ความคิดเห็นที่ 1 Japanese government was 'warned that nuclear plants could not withstand quake' credit: dailymail.co.uk, By Daily Mail Reporter Last updated at 9:14 AM on 16th March 2011 Japanese officials faced added pressure today after it emerged that they were warned more than two years ago that the country's nuclear power plants could not withstand powerful earthquakes. The international nuclear watchdog raised concerns that safety measures were outdated and a major tremor could cause 'serious problems', leaks cables have revealed. It is not known what changes the Japanese government made after an official from the International Atomic Energy Agency made the comments in December 2008. Warning: US Embassy cables revealed how the Japanese government was warned that an earthquake could pose 'serious problems' for nuclear plants including Fukushima, pictured, which suffered three explosions จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:48:32

ความคิดเห็นที่ 2 The government will face tough questions on whether they acted on a pledge to upgrade all their nuclear facilities to be able to withstand a quake as powerful as the one that struck last Friday. Details of the warnings came from a US Embassy diplomatic cable that was leaked to the information website Wikileaks. The government is said to have responded to the nuclear watchdog's concerns by building an emergency response centre at the Fukushima powerplant. The doomed plant has suffered three major explosions and one fire that have spilled radiation into the atmosphere and forced thousands of people to be evacuated. The plant was only designed to withstand 7.0 magnitude quakes but the massive disaster that struck last Friday measured 9.0 on the Richter scale. Dangerous: A fuel storage tank inside the Fukushima plant's third reactor building that was taken before the disaster struck. Four of the six reactors at the Fukushima No.1 plant have now overheated and sparked explosions จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:49:51

ความคิดเห็นที่ 3 Japan's Prime Minister Naoto Kan has been criticised for 'dithering' and accused by his own people of playing down the crisis. He is now likely to face even stronger accusations about whether he paid full attention to the advice from the watchdog. The concerns were first raised at a meeting of the G8's nuclear safety and secutiy group in Tokyo in 2008, The Daily Telegraph reports today. An unnamed expert was quoted in the diplomat's US embassy cable about safety advice for Japan's nuclear plants. The document states: 'He [the expert] explained that safe guides for the seismic safety have only been revised three times in the last 35 years and that the IAEA is now re-examing them. Reinforcements: Japan's Ground Self-Defence Force soldiers mobilised yesterday to wash away radioactive material leaked from the plant จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:51:06

ความคิดเห็นที่ 4 'Also, the presenter noted recent earthquakes in some cases have exceeded the design basis for some nuclear plants, and that this is a serious problem that is now driving seismic safety work.' The cables reveal how the Japanese government even opposed a court order to close down a nuclear plant that was feared unsafe in the face of an earthquake above 6.5 magnitude. The government later overturned in 2009 the court's ruling top shut down the 'unsafe' plant. The cable added: 'Japan's Nuclear and Industrial Safety Agency believes the reactor is safe and that all safety analyses were appropriately conducted.' Cables also revealed to US officials in Washington that there were concerns that the new nuclear power stations were jeopardising safety ahead of profit. Quoting a report from a local newspaper, the cable reports: 'We have seen too many cases of cost reduction competition through heightened efficiency jeopardising safety. Taro Kono, a senior member of the Japan's lower house, told the US said that the Japanese government was covering up nuclear incidents. The Prime Minister, Mr Kan, was not in office when the warnings were made but they will put added pressure on the government and those who received the warnings. Cleansing: Officials wearing white clothing to protect themselves against harmful radiation work in a centre to scan residents who have been living within the danger zone of the damaged Fukushima plant จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:52:33

