Category Archives: Japan

Fallout forensics hike radiation toll

Fallout forensics hike radiation toll : Nature News.

The disaster at the Fukushima Daiichi nuclear plant in March released far more radiation than the Japanese government has claimed. So concludes a study1 that combines radioactivity data from across the globe to estimate the scale and fate of emissions from the shattered plant.

The study also suggests that, contrary to government claims, pools used to store spent nuclear fuel played a significant part in the release of the long-lived environmental contaminant caesium-137, which could have been prevented by prompt action. The analysis has been posted online for open peer review by the journal Atmospheric Chemistry and Physics.

Andreas Stohl, an atmospheric scientist with the Norwegian Institute for Air Research in Kjeller, who led the research, believes that the analysis is the most comprehensive effort yet to understand how much radiation was released from Fukushima Daiichi. “It’s a very valuable contribution,” says Lars-Erik De Geer, an atmospheric modeller with the Swedish Defense Research Agency in Stockholm, who was not involved with the study.

The reconstruction relies on data from dozens of radiation monitoring stations in Japan and around the world. Many are part of a global network to watch for tests of nuclear weapons that is run by the Comprehensive Nuclear-Test-Ban Treaty Organization in Vienna. The scientists added data from independent stations in Canada, Japan and Europe, and then combined those with large European and American caches of global meteorological data.

Stohl cautions that the resulting model is far from perfect. Measurements were scarce in the immediate aftermath of the Fukushima accident, and some monitoring posts were too contaminated by radioactivity to provide reliable data. More importantly, exactly what happened inside the reactors — a crucial part of understanding what they emitted — remains a mystery that may never be solved. “If you look at the estimates for Chernobyl, you still have a large uncertainty 25 years later,” says Stohl.

Nevertheless, the study provides a sweeping view of the accident. “They really took a global view and used all the data available,” says De Geer.

Challenging numbers

Japanese investigators had already developed a detailed timeline of events following the 11 March earthquake that precipitated the disaster. Hours after the quake rocked the six reactors at Fukushima Daiichi, the tsunami arrived, knocking out crucial diesel back-up generators designed to cool the reactors in an emergency. Within days, the three reactors operating at the time of the accident overheated and released hydrogen gas, leading to massive explosions. Radioactive fuel recently removed from a fourth reactor was being held in a storage pool at the time of the quake, and on 14 March the pool overheated, possibly sparking fires in the building over the next few days.

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But accounting for the radiation that came from the plants has proved much harder than reconstructing this chain of events. The latest report from the Japanese government, published in June, says that the plant released 1.5?×?1016?bequerels of caesium-137, an isotope with a 30-year half-life that is responsible for most of the long-term contamination from the plant2. A far larger amount of xenon-133, 1.1?×?1019?Bq, was released, according to official government estimates.

The new study challenges those numbers. On the basis of its reconstructions, the team claims that the accident released around 1.7?×?1019?Bq of xenon-133, greater than the estimated total radioactive release of 1.4?×?1019? Bq from Chernobyl. The fact that three reactors exploded in the Fukushima accident accounts for the huge xenon tally, says De Geer.

Xenon-133 does not pose serious health risks because it is not absorbed by the body or the environment. Caesium-137 fallout, however, is a much greater concern because it will linger in the environment for decades. The new model shows that Fukushima released 3.5?×?1016? Bq caesium-137, roughly twice the official government figure, and half the release from Chernobyl. The higher number is obviously worrying, says De Geer, although ongoing ground surveys are the only way to truly establish the public-health risk.

Stohl believes that the discrepancy between the team’s results and those of the Japanese government can be partly explained by the larger data set used. Japanese estimates rely primarily on data from monitoring posts inside Japan3, which never recorded the large quantities of radioactivity that blew out over the Pacific Ocean, and eventually reached North America and Europe. “Taking account of the radiation that has drifted out to the Pacific is essential for getting a real picture of the size and character of the accident,” says Tomoya Yamauchi, a radiation physicist at Kobe University who has been measuring radioisotope contamination in soil around Fukushima.

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Stohl adds that he is sympathetic to the Japanese teams responsible for the official estimate. “They wanted to get something out quickly,” he says. The differences between the two studies may seem large, notes Yukio Hayakawa, a volcanologist at Gunma University who has also modelled the accident, but uncertainties in the models mean that the estimates are actually quite similar.

