June 18 2011 - News Flash - General Information: Operators of Japan's ***ushima nuclear plant have suspended an operation to clean contaminated water hours after it began due to a rapid rise in radiation.
Some 110,000 tonnes of water have built up during efforts to cool reactors hit by the 11 March earthquake and tsunami.
The contaminated water, enough to fill 40 Olympic-sized swimming pools, has been at risk of spilling into the sea.
Map of Eastern Japan with Power Plants and Cities Marked
Gif of ***ushima Plant #1 Reactor #1 Housing Building Explosion:
Picture of ***ushima Plant #1 Reactor #1 Housing Building After Explosion
Washington Post Piece On How The Nuclear Emergency Unfolded(Includes Diagrams and Good Descriptions)
New York Times Piece On ***ushima Nuclear Facility(Includes Diagrams and Good Descriptions)
IAEA News Centre
Source: http://www.bbc.co.uk/news/world-asia-pacific-12720219An explosion has been heard from a Japanese nuclear power plant hit by Friday's devastating earthquake.
Reports said smoke was seen coming from the plant at ***ushima and several workers were injured.
Japanese officials fear a meltdown at one of the plant's reactors after radioactive material was detected outside it.
Structural collapse seemed to occur during a strong aftershock.
Edit: BBC World Service just reported the outer wall of the building housing the reactor has collapsed. They have not confirmed if the reactor is exposed though. Will update as I hear more.
Edit: 0850 GMT: Chief Cabinet Secretary of Japan's Nuclear Power body reports everything is undercontrol. Wider evacuation of area possibly under way. Military and police reportedly moving people up to 60 km from reactor site.
Edit: 0850 GMT: Skynews reports the walls and roof at ***ushima Number 1 nuclear power plant have been destroyed in the blast according to reports.
Edit: 0906 GMT: BBC Live Page Devoted To Explosion at Nuclear Facility:
Edit: 0906 GMT: Live Stream of Al-Jazeera English:
Edit: 0906 GMT: Live Stream of NHK - TV
This stream just had pics up of the reactor building. Nothing but a frame sitting there at the moment.
Edit: 0912 GMT:
Edit: 0913 GMT: Japanese authorities have extended the evacuation area at the ***ushima-Daini plant - also know as ***ushima II - to 10km, the same distance as for the ***ushima-Daiichi, or ***ushima I plant.Japan's NHK TV says officials measured the level of radiation at the entrance of the ***ushima-Daiichi plant at 1529 Japanese time. If people are exposed to this level of radiation for an hour they'd receive the same amount of radiation they normally would in a year, the report says.
Edit: 0920 GMT: BBC News main page updated with video of reactor building explosion. http://www.bbc.co.uk/news/
Edit 0943 GMT: Japanese Chief Cabinet Secretary Yukio Edano has confirmed the explosion at ***ushima-Daiichi. "We are looking into the cause and the situation and we'll make that public when we have further information," he is quoted as saying by Reuters.
Edit 0957 GMT: From Richard Black, BBC environment correspondent: "Although Japan has a long and largely successful nuclear power programme, officials have been less than honest about some incidents in the past, meaning that official re-assurances are unlikely to convince everyone this time round."
Police are trying to clear residents from the evacuation zone around the ***ushima plant
Edit 1023 GMT: Japanese authorities are extending the evacuation zone around the two ***ushima nuclear plants from 10km to 20km, according to local media.
Edit 1045 GMT: BBC environment correspondent Roger Harrabin says local officials believe the release of radiation following the nuclear plant explosion is likely to be small.
Edit 1052 GMT: TepCo [the Tokyo Electric Power Company] appeared in a news conference and promised to release new radioactivity readings after 6pm. It is now 7.30pm and they have not done so. People are getting extremely frustrated at the lack of news coming from TepCo and the government - they have yet to confirm if the building that suffered an explosion housed a reactor, and we have no indication how much radiation has been released or in what direction winds are blowing.
Edit 1057 GMT: Japan's Nuclear and Industrial Safety Agency says serious damage to the nuclear reactor container is unlikely despite the explosion at the ***ushima-Daiichi plant - Kyodo news
Edit 1103 GMT: Japan's Kyodo news is also reporting that the four people injured in the nuclear plant explosion are conscious and their injuries are not life-threatening.
Edit 1110 GMT: An attempt to explain the risk to the ***ushima nuclear plants following the earthquake: The plants are designed to shut down automatically, which halts the main nuclear fission reaction, but there is a residual amount of intense heat within the system. Back-up generators should kick in to power the cooling mechanisms needed to dissipate that heat - but if they fail, as appears to have happened here, temperatures rise. If this isn't stopped, the reactor vessel itself could eventually melt and leak.
Edit 1202 GMT: Government spokesman says the nuclear reactor container at the ***ushima-Daiichi plant has not been damaged, and the level of radiation has dropped following the explosion earlier on Saturday, AFP reports
Edit 1215 GMT: Government spokesman Yukio Edano says the pressure as well as the radiation at the ***ushima-Daiichi nuclear plant has fallen following this afternoon's explosion. It seems clear now from Mr Edano's comments that the nuclear plant building that was blown apart earlier did house a reactor, but the reactor was protected by its metal casing.
Edit 1305 GMT: The International Atomic Energy Agency (IAEA) says Japanese authorities are making preparations to distribute iodine to residents in the area of both the ***ushima nuclear plants. The IAEA has reiterated its offer of technical assistance to Japan, should the government request this.
Edit 1316 GMT: Noriyuki Shikata, deputy cabinet secretary for public relations for the Japanese prime minister tweets: "Blast was caused by accumulated hydrogen combined with oxygen in the space between container and outer structure. No damage to container. TEPCO's [Tokyo Electric Power Company] efforts to depressurize the container was successful. Additional measures are now taken tonight using sea water and boric acid. "
Edit 1349 GMT: A team from the National Institute of Radiological Sciences has been despatched to ***ushima as a precaution, reports NHK. It is reportedly made up of doctors, nurses and other individuals with expertise in dealing with radiation exposure, and has been taken by helicopter to a base 5km from the nuclear plant.
Edit 1449 GMT: At least three residents evacuated from a town near quake-hit ***ushima No. 1 plant have been exposed to radiation, both Kyodo and NHK report.
Edit 1631 GMT: Japan nuclear agency rates nuclear plant accident in ***ushima at 4 on 0-7 international scale. More information on that figure: The 1986 Chernobyl disaster was rated 7 on the International Nuclear Event Scale; the 1979 Three Mile Island accident was rated 5. The rating of 4 for the ***ushima plant incident comes from an as yet unidentified official at Japan's nuclear safety agency, news wires report.
Edit 1651 GMT: Japanese government confirms that military and civilian units specializing in decontamination have arrived in the exclusion zone. Government also confirms that emergency backup plan to cool the reactor using sea water is underway. The operation is expected to take 36 to 48 hours.
Edit 1820 GMT: The World Health Organisation says the public health risk from Japan's radiation leak appears to be "probably quite low": "We understand radiation that has escaped from the plant is very small in amount," World Health Organisation spokesman Gregory Hartl told Reuters news agency.
