Kyodo: “Unit 3 MOX likely melted through” — Mixed uranium-plutonium oxide fuel may have “dribbled” out after melting again

Published: August 9th, 2011 at 5:11 am ET


Unit 3 MOX likely melted through, Kyodo, August 9, 2011:

MOX fuel […] is believed to have breached the vessel after melting again, a study said Monday.

The study […] said most of reactor 3’s mixed uranium-plutonium oxide fuel may have dribbled into the containment vessel underneath […]

Tanabe […] says the fuel at the bottom overheated and melted again over a four-day period.

Published: August 9th, 2011 at 5:11 am ET


Related Posts

  1. “Most” of the fuel at Reactor No. 3 may have breached vessel after melting down twice August 8, 2011
  2. Melted fuel in Reactor No. 3 appears to have burned through pressure vessel — Loaded with rods containing plutonium May 18, 2011
  3. Japan nuke expert: I presume melted fuel reacted violently with cement at Reactor No. 3, releasing large amounts of radioactive materials outside — TEPCO responds August 9, 2011
  4. NHK: “This is a very severe accident” — Nuclear fuel at Reactor No. 1 may have melted through 65 cm of concrete… Only 37 cm at thinnest point (PHOTOS) November 30, 2011
  5. Japan nuclear expert: Massive “re-melting” occurred at Reactor No. 3 (DIAGRAM) August 8, 2011

24 comments to Kyodo: “Unit 3 MOX likely melted through” — Mixed uranium-plutonium oxide fuel may have “dribbled” out after melting again

  • milk and cheese milk and cheese

    Most likely melted through? “Most likely” is a guess. It is meaningless. No one appears to know where the poison is.

  • lokay5 lokay5

    Melted plutonium/uranium dribbling out…….

    We’re SO screwed………..

    • Toadmac

      No not really because they can open up a drinks factory there. Just think of the potential! Imagine the types of energy drinks you could make! It should be safe enough to start making lightly salted crackers once the corium dry’s. Plutonium cocktail and crackers anyone?

  • lokay5 lokay5

    Report suggests second meltdown at reactor at Fukushima plant.BY TOMOOKI YASUDA STAFF WRITER


    A second meltdown likely occurred in the No. 3 reactor at the Fukushima No. 1 nuclear power plant, a scenario that could hinder the current strategy to end the crisis, a scientist said.

    In that meltdown, 10 days after the March 11 Great East Japan Earthquake, the fuel may have leaked to the surrounding containment vessel, according to a report by Fumiya Tanabe, a former senior researcher at what was then the government-affiliated Japan Atomic Energy Research Institute.

    His report will be announced at next month’s meeting of the Atomic Energy Society of Japan.

    Under Tokyo Electric Power Co.’s road map to deal with its crippled nuclear plant, reducing temperatures at the bottom of the core pressure vessel is one objective for bringing the accident under control. But if the fuel burned through the pressure vessel surrounding the No. 3 reactor and dropped into the containment vessel, that plan would be affected.

    The No. 3 reactor was in a state of dry boil for about six hours until cooling water was pumped into the core from 9:25 a.m. on March 13.

    Around 11 a.m. on March 14, the reactor building was hit by a large hydrogen explosion that was likely caused by a core meltdown, which led to fuel falling to the bottom of the pressure vessel.

    According to data released by TEPCO, about 300 tons of water was pumped into the No. 3 reactor core daily until March 20, which likely cooled the fuel into a large clump.

    However, between March 21 and 23, only about 24 tons of water was pumped in, while on March 24, about 69 tons entered the reactor.

    One possible cause for the decline in water volume was that pressure within the pressure vessel increased, making it more difficult for water to enter the vessel.

    According to Tanabe, who analyzed the nuclear accident at Three Mile Island in the United States when he was a researcher at the Japan Atomic Energy Research Institute, the volume of water pumped in on those days was only between 11 and 32 percent of the amount needed to remove decay heat from the nuclear fuel in the core.

