Meanwhile, Japan's nuclear safety agency said two workers were missing at the stricken plant's No. 4 reactor, where a fire broke out Wednesday.
Guardian UK - The workers were ordered to leave the facility after the level of radiation at the plant soared to 10 millisievert per hour - above the level considered harmful to human health – possibly as a result of radioactive substances being emitted from the No. 2 reactor.
Officials from the nuclear and industrial safety agency said that 70% of fuel rods at the No. 1 reactor had been significantly damaged, as well as 33% of rods at the No. 2 reactor. The cores of both reactors are believed to have partially melted, Kyodo news agency said.
The Second Unit 4 fire - The nuclear safety agency reported that flames and smoke were no longer visible half an hour later, but were unable to confirm that the fire had been extinguished.
The No. 4 reactor is an increasing cause for concern. Tepco believes that the storage pool may be boiling, raising the possibility that exposed rods will reach criticality. "The possibility of re-criticality is not zero," a Tepco spokesman said.
Yesterday the government ordered 140,000 people living within a 30-kilometre radius of the plant to remain indoors after a spike in radiation levels. A further 70,000 residents had already been moved to safe distances. The government said it had no immediate plans to widen the evacuation zone.
The crisis unfolding in Fukushima continued to raise anxiety levels in Tokyo, 50 kilometres to the south. Radiation levels in the capital was 10 times higher than normal on Tuesday evening, but posed no health hazard, the government said.
The meteorological agency said winds near the power plant would blow from the northwest and out into the Pacific Ocean on Wednesday. The winds were expected to strengthen in the afternoon, the agency added.
Early Wednesday morning recordings at Fukushima Daiichi topped out at a radiation exposure level that nuclear experts called alarmingly high but later fell to a level of 60 microsieverts per hour, a level that still requires limiting exposure, according to experts.
The currently reported Japanese radiation measurements are "well below" the U.S. Nuclear Regulatory Commission's dose limits of 10,000 microsieverts per nuclear event, according to an NRC statement. The average American receives an annual exposure of 6,200 microsieverts from background and man-made radiation, such as X-rays.
The annual occupational limit for workers who deal with radiation on the job is 50,000 microsieverts, according to an NRC spokesman.
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