Edit 1910 GMT: Japanese workers in masks and\rprotective clothing are scanning evacuees from the ***ushima area for radiation exposure, Reuters reports. Seventeen-year-old Masanori Ono says: "There is radiation leaking out, and since the possibility(of exposure) is high, it's quite scary."
Edit 2022 GMT: Reuters: The IAEA says it has been told by Japan that levels of radioactivity near the ***ushima No. 1 plant have fallen in recent hours. The IAEA says the operator of the plant has confirmed that the primary containment vessel is intact following this morning's blast.
Edit 2039 GMT: Ian Hore-Lacy of the World Nuclear Association told the BBC he believes the situation at the nuclear power plant - where sea water is being used to cool the reactor core - is under control: "The point is that the heat, decay heat from the fuel drops off very rapidly. So after an hour, an hour following the shut down, it's down to about 2 or 3% I think. And after 24 hours it's down to half a per cent. So the amount of heat you've got to cope with right now is a small fraction of what there was initially."
Edit 2042 GMT: The IAEA says it has been told by Japan that 140,000 people have been evacuated from areas around two nuclear plants.
Edit 2123 GMT: The emergency cooling system is no longer functioning at the ***ushima No. 3 reactor, an official from Japan's Nuclear and Industrial Safety Agency has told journalists.
Edit 2145 GMT Reuters: The number of people exposed to radiation near ***ushima No. 1 nuclear plant could reach 160, an official from the Japan Nuclear and Industrial Safety Agency has said. Nine people have shown signs of possible exposure.
Edit 2252 GMT: Reuters: Operators are preparing to release radioactive steam from the number three reactor at ***ushima No. 1 plant, after the cooling system failed there.
Edit 2318 GMT: US nuclear experts warn that pumping sea water to cool a quake-hit Japanese nuclear reactor is an "act of desperation" that may foreshadow a Chernobyl-like disaster, AFP reports. "The situation has become desperate enough that they apparently don't have the capability to deliver fresh water or plain water to cool the reactor and stabilise it, and now, in an act of desperation, are having to resort to diverting and using sea water," said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies
Edit 2328 GMT: CNN: A meltdown may be under way at one of ***ushima Daiichi's nuclear power reactors in northern Japan, an official with Japan's Nuclear and Industrial Safety Agency told CNN Sunday. "There is a possibility, we see the possibility of a meltdown," said Toshihiro Bannai, director of the agency's international affairs office, in a telephone interview from the agency's headquarters in Tokyo. "At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility." Though he said engineers have been unable to get close enough to the core to know what's going on, he based his conclusion on the fact that they measured radioactive cesium and radioactive iodine in the air Saturday night. "What we have seen is only the slight indication from a monitoring post of cesium and iodine," he said. Since then, he said, plant officials have injected sea water and boron into the plant in an effort to cool its nuclear fuel.
Edit 2329 GMT: Reports surfacing claiming that a single rod may have partially melted. Awaiting verification.
March 13 2011
Edit 0012 GMT: Japanese Government reports that the pressure vessel is intact and the vast majority of radiation that has been emitted has come from controlled steam releases to help stabilize the reactor.
Edit 0048 GMT: Japanese Government reports that the earlier explosion that destroyed the building surrounding Reactor One was caused by a malfunction in the pumping system.
Edit 0120 GMT: The director general of the UN nuclear watchdog (IAEA), Yukiya Amano, says he hopes the actions taken by the Japanese authorities at the power plant will be successful: "The IAEA was informed by the Japanese authorities that the explosion occurred outside the primary containment vessel at unit one and the integrity of that vessel is confirmed. The IAEA has been informed that sea water with boron is being injected into the vessel as a counter-measure to prevent possible damage to the core. I hope that the sea water will be injected successfully and that the safety of unit one will be established as soon as possible."
Edit 0158 GMT: Yaroslav Shtrombakh, a Russian nuclear expert, has told the Associated Press that it is unlikely that the Japanese plant will suffer a meltdown like the one in 1986 at Chernobyl, when a reactor exploded and sent a cloud of radiation over much of Europe. That reactor, unlike the reactors at ***ushima, was not housed in a sealed container.
Edit 0232 GMT: The plant operator says the top of the fuel rods is 3 metres above water - AFP, quoting Kyodo.
Edit 0352 GMT: The news coming from Japan remains bleak. Government spokesman Yukio Edano: "We do believe that there is a possibility that meltdown has occurred - it is inside the reactor, we can't see. However, we are acting, assuming that a meltdown has occurred and with reactor number 3 we are also assuming the possibility of a meltdown as we carry out measures."
Edit 0419 GMT: Possible fusion in two reactors - AFP, quoting government
Edit 0426 GMT: Japanese government spokesman Yukio Edano says radioactive meltdowns may have occurred in two reactors at the plant - AFP.
Edit 0545 GMT: The situation at the damaged ***ushima plant is still developing but Malcolm Grimston, an expert on the nuclear industry from Imperial College London, argues that the Japanese authorities should be proud of their foresight. "Given the circumstances, I think this is an extraordinary tribute to those scientists and engineers and designers who built these plants in the 1960s. I'm enormously impressed at the way in which these reactors have withstood the largest earthquake ever in Japan and one of the 10 largest that we've ever recorded on earth".
Edit 0603 GMT: Prime Minister Naoto Kan tells Toshiba Corp president Norio Sasaki to take "firm action" in dealing with the possible meltdown at the ***ushima No 1 nuclear plant, Japan's Nikkei reports. Toshiba constructed the facility for Tepco.
Edit 0638 GMT: The Japanese government is warning of the risk of another reactor explosion at the ***ushima plant. That's the No 3 reactor at risk of an explosion, AFP makes clear in an update. Despite that risk of a second explosion, the government spokesman says reactor No 3 could withstand a blast in the same way that reactor No 1 did.
Edit 0837 GMT: Intentional venting of Reactor Three was conducted in order to decrease pressure within the reactor vessel.
Edit 0923 GMT: The president of Toshiba Corp - which made the damaged reactors at the Japanese nuclear plants - says he has been asked by Prime Minister Naoto Kan to do everything he can to contain the problems there.
Edit 0948 GMT: Authorities say they think that there wasn't a meltdown at the no 3 reactor - as previously thought - only at the no 1 reactor. See an explainer of meltdown here. In any case, officials are insisting that there is no significant risk to human health at present.
Edit 1105 GMT: Yukio Edano, the government spokesman, is speaking now. He says authorities have begun injecting seawater at the No 3 reactor at ***ushima 1 power station. He said the water level is thought to be rising, but the gauge, which seems to be broken, is not showing this. Currently radiation monitor hasn't show any change. Trying to lower pressure at No 3 reactor at ***ushima 1 power station. Confirms risk of explosion. There's a failure of the valve at the No 3 reactor at ***ushima 1 power station. Not clear if this is cause of effect of the fact that gauge isn't showing rising water level.
