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A Saturday explosion at a closely monitored nuclear power plant in northern Japan blew the roof off a building and destroyed the walls around a reactor, local officials report, further distracting rescue efforts of hundreds of stranded and missing in the aftermath of one of the largest earthquakes on record.
Smoke rises from a stricken reactor at the Fukushima Daiichi Nuclear Power Station in Japan.
(Credit:Associated Press video, screenshot by Edward Moyer/CNET)
Officials reported that radiation levels outside the plant were coming down after they were measured at eight times above normal levels Friday night, and that a meltdown was not imminent. But a meltdown remains possible, with The Washington Post reporting that workers are now trying to control the temperature and pressure inside a total of five reactors.
What was originally a 2-mile evacuation radius has expanded to 12.5, while government officials and executives of plant operator Tokyo Electric Power have yet to be clear about the cause of the explosion and the extent of the damage, The New York Times reported.
What we do know: Tokyo Electric Power had been taking emergency measures Saturday to avert a meltdown after a power outage left a cooling system unable to supply water to cool the reactor. Representatives reported to the media that their efforts seemed to be effectively lowering the pressure inside the container. But the seawater workers poured over the fuel rods to cool them formed hydrogen, which--when released to relieve pressure--reacted with oxygen to cause the explosion, explaining why it happened outside rather than inside the high-pressure vessel.
Meanwhile, Japan's chief cabinet secretary, Yukio Edano, also reported in a news conference Saturday night that the explosion did not take place inside the reactor but rather in a structure housing turbines near the reactor, and that the container was not damaged. He urged everyone to remain calm, and said that the reactor remaining intact improved chances of continuing to cool the core and prevent a full meltdown.
"Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained," says Robin Grimes, a professor of materials physics at Imperial College London, in a statement to the press. "At the moment it does seem that they are still contained and it's a release of significant steam pressure that's caused this explosion. The key will be the monitoring of those radiation levels."
The zirconium casings of the fuel rods are hot enough at 2,200 degrees Fahrenheit to react with the cooling water and create hydrogen, which seems to have happened and caused the explosion. At 4,000 degrees, the uranium fuel pellets inside the rods could start to melt, which could lead to full core meltdown, reports Forbes.com.
The unit, a 439-megawatt boiling water reactor built by General Electric 40 years ago, was scheduled to shut down on March 26, reports The Washington Post. The nuclear state of emergency has expanded to include five reactors at two nuclear power complexes as both utility and military officials try to stabilize the systems used to cool the cores.
Tokyo Electric Power has confirmed in a press release that one worker at Unit 1 has died of injuries after becoming trapped in the crane-operating console of the exhaust stack, and that four workers are being treated at a hospital after sustaining fractures and bruises. The company adds that an employee working on unit No. 1 is being treated for radiation exposure by a special physician.
More than 83,000 people live within 10 kilometers of the two plants under evacuation orders, according to Japan's Nuclear and Industrial Safety Agency. Local officials of Fukushima Prefecture report that three hospital patients, chosen for random radiation testing out of 90 patients and staff awaiting nearby evacuation by helicopter, needed to be decontaminated, though they did not yet show symptoms of radiation poisoning.
The massive 8.9 magnitude earthquake off the coast of Honshu, Japan, triggered not only the power outage that prompted the country to declare a nuclear emergency, but also a large tsunami resulting in hundreds of drownings. (The largest earthquake on record was a magnitude 9.5 quake in Chile in 1960, which killed 1,655, left 2 million people homeless, and resulted in a tsunami that killed 61.)
Meanwhile, rescue efforts continue around Japan, with 50,000 troops joining boats and helicopters and dozens of countries offering aid. President Barack Obama says the US has sent at least two American aircraft carriers to the region.
The official count of the dead has jumped to 1,700, reports The Telegraph, with another 10,000 missing from the fishing port of Minamisanriku, where the tsunami swept six miles inland. At least 215,000 people are now spread across 1,350 temporary shelters in five prefectures, according to the Japanese national police agency. Google's 2011 Japan Earthquake Person Finder now includes 67,800 records.
