AI
Wednesday, April 06, 2011 5:51:33 AM
U.S. Sees Array of New Threats at Japan’s Nuclear Plant
Workers at the Fukushima Daiichi nuclear station are dealing with new challenges.
Reuters
By JAMES GLANZ and WILLIAM J. BROAD
Published: April 5, 2011
United States government engineers sent to help with the crisis in Japan are warning that the troubled nuclear plant there is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable, according to a confidential assessment prepared by the Nuclear Regulatory Commission.
Among the new threats that were cited in the assessment, dated March 26, are the mounting stresses placed on the containment structures as they fill with radioactive cooling water, making them more vulnerable to rupture in one of the aftershocks rattling the site after the earthquake and tsunami of March 11. The document also cites the possibility of explosions inside the containment structures due to the release of hydrogen and oxygen from seawater pumped into the reactors, and offers new details on how semimolten fuel rods and salt buildup are impeding the flow of fresh water meant to cool the nuclear cores.
In recent days, workers have grappled with several side effects of the emergency measures taken to keep nuclear fuel at the plant from overheating, including leaks of radioactive water at the site and radiation burns to workers who step into the water. The assessment, as well as interviews with officials familiar with it, points to a new panoply of complex challenges that water creates for the safety of workers and the recovery and long-term stability of the reactors.
While the assessment does not speculate on the likelihood of new explosions or damage from an aftershock, either could lead to a breach of the containment structures in one or more of the crippled reactors, the last barriers that prevent a much more serious release of radiation from the nuclear core. If the fuel continues to heat and melt because of ineffective cooling, some nuclear experts say, that could also leave a radioactive mass that could stay molten for an extended period.
The document, which was obtained by The New York Times, provides a more detailed technical assessment than Japanese officials have provided of the conundrum facing the Japanese as they struggle to prevent more fuel from melting at the Fukushima Daiichi plant. But it appears to rely largely on data shared with American experts by the Japanese.
Among other problems, the document raises new questions about whether pouring water on nuclear fuel in the absence of functioning cooling systems can be sustained indefinitely. Experts have said the Japanese need to continue to keep the fuel cool for many months until the plant can be stabilized, but there is growing awareness that the risks of pumping water on the fuel present a whole new category of challenges that the nuclear industry is only beginning to comprehend.
The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed.
David A. Lochbaum, a nuclear engineer who worked on the kinds of General Electric reactors used in Japan and now directs the nuclear safety project at the Union of Concerned Scientists, said that the welter of problems revealed in the document at three separate reactors made a successful outcome even more uncertain.
“I thought they were, not out of the woods, but at least at the edge of the woods,” said Mr. Lochbaum, who was not involved in preparing the document. “This paints a very different picture, and suggests that things are a lot worse. They could still have more damage in a big way if some of these things don’t work out for them.”
The steps recommended by the nuclear commission include injecting nitrogen, an inert gas, into the containment structures in an attempt to purge them of hydrogen and oxygen, which could combine to produce explosions. The document also recommends that engineers continue adding boron to cooling water to help prevent the cores from restarting the nuclear reaction, a process known as criticality.
Even so, the engineers who prepared the document do not believe that a resumption of criticality is an immediate likelihood, Neil Wilmshurst, vice president of the nuclear sector at the Electric Power Research Institute, said when contacted about the document. “I have seen no data to suggest that there is criticality ongoing,” said Mr. Wilmshurst, who was involved in the assessment.
The document was prepared for the commission’s Reactor Safety Team, which is assisting the Japanese government and the Tokyo Electric Power Company, which owns the plant. It says it is based on the “most recent available data” from numerous Japanese and American organizations, including the electric power company, the Japan Atomic Industrial Forum, the United States Department of Energy, General Electric and the Electric Power Research Institute, an independent, nonprofit group.
The document contains detailed assessments of each of the plant’s six reactors along with recommendations for action. Nuclear experts familiar with the assessment said that it was regularly updated but that over all, the March 26 version closely reflected current thinking.
The assessment provides graphic new detail on the conditions of the damaged cores in reactors 1, 2 and 3. Because slumping fuel and salt from seawater that had been used as a coolant is probably blocking circulation pathways, the water flow in No. 1 “is severely restricted and likely blocked.” Inside the core itself, “there is likely no water level,” the assessment says, adding that as a result, “it is difficult to determine how much cooling is getting to the fuel.” Similar problems exist in No. 2 and No. 3, although the blockage is probably less severe, the assessment says.
Some of the salt may have been washed away in the past week with the switch from seawater to fresh water cooling, nuclear experts said.
A rise in the water level of the containment structures has often been depicted as a possible way to immerse and cool the fuel. The assessment, however, warns that “when flooding containment, consider the implications of water weight on seismic capability of containment.”
Experts in nuclear plant design say that this warning refers to the enormous stress put on the containment structures by the rising water. The more water in the structures, the more easily a large aftershock could rupture one of them.
Margaret Harding, a former reactor designer for General Electric, warned of aftershocks and said, “If I were in the Japanese’s shoes, I’d be very reluctant to have tons and tons of water sitting in a containment whose structural integrity hasn’t been checked since the earthquake.”
The N.R.C. document also expressed concern about the potential for a “hazardous atmosphere” in the concrete-and-steel containment structures because of the release of hydrogen and oxygen from the seawater in a highly radioactive environment.