Edit 1309 GMT: Japan's Tokyo Electric Power Co (Tepco) is preparing to put sea water into the No 2 reactor at ***ushima Daiichi, or ***ushima 1, power station, Reuters reports. It has already been pouring water into reactors No 1 and 3 to try to cool them.
Edit 1411 GMT: The Tohoku Electric Power Company has declared a state of emergency at is Onagawa Nuclear Facility in Northeastern Japan due to excessive radiation levels in the area surrounding the plant. On the 11th a fire caused by the earthquake ravaged part of the facility.
Map Showing ***ushima and Onagawa
Edit 1439 GMT: Japanese authorities have also informed the IAEA that the first (i.e., lowest) state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company. The authorities have informed the IAEA that the three reactor units at the Onagawa nuclear power plant are under control.
As defined in Article 10 of Japan's Act on Special Measures Concerning Nuclear Emergency Preparedness, the alert was declared as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation. The IAEA has offered its "Good Offices" to Japan to support the nation's response to the 11 March earthquake and tsunami. One IAEA capability intended to help member states during crises is the Response and Assistance Network (RANET). The network consists of nations that can offer specialized assistance after a radiation incident or emergency. Such assistance is coordinated by the IAEA within the framework of the Assistance Convention.
The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.
Edit 1458 GMT: Radiation levels at the Onagawa nuclear power plant in Miyagi prefecture are about 700 times higher than normal but are still low, the Tohoku Electric Power Company has said, according to the Maichi Shinbum website. Japan's Nuclear and Industrial Safety Agency dismissed the possibility that the Onagawa plant was to blame, saying it was likely caused by the radioactive substances that scattered when a hydrogen explosion hit the troubled ***ushima plant on Saturday.
Edit 1538 GMT: Meanwhile, Japan's meteorological agency has said the wind that is blowing over the ***ushima-Daiichi plant will blow from the west during Sunday night, pushing any radioactivity towards the Pacific Ocean, the Reuters news agency reports. Earlier, the wind was blowing from the south, raising concerns radioactivity could affect residential areas.
Edit 1538 GMT: A former nuclear power plant designer has said Japan is facing an extremely grave crisis and called on the government to release more information, which he said was being suppressed. Masashi Goto told a news conference in Tokyo that one of the reactors at the ***ushima-Daiichi plant was "highly unstable", and that if there was a meltdown the "consequences would be tremendous". He said such an event might be very likely indeed. So far, the government has said a meltdown would not lead to a sizeable leak of radioactive materials.
Mr Goto said the reactors at the ***ushima-Daiichi nuclear plant were suffering pressure build-ups way beyond that for which they were designed. There was a severe risk of an explosion, with radioactive material being strewn over a very wide area - beyond the 20km evacuation zone set up by the authorities - he added. Mr Goto calculated that because Reactor No 3 at ***ushima-Daiichi - where pressure is rising and there is a risk of an explosion - used a type of fuel known as Mox, a mixture of plutonium oxide and uranium oxide, the radioactive fallout from any meltdown might be twice as bad.
He described the worst-case scenario: "It is difficult to say, but that would be a core meltdown. If the rods fall and mix with water, the result would be an explosion of solid material like a volcano spreading radioactive material. Steam or a hydrogen explosion caused by the mix would spread radioactive waste more than 50km.
Edit 1606 GMT: A pump within the cooling system of one of the reactors at the Tokai nuclear power plant has stopped working, according to the Kyodo news agency. The plant is located in the Naka district of the central prefecture of Ibaraki, and is operated by the Japan Atomic Power Company.
Edit 1651 GMT: Population Density Map of Affected Area
Edit 1706 GMT: The Japan Atomic Power Company has said the cooling system of a reactor at its Tokai nuclear power plant is working, although two of the three diesel power generators used for cooling are out of order, the Reuters news agency reports. The plant, about 120km (75 miles) north of Tokyo in Ibaraki prefecture, was automatically shut down after Friday's earthquake.
Edit 1721 GMT: Tokai nuclear power plant: A report submitted to the Ibaraki prefectural government by the Japan Atomic Power Company said that one of the two pumps being used to cool the water of a suppression pool for the plant's nuclear reactor had stopped working, according to the Kyodo news agency. However, the other pump was still working and there was no problem with cooling the reactor, the prefectural government said. All control rods were set in completely at the reactor, it added.
Edit 1749 GMT: A spokesman for the Japan Atomic Power Company has explained that one of the cooling system pumps at its Tokai nuclear power plant failed because of the tsunami. "We then manually stopped one of our cooling systems," Masao Nakano told the AFP news agency. "But the other cooling systems and other pumps are working well, and temperatures of the reactor have continued to fall smoothly.
Edit 1842 GMT: World Nuclear News has more information on the situation at the Onagawa nuclear power plant: It says a "technical emergency" was declared at 1250 after radiation levels at the site reached 21 microSieverts per hour. Within just 10 minutes, however, the level had dropped to 10 microSieverts per hour, WNN adds. The plant's three reactors remain in a safe shutdown condition at below 100C and the Tohoku Electric Power Company has reported no other issues.
Edit 1925 GMT: The US Nuclear Regulatory Commission (NRC) has said it does not foresee harmful levels of radiation reaching the US from the damaged Japanese nuclear power plants. "All the available information indicates weather conditions have taken the small releases from the ***ushima reactors out to sea away from the population," a statement said. "Given the thousands of miles between the two countries, Hawaii, Alaska, the US Territories and the US West Coast are not expected to experience any harmful levels of radioactivity.
Edit 2044 GMT: Professor Regan said when they vented the first reactor at ***ushima on Saturday - triggering the explosion at the plant - "that vapour would almost certainly have had a little bit of radioactive material called nitrogen 16 - which is in all reactors. That decays away very quickly, in 5 to 10 seconds, but if some of the fuel rods - which appears to have been the case - were compromised, some of the radioactive material from the fuel would have got into the steam and that would also have been taken out." So a key question seems to be to what extent the fuel rods had begun to melt down.
Edit 2142 GMT: Japanese authorities have told the UN nuclear watchdog, the IAEA, that radioactivity levels "at the site boundary" of the Onagawa nuclear power plant have returned to normal, Reuters reports. A state of emergency was declared at the site on Sunday after radioactivity readings exceeding allowed levels in the area.
Edit 2227 GMT: Radiation levels at ***ushima 1 nuclear plant have again topped legal limits, Kyodo News network says.
Edit 2327 GMT: Pumping seawater into damaged nuclear reactors in Japan should keep them from a catastrophic full-scale meltdown, but conditions are still so volatile that it is far too early to declare the emergency over, nuclear experts have told Reuters. It is probably the first time in the industry's 57-year history that seawater has been used in this way, a sign of how close Japan is to facing a major nuclear disaster, according to the scientists.