ความคิดเห็นที่ 5 'They've lost control': French claim Japan is hiding full scale of nuclear disaster as emergency teams desperately fire water cannon at reactors from long range credit: By David Derbyshire Last updated at 1:23 PM on 16th March 2011    * Workers battling nuclear meltdown briefly evacuated today after radiation levels increased    * French minister: 'Let's not beat about the bush, they've essentially lost control'    * Officials comandeer police water cannon to spray complex    * Attempts to dump water on reactors by helicopter fail    * Concern at radioactive steam leaking from reactor number three    * Two more previously stable reactors begin to heat up Japan's stricken nuclear power plant was abandoned for hours today, as soaring radiation forced emergency workers to flee for their lives and authorities were reduced to spraying reactors with police water cannons. All 50 emergency workers who had been fighting to keep overheating reactors cool were this morning pulled back 500 yards from the complex as radiation levels became too dangerous. And in an extraordinary attack, the French government accused the Japanese of losing control of the situation and hiding the full scale of the disaster. Military helicopters made a failed attempt to drop water on the reactors from above, amid desperate efforts to cool nuclear fuel. Police water cannons usually used in riot control were even requested to spray the site. The emergency teams had been pumping sea water into reactors using fire engines, but those efforts are thought to have stopped as the workers were pulled out. But Japanese officials said 180 workers were now back on the site. Fears of 'an apocalypse' were raised by European officials as radiation levels soared. In another attack, French Industry Minister Eric Besson said: 'Let's not beat about the bush. They have visibly lost the essential of control (of the situation). That is our analysis, in any case, it's not what they are saying.' In a sign of mounting panic, Cabinet Secretary Chief Cabinet Secretary Yukio Edano has already warned that the long-range cooling efforts may not work. He said: 'It's not so simple that everything will be resolved by pouring in water. We are trying to avoid creating other problems.' 'Out of control': This dramatic pictures shows radioactive steam pouring from the Fukushima reactor number three  after it was damaged in an explosion จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:56:33

ความคิดเห็นที่ 6 Destroyed: the four stricken reactors at Fukushima. Three were damaged in explosion while a fire broke out at the fourth จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:57:45

ความคิดเห็นที่ 7 Destroyed: Damage after the earthquake and tsunami at Fukushima Daiichi nuclear plant, 240 km (150 miles) north of Tokyo, is seen in this satellite image taken 9:35 am local time (0035 GMT) จากคุณ : july 19 เขียนเมื่อ : 16 มี.ค. 54 20:58:41

ความคิดเห็นที่ 8 ได้ติดตาม update ข่าว tsunami ทุกตอนของคุณ july 19 มาตลอด ขอบคุณมากๆคะ ที่ยังนำเสนอมาไม่ได้ขาด มีประโยชน์ต่อผู้อ่านจริงๆคะ จากคุณ : สิบล้อชอบเที่ยว เขียนเมื่อ : 16 มี.ค. 54 21:25:22

ความคิดเห็นที่ 9 ติดตามตลอด ขอบคุณจริงๆๆๆๆๆๆๆๆ จากคุณ : kraru (Kraru) เขียนเมื่อ : 16 มี.ค. 54 21:56:01

ความคิดเห็นที่ 10 ขอบคุณมากๆค่ะ จากคุณ : Talay&Me เขียนเมื่อ : 16 มี.ค. 54 23:15:09

ความคิดเห็นที่ 11 ขอบคุณคะ จากคุณ : ความไกลรักษาใจได้จริงหรือ เขียนเมื่อ : 17 มี.ค. 54 08:30:34

ความคิดเห็นที่ 12 ขอบคุณมากๆนะคะ...ที่อัพเดตสถานการณ์ให้เราทราบ ติดตามข่าวทุกวันด้วยความเป็นห่วงชาวญี่ปุ่น จากคุณ : ดอกโสนบานเช้า เขียนเมื่อ : 17 มี.ค. 54 09:18:04

ความคิดเห็นที่ 13 ขอบคุณมากค่ะ ติดตามทุกวันค่ะ จากคุณ : cascar เขียนเมื่อ : 17 มี.ค. 54 09:38:09

ความคิดเห็นที่ 14 Get out of Tokyo: Foreign Office tells all Britons to leave toxic radiation zone as Japanese 'lose control' of stricken reactor The advice followed a meeting of the Cabinet's emergency Cobra committee to discuss the meltdown-threatened Fukushima nuclear plant. The French said the Japanese have 'visibly lost essential control' as they urged their citizens to get out as 'last ditch' efforts were made at Fukushima to prevent a catastrophe. Ministers were due to hold further talks last night on whether an immediate evacuation from Japan should be considered. จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 12:53:11