Hydrogen explosions in the first few days of the disaster heavily damaged several reactor buildings and in one case may have damaged a containment structure. That hydrogen was produced by a mechanism involving the metal cladding of the nuclear fuel. The document urged that Japanese operators restore the ability to purge the structures of these gases and fill them with stable nitrogen gas, a capability lost after the quake and tsunami.
Nuclear experts say that radiation from the core of a reactor can split water molecules in two, releasing hydrogen. Mr. Wilmshurst said that since the March 26 document, engineers had calculated that the amount of hydrogen produced would be small. But Jay A. LaVerne, a physicist at Notre Dame, said that at least near the fuel rods, some hydrogen would in fact be produced, and could react with oxygen. “If so,” Mr. LaVerne said in an interview, “you have an explosive mixture being formed near the fuel rods.”
Nuclear engineers have warned in recent days that the pools outside the containment buildings that hold spent fuel rods could pose an even greater danger than the melted reactor cores. The pools, which sit atop the reactor buildings and are meant to keep spent fuel submerged in water, have lost their cooling systems.
The N.R.C. report suggests that the fuel pool of the No. 4 reactor suffered a hydrogen explosion early in the Japanese crisis and could have shed much radioactive material into the environment, what it calls “a major source term release.”
Experts worry about the fuel pools because explosions have torn away their roofs and exposed their radioactive contents. By contrast, reactors have strong containment vessels that stand a better chance of bottling up radiation from a meltdown of the fuel in the reactor core.
“Even the best juggler in the world can get too many balls up in the air,” Mr. Lochbaum said of the multiplicity of problems at the plant. “They’ve got a lot of nasty things to negotiate in the future, and one missed step could make the situation much, much worse.”
Henry Fountain contributed reporting from New York, and Matthew L. Wald from Washington.
http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html [ http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?pagewanted=all ] [comments at http://community.nytimes.com/comments/www.nytimes.com/2011/04/06/world/asia/06nuclear.html ]
===
Tiny Fish Spur Widening Worry
Japan Discovers High Radiation Levels in One Species, Stoking Environmental and Safety Concerns
APRIL 6, 2011
http://online.wsj.com/article/SB10001424052748703712504576244251331137870.html [with comments]
===
Radioactivity Found in Fish as Tepco Purges Nuclear Plant
Apr 5, 2011 1:38 PM CT
http://www.bloomberg.com/news/2011-04-05/tepco-dumping-toxic-water-angers-fishermen-stock-plunges.html
===
Fishing Halted in Japan’s Ibaraki After Radioactive Water Contaminates Sea
Apr 6, 2011 3:56 AM CT
http://www.bloomberg.com/news/2011-04-06/fishing-halted-in-japan-s-ibaraki-after-radioactive-water-contaminates-sea.html
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WRAPUP 6-Japan stops nuclear plant leak; crisis far from over
Wed Apr 6, 2011 3:24am EDT
http://www.reuters.com/article/2011/04/06/japan-idUSL3E7F526520110406 [with comment]
===
Japan earthquake: Radioactive leak plugged at reactor
6 April 2011 Last updated at 02:49 ET
[...]
Engineers also face a potential new problem of a build-up of hydrogen gas in one of the reactors at the six-unit plant. Tepco said it could inject nitrogen gas into the No 1 reactor to prevent an explosion.
[...]
On Tuesday, Japan asked Russia for the use of a floating radiation treatment plant to tackle waste water.
Russia's nuclear agency Rosatom said it was awaiting answers to some questions before granting the request to lend the Landysh, known in Japanese as the Suzuran, which is used to decommission Russian nuclear submarines in the far eastern port of Vladivostok.
One of the world's largest liquid radioactive waste treatment plants, the Landysh treats radioactive liquid with chemicals and stores it in a cement form.
It can process 35 cubic metres of liquid waste a day and 7,000 cubic metres a year.
[...]
http://www.bbc.co.uk/news/world-asia-pacific-12981243
===
Fukushima update: Data, data, everywhere ... - April 05, 2011
http://blogs.nature.com/news/thegreatbeyond/2011/04/fukushima_update_data_data_eve.html [no comments yet]
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Fukushima update: Hiroshima and Nagasaki bomb experts outline health research needs after Fukushima - April 05, 2011
http://blogs.nature.com/news/thegreatbeyond/2011/04/fukushima_update_hiroshima_and.html [no comments yet]
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Worker safety takes back seat in dealing with nuclear crisis
Workers set up a temporary power distribution board at the Fukushima No. 1 nuclear power plant in Okuma, Fukushima Prefecture.
(Provided by Tokyo Electric Power Co.)
2011/04/05
The problems continue to pile up at the Fukushima No. 1 nuclear plant, creating an unprecedented hazardous environment for the under-equipped front-line workers trying to bring the situation under control.
But given the potential widespread damage from the crisis, officials acknowledge that labor safety is not the top priority anymore.
"Under circumstances where there is no end to new problems faced, we cannot deny that the company is depending on the spirit of the workers," an executive of Tokyo Electric Power Co., the plant operator, said. "Unless we are able to both secure workers' safety while settling the nuclear accident, TEPCO will in the end face very serious criticism."
The workers continue to risk exposure to high levels of radiation in their efforts to restore cooling mechanisms for the reactor cores. But the public is growing impatient for a quick end --or even significant progress -- in the battle at the Fukushima plant, putting pressure on not only TEPCO but also the government.