Edit 2330 GMT: The experts interviewed by Reuters warn it is still far too early to definitively say the day has been saved, especially as the information from the power company and the authorities is incomplete. But they say that with every hour that goes by, the chances of a major catastrophe are diminished - as long as water from the sea or elsewhere keeps reactor cores from overheating. Japanese authorities "appear to be having enough success to have forestalled a definite core melt accident that's difficult to control", said Mark Hibbs of the Carnegie Endowment for International Peace. "After three days that is very good news." But still, he added, it is "a touch-and-go situation"
March 14th 2011
Edit 0219 GMT: New York Times - As the scale of Japan's nuclear crisis begins to come to light, experts in Japan and the United States say the country is now facing a cascade of accumulating problems that suggest that radioactive releases of steam from the crippled plants could go on for weeks or even months. Japanese reactor operators now have little choice but to periodically release radioactive steam until the radioactive elements in the fuel of the stricken reactors stop generating intense heat, a process that can continue for a year or more even after the fission process has stopped. To control that heat, the plant's operator must constantly try to flood the reactors with seawater, then release the resulting radioactive steam into the atmosphere, several experts familiar with the design of the Daiichi facility said. That suggests that the 200,000 people who have been evacuated may not be able to return to their homes for a considerable period and that shifts in the wind could blow radioactive materials toward Japanese cities rather than out to sea.
Edit 0220 GMT - A explosion(s) has rocked Reactor #3's outer containment building in ***ushima Plant #1. There is particular concern over this reactor because it is a MOX reactor, meaning it utilizes Uranium-235 and Plutonium-239 as fuel. Initial reports indicate both explosions were generated during a ventilation of the reactor which resulted in hydrogen and oxygen mixing in the building enclosing the reactor pressure vessel and other components. As a result the building has at least partially collapse. The reactor's pressure vessel has been reported intact and the reactor is not damaged according to Yukio Edano. He furthermore stated the release of major radiation is unlikely. For those of you who have been following this story this is very similar to what happened to Reactor #1 in the complex's sister plant earlier in the crisis.
Pic of explosion at Plant #1, Reactor #3
Video of explosion at Plant #1, Reactor #3
Edit 0351 GMT: Full quotes from Yukio Edano on the explosion: "We believe that there is a low possibility that a massive amount of radiation has been leaked. But it is similar to the time when the hydrogen explosion took place in number 1 reactor (which exploded on Saturday). In the case of number 3 reactor, we can see higher level of radiation. We are now collecting information for the concentration of the radiation and the dose."
Edit 0358 GMT: Initial reports indicated 3 injured and several missing after explosion. Official statements now indicate all technicians and personnel have been accounted for but a total of 6 are injured.
Edit 0409 GMT: The Japanese government has just said there was no marked change in the radiation level after the blast at Reactor 3. According to an article in the New York Times, the US aircraft carrier Ronald Reagan, which is sailing in the Pacific, passed through a radioactive cloud from Japan's stricken reactors on Sunday. Crew members received a month's worth of radiation in about an hour, government officials were quoted as saying.
Edit 0453 GMT: John Keeley from the Nuclear Energy Institute in Washington has told the BBC the hydrogen explosion was similar to the first blast at the plant: "Japanese officials to their credit have come out here quite quickly and suggested that at least at this moment they don't believe there has been any significant radiological release - we will cross our fingers and hope that's the case. It appears that was the case with Unit 1's explosion, we'll hope that's certainly the case with Unit 3.
Edit 0629 GMT: Cooling functions have stopped and water levels are falling in Reactor 2 at the ***ushima 1 nuclear plant - Jiji news agency, quoted by Reuters.
Edit 0643 GMT: Reactor 3's primary containment vessel was not damaged in today's explosion, the UN's nuclear watchdog says.
Edit 0704 GMT: Technicians have been battling to cool three reactors at the ***ushima nuclear plant complex - some 250km north of the capital Tokyo - since Friday, when the quake and tsunami combined to knock out the cooling system, prompting an explosion at one of the reactors on Saturday. The government said an operation pumping seawater into the reactors to help lower the temperature was still going on despite the explosion.
Edit 0710 GMT: Engineers have been working to stabilise two reactors at the plant which lost their cooling systems for a time after the quake and tsunami, leading to what officials believe was a partial nuclear meltdown. Tokyo Electric Power, the operator of the nuclear plant, says the reactor container was not damaged by the blast. It says says six people were injured, and 22 have been treated for the effects of radiation.
Edit 0723 GMT: The US Seventh Fleet has moved its ships and aircraft away from the stricken ***ushima plant after discovering low-level radioactive contamination, Reuters reports. The aircraft carrier USS Ronald Reagan was some 160km offshore when its instruments detected the radiation in a plume of smoke and steam released from the crippled plant. But officials said the dose of radiation was about the same as one month's normal exposure to natural background radiation in the environment. In a revised statement the USN said that only 17 crew members were exposed to levels which required special attention.
Edit 0729 GMT: Japan's government has confirmed 11 people were injured in the latest blast at the ***ushima plant's number three reactor. The plant's operator, Tokyo Electric Power, says the reactor container was not damaged by the blast.
Edit 0751 GMT: Japan's Prime Minister Naoto Kan has described the situation at the ***ushima nuclear plant as alarming, saying Friday's earthquake had thrown Japan into "the most severe crisis since World War II". Government spokesman Yukio Edano said there was a low possibility of radioactive contamination from the latest explosion at the plant, but added that the reactor's containment vessel had resisted the explosion. Experts say a disaster on the scale of Chernobyl in the 1980s is highly unlikely because the reactors are built to a much higher standard and have more rigorous safety measures.
Edit 0805 GMT: Despite the two explosions at the ***ushima plant, the metal shells around the nuclear reactors seem to be holding, says the BBC's Chris Hogg in Tokyo. Even if the nuclear rods do overheat and a partial meltdown occurs, there's a much lower risk of radiation leaking into the atmosphere, he says.
Edit 0810 GMT: Prof Paddy Regan, a nuclear physicist at Surrey University, says that the radiation levels currently being reported from the leaks at the ***ushima plant would have a similar impact to a chest x-ray, and that evacuations from the area, at this stage, are just precautionary.
Edit 0842 GMT: Japanese authorities say they have safely cooled down two nuclear reactors at the ***ushima Daini plant, near the ***ushima Daiichi plant where efforts continue to cool three overheating reactors, local media reports.
Edit 0941 GMT: BBC environment analyst Roger Harrabin explains what has happened at the ***ushima plant: "The power plant is supposed to be earthquake-proof and shut down automatically in response to the quake," he says. "But this starved power from the stations' cooling systems. Then the back-up diesel cooling system also failed. Reactor number 1 overheated, and it is said that hydrogen released exploded, causing the concrete roof of the plant to blow off. Now that's been repeated at Number 3 reactor, Numbers 2 and 4 have problems with cooling."
Edit 0943 GMT: "Some of the nuclear fuel may have partially melted down in the overheating," adds our correspondent. "But crucially the primary steel nuclear containment vessels are said to be intact. The authorities report no significant radiation leak, although some Japanese people may be disinclined to trust the authorities who have lied to them about previous nuclear accidents. It looks at the moment as though catastrophe may well be avoided, but the crisis is far from over."
Edit 0945 GMT: Local media is reporting that water levels have fallen far enough to partly expose the fuel rods at ***ushima's Number 2 reactor - increasing the likelihood of overheating.
