fukushima explosions from air, taken by global Hawk drone.

unit 3 still evaporating, remember that the weather is cooling down so any warm surface will cause condensation, does not mean it is boiling yet!

amacd_33, Rui Costa, and Kit O'Connell faved this
  • naturalflow 4y

    The explosion followed an early morning acknowledgment from Tokyo Electric Power that, because of human error, the fuel rods inside the Unit 2 reactor had been at least partly exposed to air for more than two hours during two separate incidents the previous evening, allowing them to heat up and causing a buildup of explosive hydrogen gas. Independent experts said it was a grave development that heightened the risk of an uncontrolled release of radiation into the environment.

    Authorities also disclosed that a fire broke out at the complex's Unit 4 after a blast left two gaping holes in an outer wall. The fire was later reported to have been extinguished, though it was unclear what caused it.

    The International Atomic Energy Agency said Japanese officials told them that the explosion and subsequent fire were located at the unit's spent-fuel storage pond and that radioactivity was being released directly into the atmosphere.

    By Tuesday afternoon, Kyodo was reporting that the pond was boiling because the water level was too low. Workers were struggling into the evening to pump more water into the pond.

    Authorities also reported that the only two reactors where explosions have not occurred — Units 5 and 6 — were registering rising temperatures.

    The U.S. government mobilized emergency resources to help Japan grapple with the developing nuclear crisis, dispatching a team of Nuclear Regulatory Commission experts late Monday, activating an atmospheric radioactivity monitoring center at Lawrence Livermore National Laboratory in the Bay Area and rushing additional Navy ships to the region.

    In the best-case scenario, the situation at the damaged reactors will take weeks, if not months, to stabilize, U.S. nuclear experts said.
  • David Callihan 4y

    well March Madness has taken on a whole new meaning!
  • naturalflow 4y

    from a comment on cbc news:
    They are in fact going to try and remove panels from 5 and 6 to avert hydrogen explosions. However, it seems that Most of the workforce now on site has gone back to Tepco and Japanese military. There appears to have been disagreements over the pace and procedures being used, and because the Americans weren't in charge and did not believe the Tepco course was a plausible and safe one, they have withdrawn. This is not confirmed, but sourced from someone in the military.

    There WERE 5 fire engines attempting to insert water in #2 prior the explosion of #3. 4 of these were damaged and the 5th was unable to be re-fueled due to damage to the truck, and ran out of fuel, resulting in the first loss of water in #2.

    Reports about the condition of the pool over three are sketchy, however most of the pool and its contents appear to still be in place, but potentially collapsed down onto the containment structure. The explosion took place above the pool and pushed it downward while throwing the everything else up. The object seen dropping to the left of the plume was actually the crane used to manipulate objects inside the reactor building, along with its supporting structure. No one gives me any indication that pool is still full, however occasional steam seen above it is assumed to be either from the reactor below or the water in the pool.

    Breaking update: #1 may be in complete meltdown.
  • naturalflow 4y

    # Helicopter brigade is testing to see if pool is leaking. Also, they will use this opportunity to insert Boron into the pool for neutron absorption to decrease the chances of criticality. If the pool leaks, then this isn't a solution. It will help no matter what because the boron will help keep the submerged portions from increasing in activity.

    This buys time, at best, but its time.

    Stored fuel rod pool on roof of number 4 boiled off and created hydrogen, which then exploded and damaged the pool and the reactor below. This also lit on fire. They are now going to use helicopters to try and re-fill the pool before the rods ignite.
    a contingent of CeeBee/Army Corp are assisting in forcing water into the containment of 1-4. This is like aiming a fire hose at a partially enclosed porch at this point, but its cooling the cores to some extent. If it can possibly be enough is beyond my knowledge of the situation, but I seriously cant see how its doing more than buy time and allow them to think about real solutions.

    The pools above 2, 5 and 6 are intact but need to be kept cool. The reactors underneath are like campfires. Cooling them helps. Some.
    I sincerely doubt this can be reversed at this point, but if it can, the people who could do it are there trying.

    Water in pool over reactor 2 is now boiling. Helicopter brigade cannot reach this pool with a controlled demolition of building roof.

    This pool SHOULD also be accessible to regular water insertion, though, If they are cooling it and its still boiling, then there is hours until the worst happens.Rating0Agree with comment (1 people agree)Disagree with comment (1 people disagree)ReplyPolicyReport abuse (0)
    # mikkeishstandard2011/03/15
    at 1:09 PM ETOf course, what else are we going to be told? Then a couple of years down the road we will learn that it was kept a secret............
  • naturalflow 4y

    This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.”