"It is never good to have any kind of work that requires putting one's life on the line," a high-ranking official of the Ministry of Health, Labor and Welfare said. "However, the importance of settling the situation at the nuclear plant goes beyond the range of labor policy. I cannot be confident about whether that or the safety of the workers should have priority."
TEPCO has already faced harsh criticism concerning the safety of the workers.
Labor ministry officials began investigating the company after the utility admitted that workers were not all given portable dosimeters to check for radiation. But the investigation has its limits because officials cannot enter the plant grounds.
"The public is hoping the crisis at the nuclear plant is settled quickly, and that expectation could affect measures to be taken to ensure the safety of workers," a labor ministry source said.
TEPCO officials said about 5,000 dosimeters were available before the March 11 earthquake and tsunami that crippled the plant. But the twin disasters left only 320 usable dosimeters.
TEPCO has since obtained dosimeters from other nuclear power plants for a sufficient supply. But before that, a regulation was revised to allow workers to share one dosimeter as long as they were exposed to less than 10 millisieverts of radiation and the group members were engaged in similar work.
"Because there are some locations where radiation levels are constantly changing, the new regulation does hold danger for the workers," a TEPCO source said.
Satoshi Kamata, who has written extensively about labor issues, questioned TEPCO's commitment to the safety of its workers.
"There is the possibility that those working at the Fukushima plant have already been exposed to high levels of radiation, so doubts arise about whether TEPCO was serious about labor safety conditions," Kamata said. "Because TEPCO is the only entity that can actually look after those conditions, it should obtain a good grasp of the situation and publicize what it knows."
According to an official of the Nuclear and Industrial Safety Agency, the only place within the plant grounds where workers do not have to wear protective clothing against radiation is a two-story building built with high quake-resistant standards and high air-tightness.
Workers who have finished laying cables or removing contaminated water within the plant grounds shed their protective clothing and masks for radiation measurements before entering the special building. Because many workers stay overnight in the plant grounds, there are shortages of protective gear as well as fresh clothing.
TEPCO's labor union has asked management for information about radiation levels at the plant as well as the health conditions of the workers.
"There will be a need for mass mobilization of workers so that no individual worker is exposed to radiation that exceeds legal standards. There will be a need for labor unions to understand the details about the working environment and to provide support so workers can work in safety," a labor union source said.
Despite the dangers, the workers at the Fukushima plant appear determined to push on.
"Workers keep saying, 'We will have to do something about the problem,'" a TEPCO source said.
Companies cooperating with TEPCO have conducted surveys of workers who might be asked to go to Fukushima. Although the surveys clearly stated that workers could decline with their identities concealed and no effects on their job evaluations, all those surveyed said they were willing to fight the crisis in Fukushima, the companies said.
One immediate measure being discussed to help the workers is raising the compensation amount given for hazardous work. The government has been much quicker on this issue.
The Defense Ministry decided on March 24 to increase by 1.5 times the amount given to members of the Self-Defense Forces who die or are left with disabilities as a result of working at the Fukushima nuclear plant. Families of SDF members who die can receive as much as 90 million yen ($1.07 million) while those disabled can receive a maximum of 75.6 million yen.
Those amounts are similar to those for SDF members dispatched to Iraq as well as those patrolling against pirates off the coast of Somalia.
"Considering the dangers and difficulties of the work (at Fukushima), we decided that it was similar to Iraq and Somalia," a Defense Ministry official said.
TEPCO executives, however, have been slower to commit to higher amounts paid for hazardous work.
Although TEPCO already has a three-level system for hazardous pay depending on radiation dangers, executives admitted they never expected a situation in which workers would have to toil amid continuous high radiation levels.
Some companies cooperating with TEPCO do not have hazardous pay arrangements that take into consideration situations such as the current one. The executives of those companies said they would review the system in line with what other companies sending workers to Fukushima do.
Experts said the central government would have to become involved to look after the safety of those working to end the crisis at the Fukushima plant.
"Japan's compensation system for nuclear accidents has not emphasized protection of victims because it was preconditioned on the notion that a serious accident would never occur," said Terumitsu Honma, head of the Aoyama Gakuin University Research Institute, who is knowledgeable about compensation for nuclear energy accidents.
"However, a serious accident is now unfolding, and workers have been exposed to radiation. There will be a need to create a totally new compensation system based on the actual dangers faced by the workers at the plant and nearby residents who have been affected," he said.
Copyright 2011 The Asahi Shimbun Company
http://www.asahi.com/english/TKY201104040147.html
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Town near nuclear plant rejects Japanese utility's 'token' offer
April 6, 2011 -- Updated 0212 GMT (1012 HKT)
http://edition.cnn.com/2011/WORLD/asiapcf/04/05/japan.nuclear.money/ [with comments]
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TEPCO shares hit new low, eyes on government
Wed Apr 6, 2011 4:39am EDT
http://www.reuters.com/article/2011/04/06/us-japan-tepco-idUSTRE7350NI20110406
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Japan may order Tokyo-area industry to conserve power
By Osamu Tsukimori
TOKYO | Wed Apr 6, 2011 2:39am EDT
(Reuters) - Japan's trade ministry may order big industrial electricity users in the country's economic heartland around Tokyo to cut their peak summer power use by 25 percent, a ministry official said, as efforts mount to avert crippling blackouts.
