Filtering of Tainted Water Begins at Japanese Plant

The filtering equipment, hastily cobbled together by several foreign and Japanese companies, is urgently needed because the storage facilities at the power plant are flooded with tens of thousands of tons of radioactive water and are expected to overflow as soon as next week if nothing is done.

If that occurs, Tokyo Electric, known as Tepco, would be forced to dump thousands of tons of even more tainted water into the ocean, and would probably bring down even more criticism on the embattled company and the government, which has been attacked for its handling of the crisis.

Hoping to avoid releasing any more contaminated water, Tepco in late April set out an ambitious nine-month road map for stabilizing conditions at its nuclear reactors. The plan includes setting up a sprawling water treatment plant that is expected to cost about $663 million. Built under the supervision of Toshiba and Hitachi, the filtration system is meant to sift out oil, and then cesium and other radioactive elements, before desalinating the remaining water.

The system is expected to process about 1,200 tons of water a day, which will be stored in tanks, some of which are being brought to the compound. Some of the filtered water will be reused to cool the reactors, reducing the need for fresh supplies. Tepco plans to filter water for about a year, said Junichi Matsumoto, a spokesman.

Tepco originally planned to begin operating the filtration system in July, but it sped up construction because contaminated water had been produced faster than expected at the nuclear plant. A leaky valve halted testing of the system on Thursday, and there were several more delays on Friday, before it finally got running. Tepco acknowledged that the system could falter again and might have to be shut down for repairs.

While the filtration system was being built, Tepco reduced the amount of water it was pouring into the plant’s stricken reactors to avoid filling up its storage facilities.

The beginning of the rainy season this month has complicated efforts to slow the creation of toxic water.

“It is something like a chemical plant constructed in a rush, so we have to go by trial and error,” said Hidehiko Nishiyama, deputy director general of the Nuclear and Industrial Safety Agency, referring to the repeated problems that have plagued the project. “We have had to do this in a hurry, so conditions have been very severe.”

In all, about 500 tons of water is newly contaminated at the plant each day, adding to the 105,000 tons of highly radioactive water that is already stored on the site, mostly in the trenches and basements of the turbine and reactor buildings. Many of these areas are perilously near full to the brim. In the trenches at the No. 3 reactor, for example, there was just seven inches to spare on Friday.

Critics contend that while the filtration system will delay the runoff of radioactive water for a while, Tepco will continue to face water disposal problems because it may take years to fully cool the reactors at the plant.

“It’s just a matter of time before it overflows,” said Satoshi Sato, a nuclear engineer who formerly worked for General Electric at the reactors in Fukushima. “It’s an endless game.”

The water stored at the plant is contaminated with cesium 134, cesium 137 and iodine 131 with a total radioactivity estimated at 720,000 terabecquerels, more than the amount of radioactive material that has been spewed into the air at the plant so far.

The new filtration system still faces many hurdles. The companies operating it, including Areva from France and Kurion from the United States, have little experience working with seawater. And Tepco must still dispose of the radioactive material that is being sifted out of the wastewater; it is mixed with a chemical agent to create a toxic sludge.

During the summer, Tepco will deliver 370 tanks to the Daiichi plant to store an extra 40,400 tons of radioactive water. A megafloat that can store yet more water is moored near the plant.

The contaminated water has been an unavoidable side effect of Tepco’s “feed and bleed” strategy for dealing with the four destroyed reactors at Fukushima Daiichi. To cool them for eventual dismantling, the company is pouring huge volumes of freshwater and seawater directly onto the highly radioactive reactors, which contaminates the water, creating an environmental headache.

The devilish consequences of the company’s efforts became clear in April, when rivers of contaminated water seeped through cracks in drainage pits and flowed directly into the Pacific Ocean. While that leak was plugged, a lack of storage for contaminated water soon forced Tepco to deliberately release an additional 11,500 tons into the sea.

The dumping led to an international outcry. In waters near the plant, a variety of fish and seaweed were found with higher than normal levels of radioactivity, prompting a ban on the sale of marine products harvested from parts of Japan’s Pacific coast.

