Reuters & Union of Concerned Scientists – 2011-03-12 03:36:35
VIDEO: Major Explosion Destroys Nuclear Reactor in Japan
Japan Warns of Nuclear Fuel Melting after Quake Damage
Chris Meyers and Kim Kyung-hoon / Reuters
FUKUSHIMA, Japan (March 12, 2011) — Japan warned of a meltdown on Saturday at a nuclear reactor damaged when a massive earthquake and tsunami struck the northeast coast, but said the risk of radiation contamination was small.
Media reports estimate at least 1,300 people may have been killed by the biggest earthquake ever recorded in Japan and then a 10-meter tsunami that swept inland.
Experts said any threat of widespread radiation leaks would be contained as long as the reactor’s outer container is intact.
State broadcaster NHK quoted officials as saying there was no need to extend an evacuation area already set up around the damaged plant.
Authorities have been scrambling to reduce pressure at two nuclear power plants in Fukushima, 240 km (150 miles) north of Tokyo, damaged by the quake, which measured a massive 8.9, the biggest since records began in Japan 140 years ago.
Jiji news agency quoted nuclear authorities as saying that there was a high possibility that nuclear fuel rods at Tokyo Electric Power’s (Tepco’s) Daiichi No.1 reactor may be melting or have melted.
Experts said if that is the case, it means the reactor is heating up. If that is not halted, such as by venting steam which releases small amounts of radiation, there is a chance it would result in a rupture of the reactor pressure vessel.
But the risk of contamination can be minimized as long as the external container structure is intact, they said. The worry then becomes whether the quake has weakened the structure.
There has been no official word so far on whether the structure was damaged in the quake.
Japanese officials and experts have been at pains to say that while there would be radiation leaks, they would be very small and have dismissed suggestions of a repeat of a Chernobyl-type disaster.
“No Chernobyl is possible at a light water reactor. Loss of coolant means a temperature rise, but it also will stop the reaction,” Naoto Sekimura, a professor at the University of Tokyo, said.
“Even in the worst-case scenario, that would mean some radioactive leakage and equipment damage, but not an explosion. If venting is done carefully, there will be little leakage. Certainly not beyond the 3 km radius.”
The tremor was so huge that thousands fled their homes from coastlines around the Pacific Rim, as far away as North and South America, fearful of a tsunami.
Most appeared to have been spared anything more serious than some high waves, unlike Japan’s northeast coastline which was hammered by the huge tsunami that turned houses and ships into floating debris as it surged into cities and villages, sweeping aside everything in its path.
“I thought I was going to die,” said Wataru Fujimura, a 38-year-old sales representative in Koriyama, Fukushima, north of Tokyo and close to area worst hit by the quake.
“Our furniture and shelves had all fallen over and there were cracks in the apartment building, so we spent the whole night in the car… Now we’re back home trying to clean
The unfolding natural disaster, which has been followed by dozens of aftershocks, prompted offers of search and rescue help from 50 countries.
In one of the worst-hit residential areas, people buried under rubble could be heard calling out for rescue, Kyodo news agency reported. TV footage showed staff at one hospital waving banners with the words “FOOD” and “HELP” from a rooftop.
In Tokyo, tens of thousands of office workers were stranded overnight after the quake shut down public transport. Many were forced to bed down where they could, with newspapers to lie on and briefcases for pillows.
Kyodo said at least 116,000 people in Tokyo had been unable to return home on Friday evening due to transport disruption.
The northeastern Japanese city of Kesennuma, with a population of 74,000, was hit by widespread fires and one-third of the city was under water.
City mayor Shigeo Sugawara said: “A huge number of houses have been washed away.” He said fuel storage tanks had been destroyed, sending oil flowing out which then caught fire.
The airport in coastal city Sendai, home to one million people, was on fire, Japanese media said.
“Sendai (city) is now completely sunk underwater,” said limousine driver Yoshikatsu Takayabe, 52. “What do I want the government to do? I can’t flush the toilet, I want the water back on in my house.”
TV footage from Friday showed a black torrent of water carrying cars and wrecked homes at high speed across farmland near Sendai, 300 km (180 miles) northeast of Tokyo. Ships had been flung onto a harbor wharf, where they lay helplessly.
Kyodo news agency reported that contact had been lost with four trains in the coastal area.
The disaster poses a huge challenge for Kan’s government which has come under such concerted attack from the opposition and within the ruling Democratic Party (DJP) that it has struggled to implement any policy.
Just hours before the quake struck, Kan was rejecting demands that he resign, his political future looking increasingly bleak and unable even to muster enough support to ensure the passage of bills needed to enact the new budget.