The ministry was also likely to create power-saving targets for smaller users, including individual households, the official said.
Tokyo Electric Power is scrambling to secure enough power for the capital area's factories and air-conditioners this summer after a devastating earthquake and tsunami took out more than 20 percent of its generating capacity, including the Fukushima nuclear complex.
"We are looking at a cut of around 25 percent (for large-scale users of 500 kilowatts or more)," the ministry official, who declined to be identified, told Reuters.
"Efforts will be made to boost supply, which would ease pressure on the demand side. We may also discuss less stringent constraints for households and smaller users, but if we ease up at this point we may end up being too lax."
ROLLING BLACKOUTS
The ministry is scheduled to finalize its strategies to cope with the peak summer season by the end of April, he added.
The Tokyo area and regions further north, served mainly by Tokyo Electric, account for half the economic activity of the world's third-biggest economy, Nomura Holdings estimates.
Analysts suggest power blackouts could ultimately become the greatest source of economic damage inflicted by last month's disaster on Japan, a vital player in the global manufacturing supply chain.
Tokyo Electric implemented rolling blackouts last month after the March 11 earthquake and tsunami, although it has since restarted some damaged thermal power plants and has been able to avoid blackouts since March 28, helped also by warmer weather.
The giant Fukushima nuclear complex remains down amid a protracted safety crisis, however, and Trade Minister Banri Kaieda has said there could be a shortfall of 10,000 to 15,000 megawatts when air-conditioner use kicks in over the summer, depending on how far temperatures rise.
Tokyo Electric has estimated, however, that it can rush enough thermal plants online, including mothballed facilities, to close the gap to about 5,000 MW, presuming typical summer use around 60,000 MW.
Analysts said the power savings may not need to be as draconian as those under discussion at the trade ministry.
"I am very skeptical that there will be such severe cuts. These reports seem to be part of a drive to encourage energy conservation in order to minimize disruption over the summer," said Richard Jerram, chief Asian economist at Macquarie Securities.
The ministry official nevertheless rejected media reports that the Tokyo utility would not use rolling blackouts after April, noting they may be needed to ensure there are no unexpected outages that would take down power for Tokyo Electric's entire service area.
"Rolling blackouts would remain as a last resort," he said.
(Additional reporting by Chikako Mogi and James Topham; Editing by Edmund Klamann)
© Copyright 2011 Thomson Reuters
http://www.reuters.com/article/2011/04/06/us-japan-power-savings-idUSTRE7350Y720110406
===
Japanese Plug Nuclear Plant Leak, Now Face Hydrogen Build-up
VOA News
April 06, 2011
Troubles continue at Japan's crippled nuclear plant, where technicians believe they have solved one big problem but are confronting another.
Officials said Wednesday they have finally stopped a leak of radioactive water from the Fukushima power station that was raising radiation in the nearby ocean to millions of times the legal limit.
But now they are worried about a build-up of hydrogen inside the containment vessel at another of the plant's six reactors, creating the risk of an explosion that could release large amounts of radiation into the atmosphere. Plant officials said they may pump nitrogen into the reactor in an attempt to halt the chemical reaction.
Also Wednesday, Chief Cabinet Secretary Yukio Edano apologized to neighboring countries for Japan's failure to notify them before it began pumping thousands of tons of low-level radioactive water into the sea near the plant.
Edano said the action, which could continue until Friday, is necessary to make room in a storage area for water that is 200 thousand times more dangerous. But he said steps have been taken to ensure better communication with nearby countries before such steps are taken in future.
Edano said the water leak, which had sent radiation levels in the nearby ocean to 7.5 million times the allowable limit on Saturday, had been stopped by 5:38 a.m. Wednesday. But he said it is too early to say with confidence that the problem has been solved, and that officials are still trying to determine whether radioactive water is leaking from any other locations.
Officials at the Tokyo Electric Power Company, which operates the Fukushima plant, said the latest threat of a hydrogen build-up is taking place at its number-one reactor. Japan's NHK television quoted officials saying the build-up is occurring inside the containment vessel that keeps radiation from escaping into the atmosphere, and is an indication that the reactor's core has been damaged.
Hydrogen explosions destroyed the outer buildings housing the number-one and three reactors earlier in the crisis, which began when a massive earthquake and tsunami destroyed the power plant's cooling systems on March 11. Those blasts may also have damaged the containment vessels.
The high radiation levels in the nearby ocean were caused by water leaking from a storage pit next to the number two reactor. After days of failed efforts, technicians managed to stop the leak by injecting a hardening agent called liquid glass into the soil and gravel around the pit. TEPCO is still exploring ways to make sure the seal is permanent.
Highly radioactive water has accumulated in the basements of several of the plant's reactors after weeks in which workers have pumped massive amounts of water over the reactors to prevent their fuel rods from overheating. The water needs to be removed before workers can complete repairs to the permanent cooling systems.
Technicians began Tuesday to pump 11,500 tons of lightly radioactive water into the ocean to make room in a storage area for the most dangerous water, most of it in the basement and utility tunnels at the number-two reactor. But South Korea has protested the action, suggesting it may violate international law.
National police said Wednesday the confirmed death toll in the March 11 disasters now stands at 12,468, with more than 15,000 people still unaccounted for.
http://www.voanews.com/english/news/Japanese-Plug-Nuclear-Plant-Leak-Now-Face-Hydrogen-Build-up-119311074.html [no comments yet]
Workers at the Fukushima Daiichi nuclear station are dealing with new challenges.
