says the storage pool may be boiling and further radiation leaks are feared.
The Tokyo Electric Power Co (Tepco), which operates the Fukushima plant, said it may pour water and fire retardant from helicopters to stop fuel rods from being exposed to the air and releasing even more radioactivity.
The crisis at the plant - which has six nuclear reactors - began when the earthquake struck. Explosions rocked the buildings housing reactors one and three on Saturday and Monday.
On Tuesday morning, a third blast hit the building of reactor two, while a fourth damaged the building of reactor four.
Officials say the explosions at the first three reactors, and possibly the fourth as well, were caused by a buildup of hydrogen.
Mr Edano has said that cooling seawater is being pumped into reactors one and three - which are returning to normal - and into reactor two, which remained unstable. |
發表於 2011-3-15 19:41
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