The latest fire to break out at a quake-hit Japanese nuclear power plant is under control, the government says.
“We have received information from TEPCO (the plant’s operator) that the fire and smoke is now invisible and it appears to have gone out of its own accord,” Minoru Ogoda, a spokesman for the state nuclear safety agency says.
The blaze had broken out on Wednesday 16th March on the fourth floor of the number-four reactor at the Fukushima No.1 plant, 250 kilometres northeast of Tokyo.
A fire and explosion hit the same reactor on Tuesday 15th March, causing a crack in the roof.
Japan crisis ‘worst since Chernobyl’
As Japan’s nuclear emergency escalates, the accident at the Fukushima plant now rates six on a seven-point international scale of the world’s worst nuclear disasters.
The accident at Japan’s Fukushima plant now rates six on a seven-point international scale of gravity for nuclear accidents, the head of France’s Nuclear Safety Authority (ASN) said.
The 1979 accident at Three Mile Island in Pennsylvania rates five on an international scale of zero to seven, while Chernobyl is put at seven, the highest.
Japan’s nuclear safety agency has estimated the accident at Fukushima at level four.
“The incident has taken on a completely different dimension. It is clear that we are at level six,” Andre-Claude Lacoste told a press conference.
“The order of gravity has changed,” he said.
Japan battling imminent nuclear disaster
Meanwhile Japanese crews are battling to avert a nuclear disaster and say they may pour water from helicopters to stop fuel rods from being exposed to the air and releasing even more radioactivity.
Radiation near the quake-hit Fukushima No.1 plant has reached levels harmful to health and remains high, officials said, advising thousands of people to stay indoors after two explosions and a fire at the facility.
Four of the six reactors at the crippled facility, 250 kilometres northeast of Tokyo, have now overheated and sparked explosions since Friday’s massive earthquake and tsunami knocked out their cooling systems.
The blasts at the seaside plant have shattered buildings housing the reactors but have apparently not penetrated the steel and concrete containers surrounding the fuel rods, reducing the risk of massive contamination.
Workers have used fire-fighting equipment to pump seawater into the reactors – and fears have spiked sharply after separate containment pools holding spent fuel rods at reactor number four started to heat up, threatening to run dry.
If the water in the deep pools evaporates, this would expose the fuel rods to the air, destroying them and sending radioactive materials into the air.
“We have no options other than to pour water from a helicopter, or to spray water from the ground,” a spokesman for operator Tokyo Electric Power Co (TEPCO) said on television.
“We have to take action tomorrow or the day after.”
The water in the containment pool of reactor number four may have been boiling earlier, Kyodo News reported on Wednesday.
Radiation levels worsening
Worsening levels of radiation forced the company to pull out most of its hundreds of workers who have been battling the emergency.
They later evacuated the plant’s central control room and were now monitoring the site remotely, Kyodo reported.
Tens of thousands have already been evacuated from within a radius of 20 kilometres of the 40-year-old plant, andPrime Minister Naoto Kan urged people living within 10 kilometres of that zone to stay indoors.
“There is no doubt that unlike in the past, the (radiation) figures are at the level at which human health can be affected,” chief government spokesman Yukio Edano said.
There was a danger of further leakage, Kan said.
“Please stay indoors, close windows and make your homes airtight,” Edano urged residents during a press briefing. “Don’t turn on ventilators. Please hang your laundry indoors.”
Radiation levels were monitored at 4.548 millisieverts per hour at 11pm (0100 AEDT) and rose further to 7.966 millisieverts less than an hour later at the plant’s entrance, Jiji Press reported, quoting TEPCO officials.
Levels fluctuated throughout the day.
A single dose of 1000 millisieverts – or one sievert – causes temporary radiation sickness such as nausea and vomiting.
The continuing nuclear crisis has unnerved regional residents already struggling with the aftermath of the quake and tsunami.
Radiation detected in Tokyo
Higher than normal radiation was detected in Tokyo, prompting many people to flee, but a city official said it was not considered at a level harmful to human health and the level fell later in the day.