Edit 1125 GMT: Worrying news, this: The operators of the damaged ***ushima nuclear plant say it's possible that cooling water at one of the reactors has evaporated, Reuters reports. The company says it can't rule out the possibility that the nuclear fuel rods in Number 2 reactor were now exposed and could be at risk of meltdown.
Edit 1507 GMT: Water level in reactor 2 at ***ushima has fallen and nuclear fuel rods have been exposed again at the ***ushima plant, Kyodo news is reporting.
Edit 1520 GMT: Fears of a partial meltdown at the ***ushima plant would appear to be growing, as Kyodo news agency reports that fuel rods in number 2 reactor are again "fully exposed".
Edit 1524 GMT: Japanese broadcaster NHK is saying that pressure inside reactor 2 at ***ushima rose suddenly when the air flow gauge was "accidentally" turned off. That blocked the flow of water into the reactor leading to full exposure of the rods, it says. That report has not been confirmed.
Edit 1527 GMT: Reports are coming in that ***ushima Daichi(Plant #1) Reactor #1, which experienced several severe problems since the crisis started, may have reached a state of cold shutdown. Story is developing.
Edit 1534 GMT: Japan has officially asked the UN nuclear watchdog the IAEA for experts to help in the current nuclear crisis, AFP reports, citing IAEA chief Yukiya Amano.
Edit 1550 GMT: Radiation detected at the ***ushima plant on Monday is twice the maximum seen so far, Kyodo news is reporting citing plant operator Tokyo Electric Power. Earlier in the crisis the maximum level of radiation detected was 1000 times normal background radiation. Pending official confirmation this means radiation levels may be 2000 times normal in the plant.
Edit 1648 GMT: Yukiya Amano, head of the UN's nuclear watchdog, says ***ushima's reactor vessels "have held and radioactive release is limited" despite the effects of the earthquake and tsunami.
Edit 1656 GMT: The US Nuclear Regulatory Commission says that Japan has asked the US for help with cooling its damaged nuclear reactors, Reuters reports.
Edit 1720 GMT: New satellite imagery available:
From the Left: Reactor #1, Reactor #2, Reactor #3, Reactor #4
Reactor #3 seems to have been the most heavily damaged.
Edit 1757 GMT: Nuclear safety director James Lyons says there is no indication that fuel is melting at the ***ushima plant "at this point." The situation at the quake-damaged ***ushima plant is a "very dynamic situation", IAEA nuclear safety director James Lyons says.
Edit 1806 GMT: The European Commission has asked the International Atomic Energy Agency (IAEA) to convene an extraordinary meeting in Vienna next week following the nuclear crisis in Japan, AFP news agency reports.
Edit 1820 GMT: The French ASN nuclear safety authority says the incident at the ***ushima plant could be classed as level 5 or 6 on the international scale of 1 to 7. It is currently rated at level 4.
Edit 1830 GMT: UK nuclear expert John Large tells the BBC that the wind direction off the east coast of Japan is moving round to the south, which could take any radioactive plume from the ***ushima plant over the Tokyo region.
Edit 1918 GMT: Technicians have resumed injecting seawater into the stricken reactor 2 at ***ushima after a steam vent of the pressure container was opened, Kyodo news agency reports citing Tokyo Electric Power (Tepco).
Edit 2124 GMT: Work resumed early on Tuesday morning to pump sea water into reactor 2 at ***ushima Daiichi to prevent its fuel rods inside from overheating. As of 0300 local time on Tuesday, pressure inside the reactor container had dropped and it was believed seawater had been pumped in succesfully, Tepco said, according to the Kyodo news agency. However, Tepco admitted that it had not yet been able to confirm that water levels inside the reactor had risen. The fuel rods were fully exposed at 2300 local time on Monday.
Edit 2126 GMT: Engineers were having difficulty injecting seawater into the reactor because its vents - necessary to release pressure in the containment vessel by allowing radioactive steam to escape - had stopped working properly, the New York Times reports. However, by Tuesday morning they had succeeded in opening a malfunctioning valve, reducing pressure in the container vessel. They then resumed flooding the reactor with water.
Edit 2129 GMT: Tepco said water levels inside the containment vessel were not immediately rising to the desired level, possibly because of a leak. Nevertheless, an official told a news conference: "We do not feel that a critical event is imminent."
Edit 2145 GMT: The Kyodo news agency reported that Mr Edano had told reporters that although engineers had been able to pump sea water into reactor 2 at ***ushima Daiichi, it remained unstable.
Edit 2207 GMT: Japan's Chief Cabinet Secretary, Yukio Edano, has said a partial defect has been found inside the containment vessel of reactor 3 at the ***ushima Daaich nuclear power plant, the Kyodo news agency reports. He has also said the reactor is "not necessarily in a stable condition". Early on Tuesday morning, officials said pressure inside the container had dropped and sea water was being pumped in to cool the fuel rods.
Edit 2221 GMT: The BBC's Roland Buerk says: "In the towns near the ***ushima Daiichi nuclear power plant, people have been scanned for contamination. Officials say a few have shown slightly raised levels of radiation, but nowhere near dangerous levels. Japan relies on nuclear power stations for nearly a third of its electricity. But trust in the technology, and power company officials, is being shaken. 'I don't know whether we can believe them. Not only their comments, but also the Japanese government and those of the prefectures,' one man told me. After being checked, people are being offered places at evacuation centres around ***ushima. But for some that is not far enough. They are leaving for other parts of Japan."
Edit: 2308 GMT - A new explosion has been reported at ***ushima Daiichi Reactor #2's External Containment Building. Previously Reactor #1 and #3 experienced similar explosions due to emergency hydrogen venting.
Edit: 2315 GMT - Kyodo News Agency reports possible damage to Reactor #2's suppression pool. Story developing.
Edit: 2320 GMT - Tokyo Electric Company confirms some staff are being evacuated from it's ***ushima Daiichi Nuclear Power Plant site.
Edit: 2321 GMT - Part of the container of a troubled nuclear reactor appears to be damaged, the Japanese government said early Tuesday, indicating possible serious radiation leaks.
Chief Cabinet Secretary Yukio Edano told reporters that "damage appears on the suppression pool" -- the bottom part of the container, which contains water used to cool down the reactor and control air pressure inside.
"But we have not recorded any sudden jump in radiation indicators," Edano said without elaborating.
If confirmed, it will be the first direct damage to the reactor since a massive earthquake and tsunami battered Japan's northeast coast on Friday, knocking out nuclear plants in ***ushima, north of Tokyo.
Edit: 2340 GMT - Tokyo Electric officials are now holding a news briefing. They say the blast at reactor 2 happened "near the pressure vessel". They also confirm that some staff at the nuclear power plant are being evacuated, but 50 employees are still staying at the ***ushima Plant.
March 15th 2011
Edit: 0200 GMT - Emergency News Flash - It was recently reported that the radiation levels in the area surrounding the reactor have exceeded 300 mSv/hr which are hazardous to human health.
It was recently reported that there is a fire within the External Containment Building of Reactor #4. It was started by burning debris caused by hydrogen explosions at Reactor #1 and Reactor #3 earlier in the crisis. Furthermore the radiation level currently being reported in close proximity to the reactor ( is between 300 - 400 mSv which is hazardous to human health, even in short durations of exposure if not wearing protective clothing.
