Radiation levels rose today in Japan's Fukushima nuclear plant where a new fire broke out, forcing the government to withdraw emergency workers engaged in efforts to cool overheating reactors at the quake-stricken site as authorities scrambled hard to contain the spiralling atomic crisis.
Some 50 employees were believed to be working at the plant, 220 km north of Tokyo, to avert a meltdown when the radiation levels surged suddenly.
The government's nuclear safety agency said the radiation levels briefly reached 10 millisievert per hour at the plant's entrance at 10:40 am local time, but added that it was possibly due to radioactive substances emitted from the No. 2 reactor.
Authorities were also considering spraying boric acid by helicopters to prevent spent nuclear fuel rods at another troubled reactor, No.4, from reaching criticality again, restarting a chain reaction, Kyodo news agency reported.
Around 730 workers were evacuated from the site yesterday following hydrogen explosions at the reactors, according to Tokyo Electric Power Company (TEPCO), the operator of the plant.
The remaining employees at the Fukushima Daiichi plant were withdrawn today following the sudden rise in radiation levels, Chief Cabinet Secretary told a news briefing.
The work was suspended temporarily at the plant, where an estimated 70% of the nuclear fuel rods have been damaged at the No.1 reactor and 33% at the No.2 reactor.
"Workers cannot carry out even minimal work at the plant now. Because of the radiation risk, we are on standby," Edano said
The cores of both reactors are believed to have partially melted with their cooling functions lost in the wake of Friday's magnitude 9.0 earthquake and massive tsunami that have left over 11,000 people dead or unaccounted for.
At the No.2 reactor, the pressure-suppression chamber connected to its containment vessel was damaged following an explosion yesterday.
Earlier today, a fire broke out again at the No.4 reactor, which was already posing the risk of leaks of high-level radioactive material, but flames were no longer visible about 30 minutes later, according to TEPCO.
The No.3 reactor was, however, drawing more attention after live TV footage of the plant showed white smoke coming out around 10 am local time, Kyodo reported.
"There is a possibility that the No.3 reactor's containment vessel is damaged," Edano said, indicating that radioactive steam may be spreading outside.
He, however, said the government had no plans to expand the evacuation area of within 20 kilometers from the plant for now.