Reuters
By JAMES GLANZ and WILLIAM J. BROAD
Published: April 5, 2011
United States government engineers sent to help with the crisis in Japan are warning that the troubled nuclear plant there is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable, according to a confidential assessment prepared by the Nuclear Regulatory Commission.
Among the new threats that were cited in the assessment, dated March 26, are the mounting stresses placed on the containment structures as they fill with radioactive cooling water, making them more vulnerable to rupture in one of the aftershocks rattling the site after the earthquake and tsunami of March 11. The document also cites the possibility of explosions inside the containment structures due to the release of hydrogen and oxygen from seawater pumped into the reactors, and offers new details on how semimolten fuel rods and salt buildup are impeding the flow of fresh water meant to cool the nuclear cores.
In recent days, workers have grappled with several side effects of the emergency measures taken to keep nuclear fuel at the plant from overheating, including leaks of radioactive water at the site and radiation burns to workers who step into the water. The assessment, as well as interviews with officials familiar with it, points to a new panoply of complex challenges that water creates for the safety of workers and the recovery and long-term stability of the reactors.
While the assessment does not speculate on the likelihood of new explosions or damage from an aftershock, either could lead to a breach of the containment structures in one or more of the crippled reactors, the last barriers that prevent a much more serious release of radiation from the nuclear core. If the fuel continues to heat and melt because of ineffective cooling, some nuclear experts say, that could also leave a radioactive mass that could stay molten for an extended period.
The document, which was obtained by The New York Times, provides a more detailed technical assessment than Japanese officials have provided of the conundrum facing the Japanese as they struggle to prevent more fuel from melting at the Fukushima Daiichi plant. But it appears to rely largely on data shared with American experts by the Japanese.
Among other problems, the document raises new questions about whether pouring water on nuclear fuel in the absence of functioning cooling systems can be sustained indefinitely. Experts have said the Japanese need to continue to keep the fuel cool for many months until the plant can be stabilized, but there is growing awareness that the risks of pumping water on the fuel present a whole new category of challenges that the nuclear industry is only beginning to comprehend.
The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed.
David A. Lochbaum, a nuclear engineer who worked on the kinds of General Electric reactors used in Japan and now directs the nuclear safety project at the Union of Concerned Scientists, said that the welter of problems revealed in the document at three separate reactors made a successful outcome even more uncertain.
“I thought they were, not out of the woods, but at least at the edge of the woods,” said Mr. Lochbaum, who was not involved in preparing the document. “This paints a very different picture, and suggests that things are a lot worse. They could still have more damage in a big way if some of these things don’t work out for them.”
The steps recommended by the nuclear commission include injecting nitrogen, an inert gas, into the containment structures in an attempt to purge them of hydrogen and oxygen, which could combine to produce explosions. The document also recommends that engineers continue adding boron to cooling water to help prevent the cores from restarting the nuclear reaction, a process known as criticality.
Even so, the engineers who prepared the document do not believe that a resumption of criticality is an immediate likelihood, Neil Wilmshurst, vice president of the nuclear sector at the Electric Power Research Institute, said when contacted about the document. “I have seen no data to suggest that there is criticality ongoing,” said Mr. Wilmshurst, who was involved in the assessment.
The document was prepared for the commission’s Reactor Safety Team, which is assisting the Japanese government and the Tokyo Electric Power Company, which owns the plant. It says it is based on the “most recent available data” from numerous Japanese and American organizations, including the electric power company, the Japan Atomic Industrial Forum, the United States Department of Energy, General Electric and the Electric Power Research Institute, an independent, nonprofit group.
The document contains detailed assessments of each of the plant’s six reactors along with recommendations for action. Nuclear experts familiar with the assessment said that it was regularly updated but that over all, the March 26 version closely reflected current thinking.
The assessment provides graphic new detail on the conditions of the damaged cores in reactors 1, 2 and 3. Because slumping fuel and salt from seawater that had been used as a coolant is probably blocking circulation pathways, the water flow in No. 1 “is severely restricted and likely blocked.” Inside the core itself, “there is likely no water level,” the assessment says, adding that as a result, “it is difficult to determine how much cooling is getting to the fuel.” Similar problems exist in No. 2 and No. 3, although the blockage is probably less severe, the assessment says.
Some of the salt may have been washed away in the past week with the switch from seawater to fresh water cooling, nuclear experts said.
A rise in the water level of the containment structures has often been depicted as a possible way to immerse and cool the fuel. The assessment, however, warns that “when flooding containment, consider the implications of water weight on seismic capability of containment.”
Experts in nuclear plant design say that this warning refers to the enormous stress put on the containment structures by the rising water. The more water in the structures, the more easily a large aftershock could rupture one of them.
Margaret Harding, a former reactor designer for General Electric, warned of aftershocks and said, “If I were in the Japanese’s shoes, I’d be very reluctant to have tons and tons of water sitting in a containment whose structural integrity hasn’t been checked since the earthquake.”
The N.R.C. document also expressed concern about the potential for a “hazardous atmosphere” in the concrete-and-steel containment structures because of the release of hydrogen and oxygen from the seawater in a highly radioactive environment.