Several workers at the plant have suffered burns on their feet and ankles after stepping in highly radioactive water. Reducing the amount of water in and around the power plant will make it easier for workers to undertake other repairs.

Yasuko Kamiizumi and Kantaro Suzuki contributed reporting.

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Hidden Dangers: Japanese Officials Ignored or Concealed Dangers

If such a quake struck, electrical power could fail, along with backup generators, crippling the cooling system, the lawyers predicted. The reactors would then suffer a meltdown and start spewing radiation into the air and sea. Tens of thousands in the area would be forced to flee.

Although the predictions sound eerily like the sequence of events at the Fukushima Daiichi plant following the March 11 earthquake and tsunami, the lawsuit was filed nearly a decade ago to shut down another plant, long considered the most dangerous in Japan — the Hamaoka station.

It was one of several quixotic legal battles waged — and lost — in a long attempt to improve nuclear safety and force Japan’s power companies, nuclear regulators, and courts to confront the dangers posed by earthquakes and tsunamis on some of the world’s most seismically active ground.

The lawsuits reveal a disturbing pattern in which operators underestimated or hid seismic dangers to avoid costly upgrades and keep operating. And the fact that virtually all these suits were unsuccessful reinforces the widespread belief in Japan that a culture of collusion supporting nuclear power, including the government, nuclear regulators and plant operators, extends to the courts as well.

Yuichi Kaido, who represented the plaintiffs in the Hamaoka suit, which they lost in a district court in 2007, said that victory could have led to stricter earthquake, tsunami and backup generator standards at plants nationwide.

“This accident could have been prevented,” Mr. Kaido, also the secretary general of the Japan Federation of Bar Associations, said of Fukushima Daiichi. The operator of the plant, Chubu Electric Power Company, temporarily shut down Hamaoka’s two active reactors over the weekend, following an extraordinary request by Prime Minister Naoto Kan.

After strengthening the plant’s defenses against earthquakes and tsunamis, a process that could take a couple of years, the utility is expected to restart the plant.

Japan’s plants are all located in coastal areas, making them vulnerable to both quakes and tsunamis. The tsunami is believed to have caused the worst damage at the Fukushima plant, though evidence has begun emerging that the quake may have damaged critical equipment before the waves struck.

The disaster at Fukushima Daiichi, the worst nuclear accident since Chernobyl, directly led to the suspension of Hamaoka here in Omaezaki, a city about 120 miles southwest of Tokyo. But Mr. Kan’s decision was also clearly influenced by a campaign, over decades, by small groups of protesters, lawyers and scientists, who sued the government or operators here and elsewhere.

They were largely ignored by the public. Harassment by neighbors, warnings by employers, and the reluctance of young Japanese to join antinuclear groups have diminished their numbers.

But since the disaster at Fukushima and especially the suspension of Hamaoka, the aging protesters are now heralded as truth-tellers, while members of the nuclear establishment are being demonized.

On Friday, as Chubu Electric began shutting down a reactor at 10 a.m., Eiichi Nagano, 90, and Yoshika Shiratori, 78, were battling strong winds on the shoreline leading to the plant here. Mr. Shiratori, a leader of the lawsuit, led the way as Mr. Nagano followed with a sprightly gait despite a bent back. The two men scrambled up a dune, stopping only before a “No Trespassing” sign.

“Of course, we’re pleased about the suspension,” Mr. Nagano said, as the strong wind seemed to threaten to topple him. “But if we had done more, if our voices had been louder, we could have prevented the disaster at Fukushima Daiichi. Fukushima was sacrificed so that Hamaoka could be suspended.”

Unheeded Warnings

In 1976, a resource-poor Japan still reeling from the shocks of the oil crisis was committed fully to nuclear power to achieve greater energy independence, a path from which it never strayed despite growing doubts in the United States and Europe.