    Really? Power plugs did not fit? I’m sure there’s more to this part than just that.
    morgsatlarge says:
    March 13, 2011 at 8:43 pm
    That was humor, I am sure, knowing the writer personally he would be making a very dry joke.
    Gregor Gruber says:
    March 13, 2011 at 8:53 pm
    no there are actually several reports that they were not able to connect mobile generators because of missing (fitting) cables
    Max says:
    March 13, 2011 at 9:34 pm
    that is true. there are lots of different ways to connect these things and they had some plan but were unable to get things in place because of some incompatibilities. Saw it on a live broadcast here in Japan on NHK.
  • naturalflow 4y

    Explosions at units 1 and 3 occurred due to similar causes. When an incident occurs in a nuclear power plant such as a loss of coolant accident or when power is lost, usually the first response is to depressurize the reactor. This is done by opening pressure relief valves on the reactor vessel. The water/steam mixture will then flow down into the suppression pool, which for this design of a reactor is in the shape of a torus (technical term for the shape of a donut). By blowing the hot steam into the suppression pool some of the steam is condensed to liquid phase, which helps keep the pressure low in the containment.

    The pressure in the reactor vessel is reduced by venting the water/steam mixture. It is much easier to pump water into the vessel when it is at a reduced pressure, thus making it easier to keep the fuel cooled. This procedure was well underway after the earthquake. Unfortunately, because of the enormous magnitude of the earthquake, an equally large tsunami was created. This tsunami disabled the onsite diesel generators as well as the electrical switchyard. Without power to run pumps and remove heat, the temperature of the water in the reactor vessel began to rise.

    With the water temperature rising in the core, some of the water began to vaporize and eventually uncovered some of the fuel rods. The fuel rods have a layer of cladding material made of a zirconium alloy. If zirconium is hot enough and is in the presence of oxygen (The steam provides the oxygen) then it can undergo a reaction that produces hydrogen gas. Hydrogen at concentrations above 4% is highly flammable when mixed with oxygen; however, not when it is also in the presence of excessive steam.

    As time went on, the pressure in the containment rose to a much higher level than usual. The containment represents the largest barrier to the release of radioactive elements to the environment and should not be allowed to fail at any cost. The planned response to an event like this is to vent some of the steam to the atmosphere, just to keep the pressure under control.

    Exactly what happened next is not verified; however, the following is very likely the general explanation for the explosion. It was decided to vent the steam through some piping that led to a space above and outside containment, but inside the reactor building. At this point, the steam and hydrogen gas were mixed with the air in the top of the reactor building. This was still not an explosive mixture because large amounts of steam were mixed with the hydrogen and oxygen (from the air). However, the top of this building is significantly colder than inside the containment due to the weather outside. This situation would lead to some of the steam condensing to water, thereby concentrating the hydrogen and air mixture. This likely went on for an extended period of time, and at some point an ignition source (such as a spark from powered equipment) set off the explosion that was seen in units 1 and 3. The top of the reactor building was severely damaged; however, the containment structure showed no signs of damage.

    Right after the explosions there were spikes in the radiation levels detected, because there were some radioactive materials in the steam. When the zirconium alloy cladding reacted to make hydrogen, it released some fission products. The vast majority of the radioactive materials in the fuel will remain in the fuel. However, some of the fission products are noble gases (xenon, Xe and krypton, Kr) and will immediately leave the fuel rods when the cladding integrity is compromised. Fortunately, Xe and Kr are not a serious radiological hazard because they are chemically inert and will not react with humans or plants. Additionally, small quantities of iodine (I) and cesium (Cs) can be entrained with the steam. When the steam was vented to the reactor building, the Xe and Kr would have followed as well as some small amounts of I and Cs. Thus, when the roof of the reactor building was damaged , these radionuclides that were in the reactor building would have also been released. This is the reason a sudden spike was seen in radiation levels. These heightened radiation levels quickly decreased. This is because there was no damage to the containment which would increase the quantities of radionuclide released, and because the radionuclides released during the explosion quickly decayed away or dispersed.

    Unit 2 explosion

    Recent information indicates that unit 2 may have suffered a containment breach. Pressure relief of unit 2 was complicated by a faulty pressure relief valve, which complicated the injection of sea water and the evacuation of the steam and hydrogen. It is reported that the fuel rods were completely exposed twice. More details to follow.

    Unit 4 fire

    A fire was reported at unit 4 which was in a shutdown state during the earthquake and tsunami for a planned outage. Latest reports indicate that the fire was put out. More details to come.

    via mitnse.com/
  • naturalflow 4y

    Loud noises were heard at Fukushima Daiichi 2 at 6.10am this morning. A major component beneath the reactor may be damaged.

    Confirmation of loud sounds this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that “the suppression chamber may be damaged.” It is not clear that the sounds were explosions.

    Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system.

    The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

    A close watch is being kept on the radiation levels to ascertain the status of containment. As a precaution Tokyo Electric Power Company has evacuated all non-essential personnel from the unit. The company’s engineers continue to pump seawater into the reactor pressure vessel, in an effort to cool it.

