French Nuclear Experts: Did corium pierce steel liners of Fukushima reactors? How deep did it erode concrete? (VIDEO)

Published: February 3rd, 2013 at 3:14 pm ET


Title: Understanding the accident of Fukushima Daiichi NPS
Source: IRSN (France’s Radioprotection and Nuclear Safety Institute)
Uploaded by: fukushimafuture
Date Uploaded:  February 2, 2013
Film made in February 2012

At 5:30 in

The meltdown scenario is almost the same in all three reactors, only the dates changed.

The water in the reactor vessel evaporated. The fuel became uncovered, heated up to a temperature of 2,300 degrees Celsius.

The fuel melted and mixed with the materials from the structure to form a magma called corium.

The corium flowed down to the bottom of the reactor vessel.

Source: IRSN

According to Japanese officials it pierced the reactor vessel before falling on the concrete base mat inside the containment.

What quantity of corium fell?

How deep did it erode the concrete?

Did it pierce the steel liner?

Even today it is not possible to learn more about the state of the corium in the three reactors.

Watch the video here

Published: February 3rd, 2013 at 3:14 pm ET


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  1. Wired: ‘Healthy debate’ about location of Fukushima corium — Lava can melt a foot of concrete per hour — Cooling with water may not stop corium flow April 18, 2013
  2. Yamada: Fuel could be outside containment — Concrete does not erode uniformly — No one knows shape of corium — Big problems with Tepco estimation (VIDEO) September 3, 2012
  3. French nuclear specialists agree Fukushima “could still explode”, corium a threat — Reactors remain in meltdown says expert, molten lava could break through at any point March 11, 2012
  4. IAEA Paper: Corium was not cooled in majority of tests using water injected from above, as done at Fukushima — Were studying how to stop molten core from melting through concrete December 26, 2013
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45 comments to French Nuclear Experts: Did corium pierce steel liners of Fukushima reactors? How deep did it erode concrete? (VIDEO)

  • Proton

    4172* Fahrenheit then…

    Didn't #3's core eject itself?
    Where is it?
    It's Condition?

    Who in their right mind would start a damn war to cover-up the biggest news story EVER?

    • Sol Man

      You are assuming that any of these folks has ever achieved "right-mindedness." The best we can hope for is some kind of equilibrium with sanity; quickly.

    • guezilla

      2300C is the melting point, more or less. At that point it starts to flow, so the geometry is lost… but it's going to pool somewhere, and the heating can continue.

      Single fuel rod test reached over 3000C (about 4500F) with ease and a commercial reactor with 5,000 times higher volume and higher burnup would likely reach even higher. I think most corium-interaction simulations underestimate the heat, and tend to assume some cooling circulation is regained, though the materials the fuel melts will keep diluting the corium.

  • Beyond Zero Point

    The beauty of the GE Mark 1 comes with corium ejection built in. Through the bottom of the reactor vessel. Where the control rods are managed. What a beautiful thing!

  • Beyond Zero Point

    French Nuclear Experts: Did corium pierce steel liners of Fukushima reactors? How deep did it erode concrete?
    Why do they give a damn about what happened at Fukushima, with their manipulation of nuclear material, they are destroying our environment just like Fukushima!!

  • ForwardAssist ForwardAssist

    Man is the filthiest animal on this planet. I pray we never develop space travel, the rest of the universe needs to be protected from us like a virus.

    • PavewayIII PavewayIII

      Don't worry, ForwardAssist. We have you earth-dwelling apes under constant surveillance. Your feeble attempts at space travel are humorous, but not threatening to any of us out here in the least.

      If you ever do pose such a threat, we'll simply push your ball of dirt into the sun. I have fifty glorniks bet that you'll annihilate yourselves first. The captain thinks your species still has hope, but she's not a very good gambler.

      The glorniks will be MINE!

      • m a x l i

        Didn't the information reach your planet, PavewayIII? Earth observation is cancelled, any contacts forbidden. That arm of the galaxy containing earth is a strict evacuation zone for all intelligent life. You have to pack your glorniks and leave immediately!

        Your captain is delusional. The earth worms are hopeless. We have to let them do what they can best – annihilate themselves. After 1 billion years that arm of the galaxy can be resettled again. Be patient!

        Your friendly Intergalactic Council

        • I've my galactic hitch-hikers thumb out and activated… BUT!… nobody will even like… STOP! and get me out of here!