 

Japanese Worker’s Death Not Linked to Radiation

The operator, the Tokyo Electric Power Company, said the contract worker, who was in his 60s, died after carrying heavy equipment in a waste disposal building of the Fukushima Daiichi nuclear plant. The company said that he was wearing radiation-protection clothing and a mask when he collapsed, and that his body did not show high levels of radioactive contamination.

Japanese news media reports later quoted a doctor at the plant as saying the man had apparently suffered a heart attack. The death is the first by one of the workers struggling to bring the Fukushima Daiichi plant under control since it lost power and cooling functions after the March 11 earthquake and tsunami.

Contractors who work at nuclear power plants in Japan have traditionally labored in some of the most hazardous conditions, battling intense heat and braving radiation exposure to do such jobs as cleaning radioactive materials from surfaces in the plants.

The waste disposal building the contract worker had been in has been used to store radiation-contaminated runoff taken from the plant’s damaged reactor buildings, where the water is obstructing workers’ efforts to bring the reactors under better control.

On Saturday, nuclear officials said they had found more than 12 feet of water in the basement of Reactor No. 1.

Another power company announced on Saturday that it had completed the shutdown of a nuclear plant elsewhere in Japan, honoring a request by the prime minister to suspend operations at the plant for safety reasons.

The company, Chubu Electric Power, said it had halted operations of the last active reactor at the Hamaoka plant, which sits atop a major earthquake fault line.

 

Finding on Dialects Casts New Light on the Origins of the Japanese People

The result provides support for a wider picture, controversial among linguists, that the distribution of many language families today reflects the spread of agriculture in the distant past when farming populations, carrying their languages with them, grew in numbers and expanded at the expense of hunter-gatherers. Under this theory, the Indo-European family of languages, which includes English, was spread by the first farmers who expanded into Europe from the Middle East some 8,000 years ago, largely replacing the existing population of hunter-gatherers.

In the case of Japan, archaeologists have found evidence for two waves of migrants, a hunter-gatherer people who created the Jomon culture and wet rice farmers who left remains known as the Yayoi culture.

The Jomon people arrived in Japan before the end of the last ice age, via land bridges that joined Japan to Asia’s mainland. They fended off invaders until about 2,400 years ago when the wet rice agriculture developed in southern China was adapted to Korea’s colder climate.

Several languages seem to have been spoken on the Korean Peninsula at this time, and that of the Yayoi people is unknown. The work of two researchers at the University of Tokyo, Sean Lee and Toshikazu Hasegawa, now suggests that the origin of Japonic — the language family that includes Japanese and Ryukyuan, spoken in the Ryukyu island chain south of Japan — coincides with the arrival of the Yayoi.

The finding, if confirmed, indicates that the Yayoi people took Japonic to Japan, but leaves unresolved the question of where in Asia the Yayoi culture or Japonic language originated before arriving in the Korean Peninsula.

Mr. Lee is a graduate student studying language and the mind, not a historical linguist. He has used a statistical tree-drawing method that other biologists have applied successfully to language origins, despite some linguists’ skepticism. The method, called Bayesian phylogeny, depends on having a computer draw a large number of possible trees and sampling them to find the most probable. Each language is represented by a 200-word vocabulary composed of words known to change very slowly.

If any fork in the tree can be linked to a historical event, all the other branch points can be dated. In this case, Mr. Lee knew dates for Old Japanese, Middle Japanese, and the split between the Kyoto and Tokyo dialects that began in 1603 A.D. when the capital was moved from Kyoto to Edo, the early name for Tokyo.

Mr. Lee reasoned that Japanese would have originated with the Jomon if the root of the tree turned out to be very ancient, but with the Yayoi culture if recent. The computer’s date of 2,182 years ago for the origin of the tree fits reasonably well with the archaeological dates for the Yayoi culture, he reported Tuesday in The Proceedings of the Royal Society.

John B. Whitman, an expert on Japanese linguistics who works at the National Institute for Japanese Language and Linguistics, in Tokyo, and at Cornell University, called the new finding “solid and reasonable,” although the date of the Yayoi culture, he said, has now been pushed back to around 3,000 years after a recalibration of radiocarbon dates. That would open an 800-year gap with Mr. Lee’s date but not necessarily change his conclusion.