    Prime minister Naoto Kan has requested that everyone withdraw from the ten kilometer evacuation zone around the nuclear power plant and that people that stay within remain indoors. He said his advice related to the overall picture of safety developments at Fukushima Daiichi, rather than those at any individual reactor unit.

  • naturalflow 4y

    OSLO, March 15 (Reuters) - Winds are set to blow low-level radiation from Japan's quake-crippled nuclear power plant out over the Pacific Ocean in coming hours, easing health worries after drifting towards Tokyo early on Tuesday, experts said.

    After the more serious 1986 Chernobyl disaster in the Soviet Union, radiation blew around the northern hemisphere in about three weeks. One U.N. study said Chernobyl may eventually cause up to 9,000 deaths, mainly from extra cancers near the plant.

    "The cloud is going in the direction of Tokyo for the next 15 to 20 hours or so," said Gerhard Wotawa, of the Austrian weather service ZAMG who is advising the International Atomic Energy Agency (IAEA). "Then it will go out towards the Pacific," he told Reuters. "At some point this will also spread around the world." With prevailing winds, Canada and the United States might be first to detect a much diluted cloud.
  • naturalflow 4y

    “Robert Alvarez, a senior policy expert at the Institute of Policy Studies, told a conference call with journalists that satellite pictures of the Fukushima plant showed evidence of damage. “There is clear evidence that the fuel cask cranes that haul spent fuels to and from the reactor to the pool both fell. They are gone,” he said. “There appears to be copious amounts of steam pouring of the area where the pools is located.” The damage confronts technicians with the tasks of cooling both the reactor and the fuel pools, where temperatures also began rising dangerously once the nuclear plants lost power. “The spent fuel pool in unit 4 is boiling, and once that starts you can’t stop it,” said Jim Riccio, a nuclear expert at Greenpeace. “The threat is that if you boil off the water, the metal cladding on the fuel rods that is exposed to the air and is volatile will catch fire. That will propel the radiation even further.” A report by the National Academies of Science in 2005 warned of just such a danger. The study said the spent fuel pools put America at risk of a widespread radiation leak in the event of a terrorist attack. It went on to warn of a radiation leak travelling hundreds of miles causing up to 6,000 cancer deaths. But even that report, though dire, was not new. In the early 1990s, a number of nuclear engineers, including Lochbaum, warned about the dangerous situation of spent atomic fuel in US plants that are built along the same lines as Fukushima. The engineers called for nuclear waste to be stored instead in dry casks at a distance from the reactors. Their story made the cover of Time magazine. It did not, however, lead to any improvements in nuclear safety, Lochbaum noted. “It was a design mistake to put the spent fuel in the same building as the reactor,” he said. The close proximity makes it much harder for technicians struggling to cool down the reactor and the spent fuel pool at the same time. “They are like siamese twins, you can’t separate them,” Lochbaum said. 9.07pm: A sign of the times: Apple said it is delaying its launch of the iPad 2 in Japan. “We are delaying the launch of the iPad 2 in Japan while the country and our teams focus on recovering from the recent disaster,” said Apple spokeswoman Natalie Kerris. Obviously that doesn’t mean much in the scale of things.”
  • naturalflow 4y

    22.23 The BBC's Matt Frei in Tokyo says spent fuel rods in reactors five and six are also now believed to be heating up.

    22.21 Everyone is watching the direction of the wind. Currently it is blowing out to the east into the sea but if it blows south then radioactive matter could be blown towards Tokyo 250km away.

    British rescue workers search for survivors under a roof in Ofunato

    22.16 Tokyo Electric Power is currently saying that no further explosion has been heard at reactor four where another fire has broken out.

    22.09 Tokyo Electric Power has told journalists that the fire is in the outer housing of reactor four's containment vessel. Fire engines are tackling the blaze. It is not clear what started it. An employee confirmed smoke was pouring from the number four reactor at the plant, a TEPCO spokesman told reporters. On Tuesday, a fire broke out in the reactor's fuel storage pond — an area where used nuclear fuel is kept cool — causing radioactivity to be released into the atmosphere.

    22.05 Lester Holt, an anchor for NBC NIghtly News tweets:

    Twitter My team and I have increased our distance from nuclear plant. Reporting on Nightly News tonight from mountains west of Sendai.

    22.01 Reuters says the fire is at reactor 4. It has been raging since 05.45 local time.

    21.59 Tokyo Electric Power (TEPCO) has denied that two missing plant workers from reactor four went missing after Tuesday's explosion and insisted that they have been lost since the earthquake and tsunami struck Fukushima.

    21.51 A further fire has broken out at Fukushima plant, according to local media, althought it is not clear which reactor is affected. Flames are visible from what is reported by the BBC as reactor four. Tepco has confirmed that another fire has broken out.
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