THE OPERATORS OF the troubled Fukushima I nuclear power plant were forced to call all workers out of the facility for several hours overnight, after a significant spike in radiation was noticed.
A Japanese government spokesman said levels of radiation had increased after a second fire broke out at reactor 4 – where a fire broke out in a containment pool for spent nuclear rods yesterday – and after smoke was observed coming from the building housing reactor number 3.
About 50 employees had been working in the plant to try and get its reactors to cool down at the time, spokesman Yukio Edano told a news briefing.
The evacuation order was being lifted at the time of publication. Two staff are still missing, however, following the explosion at reactor 4 that triggered the first fire yesterday.
Radiation levels being observed at the gate of the complex were now standing at between 0.6 to 0.8 millisieverts (mSv) per hour – a total still almost 2,000 times the usual annual dosage.
“Workers cannot carry out even minimal work at the plant now. Because of the radiation risk, we are on standby,” Edano said.
The second fire in reactor 4 has been extinguished, the International Atomic Energy Agency said, and local reports added that flames or smoke could not been seen any longer.
The smoke seen billowing from reactor 3 – which was thought to have emerged unharmed after its outermost containment building exploded on Sunday – is thought to be condensed steam emerging from the evaporation of water.
Seawater is still being pumped into reactors 1 and 3, and Edano said the tactic seemed to have be working, with temperatures there now returning to normal. Water is also being pumped into reactor 2, which is less stable.
Reactor 4 had been offline at the time of the earthquake and resulting tsunami last Sunday, but used nuclear fuel was still being held on site.
The plant’s other two reactors – numbers 5 and 6 – were both also offline, but the IAEA said the level of cooling fluid in reactor 5 had fallen by 40cm in five hours yesterday, leaving only two metres of cooling fluid left.
A diesel back-up generator from reactor 6 is being used to try and restore cooling facilities to reactor 5.
Two workers are missing after the first fire at reactor 4, which is thought to have been caused by a hydrogen explosion.
Japanese authorities say 70 per cent of the nuclear rods in reactor 1 have been damaged by the week’s events, while the Kyodo news agency said another reactor – though it could not say which – was 33 per cent damaged.
Japan’s Emperor Akihito has thanked the efforts of his country’s people, and of those overseas, in relief work.