The government has also ordered all people within 20km's to be evacuated and anyone within 30km's to remain inside. There is considerable concern over the release of radioactive material because people are being advised to not go outside at all, to not use air conditioning, to not collect clothes that are drying outside and to dust shoes off if coming in from the outside. It appears that considerable contamination has taken place and Prime Minister Kan said that "there is a high risk of futher radioactive material coming out."
It has also been reported some type of damage has occurred to Reactor #2's pressure vessel or it's cooling pool.
Edit 0331 GMT: A fire which broke out Tuesday at ***ushima has now been extinguished, media reports say.
Edit 0337 GMT: A low level radioactive wind could reach Tokyo in 10 hours, Reuters is quoting the French embassy in the Japanese capital as saying.
Edit 0444 GMT: Kyoto news reports detected increase in radioactive particles in Tokyo. Confirmed by Tokyo city government and later contradicted by NHK World Report. Awaiting clarification.
Edit 0454 GMT: A no-fly zone is set for 30km-radius over the ***ushima nuclear plant, the Kyodo news agency is quoting ministry officials as saying.
Edit 0636 GMT: The fire at reactor 4 may have been caused by a hydrogen explosion, the IAEA says Japanese authorities have told it.
Edit 0709 GMT: There is a fire at a spent fuel pond of a reactor and radioactivity has been released into the atmosphere, says the IAEA according to AFP news agency. This is likely to be reactor #4 as reported earlier.
Edit 0738 GMT: More on the fire at a spent fuel pond at ***ushima: It is at the number 4 reactor and "radioactivity is being released directly into the atmosphere", AFP quotes the IAEA as saying
Edit 0740 GMT: The threat from a nuclear reactor damaged by Japan's huge earthquake is judged "extremely high," AFP quotes France's foreign minister as saying as Japan met with other Group of Eight powers
Edit 0800 GMT: Japan has told the IAEA it has extinguished a fire at the spent fuel storage pond of a reactor in ***ushima, Reuters says.
Edit 0803 GMT: There has been a slight rise in temperature of two more reactors at ***ushima nuclear plant, the chief government spokesman says according to AFP. This has been reported to be reactors #5 and #6.
Edit 0814 GMT: There has been a drop in radiation levels in the ***ushima Daiichi Nuclear Power Plant the chief government spokesman says according to AFP. The level was confirmed by the IAEA to be 11.9 millisieverts per hour at 00:00 GMT and 0.6 millisieverts per hour at 06:00 GMT. This is a drop from 300-400 miliisieverts earlier.
Edit 0838 GMT: The World Health Organization in Geneva says Japan is taking the right public health measures to protect the population from radiation and says it has not received a request for help from Japan, but its radiation experts are on standby, says Reuters.
Edit 0935 GMT: Japan's nuclear safety agency has said there are two holes of 8 sq m (86 sq feet) in a wall of the outer building of the number 4 reactor after an explosion there, Reuters reports.
Edit 0938 GMT: A spent nuclear fuel pool at ***ushima's number 4 reactor may be boiling and its water level falling, Kyodo news agency is reporting.
Edit 1000 GMT: A Japanese nuclear safety official has confirmed reports that the water inside the waste fuel storage pool for the number 4 ***ushima reactor may be boiling, AP reports. Hidehiko Nishiyama refused to comment on the potential risks from the rising temperatures caused by a failure of cooling systems and said the plant's operator was considering what to do about theproblem.
Edit 1012 GMT: The UN's weather agency says Japanese winds are dispersing radioactive material over the ocean, and there is no danger for Japan or the region for now, Reuters reports.
Edit 1107 GMT: Prime Minister Naoto Kan has strongly criticised the Tokyo Electric Power Company for its handling of the ***ushima No 1 nuclear plant, according to Japan's Kyodo news. "The TV reported an explosion. But nothing was said to the premier's office for about an hour," a Kyodo News reporter overheard Mr Kan saying during a meeting with company executives. "What the hell is going on?"
Edit 1203 GMT: The International Atomic Energy Agency says Japan has monitored 150 people for radiation levels and carried out decontamination measures on 23, Reuters reports.
Edit 1228 GMT: France's nuclear safety authority says it classifies the ***ushima plant accident as level six. The maximum is level seven, used only once for the 1986 Chernobyl accident, Reuters reports. It should be noted that France is the only country to increase the rating from level four to level six.
Edit 1336 GMT: Levels of radiation in Tokyo spiked on Wednesday morning to around 20 times normal levels, according a spokesman for Tokyo's Metropolitan Government, quoted by the Japan Times. Shintaro Ishihara, said though raised they would not cause health problems.
Edit 1355 GMT: The US military has detected low levels of radiation at its Yokosuka base, south of Tokyo. The US Army has recommended that personnel and families at the base and at the Atsugi air base should take precautions, Reuters reports.
Edit 1422 GMT: China is organising a mass evacuation of its citizens from north-east Japan, the Associated Press reports. The Chinese embassy said it was sending buses to collect its nationals from Miyagi, ***ushima, Ibaraki and Iwate prefectures, "due to the seriousness of and uncertainty surrounding the accident at the ***ushima nuclear plant at present".
Edit 1430 GMT: The US Navy says more of its personnel are testing positive for low-level radiation, but its relief efforts will continue, Reuters reports.
Edit 1436 GMT: The IAEA says Monday's blast at ***ushima may have affected the integrity of the containment vessel - there are fears of more serious radioactive leaks if happen.
Edit 1456 GMT: Tepco says it may start pouring water from a helicopter over ***ushima Daiichi's reactor four in the next few days, to cool the spent-fuel pool.
Edit 1519 GMT: Michel Jarraud, the secretary general of the UN's World Meteorological Organisation, tells the BBC that at the moment, the dominant wind is blowing any radioactive particles out over the Pacific Ocean. His organisation is monitoring the situation closely, he adds.
Edit 1619 GMT: The radiation plume from the damaged nuclear power could reach Tokyo, according to predictions from a US not-for-profit group, the Union for Concerned Scientists.
Edit 1623 GMT: The head of the UN's nuclear watchdog said that there was a "possibility of core damage" at the No. 2 unit of the damaged ***ushima power plant. The damage would be "less than five percent", IAEA chief Yukiya Amano said, according to Reuters.
Edit 1739 GMT: Some 500 bone marrow transplant centres across Europe are being asked to be on standby to treat Japanese radiation victims if the need arises.
Edit 1917 GMT: The BBC's Chris Hogg in Tokyo says that, in the early hours of Wednesday morning in Japan, there are still concerns about the number four reactor at ***ushima. Officials fear the water level is still too low, meaning the spent fuel rods stored there are exposed to the atmosphere.