ความคิดเห็นที่ 15 credit: By Jason Groves Last updated at 2:57 AM on 17th March 2011        * 17,000 British nationals could be evacuated as last ditch efforts are made to stop nuclear catastrophe    * Rich scramble to book private jets out the country as fleeing passengers pack Tokyo airport    * French say Japanese have 'visibly lost essential control' as they urge their citizens to get out Plans are being drawn up to evacuate every British national in Japan amid mounting fears of a nuclear catastrophe. Thousands of Britons were last night warned to leave Tokyo and all other areas under threat of radiation poisoning. The advice – echoed by other countries around the world – followed a meeting of the Cabinet’s emergency Cobra committee to discuss the meltdown-threatened Fukushima nuclear plant. It heightened suspicions that the crisis at the plant – already ranked the second-worst nuclear disaster after Chernobyl – is worse than the Japanese authorities have publicly let on. Yesterday ‘last-ditch’ efforts were continuing at Fukushima to prevent a catastrophe with a Japanese army helicopter dumping water onto troubled nuclear reactor. Leaving: Worried residents wait to enter the Immigration Bureau of Japan in Tokyo yesterday as they evacuate the city in the wake of the earth quake and nuclear meltdown that has caused concern around the world แก้ไขเมื่อ 17 มี.ค. 54 12:58:55 จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 12:57:57

ความคิดเห็นที่ 16 A CH-47 Chinook helicopter began dumping seawater on the damaged reactor of Unit 3 at the Fukushima complex at 9.48am local time, said defense ministry spokeswoman Kazumi Toyama. The aircraft dumped at least four loads on the reactor, though much of the water appeared to be dispersed in the air. The dumping was intended both to help cool the reactor and to replenish water in a pool holding spent fuel rods, Toyama said. The plant's owner, Tokyo Electric Power Co., said earlier that the pool was nearly empty, which might cause the rods to overheat. Last night an official at Japan's Nuclear and Industrial Safety Agency said that radiation levels at the plant had fallen steadily over the past 12 hours. However, ministers were due to hold further talks last night on whether an immediate evacuation from Japan should be considered. Chaos: Passengers crowd Mar Haneda International Airport outside Tokyo as foreigners scramble to flee the country amid radiation fears จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:00:50

ความคิดเห็นที่ 17 Collecting water: The Self-Defense Forces's helicopter scoops seawater on Japan's northeast coast en route to the Fukushima plant จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:04:03

ความคิดเห็นที่ 18 Last ditch: A Japanese military helicopter can be seen in the top left of the picture as it dumps water onto reactors 3 and 4 at Fukushima nuclear plant จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:05:28

ความคิดเห็นที่ 19 About 17,000 British nationals are thought to be in the country, mostly in Tokyo. Last night’s Foreign Office warning stopped short of ordering them to leave the country – a diplomatic gesture which will be welcomed by the Japanese government. But officials conceded that in reality most Britons will have few options but to leave Japan if they want to heed the advice. Thousands of Japanese citizens are already fleeing Tokyo for the south. Officials yesterday insisted there was no significant risk to human health in Tokyo, which is less than 140 miles south of Fukushima. But Europe’s energy chief Guenther Oettinger warned the huge plant was ‘effectively out of control’ – sparking fears of a meltdown, which could send a radioactive cloud into the atmosphere. จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:07:45

ความคิดเห็นที่ 20 He warned of ‘further catastrophic events, which could pose a threat to the lives of people on the island’. Mr Oettinger predicted the dire situation could take a further turn for the worse ‘within hours’. The Japanese public was also unconvinced by its government’s reassurances. The mayor of Minimisoma, which is 12 miles from the Fukushima plant, said: ‘We weren’t told when the first reactor exploded, we only heard about it on television. The government doesn’t tell us anything. We are isolated. They’re leaving us to die.’ The Foreign Office insisted there was ‘no real human health issue’ outside the 20-mile exclusion zone surrounding the plant. But it warned that panic caused by the crisis meant there were ‘potential disruptions to the supply of goods, transport, communications, power and other infrastructure’ in Tokyo. Officials confirmed that contingency plans were being drawn up for an airlift of British nationals if the crisis worsens. Talks have already been held with airlines about laying on extra flights. The warning came as the Japanese authorities made increasingly desperate attempts to contain the crisis at the Fukushima plant. Helicopters deployed to dump water on the plant were pulled out amid concerns about soaring radiation levels. Officials were considering using water cannon – normally used to control riots – in a desperate bid to cool the overheating reactors, which have suffered a series of explosions. จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:10:29