Hydrogen explosions in the first few days of the disaster heavily damaged several reactor buildings and in one case may have damaged a containment structure. That hydrogen was produced by a mechanism involving the metal cladding of the nuclear fuel. The document urged that Japanese operators restore the ability to purge the structures of these gases and fill them with stable nitrogen gas, a capability lost after the quake and tsunami.
Nuclear experts say that radiation from the core of a reactor can split water molecules in two, releasing hydrogen. Mr. Wilmshurst said that since the March 26 document, engineers had calculated that the amount of hydrogen produced would be small. But Jay A. LaVerne, a physicist at Notre Dame, said that at least near the fuel rods, some hydrogen would in fact be produced, and could react with oxygen. “If so,” Mr. LaVerne said in an interview, “you have an explosive mixture being formed near the fuel rods.”
Nuclear engineers have warned in recent days that the pools outside the containment buildings that hold spent fuel rods could pose an even greater danger than the melted reactor cores. The pools, which sit atop the reactor buildings and are meant to keep spent fuel submerged in water, have lost their cooling systems.
The N.R.C. report suggests that the fuel pool of the No. 4 reactor suffered a hydrogen explosion early in the Japanese crisis and could have shed much radioactive material into the environment, what it calls “a major source term release.”
Experts worry about the fuel pools because explosions have torn away their roofs and exposed their radioactive contents. By contrast, reactors have strong containment vessels that stand a better chance of bottling up radiation from a meltdown of the fuel in the reactor core.
“Even the best juggler in the world can get too many balls up in the air,” Mr. Lochbaum said of the multiplicity of problems at the plant. “They’ve got a lot of nasty things to negotiate in the future, and one missed step could make the situation much, much worse.”
Henry Fountain contributed reporting from New York, and Matthew L. Wald from Washington.
http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html [ http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?pagewanted=all ] [comments at http://community.nytimes.com/comments/www.nytimes.com/2011/04/06/world/asia/06nuclear.html ]
===
Tiny Fish Spur Widening Worry
Japan Discovers High Radiation Levels in One Species, Stoking Environmental and Safety Concerns
APRIL 6, 2011
http://online.wsj.com/article/SB10001424052748703712504576244251331137870.html [with comments]
===
Radioactivity Found in Fish as Tepco Purges Nuclear Plant
Apr 5, 2011 1:38 PM CT
http://www.bloomberg.com/news/2011-04-05/tepco-dumping-toxic-water-angers-fishermen-stock-plunges.html
===
Fishing Halted in Japan’s Ibaraki After Radioactive Water Contaminates Sea
Apr 6, 2011 3:56 AM CT
http://www.bloomberg.com/news/2011-04-06/fishing-halted-in-japan-s-ibaraki-after-radioactive-water-contaminates-sea.html
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WRAPUP 6-Japan stops nuclear plant leak; crisis far from over
Wed Apr 6, 2011 3:24am EDT
http://www.reuters.com/article/2011/04/06/japan-idUSL3E7F526520110406 [with comment]
===
Japan earthquake: Radioactive leak plugged at reactor
6 April 2011 Last updated at 02:49 ET
[...]
Engineers also face a potential new problem of a build-up of hydrogen gas in one of the reactors at the six-unit plant. Tepco said it could inject nitrogen gas into the No 1 reactor to prevent an explosion.
[...]
On Tuesday, Japan asked Russia for the use of a floating radiation treatment plant to tackle waste water.
Russia's nuclear agency Rosatom said it was awaiting answers to some questions before granting the request to lend the Landysh, known in Japanese as the Suzuran, which is used to decommission Russian nuclear submarines in the far eastern port of Vladivostok.
One of the world's largest liquid radioactive waste treatment plants, the Landysh treats radioactive liquid with chemicals and stores it in a cement form.
It can process 35 cubic metres of liquid waste a day and 7,000 cubic metres a year.
[...]
http://www.bbc.co.uk/news/world-asia-pacific-12981243
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Fukushima update: Data, data, everywhere ... - April 05, 2011
http://blogs.nature.com/news/thegreatbeyond/2011/04/fukushima_update_data_data_eve.html [no comments yet]
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Fukushima update: Hiroshima and Nagasaki bomb experts outline health research needs after Fukushima - April 05, 2011
http://blogs.nature.com/news/thegreatbeyond/2011/04/fukushima_update_hiroshima_and.html [no comments yet]
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Worker safety takes back seat in dealing with nuclear crisis
Workers set up a temporary power distribution board at the Fukushima No. 1 nuclear power plant in Okuma, Fukushima Prefecture.
(Provided by Tokyo Electric Power Co.)
2011/04/05
The problems continue to pile up at the Fukushima No. 1 nuclear plant, creating an unprecedented hazardous environment for the under-equipped front-line workers trying to bring the situation under control.
But given the potential widespread damage from the crisis, officials acknowledge that labor safety is not the top priority anymore.
"Under circumstances where there is no end to new problems faced, we cannot deny that the company is depending on the spirit of the workers," an executive of Tokyo Electric Power Co., the plant operator, said. "Unless we are able to both secure workers' safety while settling the nuclear accident, TEPCO will in the end face very serious criticism."
The workers continue to risk exposure to high levels of radiation in their efforts to restore cooling mechanisms for the reactor cores. But the public is growing impatient for a quick end --or even significant progress -- in the battle at the Fukushima plant, putting pressure on not only TEPCO but also the government.
