Tag Archive: Chernobyl


What Does Fukushima’s New “Level 7” Status Mean?

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By KRISTA MAHR Krista Mahr Tue Apr 12, 3:15 am ET

Japanese officials announced on Tuesday morning that they were planning to raise the event level at the Fukushima Daiichi nuclear power plant from a 5 to the maximum level of 7, the highest on the international scale for nuclear incidents and the same level assigned to the 1986 disaster at Chernobyl in the Ukraine.

The decision was made after Japan’s nuclear safety body determined that at one point after the March 11 earthquake, the plant was releasing 10,000 terabecquerels of iodine-131 for several hours; level 7 accidents are defined as releasing tens of thousands of terabecquerels. “The INES rating itself is not an indicator of a daily phenomena, but the assessment after careful consideration and calculation on the event that happened in the past,” Ken Morita of NISA told TIME on Tuesday morning. (See inside Japan’s nuclear wasteland.)

NISA has also noted, however, that the amount of radioactive material being released at Fukushima today is less than 1 terabecquerel. The agency says that, to date, Fukushima has only released about 10% of total radiation released 25 years ago in Chernobyl, or about 1.8 million terabecquerels. About 30 people, mostly workers, died in the immediate aftermath of Chernobyl, though the UN has estimated that the long-term death toll due to exposure could eventually be as high as 4000.

The International Nuclear Event Scale (INES), designed in 1989 by the IAEA and the Nuclear Energy Agency (NEA) of the OECD, ranges from 1 (anomaly) to 7 (major accident). The scale is intended to help easily communicate with the public to indicate the seriousness of a nuclear event. Chernobyl is the only other nuclear accident to have been given a 7, an accident classified as having a major radioactive release with widespread impact on the environment and public health. According to INES, “Such a release would result in the possibility of acute health effects; delayed health effects over a wide area, possibly involving more than one country; long-term environmental consequences.” (Read the IAEA’s glossary of short- to long-term health effects of radiation exposure here.) (See the world’s top 10 environmental disasters.)

Besides Chernobyl, the only event that’s come close to a 7 before was a 1957 accident at a fuel processing plant (where spent nuclear fuel is recycled into new fuel) in Russia, in which an off-site release of radiation prompted preventative evacuations. The Three Mile Island accident in the U.S. in 1978, in which a reactor core was severely damage but off-site release of radioactivity was limited, was classified as a 5. Almost all reported events at nuclear facilities are a level 3 or under, according to INES.

Tuesday’s announcement comes on the back of a minor fire spotted by workers outside Fukushima’s reactor 4 on Tuesday morning, shortly after the second of three major aftershocks to hit the beleaguered northeast in the space of 24 hours. Three people in Iwaki died in landslides triggered by the 7.1 aftershock on Monday evening. The government also expanded the exclusion zone around Fukushima on Monday to include several towns within a 30-km (19-mile) radius that had formerly been told that they could remain at home, but were recommended to stay indoors. The towns now added to the mandatory evacuation zone were found to have high levels of radiation. (See the battle to hold Fukushima’s cores.)

Meanwhile, Greenpeace has said that in a survey conducted in Fukushima last week, its team of experts found radiation levels 75 times higher than the government recommendation in 11 samples of vegetables from gardens and small farms. The environmental group also announced that it found radiation levels equivalent to an annual exposure of 5 millisieverts – the evacuation threshold for Chernobyl – in a playground in Fukushima City, population 300,000. Greenpeace is urging the government to delay the start of the school year.

Though raising Fukushima’s level to 7 may not herald any immediate worsening of events, it is sure to add to many residents’ growing concern – and feelings of helplessness – over what could happen at dozens of other nuclear reactors spread across this seismic archipelago. On Sunday, over 17,000 people protested at two separate demonstrations in Tokyo against nuclear power. It was the first time that Yohei Nakamura, 45, had ever been to a protest. “For a long time I’ve been suspicious of nuclear power, but now I realize it’s a serious problem,” he said amidst the crowds carrying placards and shouting slogans. He said anti-nuclear demonstrations were undercovered in the Japanese press because of the influence of Tokyo Power and Electric Power Company, which owns Fukushima. “TEPCO is one of the most powerful companies in Japan,” Nakamura said. “They use a tremendous amount of money for adverstising. If the mass media shows anti-nuclear power activities like demonstrations, they risk losing TEPCO as an advertiser.”

– With reporting by Lucy Birmingham / Tokyo

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The ongoing crisis at Japan’s Fukushima Daiichi nuclear plant has turned into what one analyst calls “a slow-moving nightmare,” with fires, leaks of poisonous radiation, and mass evacuations.