ความคิดเห็นที่ 21 40 YEARS OF DOUBT ON NUCLEAR DESIGNS By DANIEL BATES The design of the reactors at the stricken Fukushima power plant has been called into question for almost 40 years. As far back as 1972, experts said the Mark 1 should be discontinued because its containment vessel was not as robust as alternatives. One report said such reactors had a 90 per cent probability of bursting should the fuel rods overheat and melt in an accident. A clutch of engineers also resigned their posts rather than carry on with a project they deemed to be unsafe. In a nuclear reactor the containment vessel is considered the last line of defence to stop a meltdown. It is usually a steel and cement ‘tomb’ and is designed to stop the melting fuel rods sending lethal radiation into the atmosphere. The cheaper Mark 1s, however, are less robust, smaller, and have long been thought to be more likely to fail in an emergency. They were designed in the U.S. in the 1960s by the utility giant General Electric. Five of the six reactors at the Fukushima plant are Mark 1s. In 1972, the U.S. Atomic Energy Commission said the design should be discontinued because it was more susceptible to explosion and rupture from a build-up in hydrogen – a problem which could have happened at Fukushima. In 1975 engineer Dale Bridenbaugh and two of his colleagues at General Electric quit work on a Mark 1 because they did not feel comfortable about safety. Escape: residents gather up their belongings and form a queue as they wait to board a bus out of Sendai, north eastern Japan, yesterday จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:13:44

ความคิดเห็นที่ 22 Destroyed: Damage after the earthquake and tsunami at Fukushima Daiichi nuclear plant, 240 km (150 miles) north of Tokyo, is seen in this satellite image taken 9:35 am local time (0035 GMT) จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:15:07

ความคิดเห็นที่ 23 Yesterday a further fire broke out, two more reactors were reported to be overheating and concerns were growing about two pools used to store spent radioactive fuel. If a reactor overheats – and its casing is breached – dangerous radioactive material could be blown for miles. Several countries advised their citizens to evacuate. France, one of the world’s leading users of nuclear energy, said its citizens should get out Japan. Industry Minister Eric Besson said: ‘Let’s not beat about the bush. They have visibly lost essential control. That is our analysis, even if it’s not what they are saying.’ French Environment Minister Nathalie Kosciusko-Morizet described the crisis as ‘catastrophic’ and said the latest information ‘does not lead to optimism’. There are 2,000 French still in the Tokyo area. Australia also urged its citizens to consider leaving Tokyo and the quake-affected areas. And the U.S. advised all Americans living within 50 miles of Fukishima to evacuate or take shelter indoors. Russia said the crisis was moving towards a grim conclusion. Sergei Kiriyenko, who presides over the bulk of the country’s nuclear facilities, declared: ‘Unfortunately, the situation is developing under the worst scenario.’ Explosions rocked the site on Saturday and Monday when hydrogen gas – released to ease pressure inside the sealed cores – ignited at reactors 1 and 3. On Monday hydrogen blasts hit reactor 2 and reactor 4, damaging its roof. Experts believe that the reactor 2 blast cracked the 80-inch steel and concrete containment unit surrounding the radioactive core – triggering a radiation leak. Last night temperatures were rising out of control in reactors 5 and 6. Scientists are also concerned about falling water levels in two tanks used to store and cool spent fuel rods. TURMOIL FOR SHARES Investors endured a roller-coaster ride on the global stock markets yesterday. The index of leading shares in Tokyo bounced back from its recent slump but there was heavy selling elsewhere including London and New York. The Nikkei 225 gained 5.7 per cent to 9,093.72 having lost more than 16 per cent of its value on Monday and Tuesday in the aftermath of the earthquake and tsunami. But shares in Europe and the US tumbled again as the Japanese crisis, violence in the Middle East, rising unemployment in Britain and deepening debt in the Eurozone hammered confidence. The FTSE 100 index was down 97.05 to 5598.23 in London – wiping £25billion off the value of Britain’s biggest companies – while the Dow Jones Industrial Average lost more than 150 points in New York. Water in at least one of the pools is boiling. If its rods are exposed to the air they could overheat, releasing radioactive material into the air. Steam rose from the pool alongside reactor 3 yesterday. Nuclear experts said the solutions being proposed to prevent leaks were ‘last-ditch efforts’. But they added that if temperatures inside the reactors are kept down, the plant could be safe within a week. The chief of the U.S. Nuclear Regulatory Commission (NRC), Gregory Jaczko, warned that all the cooling water had gone from one of the spent fuel pools. That would mean there is nothing to stop the fuel rods getting hotter and ultimately melting down and if the outer shell of the rods ignite with enough force, it could propel the radioactive fuel inside over a wide area. 'I hope my information is wrong,' said Jaczko. 'It's a terrible tragedy for Japan.' Japan's nuclear safety agency and Tokyo Electric Power, which operates the complex, denied the claim and utility spokesman Hajime Motojuku said the 'condition is stable' at Unit 4. Earlier, however, another utility spokesman contradicted that by saying the officials' greatest concerns were the spent fuel pools, which lack the protective shells that reactors have. 'We haven't been able to get any of the latest data at any spent fuel pools,' said Masahisa Otsuki. 'We don't have the latest water levels, temperatures, none of the latest information for any of the four reactors.' Crisis: A cloud of white smoke  can be seen rising from the nuclear power plant as workers battling to control the chaos were evacuated after soaring radiation levels จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:21:03