The question of Japanese origins has had political consequences, with the link to the Yayoi culture having been invoked to justify the annexation of Korea and Manchuria before World War II. After the war, the link with the Jomon culture was emphasized.

Quentin Atkinson, an expert on language phylogeny at the University of Auckland, in New Zealand, said that Mr. Lee’s time scale was plausible but that if Japonic had spread through an agriculturally driven population expansion, his language tree should be much bushier at its root. Mr. Lee said that such earlier versions of Japanese might have disappeared when the island was politically unified about 1,000 years ago.

Genetic studies have suggested interbreeding between the Yayoi and Jomon people, with the Jomon contribution to modern Japanese being as much as 40 percent. Apparently the Yayoi language prevailed, along with the agricultural technology.

 

Finding on Dialects Casts New Light on the Origins of the Japanese People

Researchers studying the various dialects of Japanese have concluded that all are descended from a founding language taken to the Japanese islands about 2,200 years ago. The finding sheds new light on the origin of the Japanese people, suggesting that their language is descended from that of the rice-growing farmers who arrived in Japan from the Korean Peninsula, and not from the hunter-gatherers who first inhabited the islands some 30,000 years ago.

The result provides support for a wider picture, controversial among linguists, that the distribution of many language families today reflects the spread of agriculture in the distant past when farming populations, carrying their languages with them, grew in numbers and expanded at the expense of hunter-gatherers. Under this theory, the Indo-European family of languages, which includes English, was spread by the first farmers who expanded into Europe from the Middle East some 8,000 years ago, largely replacing the existing population of hunter-gatherers.

In the case of Japan, archaeologists have found evidence for two waves of migrants, a hunter-gatherer people who created the Jomon culture and wet rice farmers who left remains known as the Yayoi culture.

The Jomon people arrived in Japan before the end of the last ice age, via land bridges that joined Japan to Asia’s mainland. They fended off invaders until about 2,400 years ago when the wet rice agriculture developed in southern China was adapted to Korea’s colder climate.

Several languages seem to have been spoken on the Korean Peninsula at this time, and that of the Yayoi people is unknown. The work of two researchers at the University of Tokyo, Sean Lee and Toshikazu Hasegawa, now suggests that the origin of Japonic — the language family that includes Japanese and Ryukyuan, spoken in the Ryukyu island chain south of Japan — coincides with the arrival of the Yayoi.

The finding, if confirmed, indicates that the Yayoi people took Japonic to Japan, but leaves unresolved the question of where in Asia the Yayoi culture or Japonic language originated before arriving in the Korean Peninsula.

Mr. Lee is a graduate student studying language and the mind, not a historical linguist. He has used a statistical tree-drawing method that other biologists have applied successfully to language origins, despite some linguists’ skepticism. The method, called Bayesian phylogeny, depends on having a computer draw a large number of possible trees and sampling them to find the most probable. Each language is represented by a 200-word vocabulary composed of words known to change very slowly.

If any fork in the tree can be linked to a historical event, all the other branch points can be dated. In this case, Mr. Lee knew dates for Old Japanese, Middle Japanese, and the split between the Kyoto and Tokyo dialects that began in 1603 A.D. when the capital was moved from Kyoto to Edo, the early name for Tokyo.

Mr. Lee reasoned that Japanese would have originated with the Jomon if the root of the tree turned out to be very ancient, but with the Yayoi culture if recent. The computer’s date of 2,182 years ago for the origin of the tree fits reasonably well with the archaeological dates for the Yayoi culture, he reported Tuesday in The Proceedings of the Royal Society.

John B. Whitman, an expert on Japanese linguistics who works at the National Institute for Japanese Language and Linguistics, in Tokyo, and at Cornell University, called the new finding “solid and reasonable,” although the date of the Yayoi culture, he said, has now been pushed back to around 3,000 years after a recalibration of radiocarbon dates. That would open an 800-year gap with Mr. Lee’s date but not necessarily change his conclusion.

