Video: Japanese nuclear plants under meltdown threat

  1. Closed captioning of: Japanese nuclear plants under meltdown threat

    >> the steam is slightly reacted. we'll tell you why it's so dangerous with our next guest. that's james actin who has been following the nuclear situation in japan today . i understand once you lose, as they say here, the power to the cooling supply in's an hour before basically you have coolant boiling off and possible meltdown. is that right?

    >> that's basically right, cenk. when you scram a reactor, when you turn it off, it continues to produce heat. you need a source of water to cool that while the reactor cools down over the course of a number of days. an internal power supply and backup generator all failed. it caused a series of events we don't fully understand at the moment. but the end result is a lot of steam is being reduced because the core isn't being cooled properly. that's building up and has had to be vented.

    >> i don't know if it means, if you can't call it off within an hour or if the meltdown would take a longer period of time. obviously a meltdown would be disastrous. do we have a sense of how much time do we have? or they have as we all try to -- and i know the u.s. is also bringing in things to cool this off. do you know how long before this happens?

    >> we don't know. because there's steam means there's some type of coolant within the system. the bottom line is this, if they cannot restore what's -- whatever is wrong. be that the power supply or the coolant systems themselves, then at some point over the course of the next hours or perhaps even days, this could be a very slow moving crisis.

    >> what happens if there's a meltdown?

    >> meltdown is a scary word that covers a large number of scenar scenarios. it's possible the metal surrounding the fuel starts to melt. but very little radio activity goes into the outside into the environment. that's kind of the best case meltdown scenario. the worst case is that there's a leakage of radiation into the environment. there's actually a huge range of possible jut comes here.

    >> right. and that's why i brought up nuclear bombs going off in japan earlier. it seems like they're -- you know, the nuclear issue again in japan. it's a shame, and just one more thing here, as they let off that radioactive steam, how dangerous is that? they're telling them two miles evacuate, six miles just stay inside your house. i don't think i would do that. is that okay? how bad is the radioactive steam?

    >> when you have radiation leaking out of the plant, that's an extremely serious accident. you can't play this down. that said, the radiation within the steam is not terribly intense. it will dissipate. away from the plant, people are likely to be adversely affected by it. anytime radiation is leaking, that's a call for extreme concern. what i want to emphasize is a huge range of powerful outcomes. while the core is not damaged, it may not cause any fatalities outside of the plant. if the core starts to get damaged and the steam continues to flow, then you're in a very different situation.

NBC, and news services
updated 3/12/2011 1:54:05 AM ET 2011-03-12T06:54:05

An official with Japan's nuclear safety commission says that a meltdown at a nuclear power plant affected by the country's massive earthquake is possible.

Ryohei Shiomi said Saturday that officials were checking whether a meltdown had taken place at the Fukushima Daiichi power plant, which had lost cooling ability in the aftermath of Friday's powerful earthquake.

If the fuel rods melted or are melting, a breach could develop in the nuclear reactor vessel and the question then becomes one of how strong the containment structure around the vessel is and whether it has been undermined by the earthquake, experts said.

Shiomi said that even if there was a meltdown, it wouldn't affect humans outside a six-mile (10-kilometer) radius.

Japan earlier Saturday declared states of emergency for five nuclear reactors at two power plants after the units lost cooling ability in the aftermath of Friday's powerful earthquake. Thousands of residents were evacuated as workers struggled to get the reactors under control to prevent meltdowns.

Operators at the Fukushima Daiichi plant's Unit 1 scrambled ferociously to tamp down heat and pressure inside the reactor after the 8.9 magnitude quake and the tsunami that followed cut off electricity to the site and disabled emergency generators, knocking out the main cooling system.

Story: How a nuclear plant works

Some 3,000 people within two miles (three kilometers) of the plant were urged to leave their homes, but the evacuation zone was more than tripled to 6.2 miles (10 kilometers) after authorities detected eight times the normal radiation levels outside the facility and 1,000 times normal inside Unit 1's control room.

The government declared a state of emergency at the Daiichi unit — the first at a nuclear plant in Japan's history. But hours later, the Tokyo Electric Power Co., which operates the six-reactor Daiichi site, announced that it had lost cooling ability at a second reactor there and three units at its nearby Fukushima Daini site.

