Tokyo,April 12:Engineers were fighting a fire at Japan’s crippled nuclear plant on Tuesday as another major aftershock rocked eastern Japan, swaying buildings in central Tokyo and closing Narita airport runways.
Japan is considering raising the severity level of its nuclear crisis to put it on a par with the Chernobyl accident 25 years ago, the worst atomic power disaster in history, Kyodo news agency reported on Tuesday.
Operator of the crippled Fukushima Daiichi nuclear plant, 240 km (150 miles) north of Tokyo, said on Tuesday that its workers were fighting a fire near damaged reactor No. 4.
It was unclear how serious the fire was.
“Flames and smoke are no longer visible but we are awaiting further details regarding whether the fire has been extinguished completely,” said a spokesman for Tokyo Electric Power Co (TEPCO).
News of the fire came only minutes after a 6.3 aftershock struck off the coast of Chiba, 77 km (48 miles) northwest of Tokyo. Kyodo said Japan’s main international airport Narita closed runways for checks but later resumed flights.
An aftershock measuring 6.6 quake hit Fukushima prefecture on Monday evening temporarily cutting power and forcing workers to evacuate the nuclear plant.
Japan’s Nuclear Industry and Safety Agency (NISA) said the Fukusihima aftershock, which killed one man and knocked out power to 220,000 households, did not damage the nuclear plant.
There have been hundreds of aftershocks since March 11 when a massive 9 magnitude earthquake and 15 meter tsunami hit northeast Japan, plunging the country into its worst crisis since World War Two.
Nearly 28,000 Japanese are dead or missing and the world’s third-largest economy is reeling with power blackouts, factory c closures and cuts to supply lines.
The Kyodo reported on Tuesday that the high levels of radiation that have been released by the Fukushima Daiichi plant meant it could raise the severity level from 5 to the highest 7, the same as the 1986 Chernobyl accident.
Japan had previously assessed the accident at reactors operated by TEPCO at level 5, the same level as the Three Mile Island accident in the United States in 1979.
Kyodo said the government’s Nuclear Safety Commission had estimated that at one stage the amount of radioactive material released from the reactors in northern Japan had reached 10,000 terabequerels per hour of radioactive iodine 131 for several hours, which would classify the incident as a major accident according to the INES scale.
The International Nuclear and Radiological Event Scale (INES), published by the International Atomic Energy Agency, ranks nuclear incidents by severity from 1 to a maximum of 7.
Kyodo did not say when the big increase in radiation had happened but quoted the commission as saying the release had since fallen to under 1 terabecquerel per hour.
The commission also released a preliminary calculation for the cumulative amount of external exposure to radiation, saying it exceeded the yearly limit of 1 millisieverts in areas extending more than 60 kms (36 miles) to the northwest of the plant and about 40 km to the south-southwest.
“It has been obvious all along this was a 7. There are three reactors that are not being cooled (No. 1, 2 &3) and four fuel pools too (No. 1, 2, 3, and especially 4),” saidArnie Gundersen, a 29-year veteran of the nuclear industry who worked on reactors similar to those at Daiichi and who is now chief engineer at Fairewinds Associates Inc of Burlington, Vermont.
He said that means there were at least seven cores or pools that had been in difficulty. He noted that at Chernobyl it was only one reactor that created the problem.
A spokesman for the Nuclear and Industrial Safety Agency, Japan’s nuclear safety watchdog, said he was unaware of any move by the government to raise the level.
RADIOACTIVE WATER
The March 11 tsunami, the largest recorded in quake-prone Japan, crippling the reactors’ cooling systems.
Engineers at the plant north of Tokyo said they were no closer to restoring the plant’s cooling system, which is critical to bring down the temperature of overheated fuel rods and to bringing the six reactors under control.
TEPCO said on Monday it had stopped the discharge of low-level radioactive water into the sea that have drawn complaints from neighboring China and South Korea.
It has already pumped 10,400 tonnes of low-level radioactive water into the ocean to free up storage capacity for highly contaminated water from the reactors.
In a desperate move to cool the highly radioactive fuel rods, TEPCO has pumped water onto reactors, some of which have experienced partial meltdown.
But the strategy has hindered moves to restore the plant’s internal cooling system as engineers have had to focus on how to store 60,000 tonnes of contaminated water.
Engineers are also pumping nitrogen into reactors to counter a build-up of hydrogen and prevent another explosion sending more radiation into the air, but they say the risk of such a dramatic event has lowered significantly since March 11.
EVACUATION ZONE WIDENS
Because of accumulated radiation contamination, the government is encouraging people to leave certain areas beyond its 20 km (12 mile) exclusion zone around the plant. Thousands of people could be affected by the move.
TEPCO President Masataka Shimizu visited the area on Monday for the first time the disaster. He had all but vanished from public view apart from a brief apology shortly after the crisis began and has spent some of the time since in hospital.
“I would like to deeply apologize again for causing physical and psychological hardships to people of Fukushima prefecture and near the nuclear plant,” said a grim-faced Shimizu.
Dressed in a blue work jacket, he bowed his head for a moment of silence with other TEPCO officials at 2:46 p.m. (1 a.m. EST), exactly a calendar month after the earthquake hit.
(Additional reporting by Nathan Layne in Tokyo and Scott DiSavino in New York; Writing by Jonathan Thatcshiher and Michael Perry)
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