Edit 2037 GMT: The US-based Institute for Science and International Security (ISIS) has said it agrees with the assessment of France's Nuclear Safety Authority (ASN) that the incident at ***ushima should be classified as level 6 on the International Nuclear Event Scale (INES), one below Chernobyl. Following a number of explosions and a fire at the plant which released dangerous levels of radiation, ISIS said the situation had "worsened considerably" and was now closer to a level 6 event. "It may unfortunately reach a level 7," it added.A level 6 incident is a "serious accident" which results in a "significant release of radioactive material likely to require implementation of planned countermeasures". The 1957 Kyshtym disaster was classified as level 6. An explosion at a Soviet military nuclear waste reprocessing plant in the Russian Urals led to large off-site release of radioactive material.
Edit 2120 GMT: Reuters has reported that two workers are missing at the ***ushima plant - they have not been named but Japan's nuclear safety agency said they had been in the turbine area of reactor four.
Edit 2123 GMT: he BBC's Roland Buerk in Tokyo says that as well as dropping water from helicopters onto the fourth ***ushima reactor - in an attempt to cool it down - officials are considering removing the outer panels, to reduce the build up of hydrogen which caused the previous explosions.
Edit 2126 GMT: Tokyo Electric Power Co (Tepco) has just announced it is abandoning the plan to use helicopters to drop water as it would be too impractical, AP reports. It said other options were being considered, including using fire engines. Our correspondent said there had been concerns over the proposal, not least because of the possible health impact for the helicopter pilots.
Edit 2152 GMT: AFP is reporting a new fire at the number four reactor at the ***ushima Daiichi nuclear plant. Flames are rising from the reactor, AP reports.
Edit 2154 GMT: More on those two workers reported to be missing from ***ushima. A national nuclear safety agency spokesman, Masami Nishimura, said they went missing on Friday, the day the quake and tsunami struck, not after Tuesday's explosion, AFP reports.
Edit 2157 GMT: Tepco says efforts are underway to tackle the fire inside the building which houses the number four reactor, Reuters reports.
Edit 2210 GMT: Tepco has confirmed that a fire broke out at reactor four in the early hours of Wednesday morning. Smoke is pouring from the reactor, a spokesman told reporters.
Edit 2235 GMT: Tepco spokesman Hajimi Motujuku says the fire at reactor four is in the outer housing of the containment vessel. Its cause is not yet known, AP reports.
Edit 2246 GMT: Japanese news agency Kyodo reports that the storage pool in reactor four - where the spent fuel rods are kept - may be boiling. Tepco says readings are showing high levels of radiation in the building, so it is inaccessible. Radiation levels had fallen late on Tuesday but remained abnormal.
Edit 2249 GMT: Officials said the fire new erupted, or reignited, because a blaze at the plant earlier had not been extinguished.
Edit 2314 GMT: A spokesman for the Tokyo Electric Power Company (Tepco) has said: "At around 0545 today, our employee carrying batteries to the control room discovered smoke billowing from the building of reactor 4 [at ***ushima Daiichi]."
Edit 2320 GMT: The Japanese government is now saying the fire in reactor 4 is "under control", according to the AFP news agency.
March 16th 2011
Edit 0003 GMT: A new fire that broke out inside reactor 4 at the ***ushima Daaichi nuclear plant, which was damaged in Friday's earthquake and tsunami, appears to be out. This was the second time in two days that the reactor where spent nuclear rods were being kept caught fire. Workers at the plant are pumping sea-water through several of the plant's reactors in an effort to cool and stabilise them. Japanese media reports say radiation levels at the reactors remain too high for workers there to approach them. Japan's Prime Minister, Naoto Kan, and the International Atomic Energy Agency (IAEA) have expressed concern and called for the provision of more timely, and accurate information.
Edit 0029 GMT: Tokyo Electric Power Company (Tepco) says it will be extremely difficult to spray water from a helicopter to cool down a storage pool for spent nuclear fuel in the No.4 reactor at the ***ushima Daiichi plant. Earlier Japanese news agency Kyodo reported that the storage pool could be boiling, while Tepco said readings showed high levels of radiation, making the building inaccessible.
Edit 0117 GMT: Live Japanese television pictures appear to show white smoke still billowing in the area of the building housing the No.4 reactor at the ***ushima Daiichi nuclear power plant, despite reports that a new fire there was under control.
Edit 0146 GMT: Tepco says the reactor 3 at ***ushima Daiichi nuclear power plant has been emitting white smoke for about 45 minutes, Kyodo News reports. The plant's reactor 4 was the one where a fire broke out earlier this morning, Tepco said.
Edit 0208 GMT: South Korea says it will send some 50 tonnes of its boron reserves to Japan after a request from Tokyo, Reuters reports. The metalloid is vital for stopping fission nuclear reactions in nuclear reactors.
Edit 0219 GMT: The New York Times reports on the 50 workers who have remained behind at the ***ushima nuclear power plant, "braving radiation and fire".
Edit 0236 GMT: Mr Edano, Japan's chief government spokesman, says workers trying to douse the reactors with water were forced to retreat when radiation levels surged there.0221: Japanese Cabinet Secretary Yukio Edano says the authorities are still looking for the cause of white smoke billowing from reactor 3 at ***ushima Daiichi nuclear power plant. He says the radiation reading at the plant is fluctuating by the hour.
Edit 0252 GMT: Two crew members on an Australian search and rescue helicopter showed low levels of radiation contamination after they were forced to make an emergency landing in ***ushima on Wednesday, AFP news agency reports. Australian Prime Minister Julia Gillard was quoted as saying the radiation was detected on their boots. They landed about 12 miles (20km) outside the exclusion zone surrounding the plant.
Edit 0320 GMT: Staff have now been evacuated from ***ushima because of a spike in radiation levels, Chief Cabinet Secretary Yukio Edano told a news conference.
Edit 0325 GMT: More on that news conference by Chief Cabinet Secretary Yukio Edano. He said: "At around 0830 today, at ***ushima Daiichi nuclear power plant, white smoke has been seen coming out of reactor three. And regarding this, currently we are looking for the cause.
Edit 0349 GMT: Japan says it is ready to ask the US military for help in battling the crisis at the ***ushima nuclear plant, the AFP news agency reports.
Edit 0623 GMT: Workers at the ***ushima plant have returned after being evacuated, CNN is quoting Tokyo Electric Power Company as saying.
Edit 0653 GMT: South Korea is planning to ship boric acid to Japan, Kyodo news reports. It says Japan requested the boric acid, which is used to stop fission nuclear reactions, after its own supplies were largely used up at the ***ushima nuclear power plant.
Edit 0702 GMT: Japan's NHK TV confirms that the evacuation order for nuclear plant workers has been lifted.
Edit 0719 GMT: A helicopter used to pour water over one of the reactors has taken off, Japanese TV reports.
Edit 0806 GMT: Japan's NHK TV reports that a helicopter that is to drop water over Reactor Three will pass over the reactor many times. It says the helicopter can't stay too long over the plant because of the risk of radiation to the crew. Images of the helicopter show it scooping water from the sea into a red container similar to those used in fire-fighting operations around the world.
Edit 0842 GMT: The World Health Organisation says there is no evidence of any significant spread of radiation. The WHO's Michael O'Leary urges governments and members of the public to take steps to halt rumours about "a threatening radiation cloud spreading across Asia".