The government quickly declared states of emergency for those units, too, and thousands of residents near Fukushima Daini also were told to leave.

Japan's nuclear safety agency said the situation was most dire at Fukushima Daiichi's Unit 1, where pressure had risen to twice what is consider the normal level. The International Atomic Energy Agency said in a statement that diesel generators that normally would have kept cooling systems running at Fukushima Daiichi had been disabled by tsunami flooding.

Officials at the Daiichi facility began venting radioactive vapors from the unit to relieve pressure inside the reactor case. The loss of electricity had delayed that effort for several hours.

Plant workers there labored to cool down the reactor core, but there was no prospect for immediate success. They were temporarily cooling the reactor with a secondary system, but it wasn't working as well as the primary one, according to Yuji Kakizaki, an official at the Japanese nuclear safety agency.

TEPCO said the boiling water reactors shut down at about 2:46 p.m. local time following the earthquake due to the loss of offsite power and the malfunction of one of two off-site power systems. That triggered emergency diesel generators to startup and provide backup power for plant systems.

More from Open Channel blog: 2007 Japan quake was wake-up call on nuclear safety

About an hour after the plant shut down, however, the emergency diesel generators stopped, leaving the units with no power for important cooling functions.

Nuclear plants need power to operate motors, valves and instruments that control the systems that provide cooling water to the radioactive core.

The race to restore the reactors’ cooling systems before the radioactive fuel was damaged sent ripples of concern across Pacific, where scientists on both sides of the U.S. debate over the safety of nuclear power acknowledged that the company was facing a serious situation.

Edwin Lyman, a senior scientist with the Union of Concerned Scientists, which opposes nuclear energy, told that TEPCO was facing a potential catastrophe.

'It's just as bad as it sounds'
“It’s just as bad as it sounds,” he said. “What they have not been able to do is restore cooling of the radioactive core to prevent overheating and that’s causing a variety of problems, including a rise in temperature and pressure with the containment (buildings).

“What’s critical is, are they able to restore cooling and prevent fuel damage? If the fuel starts to get damaged, eventually it will melt through the reactor vessel and drop to the floor of the containment building,” raising the odds that highly radioactive materials could be released into the environment.

But Steve Kerekes, spokesman for the U.S.-based Nuclear Energy Institute, said that while the situation was serious, a meltdown remains unlikely and, even if it occurred would not necessarily pose a threat to public health and safety.

“Obviously that wouldn’t be a good thing, but at Three Mile Island about half the core melted and, at the end of the day … there were no adverse impacts to the public,” he said.

Experts also downplayed the seriousness of the trace levels of radiation detected at the Fukushima Daiichi plant.

Image: Fukushima nuclear plant
Kyodo via Reuters
The Fukushima nuclear plant, the site of a coolant failure after Friday's quake, is pictured in a 2008 file photo.

Japan’s Asahi Shimbum newspaper reported that radiation levels per hour in the area near the front entrance of the No. 1 Fukushima plant reached 0.59 micro Sievert, which is eight times the normal levels. The central control room of the reactor recorded radiation levels 1,000 times the normal level, which would be approximately 70 microsieverts per hour, or 7 millirems, according to calculations by

Health effects unlikely
Generally it would take much higher levels of outside exposure to cause health problems in humans. Radiation exposure is often measured in units called “millirem,” which is 1/1000 of a rem. The average American is exposed to about 620 millirem each year, with about half from natural sources and half from manmade sources, according to the Nuclear Regulatory Commission.

Exposures of less than 50 millirem typically produce changes in blood chemistry, but no symptoms, according to the U.S. Environmental Protection Agency.

By comparison, normal exposure rates range from approximately 0.03 microsieverts per hour to 0.23 microsieverts per hour in La Paz, Bolivia, the highest city in the world.

Average U.S. exposure to all sources of radiation is 360 millirems per year, with 300 millirems from natural sources. A chest X-ray results in an exposure of about 8 to 10 millirems per film. A cross-country airplane flight results in a dose of 4 millirems.

Dr. Fred Mettler, emeritus professor of radiology at the University of New Mexico, studied the health effects of the Chernobyl Nuclear Power Plant explosions in Ukraine and has spent decades researching and writing about radiation exposure.