But after the tremor, politicians pushed for an emergency budget to fund relief efforts, with Kan urging them to “save the country,” Kyodo reported.
Japan is already the most heavily indebted major economy in the world, meaning any additional borrowing by the government would be closely scrutinized by financial markets.
The quake, the most powerful since Japan started keeping records 140 years ago, sparked at least 80 fires in cities and towns along the coast, Kyodo said.
Other nuclear power plants and oil refineries were shut down and one refinery was ablaze. Power to millions of homes and businesses was knocked out. Several airports, including Tokyo’s Narita, were closed on Friday and rail services halted. All ports were shut.
Nuclear power plant operator Tepco warned of severe power shortages over the weekend.
The central bank said it would cut short a two-day policy review scheduled for next week to one day on Monday and promised to do its utmost to ensure financial market stability.
The disaster struck as the world’s third-largest economy had been showing signs of reviving from an economic contraction in the final quarter of last year. It raised the prospect of major disruptions for many key businesses and a massive repair bill running into tens of billions of dollars.
The earthquake was the fifth most powerful to hit the world in the past century. It surpassed the Great Kanto quake of September 1, 1923, which had a magnitude of 7.9 and killed more than 140,000 people in the Tokyo area.
The 1995 Kobe quake caused $100 billion in damage and was the most expensive natural disaster in history.
Writing by Jonathan Thatcher; Editing by Andrew Marshall.
(c) Thomson Reuters 2011. All rights reserved.
NUCLEAR CRISIS IN FUKUSHIMA: WHAT WE KNOW
Nickolas Roth / The Union of Concerned Scientists
(March 11, 2011) — The massive earthquake off the northeast coast of Japan has caused a potentially catastrophic situation at one of Japanâ€™s nuclear power plants. The situation is still evolving, but below is a preliminary assessment based on the facts as experts at the Union of Concerned Scientists currently understand them.
The plantâ€™s owner, Tokyo Electric Power Company (TEPCO), reported that at 2:46 p.m. local time (12:46 a.m. EST) â€œturbines and reactors of Tokyo Electric Power Companyâ€™s Fukushima Daiichi Nuclear Power Station Unit 1 â€¦ and Units 2 and 3 â€¦ automatically shut down due to the Miyagiken-oki Earthquake.â€
These reactors are three of the six operating reactors at the Fukushima I nuclear facility. All are boiling water reactors. Unit 1 has a rated output of 460 megawatts, and Units 2 and 3 each have a rated output of 784 megawatts.
TEPCO went on to state the shutdowns were caused by the loss of off-site power â€œdue to malfunction of one out of two off-site power systems.â€ This loss of power triggered emergency diesel generators, which automatically started to provide backup power to the reactors.
However, at 3:41 p.m. local time (1:46 a.m. EST), the emergency diesel generators shut down â€œdue to malfunction, resulting in the complete loss of alternating current for all three units,â€ according to TEPCO. The failure of the diesel generators was most likely due to the arrival of the tsunami, which caused flooding in the area. The earthquake was centered 240 kilometers from Japan, and it would have taken the tsunami approximately an hour to reach the Japanese islands.
This power failure resulted in one of the most serious conditions that can affect a nuclear plant — a â€œstation blackoutâ€ — during which off-site power and on-site emergency alternating current (AC) power is lost. Nuclear plants generally need AC power to operate the motors, valves and instruments that control the systems that provide cooling water to the radioactive core. If all AC power is lost, the options to cool the core are limited.
The boiling water reactors at Fukushima are protected by a Reactor Core Isolation Cooling (RCIC) system, which can operate without AC power because it is steam-driven and therefore does not require electric pumps. However, it does require DC power from batteries for its valves and controls to function.
If battery power is depleted before AC power is restored, however, the RCIC will stop supplying water to the core and the water level in the reactor core could drop. If it drops far enough, the core would overheat and the fuel would become damaged. Ultimately, a â€œmeltdownâ€ could occur: The core could become so hot that it forms a molten mass that melts through the steel reactor vessel. This would release a large amount of radioactivity from the vessel into the containment building that surrounds the vessel.
The containment buildingâ€™s main purpose is to keep radioactivity from being released into the environment. A meltdown would build up pressure in the containment building. At this point we do not know if the earthquake damaged the containment building enough to undermine its ability to contain the pressure and allow radioactivity to leak out.
According to technical documents translated by Aileen Mioko Smith of Green Action in Japan, if the coolant level dropped to the top of the active fuel rods in the core, damage to the core would begin about 40 minutes later, and damage to the reactor vessel would occur 90 minutes after that.