The new analysis also claims that the spent fuel being stored in the unit 4 pool emitted copious quantities of caesium-137. Japanese officials have maintained that virtually no radioactivity leaked from the pool. Yet Stohl’s model clearly shows that dousing the pool with water caused the plant’s caesium-137 emissions to drop markedly (see ‘Radiation crisis’). The finding implies that much of the fallout could have been prevented by flooding the pool earlier.

The Japanese authorities continue to maintain that the spent fuel was not a significant source of contamination, because the pool itself did not seem to suffer major damage. “I think the release from unit 4 is not important,” says Masamichi Chino, a scientist with the Japanese Atomic Energy Authority in Ibaraki, who helped to develop the Japanese official estimate. But De Geer says the new analysis implicating the fuel pool “looks convincing”.

The latest analysis also presents evidence that xenon-133 began to vent from Fukushima Daiichi immediately after the quake, and before the tsunami swamped the area. This implies that even without the devastating flood, the earthquake alone was sufficient to cause damage at the plant.

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The Japanese government’s report has already acknowledged that the shaking at Fukushima Daiichi exceeded the plant’s design specifications. Anti-nuclear activists have long been concerned that the government has failed to adequately address geological hazards when licensing nuclear plants (see Nature 448, 392–393; 2007), and the whiff of xenon could prompt a major rethink of reactor safety assessments, says Yamauchi.

The model also shows that the accident could easily have had a much more devastating impact on the people of Tokyo. In the first days after the accident the wind was blowing out to sea, but on the afternoon of 14 March it turned back towards shore, bringing clouds of radioactive caesium-137 over a huge swathe of the country (see ‘Radioisotope reconstruction’). Where precipitation fell, along the country’s central mountain ranges and to the northwest of the plant, higher levels of radioactivity were later recorded in the soil; thankfully, the capital and other densely populated areas had dry weather. “There was a period when quite a high concentration went over Tokyo, but it didn’t rain,” says Stohl. “It could have been much worse.” 

Additional reporting by David Cyranoski and Rina Nozawa.

Japan struggles to rebuild

Insight: Japan struggles to rebuild, leaving lives in limbo | Reuters.

Severe storms hit the Midwest on Saturday and are expected later in the Northeast, where flash flooding killed at least four people in Pittsburgh on Friday.

Heavy rains submerged cars in flood water that was nine feet deep in places in Pittsburgh, authorities said.

A mother and her two daughters died when water engulfed their vehicle in a low-lying section of the city’s Washington Boulevard near the Allegheny River.

Kimberly Griffith, 45, and her daughters Brenna, 12, and Mikaela, 8, were pronounced dead at the scene, a spokeswoman for the Allegheny County medical examiner’s office said.

The water pinned their vehicle to a tree and they were unable to escape, authorities said.

Also recovered after the flood was the body of Mary Saflin, 72, who had been reported missing earlier, according to the Allegheny County medical examiner’s office.

The Philadelphia area was also soaked by heavy thunder showers Friday, bringing a record rainfall of 12.95 inches for August, close to the record for any month, according to NWS meteorologist Lee Robertson.

The previous record is from September 1999, set when a hurricane pushed rainfall to 13.07 inches.

As more storms were forecast for the region Sunday, the NWS warned in a flood advisory that nearly half of all flood fatalities are vehicle-related.

“As little as six inches of water will cause you to lose control of your vehicle,” the NWS stated.

MORE STORMS

The Weather Channel forecast more storms from the Great Lakes to the Central Plains into Saturday night.

One man died as storms and a tornado roared across northern Wisconsin Friday night, cutting an 8-mile-wide swath 65 miles north of Green Bay and taking out power to around 2,000 homes, officials said.

Douglas Brem, 43, was staying in a rented trailer at a recycling center in the path of the storm, which caused extensive damage to homes, Marinette County Coroner George Smith said.

A fierce thunderstorm in the Chicago area Saturday suspended the Chicago Air & Water Show until about 2 p.m., leaving time for a condensed show. The two-day free annual event was expected to attract around 2 million spectators.

Saturday’s thunderstorm threat will shift to the Northeast Sunday.

The Southeastern Virginia Hampton Roads region was spared from severe storm activity, but smoke from a 6,000-acre fire in the Great Dismal Swamp continues to plague the region down into North Carolina.

