Workers pulled from nuclear plant as radiation spikes
Published Tuesday, March 15, 2011 11:21PM EDT
Last Updated Saturday, May 19, 2012 4:12AM EDT
The remaining workers desperately seeking to stop a meltdown at a stricken Japanese nuclear plant have been pulled from the site Wednesday because of the radiation risk.
Chief Cabinet Secretary Yukio Edano said work on attempting to cool the reactors at the damaged Fukushima Dai-Ichi nuclear power plant with sea water has been disrupted by the withdrawal.
Radiation levels spiked to 1,000 millisieverts Wednesday before coming down to the 600-800 range.
"So the workers cannot carry out even minimal work at the plant now," Edano said. "Because of the radiation risk, we are on standby."
Exposure to about 1,000 millisieverts can cause radiation sickness.
The move is the latest setback after a fire erupted at Fukushima Dai-Ichi plant Wednesday.
Officials are now considering desperate measures such as spraying water and boric acid over the plant to prevent radiation from spreading.
Tokyo Electric Power Co. spokesman Hajimi Motojuku said the fire erupted at about 6 a.m. Wednesday local time in the outer portion of the No. 4 reactor unit's containment vessel.
No smoke or flames were visible shortly after the initial announcement, officials said, but that does not mean the fire has been extinguished.
However, public broadcaster NHK showed live images of smoke billowing from the plant at about 10:15 a.m. local time. The smoke is believed to be coming from the No. 3 reactor.
The fire erupted because an earlier blaze at the No. 4 reactor was not put completely out.
The causes of the fire was unknown because workers have been unable to get near the troubled reactor.
Earlier Wednesday, the operators of the plant said they were not moving ahead with a plan to use helicopters to dump water into a reactor that is emitting radiation from its overheated fuel storage unit.
Motojuku said the helicopter plan was impractical, but they are looking at other options, such as using fire engines to send water through a hole in the wall that was caused by an earlier explosion.
The No. 4 reactor had an earlier fire on Tuesday in its spent-fuel storage pond. The reactor had been shut down for maintenance at the time of last Friday's quake.
Also on Wednesday, Japan's nuclear agency said 70 per cent of the nuclear fuel rods at the No. 1 reactor appear to be damaged, along with 33 per cent of the fuel rods at the No. 2 reactor.
"But we don't know the nature of the damage, and it could be either melting, or there might be some holes in them," agency spokesperson, Minoru Ohgoda, said.
On Tuesday, the plant was hit with an explosion at its No.2 reactor, leading authorities to order 140,000 people to seal themselves indoors.
Since Friday, workers at the nuclear power plant have been battling to deal with damage from a 9.0 magnitude earthquake and a devastating tsunami.
Prime Minister Naoto Kan said in a televised statement that radiation had spread from the Dai-Ichi's four damaged reactors across Japan's northeastern coast.
"I would like to ask the nation, although this incident is of great concern, I ask you to react very calmly," Kan said during his brief address Tuesday.
While levels of radiation had fallen by late Tuesday, Japanese officials told the International Atomic Energy Agency that the fire released radioactivity "directly into the atmosphere."
Hours after the first fire was extinguished, Japanese Economy Ministry spokesperson Hidehiko Nishiyama told reporters that "we cannot deny the possibility of water boiling" in the spent fuel storage pool.
If the spent fuel rods remain hot, they may evaporate enough water in the pool to expose the rods. The rods are encased in safety containers designed to prevent nuclear reactions, but it's not clear whether the containers have been damaged.
When pressed on the potential risk, Nishiyama skirted the issue.
"We have no information about whether the spent fuel rods are exposed," he said, telling reporters that the plant's operator is considering what to do about the situation.
Steve Crossley, an Australia-based radiation physicist, said the amount of radiation released would not immediately cause harm.
"It's not good, but I don't think it's a disaster," Crossley told The Associated Press.
John Luxat, NSERC industrial research chair in nuclear safety analysis at McMaster University, said the greatest risk appears limited to those working at the nuclear plant.
"The indications are the amount of radiation that is being transported away from the site of the unit is still at relatively low levels," he said on CTV's Power Play. "The dangers are mainly to the personnel at the plant."
Luxat added the scale of the crisis may be lowering.
"The risk of a nuclear meltdown has been significantly reduced, but is still there," he said.
Canadian officials stated Tuesday that the nuclear crisis in Japan does not pose a health risk to Canadians.
Prime Minister Stephen Harper said experts have assured him there's no evidence the radiation in Japan poses a risk to Canada.
British Columbia's health officer, Dr. Perry Kendall said it would take almost a week for radiation to cross the Pacific Ocean to the province and by that point it would have dispersed into the atmosphere.
Scale of the crisis
Responding to Japan's struggle to contain a possible nuclear catastrophe, the French nuclear safety authority upgraded the severity of the ongoing accident to level six out of seven on the international scale.
Level seven on the International Nuclear and Radiological Event Scale has been invoked only once, following the 1986 disaster at the Chernobyl Nuclear Power Plant in Ukraine.