With events shifting quickly, and a sometimes confusing succession of announcements coming from authorities, it can be hard to get a clear sense of exactly what’s happening, and of what to expect going forward. So here’s a rundown, based on several recent news reports, on where things stand five days in…

 

What’s at the root of the problem?

Friday’s earthquake and tsunami caused power outages across northern Japan — including at the Daiichi plant, which comprises six separate reactors. That in turn caused a failure of the reactors’ cooling systems, which are needed to keep the nuclear fuel from overheating and melting down and/or triggering an explosion, releasing poisonous radiation into the atmosphere.

What’s the current situation at the plant?

Yesterday, an explosion caused the containment vessel covering the Number 2 reactor to crack, releasing into the air a surge of radiation 800 times more intense than the recommended hourly exposure limit in Japan. One third of the fuel rods at the reactor were reportedly damaged. In addition, another powerful explosion blew a 26-foot wide hole in the side of Number 4 reactor, causing fires to break out and a pool containing spent fuel rods to begin dangerously overheating.

The Japanese military tried to use helicopters to dump water from the air to cool the Number 4 reactor, but that plan was abandoned after a third explosion — this one damaging the roof and cooling system of the Number 3 reactor — because it would have meant flying a helicopter into radioactive steam. Gregory Jaczko, the top U.S. nuclear official, said today that all the water was gone from the pool containing the fuel rods at the Number 4 reactor — an assertion denied by a spokesman for the Japanese power company that runs the plant. If Jaczko is correct, it would mean there is nothing to stop the fuel from melting down, spewing radiation.

Water was also poured into the Numbers 5 and 6 reactors, suggesting that essentially the entire plant could be at risk of overheating.

In what appears to have been an understatement, the plant operator described the situation at the Number 4 reactor as “not so good.” But in some ways the rupture at the Number 3 reactor is especially troubling, because it’s the only reactor that uses plutonium as part of its fuel mix. If absorbed into the bloodstream, plutonium can stay in the liver or bone marrow and cause cancer.

Japanese officials said early Thursday they’re close to completing a new power line which would restore the cooling systems for the reactors, but it’s unclear when the line will be up and running.

How much of the surrounding area is likely to be affected by the radiation?

The government has told the roughly 140,000 people who live within 18 miles of the plant to stay indoors, but has said that people outside that zone can safely go outside. However, some experts have accused the Japanese authorities of underplaying the severity of the crisis. The U.S. embassy has recommended that Americans within 50 miles of the plant evacuate the area or stay indoors.

Tokyo, 180 miles south of the plant, has recorded radiation levels only slightly above normal. Still, both France and Australia have urged their nationals throughout the country to leave, and many Tokyo residents have been staying indoors. One American couple living in Tokyo told family they don’t yet see a need to leave, but are monitoring the situation closely.

What other ideas are being considered?

In what experts describe as a last-ditch effort, police are hoping to use a water cannon — usually used to quell riots — to cool the nuclear fuel. Officials have also proposed using boric acid, which can help slow nuclear reactions by absorbing neutrons.

On Monday, 750 workers were withdrawn from the facility, leaving a core of 50 to battle the crisis alone while exposing themselves to potentially deadly levels of radiation. But even those workers appeared to have been withdrawn today after a surge in radiation caused by new explosions made the area too dangerous.

What are the best- and worst-case scenarios?

The best case scenario is that efforts to cool the fuel rods succeed, and damage to the surrounding environment is limited to an area within about 15 miles of the plant. The worst is a full-scale meltdown of the reactors caused by overheating, which would release much larger amounts of radiation into the air than has yet occurred.  In that case, the damage could potentially approach the level of the Soviet Union’s 1986 Chernobyl disaster, for which estimates of deaths vary from 4000 to close to one million.

How does the crisis rank, in terms of nuclear plant accidents?

On Saturday, Japanese authorities ranked the incident a Level Four on a one-to-seven scale used to rank nuclear accidents. but things have worsened since then, and yesterday France’s nuclear authority said it should be classified as a Level Six. Chernobyl is the only Level 7 accident ever to have occurred.

In this image released by Tokyo Electric Power Co., smoke billows from the No. 3 unit among four housings cover four reactors at the Fukushima Dai-ichi nuclear complex in Okumamachi, Fukushima Prefecture, northeastern Japan, on Tuesday, March 15, 2011.  (AP Photo/Tokyo Electric Power Co.)

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