ความคิดเห็นที่ 24 Regret, loss for a Japanese hero "My wife, my son's family and four grandchildren ... I've lost them all. I can't take it," cries a Japanese firefighter after returning home for the first time since Friday to see his house in ruins. Now he regrets putting his job ahead of his family..... Praise for 'heroes' working to avert Japan's nuclear catastrophe credit: By Bryony Jones, for CNN March 17, 2011 -- Updated 0344 GMT (1144 HKT) (CNN) -- As the rest of the world waits to see if Japan can avert a nuclear catastrophe, a small band of experts is putting their lives at risk to prevent the disaster. Thousands of people living near the troubled Fukushima Daiichi nuclear power plant have been evacuated from their homes because of the risk of radiation leaks from reactors damaged by last week's devastating earthquake and tsunami. But while most hurry in the opposite direction, about 180 plant workers are staying put -- despite the fact that doing so could result in serious illness or even death -- to battle the meltdown threat. "The workers at this site are involved in a heroic endeavor," former U.S. Department of Energy Official Robert Alvarez told CNN. "There is at least fragmentary evidence that in some places on this site there are life-threatening doses of radiation. I think they are doing enormously heroic work." The workers left at the site are said to be highly trained and experienced nuclear operators, engineers and safety staff with highly specialized knowledge. Richard Wakeford, of the Dalton Nuclear Institute at the University of Manchester, said for many of them -- despite the highly unusual and potentially dangerous circumstances -- it will be just another day at the office. "They see it as doing their job," he said. "The Japanese in particular are dedicated to duty, and they will see it as their duty to do what they are doing." According to the World Health Organisation, the average person is exposed to about 3.0 millisieverts (mSv) a year of radiation, from naturally-occurring, medical and other sources. But monitoring at the Fukushima Daiichi site has recorded radiation as high as 400 millisieverts an hour -- a level known to be a risk to human health. Exposure to 1,000 millisieverts (1 Sievert) of radiation can cause radiation sickness. "It is difficult to get a clear picture, but there have been spikes in radiation to enormous doses, high enough to risk radiation sickness," said Dr. Ira Helfand, a member of the organization Physicians for Social Responsibility. "These people are undergoing total body radiation, which can cause leukaemia and lymphoma as well as thyroid cancer later on," he said. Experts say lessons have been learned since the nuclear disaster at Chernobyl 25 years ago, when an unauthorized experiment saw radioactive dust spread across swathes of Ukraine, Belarus, Russia and western Europe. Then, emergency workers were sent in with little or no protection to deal with the fallout. "It was pandemonium; there was no monitoring, no idea of the risks," Wakeford said. By contrast, he said, staff at Fukushima Daiichi will be kitted out in protective clothing and breathing apparatus, they will be closely monitored and working in teams to limit their exposure to radiation. "If I were them I would be more worried about the hydrogen explosions, which have been huge -- enough to blow the roofs off two buildings -- and which I think are a much bigger risk to the workers on the ground," he told CNN. But Dr. Helfand said reports suggested that the operation was not going 100% to plan, describing it as "something out of an adventure movie." "We are in totally uncharted waters, people are ad-libbing to deal with the situation," he said. "Using fire trucks to pump a mixture of sea water and boron onto the reactors is not in any of the manuals." Wakeford said the workers will have known they may one day face a risky situation such as this. However, Helfand said that made them even braver, and their work more admirable. "These workers are trained to understand the risks, but that only makes it all the more heroic that they have agreed to stay and work to prevent a disaster," he said. "They know that if there is a reactor meltdown it could be a major disaster affecting huge areas and massive numbers of people, and they are risking their lives to try and prevent that. All of us owe them a huge debt of gratitude." Professor Wakeford agreed: "They are heroic, there is no doubt about that -- it's a pity that isn't recognised more. They are heroes, and I bow down to them." จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:31:43