"It is never good to have any kind of work that requires putting one's life on the line," a high-ranking official of the Ministry of Health, Labor and Welfare said. "However, the importance of settling the situation at the nuclear plant goes beyond the range of labor policy. I cannot be confident about whether that or the safety of the workers should have priority."
TEPCO has already faced harsh criticism concerning the safety of the workers.
Labor ministry officials began investigating the company after the utility admitted that workers were not all given portable dosimeters to check for radiation. But the investigation has its limits because officials cannot enter the plant grounds.
"The public is hoping the crisis at the nuclear plant is settled quickly, and that expectation could affect measures to be taken to ensure the safety of workers," a labor ministry source said.
TEPCO officials said about 5,000 dosimeters were available before the March 11 earthquake and tsunami that crippled the plant. But the twin disasters left only 320 usable dosimeters.
TEPCO has since obtained dosimeters from other nuclear power plants for a sufficient supply. But before that, a regulation was revised to allow workers to share one dosimeter as long as they were exposed to less than 10 millisieverts of radiation and the group members were engaged in similar work.
"Because there are some locations where radiation levels are constantly changing, the new regulation does hold danger for the workers," a TEPCO source said.
Satoshi Kamata, who has written extensively about labor issues, questioned TEPCO's commitment to the safety of its workers.
"There is the possibility that those working at the Fukushima plant have already been exposed to high levels of radiation, so doubts arise about whether TEPCO was serious about labor safety conditions," Kamata said. "Because TEPCO is the only entity that can actually look after those conditions, it should obtain a good grasp of the situation and publicize what it knows."
According to an official of the Nuclear and Industrial Safety Agency, the only place within the plant grounds where workers do not have to wear protective clothing against radiation is a two-story building built with high quake-resistant standards and high air-tightness.
Workers who have finished laying cables or removing contaminated water within the plant grounds shed their protective clothing and masks for radiation measurements before entering the special building. Because many workers stay overnight in the plant grounds, there are shortages of protective gear as well as fresh clothing.
TEPCO's labor union has asked management for information about radiation levels at the plant as well as the health conditions of the workers.
"There will be a need for mass mobilization of workers so that no individual worker is exposed to radiation that exceeds legal standards. There will be a need for labor unions to understand the details about the working environment and to provide support so workers can work in safety," a labor union source said.
Despite the dangers, the workers at the Fukushima plant appear determined to push on.
"Workers keep saying, 'We will have to do something about the problem,'" a TEPCO source said.
Companies cooperating with TEPCO have conducted surveys of workers who might be asked to go to Fukushima. Although the surveys clearly stated that workers could decline with their identities concealed and no effects on their job evaluations, all those surveyed said they were willing to fight the crisis in Fukushima, the companies said.
One immediate measure being discussed to help the workers is raising the compensation amount given for hazardous work. The government has been much quicker on this issue.
The Defense Ministry decided on March 24 to increase by 1.5 times the amount given to members of the Self-Defense Forces who die or are left with disabilities as a result of working at the Fukushima nuclear plant. Families of SDF members who die can receive as much as 90 million yen ($1.07 million) while those disabled can receive a maximum of 75.6 million yen.
Those amounts are similar to those for SDF members dispatched to Iraq as well as those patrolling against pirates off the coast of Somalia.
"Considering the dangers and difficulties of the work (at Fukushima), we decided that it was similar to Iraq and Somalia," a Defense Ministry official said.
TEPCO executives, however, have been slower to commit to higher amounts paid for hazardous work.
Although TEPCO already has a three-level system for hazardous pay depending on radiation dangers, executives admitted they never expected a situation in which workers would have to toil amid continuous high radiation levels.
Some companies cooperating with TEPCO do not have hazardous pay arrangements that take into consideration situations such as the current one. The executives of those companies said they would review the system in line with what other companies sending workers to Fukushima do.
Experts said the central government would have to become involved to look after the safety of those working to end the crisis at the Fukushima plant.
"Japan's compensation system for nuclear accidents has not emphasized protection of victims because it was preconditioned on the notion that a serious accident would never occur," said Terumitsu Honma, head of the Aoyama Gakuin University Research Institute, who is knowledgeable about compensation for nuclear energy accidents.
"However, a serious accident is now unfolding, and workers have been exposed to radiation. There will be a need to create a totally new compensation system based on the actual dangers faced by the workers at the plant and nearby residents who have been affected," he said.
Copyright 2011 The Asahi Shimbun Company
http://www.asahi.com/english/TKY201104040147.html
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Town near nuclear plant rejects Japanese utility's 'token' offer
April 6, 2011 -- Updated 0212 GMT (1012 HKT)
http://edition.cnn.com/2011/WORLD/asiapcf/04/05/japan.nuclear.money/ [with comments]
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TEPCO shares hit new low, eyes on government
Wed Apr 6, 2011 4:39am EDT
http://www.reuters.com/article/2011/04/06/us-japan-tepco-idUSTRE7350NI20110406
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Japan may order Tokyo-area industry to conserve power
By Osamu Tsukimori
TOKYO | Wed Apr 6, 2011 2:39am EDT
(Reuters) - Japan's trade ministry may order big industrial electricity users in the country's economic heartland around Tokyo to cut their peak summer power use by 25 percent, a ministry official said, as efforts mount to avert crippling blackouts.
The ministry was also likely to create power-saving targets for smaller users, including individual households, the official said.