The question of Japanese origins has had political consequences, with the link to the Yayoi culture having been invoked to justify the annexation of Korea and Manchuria before World War II. After the war, the link with the Jomon culture was emphasized.

Quentin Atkinson, an expert on language phylogeny at the University of Auckland, in New Zealand, said that Mr. Lee’s time scale was plausible but that if Japonic had spread through an agriculturally driven population expansion, his language tree should be much bushier at its root. Mr. Lee said that such earlier versions of Japanese might have disappeared when the island was politically unified about 1,000 years ago.

Genetic studies have suggested interbreeding between the Yayoi and Jomon people, with the Jomon contribution to modern Japanese being as much as 40 percent. Apparently the Yayoi language prevailed, along with the agricultural technology.

 

Many Japanese Factories Recover After Quake

The ceiling is still not fixed. But employees are back at their posts, working under temporary lighting and wearing hard hats to protect themselves in case debris falls.

The factory may be a case study for the can-do recovery of Japan’s manufacturing industry. Only seven weeks after the huge earthquake in northeastern Japan collapsed the ceiling, toppled a huge water tank and upended assembly line equipment, the Ricoh factory here is nearly back to full production. And so, for the most part, is all of Ricoh, a nearly $25 billion company that makes copiers and other office equipment.

“The influence of this disaster is not as large as the world thinks,” Shiro Kondo, Ricoh’s president, said in an interview at the company headquarters in Tokyo.

At varying speeds, Ricoh’s story is being played out all over the quake-affected parts of Japan. The pattern suggests that whatever the long-term effect of the natural and nuclear disasters on this country, manufacturing — the most important cog in Japan’s export-oriented economy — might largely rebound within a few months.

Without doubt, things are not back to normal yet. And some sectors, particularly automobile manufacturing, are suffering more than others. Still, almost every day companies are reporting progress on some of the hundreds of factories knocked out of commission by the quake or ensuing tsunami. The government estimates that 7 percent of Japanese factories were in the region heavily affected by the earthquake.

A survey of 70 damaged factories released last week by Japan’s Ministry of Economy, Trade and Industry found that nearly two-thirds of them had recovered while most of the rest in the survey group expected to do so by summer.

Shin-Etsu Chemical, a leading producer of silicon wafers used to make computer chips, said last week that it expected to return to pre-earthquake production levels by July. Sony has resumed operations at nine of its 10 halted factories, with the 10th expected to come online in phases from May to July.

Masatomo Onishi of Kansai University, who studied the recovery after the 1995 Kobe earthquake, said that when a disaster strikes, Japanese companies tend to cooperate with one another and workers rally to the cause.

That seems to be the case at the Ricoh factory here. Even many of the Ricoh workers who lost family members to the tsunami came to work. Some whose homes were destroyed or flooded slept on blankets on the floor of a factory conference room. With gasoline scarce, many rode bicycles. And with bathrooms not working because of blocked sewer lines, employees improvised with plastic bags.

Still, the disaster exposed vulnerabilities that simply restoring any one factory’s assembly line cannot fully resolve.

The biggest susceptibility for Ricoh and many other companies has proven to be parts shortages. Although Japanese manufacturers have spread their factories around the world — Ricoh makes 70 percent of its products outside of Japan — many of those overseas plants often still depend on parts made in Japan.

For example, Tohoku Ricoh, as this plant is known, is the company’s only factory making a particular motor used in copiers. When the factory here went down, a giant Ricoh plant in Shenzhen, China — which supplies most of the Ricoh copiers sold in the United States — had to stop production for a full week. (Mr. Kondo said he did not think Ricoh’s sales in the United States would be affected much.)

Ricoh is also dependent on parts from various suppliers in Japan, some of which suffered their own damage from the earthquake.

That is forcing Ricoh to live off its inventory of certain computer chips and connectors. If production of those parts does not resume in the next couple of months, Ricoh might have to slow or halt production.