ความคิดเห็นที่ 25 Japan steps up cooling operation Analysis By Richard Black Environment correspondent, BBC News Over the days of the Fukushima crisis, attention has switched from reactor building 1 to 3, to 2, back to 3 - and now, to 4. This is a surprise. Reactors 4, 5 and 6 were shut down at the time of Friday's earthquake, with some or all of their fuel rods extracted and left in the cooling ponds that each reactor building has under its roof. Once a reactor is turned off, radioactivity and heat generation in the rods die away quickly; down to 7% of the original power within a second of switch-off, 5% within a minute, 0.5% within a day. Transferred to the cooling pond, allowing technicians to do routine maintenance on the reactor, the rods are supposed to sit quietly until the time comes for their re-insertion or their journey towards disposal. The tops of the rods are supposed to be about 5m (16ft) below the water surface. The water keeps them cool and also blocks radiation. Over the last few days there have been reports suggesting water levels were low and the water "boiling"; and now the US Nuclear Regulatory Commission (NRC), which has a team of 11 experts advising in Japan, says the pool is completely dry. This means the fuel rods are exposed to the air. Without water, they will get much hotter, allowing radioactive material to escape. Continue reading the main story “Start Quote    The moment when fuel rods are covered with water, the situation is basically stabilised” End Quote Jasmina Vujic University of California More remarkably, the Tokyo Electric Power Company (Tepco), which owns the power station, has warned: "The possibility of re-criticality is not zero". If you are in any doubt as to what this means, it is that in the company's view, it is possible that enough fissile uranium is present in the cooling pond in enough density to form a critical mass - meaning that a nuclear fission chain reaction could start. The pool lies outside the containment chamber. So if it happened, it would lead to the enhanced and sustained release of radioactive materials - though not to a nuclear explosion - with nothing to stop the radioactive particles escaping. Chain reaction The first event in this chain appears to be that the level of water in the pond fell. Why that should happen is not entirely clear. Was the fuel so hot that it caused an unanticipated amount of evaporation? Did the earthquake somehow crack the building's structure, allowing water to leak out? Did the two fires in the building have an impact? Visually, the building housing reactor 4 is the most damaged on the site - suggesting that reports of the two fires being relatively minor were wide of the mark. Or, did technicians at some point take water from the pond for use in reactor 4's cooling system? There is nothing to say they did; but during the chaos of the weekend, with power systems and options disappearing before their eyes, it might have seemed like a good idea. Whatever the reason, the rods became hot enough that steam reacted with the zirconium cladding around the fuel rods, generating hydrogen and causing an explosion. The same thing happened earlier in reactor buildings 1, 2 and 3 - except that in building 4, the rods were in the fuel pond, not in a reactor. The government ordered Tepco to put water back in the pool. But either because of high radiation levels or broken pumps or some other reason, they could not. Wednesday's plan to drop water in from a helicopter - a technique that is used to fight forest fires - had to be scrapped because of concerns about radiation affecting the pilots. Without the water, gamma-rays travel straight up into the air. There are reports that the authorities have asked US military personnel to bring in water cannon, which would presumably be fired from the ground, aiming to shoot the water in through the broken roof. 'Rock and a hard place' The NRC says that in the current dry state, radiation levels from the pond are probably "extremely high", creating a danger to workers at the plant. Still, in principle this should not raise any possibility of resumed criticality. According to Laurence Williams, professor of nuclear safety at the University of Central Lancashire, it could depend on how the rods are arranged in the water. "In some fuel ponds, they dose the water with boric acid at low levels," he told BBC News. "In some systems they've re-racked the fuel assembly making it possible to put more rods in the pond than it was originally designed for, and then you might put extra sheets of boron in between." Boron and boric acid mop up neutrons, the particles that sustain the chain reaction. In this sort of reactor, water is a crucial component of the fission process. It acts as a moderator - it reduces the speed of the neutrons, meaning they can be captured by uranium nuclei in the fuel rods, inducing them to split. Without water, the neutrons travel too fast, and are not captured. Professor Williams raised a scenario that may be unfolding in the cooling pond in building 4. It is just a possibility, because information is scanty; but here it is. If the fuel rods are dry and hot, there could be damage to the cladding and the release of light radioactive nuclei. To prevent that, you would want to inject water. But water on its own is a neutron moderator and would enhance the chances, however small, of criticality. "You're caught between a rock and a hard place," he observed. Now, Tepco is also talking about putting boric acid into the cooling pond of number 4 building. How closely the rods were packed, whether any boron sheets were in place and if so whether they were damaged by one of the two fires in the building; these are among the many unanswered questions. ***The building housing reactor 4 (left) appears severely damaged - despite the reactor itself being shut down จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:45:03