Mettler said the plants in the U.S. and Japan are far advanced from Chernobyl, which he likened to an airplane hangar with the nuclear reactor core sitting out in the open.

Japanese scientists have had more than 60 years since World War II to study the health effects of radiation poisoning and they won't take any step lightly, including releasing radioative vapors into the atmosphere to ease building pressure in a reactor, he said.

"These people are more knowledgeable about radiation than anyone," Mettler said.

"People don't become acutely sick until they're over 50 rem and more like 100 rem," Mettler said.

However, he noted that Japanese scientists studying health effects since Hiroshima have determined that some health effects can start to occur at exposures of 15 rem, even if the results aren't apparent for 10 years.

There were about 80,000 survivors of the atomic bomb, for instance, with an average exposure of 23 rem, Mettler said. During the next 50 years about 9,000 of those survivors died of cancer. However, Japanese scientists concluded that the toll included about 500 excess deaths, that is, deaths that would not otherwise have been expected.

The Daiichi site is located in Onahama city, about 170 miles (270 kilometers) northeast of Tokyo. The 460-megawatt Unit 1 began operating in 1971 and is the oldest at the site. It is a boiling water reactor that drives the turbine with radioactive water, unlike pressurized water reactors usually found in the United States. Japanese regulators decided in February to allow it to run another 10 years.

U.S. President Barack Obama said he spoke with Japanese Prime Minister Naoto Kan earlier Friday, and that the Japanese leader told him there were no radiation leaks from Japan's nuclear power plants.

"Right now our Department of Energy folks are in direct contact with their counterparts in Japan and are closely monitoring the situation," a senior administration official who handles nuclear issues told NBC News. "So far the government of Japan has not asked for any specific assistance with regard to the nuclear plant, but DOE and other U.S. government agencies are assessing the role they could play in any response and stand by to assist if asked."

Japan has a "tremendous amount of technical capability and resources" to respond to the issue themselves for now, sources told NBC News.

Meanwhile, new power supply cars to provide emergency electricity for systems that failed at the Fukushima-Daiichi plant have arrived there, the World Nuclear Association said.

"The World Nuclear Association understands that three to four power supply cars have arrived and that additional power modules are being prepared for connection to provide power for the energy cooling system," said Jeremy Gordon, analyst at the London-based WNA.

The cables were being set up to supply emergency power. Other power modules were in transit by air, WNA added on its website.

NBC News, staff, Reuters and The Associated Press contributed to this report.

Photos: After Japan's earthquake and tsunami - week 8

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  1. A radiation measuring instrument is seen next to some residents in Kawauchimura, a village within the 12- to 18-mile zone around the Fukushima Daiichi nuclear plant, on April 28. Most residents of Kawauchimura have evacuated in order to avoid the radiation, but some remain in the area of their own accord. (Koichi Kamoshida / EPA) Back to slideshow navigation
  2. A brazier heats the house of Masahiro Kazami, located within a 12-mile radius of the Fukushima Daiichi nuclear plant, April 28. (Koichi Kamoshida / EPA) Back to slideshow navigation
  3. Volunteers help clean a cemetery at Jionin temple in Ishinomaki, Miyagi prefecture, northeastern Japan, on April 29. Many volunteers poured into the disaster-hit region at the beginning of the annual Golden Week holiday. (Hiro Komae / AP) Back to slideshow navigation
  4. Japanese government adviser Toshiso Kosako is overcome with emotion during a news conference on April 29 in Tokyo announcing his resignation. The expert on radiation exposure said he could not stay on the job and allow the government to set what he called improper radiation limits for elementary schools in areas near the tsunami-damaged Fukushima nuclear plant. (AP) Back to slideshow navigation
  5. Fuel rods are seen inside the spent fuel pool of the Fukushima Daiichi nuclear plant reactor 4 on April 30. (Reuters) Back to slideshow navigation
  6. A volunteer girl from Tokyo works to clean the debris of a house in Higashimatsushima, northern Japan, on April 30. (AP) Back to slideshow navigation
  7. Farmer Tsugio Sato tends to his Japanese pear trees in Fukushima city, May 1. He said he expects to harvest the pears in October. Farmers and businesses face so-called "fuhyo higai," or damages stemming from the battered reputation of the Fukushima brand. (Hiro Komae / AP) Back to slideshow navigation
  8. Members of Japan Ground Self-Defense Force in protective gear receive radiation screening in Minamisoma in Fukushima prefecture, after searching for bodies at an area devastated by the March 11 earthquake and tsunami. (Reuters) Back to slideshow navigation
  9. Ruriko Sakuma, daughter of dairy farmer Shinji Sakuma, rubs a cow at their farm in the village of Katsurao in Fukushima prefecture on May 3. Thousands of farm animals died of hunger in the weeks following the quake. (Yoshikazu Tsuno / AFP - Getty Images) Back to slideshow navigation
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Explainer: The 10 deadliest earthquakes in recorded history