Another weakness was in emergency planning.

David Jolly contributed reporting from Tokyo.

 

Life in Limbo for Japanese Near Nuclear Plant

  Kyodo News, via Associated PressTakaharu Ando, the chief of the National Police Agency, with reporters last Monday in an evacuated Japanese town.

TENEI, Japan — For seven generations, Yoshitoshi Sewa and his ancestors have tilled this farm in a gently curving valley filled with green rice paddies. But now he will not let his young grandchildren play outside their tile-roofed home for fear of an invisible and potentially long-lasting threat, radiation.

Yoshitoshi Sewa, a farmer, in his home in Tenei, 40 miles from Japan's stricken nuclear plant. He will not let his grandchildren play outdoors.

“Even if the government says it’s O.K., no one here wants to take the risk of radiation,” said Mr. Sewa, 63, whose farm sits about 40 miles west of Japan’s stricken Fukushima Daiichi nuclear power plant — well beyond the zone where residents have been told to leave or remain indoors.

Since an earthquake and tsunami on March 11 crippled the plant, spewing radioactive particles into the air and sea, Tokyo has ordered the evacuation of a 12-mile radius, and some villages beyond that. But those living outside the evacuation zones have felt left in limbo, exposed to levels of radiation that are several times the normal level, though not high enough to cause observable health risks. Still, experts admit that there is a lack of knowledge about the health effects of lower doses of radiation, especially over an extended period of time. Japan’s plant has been dispersing radioactive material for nearly two months and counting, far longer than the 10 days during which the Chernobyl plant released a much larger burst of radioactive particles in 1986.

It is difficult for Japanese experts to even agree on clear-cut numerical levels of radiation for deciding which areas are safe to inhabit — decisions that might affect hundreds of thousands of people living in hundreds of square miles of this densely population nation.

“This is an unprecedented situation, to which none of our textbooks apply,” said Shigenobu Nagataki, former chairman of the Nagasaki-based Radiation Effects Research Foundation, which studied victims of the World War II atomic bombings. “Decisions are being made now that will have a huge impact on Japan’s future.”

The disagreements came to the forefront on Friday, when a government adviser on radiation safety quit, calling on Japan to lower the permissible radiation dose of 20 millisieverts per year that the Education Ministry has set for schools for younger children, including elementary and junior high, in affected areas.

Other Japanese critics point out that the figure comes from the International Commission on Radiological Protection, which sets it as the upper limit of radiation exposure in inhabited areas after a nuclear accident, and thus too high for schools because children are more vulnerable. Government officials and some experts retort that the level was still low enough not to pose a health risk. They also said that radiation levels would fall over the next two months with the disappearance of short-lived iodine 131, which accounts for about half of the radioactive material emitted by the plant. Other measures are being taken to clean up the remaining radioactive matter, mainly cesium 137, which can last for generations.

Acting on its own, the city of Koriyama, about 35 miles west of the plant, will change the topsoil at 15 elementary schools where the city detected radiation doses above 20 millisieverts per year, and at 13 kindergartens where it found slightly lower radiation levels.

The Education Ministry has also found similarly high levels At 13 elementary schools, kindergartens and preschools in Fukushima Prefecture. In the city of Fukushima, 35 miles northwest of the plant, some schools have barred students from playing outside while at school. At least one school also requires children to wear hats and surgical masks, and to avoid contact with playground equipment.

The Education Ministry’s guidelines take into account the child’s exposure to radiation during the entire day, both at home and school, and experts say clean-up will have to happen all over towns, not just on school grounds. The radiation levels at schools is just one of the many decisions that Japan must make, whether on farm produce or the safety of entire towns. In Fukushima Prefecture, where the nuclear plant is located, the authorities conduct 50 tests a day on vegetables and milk, as much to reassure consumers as to find contaminated products.

Even so, Mr. Sewa, the farmer in Tenei, said that he had to destroy this spring’s crop of 880 pounds of cucumbers because he could find no buyers.

