The Fukushima incident is given the highest rating of 7, but the International Atomic Energy Agency says the amount of radioation at Chernobyl was ‘far higher’.
Japan’s decision to raise the severity level of its Fukushima nuclear accident to the highest notch of 7 does not mean it is comparable to Chernobyl, a senior IAEA official has said.
Denis Flory told a news conference: “This is a totally different accident.” He said the amount of radiation released at Chernobyl in 1986 was far higher.
The World Health Organisation also said the risk to public health from the incident was no worse after a change in the disaster’s status.
“Our public health assessment is the same today as it was yesterday,” WHO spokesman Gergory Hartl said. “At the moment there is very little public health risk outside the 30-kilometre (evacuation) zone”.
He said the higher severity rating was the result of combining the amounts of radiation leaking from three reactors and counting them as a single incident, he said.
On Tuesday, an official at Japan’s Nuclear and Industrial Safety Agency raised the Fukushima accident to a 7, the worst on the internationally recognised scale, due to the overall levels of radiation released into the air and sea.
As aftershocks continued to rock Japan, a major fire also broke out at the nuclear plant (pictured). Engineers managed to extinguish the blaze but its very existence is a blow to those hoping the reactors had been sufficiently cooled to avoid further problems.
Almost a month on from the earthquake and tsunami which devastated much of north east Japan and damaged the Fukushima plant, Japan also increased the evacuation zone around the plant in a sign of the severity of the accident.
As Japan struggles to contain the nuclear disaster, it is also still coping with the twin impact of 11 March earthquake and tsunami. Up to 28,000 people may have died, with 150,000 made homeless. The estimated cost stands at $300bn – the world’s most expensive disaster.
Disaster still gathering pace
Even whilst I was in the area around Fukushima three and a half weeks ago, the nuclear operators seemed vague, indistinct, even unwilling to admit what was actually happening, writes Jon Snow.
Today I feel more forgiving, I suspect they simply did not know, and still do not know.
The exclusion zone is being expanded. Three communities beyond even twenty miles are to be evacuated this week…two more inside the zone have been told to pack up today. Twenty one workers at the plant have now exceeded the radiation levels any man is supposed to be able to tolerate without serious life threatening consequences.
The disaster that is Fukushima is still gathering pace...
Read more on Snowblog: disaster that is Fukushima still gathering pace
The picture, left, shows shots of the Fukushima nuclear plant before and after the tsunami struck on 11 March.
Previously, the Fukushima nuclear crisis had been rated a 5, in line with the Three Mile Island incident in the United States in 1979. According to the International Atomic Energy Agency (IAEA), a level 5 accident is a limited release of radioactive material, with several deaths, whereas a level 7 means a major release of radiation with widespread health and environmental impact.
Some experts suggested the rating was hysterical, pointing out that Chernobyl blew its containment vessels and spewed radioactive material into the atmosphere, while the Fukushima buildings remain mostly intact and the leaks steady.
However others said the rating was a sign of the seriousness of the accident.
Kenji Sumita, a nuclear expert at Osaka University, said: “Raising the level to 7 has serious diplomatic implications. It is telling people that the accident has the potential to cause trouble to our neighbours.”
Institute of Electrical and Electronics Engineers member Victor J. Petrelli, who helped design a nuclear plant in Illinois, in the United States, told Channel 4 News that the solution to the ongoing problem would be to bury or concrete the reactors.
“If the containment leak cannot be mitigated in any other way, the most likely scenario would be to pump the area full of concrete which would seal the containment leak as it hardens,” he said.
He said that the time for cooling the reactors was over, if the radiation continued to leak.
“Stop trying to cool the reactor with liquids. Bury it,” he said.
Long term, he said the radiation risks and how the authorities cleared them up depended on the type of material leaking.
“It depends on what radioactive material is leaking – specifically its half life. Iodine-131 has only an eight day half life before becoming harmless, whereas plutonium-239 has a half life of 24,000 years. Isolated trace quantities of plutonium found in the soil could be simply dug up and moved to a long term storage area.
“But note that ingesting plutonium is not very harmful, however breathing it is harmful as it is very toxic to the lungs. So eating spinach fertilized with plutonium laced soil would not be very harmful wherein inhaling dust from the soil would be.”
Eventually, the accident will be cleared up and dealt with, he said.
“Long term containment is to encase the reactor in concrete which was done at Chernobyl,” he said.
“Now, some 30 years later, nature has reclaimed the Chernobyl area with plant and animal life. So apparently Nature believes the area to now be safe.”
The Japanese authorities said the amount of radiation released into the atmosphere was around 10 per cent that of Chernobyl – but plant operator Tokyo Electric Power (Tepco) warned that the release could eventually exceed the 1986 disaster if leaks were not fixed.
People living in five communities in areas beyond the 20km exclusion zone have also been encouraged to leave the area because of the long-term risks to health.
In Pictures – Fukushima nuclear crisis worsens