ความคิดเห็นที่ 26 Core task Meanwhile, the most important task remains to get enough water flowing into reactors 1, 2 and 3 to cool the cores. Following Tuesday's apparent cracking of the suppression chamber in reactor 2 - a likely cause of the radioactivity spike then seen - there were concerns that the same thing might have occured on Wednesday in reactor 3. However, the latest reports from Japanese news sources suggest reactor 3's containment system is intact. If that proves to be the case, the source of Wednesday's radiation spike remains a mystery. It seems to have been big enough to force technicians to leave the plant. Clearly, their presence is crucial to stabilising the reactors - and to control the situation in the dry pool in building 4. If they were forced away for long periods, the chances of containing the crisis would fall. "If water is continuously pumped, they could stabilise the position, because the moment when fuel rods are covered with water, the situation is basically stabilised," observed Jasmina Vujic, professor of nuclear engineering at the University of California, Berkeley. Tepco sounded a rare optimistic note by saying engineers would soon restore an electrical connection from the national grid - which should allow them to re-start water pumps, provided they have not been damaged by the tsunami or the hydrogen explosions. While this work continues, so do the questions over the building 4 fuel pond. Re-criticality seems an extraordinary thing to contemplate; but if it is not a real possibility, why was such an idea floated by the company itself? The bigger picture, though, is still one of a serious local incident, with minor impacts outside the plant. US Energy Secretary Steven Chu, however, suggested Fukushima was now more serious than the 1979 Three Mile Island incident in the US - and if contamination does spread outside the immediate area, that will prove to be the case. จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 13:51:34

ความคิดเห็นที่ 27 From tsunami to nuke plant crisis: Japanese fear invisible killer จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 14:16:24

ความคิดเห็นที่ 28 ขอบคุณสำหรับข่าวค่ะ จากคุณ : CMV เขียนเมื่อ : 17 มี.ค. 54 16:01:40

ความคิดเห็นที่ 29 แตกทู้นะคะ จากคุณ : july 19 เขียนเมื่อ : 17 มี.ค. 54 16:54:15