  • A look at the worst earthquakes in recorded history, in loss of human life. (The March 11, 2011, earthquake and tsumani that affected eastern Japan is not included because the fatalities caused, about 15,000, are fewer than those resulting from the temblors listed below.) Sources: United States Geological Survey, Encyclopedia Britannica

  • 1: Shensi, China, Jan. 23, 1556

    Magnitude about 8, about 830,000 deaths.

    This earthquake occurred in the Shaanxi province (formerly Shensi), China, about 50 miles east-northeast of Xi'an, the capital of Shaanxi. More than 830,000 people are estimated to have been killed. Damage extended as far away as about 270 miles northeast of the epicenter, with reports as far as Liuyang in Hunan, more than 500 miles away. Geological effects reported with this earthquake included ground fissures, uplift, subsidence, liquefaction and landslides. Most towns in the damage area reported city walls collapsed, most to all houses collapsed and many of the towns reported ground fissures with water gushing out.

  • 2: Tangshan, China, July 27, 1976

    Chinese Earthquake
    Keystone  /  Getty Images
    1976: Workers start rebuilding work following earthquake damage in the Chinese city of Tangshan, 100 miles east of Pekin, with a wrecked train carriage behind them. (Photo by Keystone/Getty Images)
    Magnitude 7.5. Official casualty figure is 255,000 deaths. Estimated death toll as high as 655,000.

    Damage extended as far as Beijing. This is probably the greatest death toll from an earthquake in the last four centuries, and the second greatest in recorded history.

  • 3: Aleppo, Syria, Aug. 9, 1138

    Magnitude not known, about 230,000 deaths.

    Contemporary accounts said the walls of Syria’s second-largest city crumbled and rocks cascaded into the streets. Aleppo’s citadel collapsed, killing hundreds of residents. Although Aleppo was the largest community affected by the earthquake, it likely did not suffer the worst of the damage. European Crusaders had constructed a citadel at nearby Harim, which was leveled by the quake. A Muslim fort at Al-Atarib was destroyed as well, and several smaller towns and manned forts were reduced to rubble. The quake was said to have been felt as far away as Damascus, about 220 miles to the south. The Aleppo earthquake was the first of several occurring between 1138 and 1139 that devastated areas in northern Syria and western Turkey.

  • 4: Sumatra, Indonesia, Dec. 26, 2004

    Aerial images show the extent of the devastation in Meulaboh
    Getty Images  /  Getty Images
    MEULABOH, INDONESIA - DECEMBER 29: In this handout photo taken from a print via the Indonesian Air Force, the scene of devastation in Meulaboh, the town closest to the Sunday's earthquake epicentre, is pictured from the air on December 29, 2004, Meulaboh, Aceh Province, Sumatra, Indonesia. The western coastal town in Aceh Province, only 60 kilometres north-east of the epicentre, has been the hardest hit by sunday's underwater earthquake in the Indian Ocean. Officials expected to find at least 10,000 killed which would amount to a quarter of Meulaboh's population. Three-quarters of Sumatra's western coast was destroyed and some towns were totally wiped out after the tsunamis that followed the earthquake. (Photo by Indonesian Air Force via Getty Images)

    Magnitude 9.1, 227,898 deaths.