          • haizedustrium-1234 haizedustrium-1234

            They use the gtfo system: Galactic Turbulent Frequency Observation.
            The low frequencies are: inquisitiveness, amusement, confusion, stunned.They don’t pass the Xenon Galaxy.
            The medium frequencies are intimidation,
            harassment, assurance, confirmation. These are blocking the entrance of the high frequencies and are therefore decoded by the Krypton Galaxy. They only allow the high frequencies which is so rare that they offer a free trip to the spotter to the Krypton Galaxy to view it from a safe distance.

  • Pierpont

    Best graphics I've seen of Fukup. This has been out for a year.

  • Beyond Zero Point

    Damn Paveway you are as sarcastic as I am.

  • snowwy snowwy

    very strange that the video shows only 2 stories of the building destroyed and claims that the reactor vessel was still covered. how come that we could clearly see the yellow tops of the reactor? if those diagrams are correct then the blast should have blown away at least some of the cooling pools if 3 stories of any building were blown away in the uncontrolled blasts.

    the picture shows that at least two reactor buildings had been destroyed by more than two neat top levels and if you look very closely then you can also spot the yellow of the reactor lid. so if the diagram is right and the spent fuel pools sit exactly where they show them in the video then at least half of the fuel pools were lost in at least 2 building. which is kind of significant as it would nicely explain the uncovering of fuel in fields around a mile away and the fact that they barely mentioned if it all the need to cool more than just spent fuel pool number 4.

    that video educates nobody very much apart from explaining somewhat how hydrogen behaves when it comes into contact with coxigen, a knowledge that everyone can aquire and in more depth if they go on wikipedia or even, god forbid, pay attention in their chemistry classes. (wasnt that lesson 1 on the first day?)

    • guezilla

      Unit 4 was in refueling mode, meaning the concrete hatch on top of the reactor well had been removed, as well as the yellow containment vessel cover. It had been lifted up and lied down on edge of the cooling pool. This confuses many, as they expect to see a similar yellow cap at the same location in Unit 3, but there clearly isn't one. shows the process of opening the reactor for refueling at similar nuclear power plant. It's actully quite long process, they aren't done after the concrete hatch and PCV lid, but next follows the RPV lid. The cavity is then flooded with water to protect people from radiation as the steam dryer and steam-water separator are moved into the pit opposite from the fuel pool.

      The walls of the floor above the cooling pool are blow-away panels that give in to pressure specifically to direct the force outward in case of explosion. This would the the two upper segments almost gone. Regardless it can be seen that as with Unit 4, the walls under it have suffered significant damage, and we never seem to get very useful or new pictures of it. Best we get is something like or – even from these it's hard to believe the reactor well survived intact, in fact there's considerable evidence to contrary.

    • SwimsWithGators

      @ Snowwy… Good questions. Wall of 4 under the fuel pool, south side shows a blowout.

      As far as we know the pools still hold water, so the pools may be intact.

      So what did cause the walls under the pools to blow? Had to been part of the reactor or the torus or piping giving way. And with 3 it had to have been a nuclear explosion to not only blow out but up like it did.

      • guezilla

        TEPCO's analysis of Unit 4 soundness clarifies many issues: Some useful notes are that the fifth and sixth (equipment) floor are now completely removed. Third and fourth floors outer walls are considered to be completely destroyed. The blowout on the south wall is not over the fuel pool, but next to it. The outer walls were up to 65cm, the reactor well and spent fuel pool walls 185cm thick. They basically poured the area under the spent fuel pool full of concrete to reinforce it, though there's been some discussion on the reinforcement.

        However as said above, Unit 4 was in refueling outage, with the reactor completely open and the lids and caps visible next to it, so no pressure could have built in it: I believe the explosion of Unit 4 is one of the bigger mysteries, no? Official story is hydrogen from Unit 3 migrated into it through underground passages and blew it up I think.

        Unit 3 is a different matter. Gundersen seemed to think it was prompt criticality in the fuel pool, but the evidence seems to actually match what was considered the classic China Syndrome: (is down today). There's also – though there may be some confusion…

        • SwimsWithGators

          Yeah, its all still such a mystery. And given we can't trust the industry or Tepco, and that reports with pictures, videos and independent inspections are not forthcoming, all we are left to do is speculate.

          First I heard about solid concrete under FP#4, but that seems to have been the only solution.

          They are hiding a lot, even now almost two years gone by.

          Hey, guezilla, what about this theory? They were trying to make gold out of something else. Trying a Midas touch?

          • they had breeder rods in transfer casks.. sealed up and lost cooling.. that's what did the damages.. couple of them did the oxy-hydro split and exploded. But #4 core had even more fuel in it @ time.. so it's corium got blasted out the north wall.