Virginia’s Environmental Quality Department downgraded Friday’s air quality red alert in some areas to orange, advising of possible health problems for sensitive individuals.

(Additional reporting by John Rondy in Milwaukee, Cynthia Johnston in Las Vegas, Matthew A. Ward in Chesapeake, Va., David Warner in Philadelphia; Writing by Molly O’Toole and Mary Wisniewski; Editing by Jerry Norton)

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ACTION PLAN NEEDED

<span class="articleLocation”>More than five months after a massive magnitude 9.0 earthquake and a deadly tsunami ravaged Japan’s northeast coast, the nation has yet to come up with a detailed action plan and the money needed to rebuild the devastated areas.

The following is a summary of where Japan’s rebuilding efforts stand.

DEATH TOLL, EVACUEES AND SHRINKING WORKING-AGE POPULATION

— About 15,690 were killed, 4,740 are missing, and 5,710 were injured.

— Many of about 5.6 million residents of the three prefectures worst hit by the March disaster have lost their homes and the number of evacuees peaked at more than 475,000 on March 14.

— Some 9,900 still live in evacuation shelters while 34,100 are staying in hotels or with relatives or friends and about 40,000 live in temporary housing.

— Japan’s northeast is aging faster than other area of a country whose population is already graying at a rapid pace. By 2030, 31.6 percent of the population is expected to be above 65 in Tohoku, whereas the country-wide estimate is 29.6 percent.

According to BNP Paribas estimates the region’s working population shrunk 8.4 percent over the past 15 years and is expected to decline by further 12.6 percent over the next decade.

RUBBLE

— The quake and tsunami left an estimated 22.6 million tonnes of rubble in the coastal towns. Out of that, nearly half has been moved to temporary storage destinations.

— By end-August, the government aims to remove debris from areas where people live and work and this goal is likely to be met. But removal of all rubble and dismantling of damaged buildings will take months, if not years, and the government aims to dispose the stored rubble by end of March, 2014.

ECONOMIC DAMAGE

— The quake and tsunami destroyed supply chains given that the northeast is home to many manufacturers. Japan’s gross domestic product fell 0.9 percent in the first quarter, tipping the economy into its second recession in three years. But in the second quarter, the economy shrank much less than foreseen as companies made strides in restoring output and is expected to bounce by 1.2 percent this quarter — probably the best performance among major industrialized nations.

— The government initially estimated the material damage from the March 11 disaster at 16-25 trillion yen ($190-$300 billion) but later lowered it to 16.9 trillion yen ($210 billion). The estimated damage is roughly double that from the 1995 Kobe earthquake.

EMERGENCY BUDGET FOR RELIEF

— The government enacted its first extra budget of 4 trillion ($50 billion) in May, and its second emergency budget of 2 trillion ($25 billion) in July.

— The government hopes to pass the third extra budget by the end of September under a new prime minister, though whether this can materialize so quickly is unclear.

DAMAGE TO FISHING AND FARMING

— Northeast Japan is known for fishing and farming. Damages in the fishing industry are estimated at 1.23 trillion yen. About 320 fishing ports, or 11 percent of all fishing ports in Japan, have been closed due to the March disaster and it would take at least another decade for full operations to resume at these ports.

— About 2.6 percent of the total farm area in Japan, or 23,600 Ha, has been washed away or submerged due to the disaster.

AID MONEY

— The Japanese Red Cross Society has so far collected 259 billion yen in relief money. Out of this, about 48 percent has been distributed to disaster victims, while the remaining amount is stuck at overburdened local governments.

(Sources: The Cabinet Office’s Reconstruction Headquarters in response to the Great East Japan Earthquake, Environment Ministry, Fukushima Prefecture, Miyagi Prefecture, Statistics Bureau, Fisheries Agency, Farm Ministry, Japanese Red Cross Society, Cabinet Office, National Police Agency, Tohoku Trade department)

(Reporting by Yuko Takeo; Additional reporting by Yoko Kubota)

 

Zone Near Fukushima Daiichi May Be Off Limits for Decades

Zone Near Fukushima Daiichi May Be Off Limits for Decades – NYTimes.com.

 

TOKYO — Broad areas around the stricken Fukushima Daiichi nuclear plant could soon be declared uninhabitable, perhaps for decades, after a government survey found radioactive contamination that far exceeded safe levels, several major media outlets said Monday.