    This was the third largest earthquake in the world since 1900 and the largest since the 1964 Prince William Sound, Alaska temblor. In total, 227,898 people were killed or were missing and presumed dead and about 1.7 million people were displaced by the earthquake and subsequent tsunami in 14 countries in South Asia and East Africa. (In January 2005, the death toll was 286,000. In April 2005, Indonesia reduced its estimate for the number missing by over 50,000.)

  • 5: Haiti, Jan 12, 2010

    Haitians walk through collapsed building
    Jean-philippe Ksiazek  /  AFP/Getty Images
    Haitians walk through collapsed buildings near the iron market in Port-au-Prince on January 31, 2010. Quake-hit Haiti will need at least a decade of painstaking reconstruction, aid chiefs and donor nations warned, as homeless, scarred survivors struggled today to rebuild their lives. AFP PHOTO / JEAN-PHILIPPE KSIAZEK (Photo credit should read JEAN-PHILIPPE KSIAZEK/AFP/Getty Images)

    Magnitude 7.0. According to official estimates, 222,570 people killed.

    According to official estimates, 300,000 were also injured, 1.3 million displaced, 97,294 houses destroyed and 188,383 damaged in the Port-au-Prince area and in much of southern Haiti. This includes at least 4 people killed by a local tsunami in the Petit Paradis area near Leogane. Tsunami waves were also reported at Jacmel, Les Cayes, Petit Goave, Leogane, Luly and Anse a Galets.

  • 6: Damghan, Iran, Dec. 22, 856

    Magnitude not known, about 200,000 deaths.

    This earthquake struck a 200-mile stretch of northeast Iran, with the epicenter directly below the city of Demghan, which was at that point the capital city. Most of the city was destroyed as well as the neighboring areas. Approximately 200,000 people were killed.

  • 7: Haiyuan, Ningxia , China, Dec. 16, 1920

    7.8 magnitude, about 200,000 deaths.

    This earthquake brought total destruction to the Lijunbu-Haiyuan-Ganyanchi area. Over 73,000 people were killed in Haiyuan County. A landslide buried the village of Sujiahe in Xiji County. More than 30,000 people were killed in Guyuan County. Nearly all the houses collapsed in the cities of Longde and Huining. About 125 miles of surface faulting was seen from Lijunbu through Ganyanchi to Jingtai. There were large numbers of landslides and ground cracks throughout the epicentral area. Some rivers were dammed, others changed course.

  • 8: Ardabil, Iran, March. 23, 893

    Magnitude not known, about 150,000 deaths

    The memories of the massive Damghan earthquake (see above) had barely faded when only 37 years later, Iran was again hit by a huge earthquake. This time it cost 150,000 lives and destroyed the largest city in the northwestern section of the country. The area was again hit by a fatal earthquake in 1997.

  • 9: Kanto, Japan, Sept. 1, 1923

    Kanto Damage
    Hulton Archive  /  Getty Images
    1923: High-angle view of earthquake and fire damage on Hongokucho Street and the Kanda District, taken from the Yamaguchi Bank building after the Kanto earthquake, Tokyo, Japan. (Photo by Hulton Archive/Getty Images)
    7.9 magnitude, 142,800 deaths.

    This earthquake brought extreme destruction in the Tokyo-Yokohama area, both from the temblor and subsequent firestorms, which burned about 381,000 of the more than 694,000 houses that were partially or completely destroyed. Although often known as the Great Tokyo Earthquake (or the Great Tokyo Fire), the damage was most severe in Yokohama. Nearly 6 feet of permanent uplift was observed on the north shore of Sagami Bay and horizontal displacements of as much as 15 feet were measured on the Boso Peninsula.

  • 10: Ashgabat, Turkmenistan, Oct. 5, 1948

    7.3 magnitude, 110,000 deaths.

    This quake brought extreme damage in Ashgabat (Ashkhabad) and nearby villages, where almost all the brick buildings collapsed, concrete structures were heavily damaged and freight trains were derailed. Damage and casualties also occurred in the Darreh Gaz area in neighboring Iran. Surface rupture was observed both northwest and southeast of Ashgabat. Many sources list the casualty total at 10,000, but a news release from the newly independent government on Dec. 9, 1988, advised that the correct death toll was 110,000. (Turkmenistan had been part of the Soviet Union, which tended to downplay the death tolls from man-made and natural disasters.)


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