Edit 0901 GMT: The Japanese Army has aborted an operation to spray water on the damaged ***ushima Daiichi nuclear plant, Japan's NHK TV reports.
Edit 0913 GMT: Chief cabinet secretary Edano says preparations are being made to inject water from the ground into Reactor Four at the ***ushima Daiichi plant.
Edit 0956 GMT: Water is being poured into Reactors Five and Six at the ***ushima Daiichi nuclear plant, Reuters reports, quoting the operating company.
Edit 1145 GMT: Tepco, which runs the ***ushima Daiichi nuclear plant, has apologised on its website for an earlier incident in which "an abnormal noise began emanating from [a] pressure suppression chamber". This led to a temporary evacuation of workers. "We are aware of and sincerely apologize for the great distress and inconvenience this incident has caused to not just those inhabitants residing in the immediate vicinity but also society at large," Tepco says.
Edit 1214 GMT: Japanese police have been asked to send watercannon truck to hose down the nuclear plant, Japan's broadcaster NHK is reporting, according to AFP.
Edit 1324 GMT: Japan has raised the maximum radiation dose allowed for nuclear workers, to 250 millisieverts from 100 millisieverts. It described the move as "unavoidable due to the circumstances", AP reports.
Edit 1356 GMT: More from Russia's nuclear chief. He has just said the situation in Japan is playing out according to a worst-case scenario, Reuters reports.
Edit 1515 GMT: US Energy Secretary Steven Chu has just described events at the ***ushima plant as "appearing to be more serious than Three Mile Island". How much worse was not clear, he said, adding that it was very hard to tell how bad things were on the ground.
Edit 1520 GMT: The IAEA says the Japanese authorities "have reported concerns about the condition of the spent nuclear fuel pool at ***ushima Daiichi Unit 3 and Unit 4". The pools are where the still-radioactive fuel rods are kept after they have completed their useful life in the reactor.
Edit 1525 GMT: The EU's energy chief Guenther Oettinger has said that in the coming hours "there could be further catastrophic events, which could pose a threat to the lives of people on the island". He told the European Parliament the ***ushima nuclear site was "effectively out of control". "The cooling systems did not work, and as a result we are somewhere between a disaster and a major disaster."
Edit 1529 GMT: More from the IAEA. Its latest briefing says that officials are preparing to spray water onto reactor four and possibly three. "Some debris on the ground from the 14 March explosion at Unit 3 may need to be removed before the spraying can begin.
Edit 1545 GMT: The Pentagon has announced that US forces must stay 50 miles (80km) away from the ***ushima reactor unless they have specific authorisation, Reuters reports.
Edit 1548 GMT: The Pentagon said some US air crews in Japan have been given iodine tablets as a precautionary measure.
Edit 1555 GMT: ***ushima's operators, Tepco, have said they want the military to make another attempt at dumping water from a helicopter onto the damaged reactor on 17 March.
Edit 1556 GMT: Kyodo is reporting new plumes of smoke coming from the building housing reactor three.
Edit 1720 GMT: Kyodo reports that the US military is to fly an unmanned plane over ***ushima, equipped with infrared sensors, to give an aerial view of what is going on.
Edit 1832 GMT: The AP news agency is quoting Tepco as saying a new power line is almost ready which could end the crisis. The disruption of power to the pumps which send coolant through the reactors is what led to their overheating.
Edit 1837 GMT: Gregory Jaczko, head of the US Nuclear Regulatory Commission (NRC) has said there is no water left in the spent fuel pool in reactor four, adding: "We believe that radiation levels are extremely high." Mr Jaczko was speaking to Congress in Washington and it was not immediately clear where his information had come from.
Edit 1859 GMT: More from NRC chair Gregory Jaczko. He told Congress: "We believe that secondary containment has been destroyed and there is no water in the spent fuel pool and we believe that radiation levels are extremely high which could possibly impact the ability to take corrective measures." Mr Jackzo said the high radiation levels would make it very difficult for workers to get near the reactor. "The doses they could experience would potentially be lethal doses in a very short period of time," he said, but added that the NRC's information on the situation was "very limited".
Edit 1933 GMT: Yukiya Amano, the director general of the International Atomic Energy Agency (IAEA), has said he plans to fly to Japan on Thursday to get further information about the situation at the ***ushima Daiichi nuclear plant. The BBC's Kerry Skyring says Mr Amano is under pressure to demonstrate his agency is informed and able to communicate a clear picture of what is happening. "At daily press briefings he has been unable to explain why the information provided is so sketchy. As well as flying to Japan to what he says are high level meetings he is creating two teams who will also go there, one with expertise in nuclear safety, the other in radiation protection," our correspondent adds. Asked if the situation at ***ushima was now out of control, Mr Amano said: "It is very serious. The government and operators are doing everything they can. I hope their efforts will be successful."
Edit 2010 GMT: More on the power line being laid to the ***ushima Daiichi plant to help restore the reactor cooling systems: Tokyo Electric Power Company (Tepco) spokesman Naoki Tsunoda has said it is almost complete, and that engineers plan to test it "as soon as possible", according to the Associated Press. Reviving the electric-powered pumps might allow the engineers to finaly cool the overheated reactors and spent fuel storage ponds.
Edit 2014 GMT: A special police van equipped with a water cannon - normally used to disperse rioters - meanwhile arrived at the power station early on Thursday. Tepco plans to use the cannon to spray water onto reactor 4's spent fuel storage pond. The cannon is thought to be strong enough to allow engineers to remain a safe distance from the complex and limit their exposure to radiation.
Edit 2019 GMT: The US military will also fly one of its Global Hawk unmanned high-altitude reconnaissance aircraft over the site, possibly later on Thursday, to take photographs of the inside the building which houses reactor 4, Japanese government sources have told the Kyodo news agency. Global Hawks are already being used to survey the devastation caused by the earthquake and tsunami.
Edit 2027 GMT: Japan's Nuclear and Industrial Safety Agency has said it is also concerned about the spent fuel storage pool inside the building housing reactor 3 at ***ushima Daiichi. The pools at both reactors 3 and 4 are reportedly boiling - there may not even be any water left in reactor 4's pool - and unless the spent fuel rods are cooled down, they could emit large quantities radiation. Radioactive steam was earlier said to be coming from reactor 3's pool. If cooling operations did not proceed well, the situation would "reach a critical stage in a couple of days", an agency official told the Kyodo news agency.
Edit 2035 GMT: US officials have concluded that the Japanese warnings have been insufficient, and that, deliberately or not, they have understated the potential threat of what is taking place inside the nuclear facility, according to the New York Times. Gregory Jaczko, the chairman of the US Nuclear Regulatory Commission, earlier said he believed that all the water in the spent fuel pool at reactor 4 had boiled dry, leaving fuel rods stored there exposed. "We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures," he told a Congressional committee.
To help people understand what has happened during the Japanese Nuclear Crisis BBC has provided the following Q&A:
The Q&A can now be found at: http://www.bbc.co.uk/news/health-12722435
I have removed it from this thread as I need the space to keep updating on news.