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Smoke rises from a stricken reactor at the Fukushima Daiichi Nuclear Power Station in Japan.(Credit:Associated Press video, screenshot by Edward Moyer/CNET)
Officials reported that radiation levels outside the plant were coming down after they were measured at eight times above normal levels Friday night, and that a meltdown was not imminent. But a meltdown remains possible, with The Washington Post reporting that workers are now trying to control the temperature and pressure inside a total of five reactors.
What was originally a 2-mile evacuation radius has expanded to 12.5, while government officials and executives of plant operator Tokyo Electric Power have yet to be clear about the cause of the explosion and the extent of the damage, The New York Times reported.
What we do know: Tokyo Electric Power had been taking emergency measures Saturday to avert a meltdown after a power outage left a cooling system unable to supply water to cool the reactor. Representatives reported to the media that their efforts seemed to be effectively lowering the pressure inside the container. But the seawater workers poured over the fuel rods to cool them formed hydrogen, which--when released to relieve pressure--reacted with oxygen to cause the explosion, explaining why it happened outside rather than inside the high-pressure vessel.
Meanwhile, Japan's chief cabinet secretary, Yukio Edano, also reported in a news conference Saturday night that the explosion did not take place inside the reactor but rather in a structure housing turbines near the reactor, and that the container was not damaged. He urged everyone to remain calm, and said that the reactor remaining intact improved chances of continuing to cool the core and prevent a full meltdown.
"Despite the damage to the outer structure, as long as that steel inner vessel remains intact, then the vast majority of the radiation will be contained," says Robin Grimes, a professor of materials physics at Imperial College London, in a statement to the press. "At the moment it does seem that they are still contained and it's a release of significant steam pressure that's caused this explosion. The key will be the monitoring of those radiation levels."
The zirconium casings of the fuel rods are hot enough at 2,200 degrees Fahrenheit to react with the cooling water and create hydrogen, which seems to have happened and caused the explosion. At 4,000 degrees, the uranium fuel pellets inside the rods could start to melt, which could lead to full core meltdown, reports Forbes.com.
The unit, a 439-megawatt boiling water reactor built by General Electric 40 years ago, was scheduled to shut down on March 26, reports The Washington Post. The nuclear state of emergency has expanded to include five reactors at two nuclear power complexes as both utility and military officials try to stabilize the systems used to cool the cores.
Tokyo Electric Power has confirmed in a press release that one worker at Unit 1 has died of injuries after becoming trapped in the crane-operating console of the exhaust stack, and that four workers are being treated at a hospital after sustaining fractures and bruises. The company adds that an employee working on unit No. 1 is being treated for radiation exposure by a special physician.
More than 83,000 people live within 10 kilometers of the two plants under evacuation orders, according to Japan's Nuclear and Industrial Safety Agency. Local officials of Fukushima Prefecture report that three hospital patients, chosen for random radiation testing out of 90 patients and staff awaiting nearby evacuation by helicopter, needed to be decontaminated, though they did not yet show symptoms of radiation poisoning.
The massive 8.9 magnitude earthquake off the coast of Honshu, Japan, triggered not only the power outage that prompted the country to declare a nuclear emergency, but also a large tsunami resulting in hundreds of drownings. (The largest earthquake on record was a magnitude 9.5 quake in Chile in 1960, which killed 1,655, left 2 million people homeless, and resulted in a tsunami that killed 61.)
Meanwhile, rescue efforts continue around Japan, with 50,000 troops joining boats and helicopters and dozens of countries offering aid. President Barack Obama says the US has sent at least two American aircraft carriers to the region.
The official count of the dead has jumped to 1,700, reports The Telegraph, with another 10,000 missing from the fishing port of Minamisanriku, where the tsunami swept six miles inland. At least 215,000 people are now spread across 1,350 temporary shelters in five prefectures, according to the Japanese national police agency. Google's 2011 Japan Earthquake Person Finder now includes 67,800 records.
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