  • dosdos dosdos

    "Even today it is not possible to learn more about the state of the corium in the three reactors."

    Uh, maybe because it's no longer inside the reactors.

  • AGreenRoad AGreenRoad

    And then we have people running around trying to sell people MORE nuclear power plants…

    Bill Gates Traveling Wave Terra Power Nuclear Reactor Analyzed; via A Green Road

  • AGreenRoad AGreenRoad

    12 reasons why all nuclear power plants must be shut down; via A Green Road

    • I say just bring back public hangings for ALL the ones responsible…

      And I'd hazard to guess that this sort of shite would stop with all due haste!

  • TepcoSievert TepcoSievert

    Although this may be obvious to most of our readers, I think it is necessary to point out that the IRSN, supposed to be an institute for radioprotection and nuclear safety for protecting the public, is of course primarily concerned with making nuclear industry appear safe. Therefore, although it is acknowledging that there were some unforeseen problems and that a few questions remain open (situation of the coriums, solutions for removing spent fuel and "decommissioning" the plant), its presentation carefully avoids discussing what damage was caused initially by the earthquake, the origin of the massive leaks of air and water contamination. It stresses the "successes" achieved in "bringing the situation under control", like putting a nice cover on R1. But it makes no mention of the 10 000 000 Bq still being released evey hour. And it offers no convincing explanation for the extensive damage at R4.

  • Atomfritz Atomfritz

    The picture is so cute.

    It looks as if the nuclear spaceship would take off in a second.

  • PhilipUpNorth PhilipUpNorth

    "Did it pierce the steel liner?"
    This question refers to Containment steel liners, under the base concrete, not Reactor steel liners as the headline reads.
    The answer is that corium lava eats anything and everything in its path. In less than a week, the corium was probably out of Buildings1,2,&3.
    TEPCO, how can your 40 year decommissioning plan not include locating and encapsulating the corium from Units1,2,&3?

  • happy9kids

    Old insider's report leaked from a young TEPCO researcher:
    One Japanese guy, who has been searching for the truth of nuclear power industry in Japan, received this information from young researchers working in TEPCO's research department. The grief-strucken researcer reported to him that " although the corium had been already sunk down to about 4km (1 mile = 1.6km) below the surface of the ground, the Japanese government had been forcing us (researchers) to find the exact location of the corium and a way to get rid of. we and our families are sick and some of us are dying due to radiation". (This information was reported on April, 2012.)
    Believe it or not, mankind has been experiencing "much-worse-than the-worst nuclear crisis ever in the history of mankind. I desperately pray and wish that our Mother Nature/Earth has a power to dissipate gigantic amount of radioactive materials.
    I am a layman, but can guess this corium may cause another enormous crustal movement soon or later.

    • Time Is Short Time Is Short

      It's getting harder to hide.

      Like someone said, work your bucket lists. We don't have much time, and it will probably be quick, before we have time to say goodbye.

      Apparently, with high levels of plutonium in our bodies, we will die from some type of radiation induced physical damage before we die of cancer.

  • bwoodfield bwoodfield

    So at what point would the corium cool enough that it would stop chewing a hole to the core of the planet. Would the surrounding ground absorb/dilute the fissile material enough to stop it?

    So once/if the corium reaches the magma what would the effect be on the material? Would it be absorbed/dispersed or would it stay congealed and continue to burn? Would the path cause a path for a magma intrusion and possible release? It would be somewhat poetic justice for a volcanic eruption to occur at the NPP. Like the earth's retribution for poisoning it and encasing the area in molten rock.

    • 16Penny 16Penny

      It would be somewhat poetic justice for a volcanic eruption to occur at the NPP. Like the earth's retribution for poisoning it and encasing the area in molten rock.

      Love it! wonder what mommy has in store for the D of C? District wide pit of fire? Time will tell.

    • cool enough…? Humans haven't been alive long enough to make safe to touch but, 30-40 years..? should do to solidify it mostly.

  • " What quantity of corium fell?
    How deep did it erode the concrete?
    Did it pierce the steel liner?"

    Who cares about that today? This is an old story to distract people from real concerns:
    – Soil in Tokyo can be considered as "radioactive waste", and still people are kept into darkness there…
    – Not to talk about Fukushima city evacuation… dispite noduls found in children's thyroids….

    french expert said: "let us distract them so they may loose attention to real concerns…"

    If he is an expert, then his expertise is needed to stabilise the N°4 pool…