    In such a situation, the fuel could reach high enough temperatures to begin melting again in just one day.

    Tanabe also estimates that the second meltdown led to the release of large amounts of radioactive materials, and that much of the fuel fell through the pressure vessel to the surrounding containment vessel.

    The fuel is now believed to have formed another clump after being cooled.

    Achieving a cold shutdown with the fuel sufficiently cooled would mark the completion of the second step of TEPCO’s road map for dealing with the Fukushima nuclear accident. The central government has compiled its own road map based on TEPCO’s objectives.

    However, Tanabe said: “In deciding if a cold shutdown has occurred, the location where temperatures are measured will depend on where the melted fuel is. A thorough analysis should be conducted on what has really occurred in the reactor core.”

    Even officials of TEPCO and the central government acknowledge that they do not know the specific condition of the core at the No. 3 reactor. But their view until now has been that the melted fuel has settled at the bottom of the pressure vessel.

    One factor used by Tanabe in speculating that a second meltdown occurred is the increase in radiation levels from the morning of March 21 in areas downwind from the Fukushima No. 1 plant, such as the Fukushima No. 2 nuclear power plant as well as the Kanto region municipalities of Kita-Ibaraki, Takahagi and Mito.

    Initially, officials of the Nuclear and Industrial Safety Agency explained that the higher radiation levels were caused by radioactive materials falling to the ground with the rain.

    But there is also the possibility that additional radioactive materials emitted from the second meltdown may have been blown by the wind.

    Between 1 a.m. and 3 a.m. on March 21, the pressure within the pressure vessel of the No. 3 reactor core increased sharply to about 110 atmospheres, likely caused by an explosion within the pressure vessel due to a lack of cooling of the fuel. That was probably the start of the second meltdown, Tanabe said.

    As for the sudden pressure increase, Tanabe points to the possibility that the clump of melted fuel in the pressure vessel may have fallen apart due to a lack of cooling. The magma-like substance with high temperatures may have leaked out of the vessel and emitted large amounts of steam when it came in contact with water.

    At the No. 3 reactor building, black smoke spewed from the reactor building on the afternoons of March 21 and March 23. Tanabe said the smoke may have been the result of what is referred to as a core-concrete reaction, when melted fuel comes in contact with the concrete of the containment vessel. Such a reaction typically occurs when insufficient cooling follows a core meltdown.

    TEPCO officials said the black smoke was probably caused by rubber or lubricant oil catching fire.

    They acknowledged the possibility that some of the fuel may have fallen into the containment vessel, but they did not explain how the fire started.

    Kunihisa Soda, a former commissioner at the Nuclear Safety Commission of Japan who is a specialist on severe accidents at nuclear plants, said the possibility of a second meltdown could not be ruled out. But he said that accurately estimating the level of possibility is impossible because of uncertainties surrounding the validity of the released data.

    Tanabe also suggested that TEPCO officials think about what steps should be taken to monitor whether the fuel that has fallen into the containment vessel is being properly cooled.

  • arclight arclight

    telling bit here!
    “However, Tanabe said: “In deciding if a cold shutdown has occurred, the location where temperatures are measured will depend on where the melted fuel is. A thorough analysis should be conducted on what has really occurred in the reactor core.”

    Even officials of TEPCO and the central government acknowledge that they do not know the specific condition of the core at the No. 3 reactor. But their view until now has been that the melted fuel has settled at the bottom of the pressure vessel.”

  • stock

    Most likely all of these blobs of fuel have escaped and are in the basement or now in the ground below the basement. Sheesh, even in chernobyl, they had pictures of the blob.

    Seriously, why have they not presented evidence showing where the blobs are. Simple, because answer is too damn bad, and impossible to deal with, and they want to kick the can down the road until they have to “admit more”, and people get past the anger and fall into acceptance and despair.

    Nice game plan boyz, there will be a special place in hell for you since you couldn’t stand up and be men.