“Fukushima products are seen as tainted,” he said.

Martin Fackler reported from Tenei, and Matthew L. Wald from Washington. Makiko Inoue contributed reporting from Tokyo.

 

Life in Limbo for Japanese Near Nuclear Plant

  Kyodo News, via Associated PressTakaharu Ando, the chief of the National Police Agency, with reporters last Monday in an evacuated Japanese town.

TENEI, Japan — For seven generations, Yoshitoshi Sewa and his ancestors have tilled this farm in a gently curving valley filled with green rice paddies. But now he will not let his young grandchildren play outside their tile-roofed home for fear of an invisible and potentially long-lasting threat, radiation.

Yoshitoshi Sewa, a farmer, in his home in Tenei, 40 miles from Japan's stricken nuclear plant. He will not let his grandchildren play outdoors.

“Even if the government says it’s O.K., no one here wants to take the risk of radiation,” said Mr. Sewa, 63, whose farm sits about 40 miles west of Japan’s stricken Fukushima Daiichi nuclear power plant — well beyond the zone where residents have been told to leave or remain indoors.

Since an earthquake and tsunami on March 11 crippled the plant, spewing radioactive particles into the air and sea, Tokyo has ordered the evacuation of a 12-mile radius, and some villages beyond that. But those living outside the evacuation zones have felt left in limbo, exposed to levels of radiation that are several times the normal level, though not high enough to cause observable health risks. Still, experts admit that there is a lack of knowledge about the health effects of lower doses of radiation, especially over an extended period of time. Japan’s plant has been dispersing radioactive material for nearly two months and counting, far longer than the 10 days during which the Chernobyl plant released a much larger burst of radioactive particles in 1986.

It is difficult for Japanese experts to even agree on clear-cut numerical levels of radiation for deciding which areas are safe to inhabit — decisions that might affect hundreds of thousands of people living in hundreds of square miles of this densely population nation.

“This is an unprecedented situation, to which none of our textbooks apply,” said Shigenobu Nagataki, former chairman of the Nagasaki-based Radiation Effects Research Foundation, which studied victims of the World War II atomic bombings. “Decisions are being made now that will have a huge impact on Japan’s future.”

The disagreements came to the forefront on Friday, when a government adviser on radiation safety quit, calling on Japan to lower the permissible radiation dose of 20 millisieverts per year that the Education Ministry has set for schools for younger children, including elementary and junior high, in affected areas.

Other Japanese critics point out that the figure comes from the International Commission on Radiological Protection, which sets it as the upper limit of radiation exposure in inhabited areas after a nuclear accident, and thus too high for schools because children are more vulnerable. Government officials and some experts retort that the level was still low enough not to pose a health risk. They also said that radiation levels would fall over the next two months with the disappearance of short-lived iodine 131, which accounts for about half of the radioactive material emitted by the plant. Other measures are being taken to clean up the remaining radioactive matter, mainly cesium 137, which can last for generations.

Acting on its own, the city of Koriyama, about 35 miles west of the plant, will change the topsoil at 15 elementary schools where the city detected radiation doses above 20 millisieverts per year, and at 13 kindergartens where it found slightly lower radiation levels.

The Education Ministry has also found similarly high levels At 13 elementary schools, kindergartens and preschools in Fukushima Prefecture. In the city of Fukushima, 35 miles northwest of the plant, some schools have barred students from playing outside while at school. At least one school also requires children to wear hats and surgical masks, and to avoid contact with playground equipment.

The Education Ministry’s guidelines take into account the child’s exposure to radiation during the entire day, both at home and school, and experts say clean-up will have to happen all over towns, not just on school grounds. The radiation levels at schools is just one of the many decisions that Japan must make, whether on farm produce or the safety of entire towns. In Fukushima Prefecture, where the nuclear plant is located, the authorities conduct 50 tests a day on vegetables and milk, as much to reassure consumers as to find contaminated products.

Even so, Mr. Sewa, the farmer in Tenei, said that he had to destroy this spring’s crop of 880 pounds of cucumbers because he could find no buyers.