The head of France's Nuclear Safety Authority, Andre-Claude Lacoste told reporters on Tuesday that the situation in Japan is less severe than the core explosion at Chernobyl, but worse than the 1979 partial core meltdown at Three Mile Island, Pennsylvania.
"We are now in a situation that is different from yesterday's. It is very clear that we are at a level six, which is an intermediate level between what happened at Three Mile Island and Chernobyl," the ASN president said at a news conference in Paris.
The incident at Three Mile Island was rated a level 5, which corresponds to "an accident with wider consequences," while level 6 is reserved for a "serious accident." Japanese officials had rated the situation at the plant in Fukushima prefecture as a 4 on the seven-point scale, meaning it's an accident with "local consequences."
But, pointing to the explosions that continued to wrack the Dai-ichi nuclear plant despite days of frantic efforts to cool them, Lacoste said the outlook is worsening.
"We are clearly in a catastrophe," he said.
The Dai-ichi plant -- which is one of three nuclear facilities that have declared emergencies in the aftermath of the magnitude 9.0 earthquake and ensuing tsunami that struck on March 11 -- has since suffered fires and a series of explosions.
While firefighters struggled to douse Tuesday's blaze, Japan's top government spokesperson told reporters that the measurements taken at the gate of the Dai-ichi plant were less than 600 microsieverts per hour at 3:30 p.m. local time.
That was down from a high reading of nearly 12,000 less than 7 hours earlier.
The crisis is not over, and the government has ordered all 47 prefectures (provinces) to report the results of their environmental radiation observations every day, twice a day if possible.
"We have to monitor the situation closely, but the high concentration of radioactive material is not emitting constantly from the No. 4 reactor right now," Japan's Chief Cabinet Secretary Yukio Edano said.
'Please do not go outside'
Earlier Tuesday Edano alerted the 140,000 people living within a 20- to 30-kilometre radius of the Dai-ichi plant to seek shelter. The facility is approximately 40 kilometres south of the hard-hit city of Sendai.
"Please do not go outside. Please stay indoors. Please close windows and make your homes airtight," Edano said in the first official warning that radiation posed a threat to human health since the quake struck.
"These are figures that potentially affect health. There is no mistake about that," he said, warning of the danger of more leaks.
In the hours following the fire, there were reports of radiation levels reaching nine times higher than normal in Kanagawa prefecture near Tokyo which is some 270 kilometres to the south. Elevated levels were also recorded in the capital, but officials insisted there was no risk to the health of the city's population of 39 million people.
"The amount is extremely small, and it does not raise health concerns. It will not affect us," Tokyo government official Takayuki Fujiki said.
Following reports of the radiation emissions, the transportation ministry imposed a no-fly zone over 30 kilometre radius around the plant. Approximately 70,000 people living within 20 km of the plant had already been evacuated.
The explosion at the No. 2 reactor shortly after 6 a.m. local time Tuesday, was the third blast to rock the crippled plant in four days.
Representatives for Tokyo Electric Power said the explosion occurred near the suppression pool in the reactor's containment vessel, which is the last line of defence before radiation is released into the environment.
Company officials told reporters that pressure had fallen in the suppression pool, indicating that it had sustained some damage in the blast.
Fifty workers remain at the power plant, locked in a struggle to stabilize the three reactors that have suffered explosions since the quake struck. Officials say they managed to extinguish the fire, but not before it released radiation "directly into the atmosphere".
"The Japanese authorities are saying that there is a possibility that the fire was caused by a hydrogen explosion," the United Nations International Atomic Energy Agency said in a statement.
Engineers have been pumping sea water into the Nos. 1, 2, and 3 reactors in an effort to keep them cool after the normal cooling systems were crippled in the quake.
But they have had difficulty keeping the nuclear fuel cells submerged, leading to dangerous heat levels.
The coolant water level dropped precipitously inside the Unit 3 reactor on Monday, leaving the uranium fuel rods completely exposed just hours after it was rocked by a hydrogen explosion that injured 11 workers. A similar hydrogen blast occurred Saturday at the No. 1 reactor, injuring four people.
Normally, the series of metal rods containing pellets of uranium fuel inside a nuclear reactor's core are kept cool with purified water that is pumped between the pipes. The resulting steam then drives an electricity-generating turbine, and the heat is then removed by coolant pumps.
But those pumps at the Fukushima plant, as well as its back-up power supply, were knocked out by the devastating earthquake and tsunami.
Norm Rubin, director of nuclear power research at Energy Probe, told CTV News that the Dai-ichi plant is almost 40 years old and had only been designed to withstand a quake of 6.5 magnitude.
"In hindsight, a few days after an 8.9 earthquake, that really seems like cutting corners … it seems nuts," he said.
Yukiya Amano, the head of the UN nuclear watchdog and a veteran Japanese diplomat, said Japan has now responded to the International Atomic Energy Agency's offer to assist with the crippled nuclear plants and said his staff are working "around the clock" to help.
"Japan and all our member states can be assured that all resources put at our disposal are fully mobilised. That will remain the case until this crisis has been resolved."
If there is a partial or total meltdown, it could become impossible to remove the fuel. That's what happened in 1979 at Three Mile Island, which remains sealed off to this day.
With files from The Associated Press