    • BreadAndButter BreadAndButter

      Hi stock@hawaii, I think in Chernobyl it took the mess a couple of years to cool before anyone could take that photo, didn’t it?
      Too hot to handle…

    • Darth


      Like how you summarized. TEPCO has already admitted these reactors experienced a melt-through. And now we get jerked around again with some more speculation a shill or shill wantabee dumps into the Internet.

    • Misitu

      The answer IS too damn bad, and difficult to present to the public, because honourable authorities would have to admit they do not have any detailed knowledge of hot blobs’ whereabouts or shapes and no means of finding out, so basically whole thing is toast and worst case scenario is honourable Japanese people finally flip out of honourable self and social discipline and go for it bigtime.

      I could put that better!

    • bigisland bigisland

      Howzit Stock,

      Did you know about these free/workshop meetings on island chain? Missed the one last night here.

  • Steven Steven

    “accurately estimating the level of possibility is impossible because of uncertainties surrounding the validity of the released data”

    Yep we’re familiar with this problem.

  • BreadAndButter BreadAndButter

    Does anybody know anything about the first rice testing they announced last week??

    • arclight arclight

      @b and b repost
      #Radioactive Rice to Come? Rice Growing in a Rice Paddy with 35,000 Becquerels/kg of Radioactive Cesium?
      “The transfer factor from the soil to rice is considered to be about 0.1. 35,000 becquerels/kg in soil may result in 3,500 becquerels/kg of harvested rice, 7 times the provisional safety limit which is already far too loose for the staple like rice.
      I’ve found the video clip for this part. It’s the rice paddy in Fukushima City. Fukushima City was OUTSIDE the evacuation zone of any kind, so the soil was apparently never tested by the prefectural government. The reporter asks the question in English, with a Japanese interpreter.”
      And this
      “Japanese people who watched the video or knew about it from Kino’s tweets are thanking ZDF for having shown up and asked questions at the press conference. It’s been a very long time any foreign media showed any interest in these conferences given by TEPCO/government on Fukushima I Nuke Plant and radiation contamination.
      I hope more foreign media (not their Japanese bureaus) will come and ask hard questions.
      35,000 becquerels/kg of cesium in soil would translate into 2,275,000 becquerels/square meter (35,000 x 65), which is way above the forced evacuation criterion in the Chernobyl accident (1,480,000 becquerels/square meter). “

  • Look they are looking to shift out or have back up to the Capital Tokyo. And the hotspot maximum is moving towards Tokyo: See the Web Fire Mapper just now(11h UTC 9 Aug 11): Maximum:
    Total number of fires detected : 63
    Latitude Longitude Date Time Brightness Confidence Scan Track Satellite Version Bright.T31 FRP
    37.033 137.845 2011-08-07 01:05 313.6 0 2.5 1.5 T 5.0 291.0 28.8/
    35.939 140.682 2011-08-07 01:05 318.0 0 1.6 1.2 T 5.0 293.6 15.8/
    36.08 138.064 2011-08-07 01:05 314.8 21 2.3 1.5 T 5.0 294.1 39.2/
    35.982 137.992 2011-08-07 01:05 311.3 40 2.4 1.5 T 5.0 293.5 31.6/
    37.031 137.857 2011-08-07 04:20 315.3 38 1.8 1.3 A 5.0 295.4 21.1/