Concern about a serious accident is high enough that while TEPCO is trying to restore cooling the government has evacuated a 3-km (2-mile) radius area around the reactor.
Bloomberg News reported that the battery life for the RCIC system is eight hours. This means that the batteries would have been depleted before 10 a.m. EST today. It is unclear if this report is accurate, since it suggests that several hours have elapsed without any core cooling. Bloomberg also reported that Japan had secured six backup batteries and planned to transport them to the site, possibly by military helicopter. It is unclear how long this operation would take.
There also have been news reports that Fukushima I Unit 2 has lost its core cooling, suggesting its RCIC stopped working, but that the situation â€œhas been stabilized,â€ although it is not publicly known what the situation is. TEPCO reportedly plans to release steam from the reactor to reduce the pressure, which had risen 50 percent higher than normal. This venting will release some radioactivity.
UCS will issue updates as more information becomes available.
Nickolas Roth is a Policy Analyst with the Union of Concerned Scientists.
The Union of Concerned Scientists is the leading U.S. science-based nonprofit organization working for a healthy environment and a safer world. Founded in 1969, UCS is headquartered in Cambridge, Massachusetts, and also has offices in Berkeley, Chicago and Washington, D.C. (1825 K Street NW Suite 800, Washington DC 20006-1232). For more information, go to www.ucsusa.org.
TImeline of Nuclear Plant Damage in Japan
0923: Before the explosion, the government had declared a state of emergency at five nuclear reactors after the generators pumping cooling water at the reactors failed.
0919: So, just to recap, there are growing fears about damage to two Japanese nuclear plants following Friday’s 8.9-magnitude earthquake. There’s recently been an explosion at a building at one of the plants, which is called Fukushima-Daiichi, or Fukushima I. It’s not clear what the building contained.
0914: Japanese authorities have extended the evacuation area at the Fukushima-Daini plant — also know as Fukushima II — to 10km, the same distance as for the Fukushima-Daiichi, or Fukushima I plant.
0908: The International Atomic Energy Agency (IAEA) is urgently seeking information about the explosion at the Fukushima-Daiichi plant.
0905: Japan’s NHK TV says officials measured the level of radiation at the entrance of the Fukushima-Daiichi plant at 1529 Japanese time. If people are exposed to this level of radiation for an hour they’d receive the same amount of radiation they normally would in a year, the report says.
0859: Tomoaki Furuno in Tokyo writes: “We Japanese appreciate offering of aid and heart-warming messages from the world. After the earthquake, I walked to the government offices to pick up my pregnant wife who works as a civil servant. I passed through thousands of people walking, because all trains stopped. We could not go get back home. Finally, I found something to eat and a building to stay in. We borrowed the blanket and stayed one night inside the building.” Have Your Say
0857: The BBC’s Nick Ravenscroft was on his way towards Fukushima, but about 60km from the plant was stopped by the police and told it was too dangerous to proceed. He says there is lots of traffic coming in the other direction. Authorities in vehicles with sirens are making public announcements to the crowds.
0855: Some pictures have come through now on Japanese TV of that explosion. It looks very strong. You can see debris being blasted from the building, then a cloud of smoke mushrooming up from the plant.
0850: Japan’s Kyodo news agency reporting that four people have been injured in an explosion at the Fukushima-Daiichi plant.
0847: NHK TV carrying advice to people to protect themselves against radiation. Experts say people should cover their mouths and noses with wet towels. Exposed skin should also be covered and people should wash after coming indoors. People should also avoid vegetables and other fresh food, as well as tap water, until authorities give the all-clear.
0841: Malcolm Grimston, a nuclear energy expert from Imperial College London, has told the BBC that as long as any nuclear meltdown is small-scale, it can be contained: “For example, there was one in the Chapel Cross plant in south-west Scotland in the 1960s, and at the end of that it only affected two of what they call the fuel channels, the long tubes where the fuel is put. They simply sealed those off, there was no release of radioactivity offsite and the plant continued to operate for 30 years.”
0828: Japan’s NHK TV showing before and after pictures of the Fukushima-Daiichi plant. It appears to show that the outer structure of one of four buildings at the plant is no longer there.
0822: The Associated Press cites Fukushima Prefecture official Masato Abe as saying the cause of the white smoke seen above the plant is still under investigation, and that it’s unclear whether there was an explosion.
0810: Japanese media reports say that radioactivity has risen 20-fold outside the Fukushima-Daiichi plant.
0803: Japan’s NHK TV also has that report of an explosion, which it says was “near” the Fukushima-Daiichi plant. The Tokyo Electric Power Company — which runs the plant — says some workers were injured, NHK reports.