Tokyo Electric Power is scrambling to secure enough power for the capital area's factories and air-conditioners this summer after a devastating earthquake and tsunami took out more than 20 percent of its generating capacity, including the Fukushima nuclear complex.
"We are looking at a cut of around 25 percent (for large-scale users of 500 kilowatts or more)," the ministry official, who declined to be identified, told Reuters.
"Efforts will be made to boost supply, which would ease pressure on the demand side. We may also discuss less stringent constraints for households and smaller users, but if we ease up at this point we may end up being too lax."
ROLLING BLACKOUTS
The ministry is scheduled to finalize its strategies to cope with the peak summer season by the end of April, he added.
The Tokyo area and regions further north, served mainly by Tokyo Electric, account for half the economic activity of the world's third-biggest economy, Nomura Holdings estimates.
Analysts suggest power blackouts could ultimately become the greatest source of economic damage inflicted by last month's disaster on Japan, a vital player in the global manufacturing supply chain.
Tokyo Electric implemented rolling blackouts last month after the March 11 earthquake and tsunami, although it has since restarted some damaged thermal power plants and has been able to avoid blackouts since March 28, helped also by warmer weather.
The giant Fukushima nuclear complex remains down amid a protracted safety crisis, however, and Trade Minister Banri Kaieda has said there could be a shortfall of 10,000 to 15,000 megawatts when air-conditioner use kicks in over the summer, depending on how far temperatures rise.
Tokyo Electric has estimated, however, that it can rush enough thermal plants online, including mothballed facilities, to close the gap to about 5,000 MW, presuming typical summer use around 60,000 MW.
Analysts said the power savings may not need to be as draconian as those under discussion at the trade ministry.
"I am very skeptical that there will be such severe cuts. These reports seem to be part of a drive to encourage energy conservation in order to minimize disruption over the summer," said Richard Jerram, chief Asian economist at Macquarie Securities.
The ministry official nevertheless rejected media reports that the Tokyo utility would not use rolling blackouts after April, noting they may be needed to ensure there are no unexpected outages that would take down power for Tokyo Electric's entire service area.
"Rolling blackouts would remain as a last resort," he said.
(Additional reporting by Chikako Mogi and James Topham; Editing by Edmund Klamann)
© Copyright 2011 Thomson Reuters
http://www.reuters.com/article/2011/04/06/us-japan-power-savings-idUSTRE7350Y720110406
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Japanese Plug Nuclear Plant Leak, Now Face Hydrogen Build-up
VOA News
April 06, 2011
Troubles continue at Japan's crippled nuclear plant, where technicians believe they have solved one big problem but are confronting another.
Officials said Wednesday they have finally stopped a leak of radioactive water from the Fukushima power station that was raising radiation in the nearby ocean to millions of times the legal limit.
But now they are worried about a build-up of hydrogen inside the containment vessel at another of the plant's six reactors, creating the risk of an explosion that could release large amounts of radiation into the atmosphere. Plant officials said they may pump nitrogen into the reactor in an attempt to halt the chemical reaction.
Also Wednesday, Chief Cabinet Secretary Yukio Edano apologized to neighboring countries for Japan's failure to notify them before it began pumping thousands of tons of low-level radioactive water into the sea near the plant.
Edano said the action, which could continue until Friday, is necessary to make room in a storage area for water that is 200 thousand times more dangerous. But he said steps have been taken to ensure better communication with nearby countries before such steps are taken in future.
Edano said the water leak, which had sent radiation levels in the nearby ocean to 7.5 million times the allowable limit on Saturday, had been stopped by 5:38 a.m. Wednesday. But he said it is too early to say with confidence that the problem has been solved, and that officials are still trying to determine whether radioactive water is leaking from any other locations.
Officials at the Tokyo Electric Power Company, which operates the Fukushima plant, said the latest threat of a hydrogen build-up is taking place at its number-one reactor. Japan's NHK television quoted officials saying the build-up is occurring inside the containment vessel that keeps radiation from escaping into the atmosphere, and is an indication that the reactor's core has been damaged.
Hydrogen explosions destroyed the outer buildings housing the number-one and three reactors earlier in the crisis, which began when a massive earthquake and tsunami destroyed the power plant's cooling systems on March 11. Those blasts may also have damaged the containment vessels.
The high radiation levels in the nearby ocean were caused by water leaking from a storage pit next to the number two reactor. After days of failed efforts, technicians managed to stop the leak by injecting a hardening agent called liquid glass into the soil and gravel around the pit. TEPCO is still exploring ways to make sure the seal is permanent.
Highly radioactive water has accumulated in the basements of several of the plant's reactors after weeks in which workers have pumped massive amounts of water over the reactors to prevent their fuel rods from overheating. The water needs to be removed before workers can complete repairs to the permanent cooling systems.
Technicians began Tuesday to pump 11,500 tons of lightly radioactive water into the ocean to make room in a storage area for the most dangerous water, most of it in the basement and utility tunnels at the number-two reactor. But South Korea has protested the action, suggesting it may violate international law.
National police said Wednesday the confirmed death toll in the March 11 disasters now stands at 12,468, with more than 15,000 people still unaccounted for.
http://www.voanews.com/english/news/Japanese-Plug-Nuclear-Plant-Leak-Now-Face-Hydrogen-Build-up-119311074.html [no comments yet]
Greensburg, KS - 5/4/07
"Eternal vigilance is the price of Liberty."
from John Philpot Curran, Speech
upon the Right of Election, 1790
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