    The potential for explosion like several Hiroshima type bombs is discussed in this context here:
    R E Webb is a PhD in Nuclear Engineering and has analysed nuclear meltdown scenarios.
    a sample in the Fukushima context from the URL:
    A meltdown of the reactor core would pose the danger of a catastrophic steam explosion, due to the interaction of molten fuel and any residual water in the reactor vessel. The full potential of such steam explosions is of the order of 100,000 pounds of TNT equivalent explosion. The involvement of just ten to twenty percent (10-20%) of the core fuel mass could cause a steam explosion of such a force to propel the 100-ton reactor vessel closure head upwards to a height of the order of a kilometer. The nuclear industry and the nuclear licensing authorities (the NRC in America, though an unconstitutional government body, in my opinion) claim that the probability of a catastrophic steam explosion given a core meltdown is low, because of a contention that the efficiency of an interaction of molten fuel with water to convert thermal energy into destructive mechanical energy would be low. However, this contention is mere assumption, based on inadequate miniature-scale experimentation and unscientific and arbitrary interpretations of the results of the experiments. In fact, in a 1984 experiment at Sandia Laboratories in the United States a surprise “spectacular” steam explosion occurred in a small-scale fuel melt simulation experiment that destroyed the test facility; and the chief scientist for the experiment has published an analysis concluding that a fully efficient thermal-to-mechanical energy conversion in the observed explosion cannot be excluded. (The efficiency was not be measured in the experiment, perhaps due in part to the destruction that occurred.) In Great Britain, a small-scale steam explosion experiment resulted in damage to the simulated reactor vessel – a fact not revealed to the public by the United Kingdom Atomic Energy Authority (UKAEA), who conducted the experiment, until I inquired into the facts of the experiment, when I confronted the authorities with evidence that damage had occurred. Furthermore, the UKAEA has refused my requests for a disclosure of the full details of the experimental results, which are needed so that one could determine just how energetic and efficient the observed steam explosion was; and they refused my requests to examine the test facility and question the scientists who performed the experiments.

  • jec jec

    On where the fuel rods or “contents” are located, someone should remember the Youtube video of the TEPCO webcam showing a crane busy trying to cover/collect material near the #1 reactor. There was also a bright yellow orange glowing area on the surface of the area..GLOWING! and smoking.Its likely to be pieces from an explosion, and is near the HIGHLY radioactive area measured recently with 10 sieverts, with in a meter or so. All the radioactive contents maybe difficult to account for once someone is able to survey the actual containment vessels. What then? Its gone? Its all okay? Or is ejected radioactive material why the rice straw and now the rice is so highly contaminated or 7 times the legal limit. The rice paddys are over 80 KM away. If the radioative material is still all INSIDE the vessels, radioactivity should not be at danger levels outside the 12 KM area around the plants.

  • shaktasna999

    and here we go

    I wonder how many of the politicians will opt for “somewhere else”.

    • Sickputer

      Yes… They used the same excuse (earthquakes) back in late March. News accounts should still show that.

  • bigisland bigisland

    It’s 107F in Dallas today. Think there’s enuff electricity for the nuclear power plants there, ought the grid go down? Hmm any near Dallas??? Texas is rather secretive about their plant:4 operating nuclear power reactors – 2 in Glen Rose (40 miles South of Fort Worth) and 2 in Bay City (90 miles SW of Houston)
    3 research and test reactors but it won’t say where for security reasons
    4 power reactors but again won’t specify where
    3 projected new nuclear power reactors (sort of in the same vicinity of the 4 we already have)
    it goes on and on. very interesting.
    And this:

    Would love to see a pie chart of the US power grid in percentages of nuclear, coal-fired, natural gas-fired, hydroelectric, petroleum-fired, biomass, geothermal, solar, and wind power plants.

    • Pallas89juno

      Tejas is very fascist. The more secretive when it comes to nuke power, the more to hide. I would visit a research librarian to determine where the unknown research reactors are. According to Freedom of Information Act that sort of thing must be made public, the jingoism of National Security or no; and if I’m mistaken, then there are definitely people who know. The nature of reality is the greedy profiteering soulless slobs who benefit (always short term and money) from having a nuke plant need thousands of us worker types to make one happen. Therefore, there’s people who know out there that are perfectly accessible using the right research strategies out there. I’m always being surprised by where Plutoniu, radium, radioactive this or that will show up next time I get on here, which is GREAT!!! This is exactly what we need to be doing in lieu of hot latest news (sorry about the pun) is finding, recording where the nuke plants we are near are, so that society can shut these the fuck down as soon as possible.