by tubby » Tue Mar 15, 2011 9:24 am
Radiation from Japan's quake-stricken Fukushima Daiichi nuclear plant has reached harmful levels, the government says.
The warning comes after the plant was rocked by a third blast which appears to have damaged one of the reactors' containment vessels for the first time.
If it is breached, there are fears of more serious radioactive leaks.
Officials have extended the danger zone, warning residents within 30km (18 miles) to evacuate or stay indoors.
As radiation levels near the plant rise, people are being checked for exposure
The crisis was sparked by a 9.0-magnitude quake and tsunami on Friday.
'Don't go outside'
On Tuesday morning, reactor 2 became the third to explode in four days at the Fukushima Daiichi plant - 250km (155 miles) north-east of Tokyo.
A fire also briefly broke out at the plant's reactor 4 on Tuesday and is believed to have led to radioactive leaks.
Reactor 4 had been shut down before the quake for maintenance but its nuclear fuel rods are still stored on the site.
Radiation levels in the Japanese capital were reported to be higher than normal, but officials said there were no health dangers.
In a televised address, Prime Minister Naoto Kan said: "There is still a very high risk of more radiation coming out."
He added that the last remaining people within the existing 20km (12 mile) exclusion zone around the plant must leave.
Those living between 20km and 30km were also at risk and should not leave their homes.
"Now we are talking about levels that can impact human health," said Chief Cabinet Secretary Yukio Edano.
He told residents: "Please do not go outside. Please stay indoors. Please close windows and make your homes airtight.
"Don't turn on ventilators. Please hang your laundry indoors."
No-fly zone
Japan also announced a 30-km no-fly zone around the reactors to prevent planes spreading the radiation further afield.
Radiation levels around Fukushima for one hour's exposure rose to eight times the legal limit for exposure in one year, said the plant's operator, the Tokyo Electric Power Co (Tepco).
The radiation reading at 0831 local time (2331 GMT) climbed to 8,217 microsieverts an hour from 1,941 about 40 minutes earlier, Tepco said. The annual legal limit is 1,000 microsieverts.
Shares on the Tokyo stock exchange plummeted 14% before recovering slightly. The leading Nikkei index ended the day 10.55% lower. It had already fallen by 7% on the previous day.
On Monday, a hydrogen blast at the Fukushima plant's reactor 3 was felt 40km (25 miles) away. It followed a blast at reactor 1 on Saturday.
All explosions have followed cooling system breakdowns. Engineers are trying to prevent meltdowns by flooding the chambers of the nuclear reactors with seawater.
Japan's nuclear safety agency said it suspects Tuesday's blast may have damaged the vessel that holds reactor 2.
The BBC's Chris Hogg in Tokyo says that would make it a more serious incident than the previous explosions, which were thought just to have damaged the buildings that housed the reactors.
Meanwhile, five days after the tsunami triggered by the earthquake, the relief operation is continuing.
The latest official death toll stands at about 2,400 - but some estimates suggest at least 10,000 may have been killed.
Thousands are still unaccounted for - including hundreds of tourists - while many remote towns and villages have not been reached.
More than 500,000 people have been made homeless.
The government has deployed 100,000 troops to lead the aid effort.
The UK Foreign Office has updated its travel advice to warn against all non-essential travel to Tokyo and north-eastern Japan. British nationals and friends and relatives of those in Japan can contact the Foreign Office on +44(0) 20 7008 0000.