“Fukushima products are seen as tainted,” he said.

Martin Fackler reported from Tenei, and Matthew L. Wald from Washington. Makiko Inoue contributed reporting from Tokyo.

 

Japanese Officials on Defensive as Nuclear Alert Level Rises

  A volunteer in Ofunato, Japan, cleaned photographs that were found in the tsunami debris.

TOKYO — Japanese officials struggled through the day on Tuesday to explain why it had taken them a month to disclose large-scale releases of radioactive material in mid-March at a crippled nuclear power plant, as the government and an electric utility disagreed on the extent of continuing problems there.

A policeman watched colleagues prepare to transport a body by van in Minamisoma, Japan, on Thursday, inside a deserted nuclear evacuation zone.

The government announced Tuesday morning that it had raised its rating of the severity of the accident at the Fukushima Daiichi Nuclear Power Station to 7, the worst on an international scale, from 5. Officials said that the reactor had released one-tenth as much radioactive material as the Chernobyl accident in 1986, but still qualified as a 7 according to a complex formula devised by the International Atomic Energy Agency.

Japan’s new assessment was based largely on computer models showing very heavy emissions of radioactive iodine and cesium from March 14 to 16, just after the earthquake and tsunami rendered the plant’s emergency cooling system inoperative. The nearly monthlong delay in acknowledging the extent of these emissions is a fresh example of confused data and analysis from the Japanese, and put the authorities on the defensive about whether they have delayed or blocked the release of information to avoid alarming the public.

Seiji Shiroya, a commissioner of Japan’s Nuclear Safety Commission, an independent government panel that oversees the country’s nuclear industry, said that the government had delayed issuing data on the extent of the radiation releases because of concern that the margins of error had been large in initial computer models. But he also suggested a public policy reason for having kept quiet.

“Some foreigners fled the country even when there appeared to be little risk,” he said. “If we immediately decided to label the situation as Level 7, we could have triggered a panicked reaction.”

The Japanese media, which has a reputation for passivity but has become more aggressive in response to public unhappiness about the nuclear accident, questioned government leaders through the day about what the government knew about the accident and when it knew it.

Prime Minister Naoto Kan gave a nationally televised speech and press conference in the early evening to call for national rebuilding, but ended up defending his government’s handling of information about the accident.

“What I can say for the information I obtained — of course the government is very large, so I don’t have all the information — is that no information was ever suppressed or hidden after the accident,” he said. “There are various ways of looking at this, and I know there are opinions saying that information could have been disclosed faster. However, as the head of the government, I never hid any information because it was inconvenient for us.”

Junichi Matsumoto, a senior nuclear power executive from the plant’s operator, the Tokyo Electric Power Company, fanned public fears about radiation when he said at a separate news conference on Tuesday morning that the radiation release from Daiichi could, in time, surpass levels seen in 1986.

“The radiation leak has not stopped completely, and our concern is that it could eventually exceed Chernobyl,” Mr. Matsumoto said.

But Hidehiko Nishiyama, deputy director general of Japan’s nuclear regulator, the Nuclear and Industrial Safety Agency, said in an interview on Tuesday evening that he did not know how the company had come up with its estimate. “I cannot understand their position,” he said.

He speculated that Tokyo Electric was being “prudent and thinking about the worst-case scenario,” adding, “I think they don’t want to be seen as optimistic.”

Mr. Nishiyama said that his agency did not expect another big escape of radiation from Daiichi, saying that “almost all” the material that is going to escape has already come out. He said that the rate of radiation release had peaked in the early days after the March 11 earthquake, and that the rate of radiation had dropped by 90 percent since then.

The peak release in emissions of radioactive particles took place following hydrogen explosions at three reactors, as technicians desperately tried to pump in seawater to keep the uranium fuel rods cool, and bled radioactive gas from the reactors in order to make room for the seawater.

Mr. Nishiyama took pains to say — and other nuclear experts agreed — that the Japanese accident posed fewer health risks than Chernobyl.