The formal announcement, expected from the government in coming days, would be the first official recognition that the March accident could force the long-term depopulation of communities near the plant, an eventuality that scientists and some officials have been warning about for months. Lawmakers said over the weekend — and major newspapers reported Monday — that Prime Minister Naoto Kan was planning to visit Fukushima Prefecture, where the plant is, as early as Saturday to break the news directly to residents. The affected communities are all within 12 miles of the plant, an area that was evacuated immediately after the accident.

The government is expected to tell many of these residents that they will not be permitted to return to their homes for an indefinite period. It will also begin drawing up plans for compensating them by, among other things, renting their now uninhabitable land. While it is unclear if the government would specify how long these living restrictions would remain in place, news reports indicated it could be decades. That has been the case for areas around the Chernobyl plant in Ukraine after its 1986 accident.

Since the Fukushima accident, evacuations have been a sensitive topic for the government, which has been criticized for being slow to admit the extent of the disaster and trying to limit the size of the areas affected, despite possible risks to public health. Until now, Tokyo had been saying it would lift the current evacuation orders for most areas around the plant early next year, when workers are expected to stabilize Fukushima Daiichi’s damaged nuclear reactors.

The government was apparently forced to alter its plans after the survey by the Ministry of Science and Education, released over the weekend, which showed even higher than expected radiation levels within the 12-mile evacuation zone around the plant. The most heavily contaminated spot was in the town of Okuma about two miles southwest of the plant, where someone living for a year would be exposed to 508.1 millisieverts of radiation — far above the level of 20 millesieverts per year that the government considers safe.

The survey found radiation above the safe level at three dozen spots up to 12 miles from the plant. That has called into question how many residents will actually be able to return to their homes even after the plant is stabilized.

Some 80,000 people were evacuated from communities around the plant, which was crippled by the magnitude 9.0 earthquake and towering tsunami on March 11. Many of those residents now live in temporary housing or makeshift refugee shelters, and are allowed back to their homes only for brief, tightly supervised visits in which they must wear protective clothing.

Nuclear worries for Japan as quake rocks south coast

Short Sharp Science: Nuclear worries for Japan as quake rocks south coast.

Wendy Zukerman, Asia-Pacific reporter

An earthquake shook Japan’s south coast on Monday, close to Hamaoka, which has the dubious status of hosting the nation’s most perilous nuclear plant.

No damage was reported – the plant had been shut down while a tsunami-proof seawall was built – but Japan is by no means free of nuclear worries. In Fukushima, the Tokyo Electric Power Company (Tepco) reported that radiation exceeding 10 sieverts (10,000 millisieverts) per hour was found at the bottom of a ventilation stack standing between two reactors.

 

The Japan Meteorological Agency recorded that a 6.1 magnitude earthquake jolted Shizuoka Prefecture and the surrounding areas. Hamaoka is 40 kilometres from the quake’s epicentre and is considered one of the world’s most dangerous because it straddles two major geological faults.

Shingo Tsumura, an engineer at Chubu Electric Power Company (CEPC), which runs Hamaoka, told New Scientist that it is unlikely that yesterday’s 6.1 magnitude quake would have caused any damage to the nuclear plant, had it been switched on.

According to Tsumura, the ground at the power plant accelerated only 40 to 50 Gal (centimetres per second). “It is very small,” he says. “The plant will automatically shut down at 120 Gal.”

Tests last month reported that the plant could withstand ground motion of 300 Gal, with a “low possibility of collapse or damage that would cause functional failure.”

But Japanese prime minister Naoto Kan has said there is a high chance of a magnitude-8 quake in the region within 30 years – and in any case less powerful quakes have been known to affect the Hamoaka plant.

In August 2009, a magnitude-6.4 earthquake automatically shut down reactors 4 and 5 at the Hamaoka. According to the World Nuclear Association, of which CEPC is a member, some equipment was also damaged.

At Fukushima, a Tepco spokesman said that the potentially lethal doses of radiation were detected in areas that would not hamper recovery efforts. Tepco regulations state that workers at Fukushima not be exposed to more than 250 millisieverts of radiation a year.

Tepco said that the spots of high radiation could stem from debris left behind by emergency venting conducted after the March 11 earthquake and tsunami.

Meanwhile Iwate Prefecture became the third to ban the shipment of beef cattle following the detection in cows of caesium above safety limits.

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