Tepco finds bent, damaged spent fuel assemblies in multiple fuel pools at Japan nuclear plant — Concern about prompt moderated criticality

Published: December 23rd, 2012 at 9:41 am ET


Title: TEPCO investigation finds multiple spent fuel pools at Kashiwazaki-Kariwa plant house damaged spent fuel assemblies
Source: Enformable
Date: Dec 22, 2012

After a Level 1 incident was announced upon the disclosure of two deformed fuel rods which were stick together at the Kashiwazaki-Kariwa nuclear power plant, TEPCO investigated 65 spent fuel assemblies at the Unit 5 spent fuel pool and discovered that 18 of the 65 assemblies were found to be bent.

Of the 65 rods, TEPCO found some where deformation was found in the weaker areas on the lower parts of the rod […] They also discovered that some of the fuel rods adjacent to the deformed water rods were now touching or closer to one another in the rack.

As a result of inspecting 31 fuel assemblies in Unit 2, part of the 2 spent fuel assembly water rods were found to be bent […]

Fairewinds Chief Engineer Arnie Gundersen writes in to ENENews:

When the fuel gets too close together, a prompt moderated criticality is possible.  I designed nuclear fuel racks and I know how close the tolerances are.  This is why I am concerned about Daiichi Unit 3.

See also: [intlink id=”nuclear-expert-powerful-explosion-at-reactor-no-3-may-have-been-from-prompt-criticality-in-spent-fuel-pool-video” type=”post”]{{empty}}[/intlink]

Published: December 23rd, 2012 at 9:41 am ET


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  2. Multiple assemblies ‘deformed’ in Fukushima Unit 4 pool — One “bent at a 90-degree angle” — Tepco: Mistake occurred when handling the fuel… 25 years ago November 13, 2013
  3. Now revealed there’s 80 damaged spent fuel assemblies leaking radioactive materials in Fukushima storage pools — Kyodo: Removal attempt at Unit 4 starts later today — Japan nuclear official ‘nervous’, as one slip could result in monumental chain reaction (AUDIO) November 17, 2013
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  5. Damaged fuel rods are cracked and leaking radioactive gases in Fukushima Unit 4 pool; Wire appears trapped in racks — Another assembly bent when “mishandled during a transfer” November 14, 2013

18 comments to Tepco finds bent, damaged spent fuel assemblies in multiple fuel pools at Japan nuclear plant — Concern about prompt moderated criticality

  • ForwardAssist ForwardAssist

    A sprinkle of truth here, a sprinkle of truth there….

    ……just enough for cognitive people to know how bad the situation really is, and for the conflict of interest crowd to run their spin games in the muddy water.

    And the data which could illuminate, it's either destroyed, misinterpreted, or never collected.

    • Looks like they haven't quite got the spin to their liking yet. Further "investigations" should correct that.

      23 DECEMBER 2012
      Japan's Abe 'to review Fukushima' atomic crisis

      "AFP – Japan's incoming pro-nuclear premier Shinzo Abe said Sunday his government will again investigate the Fukushima atomic crisis, after which the country's reactors could be restarted, reports said.

      His comments will add to speculation that plans to ditch atomic power in disaster-scarred Japan will be shelved by his Liberal Democratic Party (LDP) when it takes power after scoring a landslide election win last week.

      "We are yet to completely clarify what went wrong (in Fukushima)," he told a political show on Fuji TV on Sunday.

      "As a government, we want to once again analyse why Fukushima Daiichi failed," he said. He gave no further details and did not set out a timeframe for a probe.

      "After that, I wish to think of next steps, including the restart of reactors," he said on the programme, according to broadcaster NHK."


      Just a note, whatever Shinzo Abe comes up with will affect all of us, once again.

      I only wish he'd get his head out from the backside of his kimono and take a look at geothermal instead:

      25 Nuclear Power Plants Could Be Replaced By Geothermal In Japan
      December 22, 2012Jake Richardson

      • m a x l i

        And if thousands of experts spend millenia to "investigate the Fukushima atomic crisis", to "completely clarify what went wrong (in Fukushima)" and to "analyse why Fukushima Daiichi failed"; it will not give an answer to the question: What will go wrong next time.

  • dosdos dosdos

    I wish the nomenclature was more specific. Are the units specified at Kashiwazaki-Kariwa or Fukushima Daiichi?

    • PavewayIII PavewayIII

      It's the SPFs for KK Units 2 and 5. Unit 1 – 6 at KK are BWRs and used Global Nuclear Fuel – Japan (GNF-J) produced Step II fuel bundles for refueling around that time. That's the type shown in the diagram/picture. This is the first report for Unit 2:


      These have nothing to do with KK Units 7 and 8 which are APWRs.

      Nobody could be on the refueling floor of Fuku Unit 2 for more than a few minutes without burning out – the radiation is too high. It will not be possible to pull even a single bundle from that SPF for years.

      This story is still relevant to Fukushima. I would assume there are similar defective GNF-J Step II bundles in all the SPFs. That would have been there before they got rattled around with magically flameless hydrogen explosions or had I-beams bouncing off them.

      Thank God core #3 ejected the quality 10×10 or MOX bundles. It just wouldn't do to have those shoddy Step IIs with their crazy-straw water tubes flying around the neighborhood.

  • Sickputer

    From that incident report: "TEPCO assumes that the water rods were bent because of the excessive force applied while installing the channel box."

    SP: Spent fuel rods "stuck together" are highly unlikely the result of operator error or mechanical "excessive force ".

    Look at other more plausible reasons. Earthquake damage and fuel ponds boiling from low water levels might be the real reason.

    What is alarming is the fact the Kashiwazaki nuclear power plant is the first Generation III Advanced Boiling Water Reactor (ABWR) built and fully operational. It is the largest nuclear generating plant in the world. Two more ABWRs were planned for us lucky Texans, but by the grace and the horror of Fukushima Daiichi we have dodged those ELE twin monsters.

    Unfortunately for us all the nucleocrats at GE-Hitachi have succeeded so far in nearly completing the next two ELE monsters in Taiwan despite construction fires and other problems:

    Year old article:


    SP: The nuke pukes have high hopes to finish off the human race:

    "But with China and India getting up to speed in nuclear energy and a world energy demand double the 1980 level in 2015, a realistic estimate of what is possible (but not planned at this stage) might be the equivalent of one 1000 MWe unit worldwide every 5 days."


    • Sickputer

      Sorry… Got hit by word restriction:


    • weeman

      What worries me about India operating is the amount of rampant corruption in that country and their habit of making fake parts that are not certified, there complete disregard for health and safety never mind the ability to produce nuclear bombs and there hatred for Pakistan due to religious overtones.

      No aid to any country that builds nuclear reactors, if they have the money to build one don't need aid, spend that money on feeding and educating your people etc.

      • PavewayIII PavewayIII

        Fukushima will be nothing compared to the future rounds of Far East nuclear disasters. Think TEPCO and the Japanese government lie or censor information to save face? They're nothing but rank amateurs compared to the PRC. Not sure about India's transparency – it would just take three weeks to get an 'evacuate now' message through their bureaucracy.

        China and India have no intention of buying foreign reactors forever. They just need a few operating plants to study the designs and make cheap knock-offs for themselves. As soon as they get all nuked up, they'll be exporting their 'cheap' reactors to any country with cash.

        • weeman

          You said it cheap knock offs, never mind the ability to make nuclear bombs, where are we going to be when every one has the bomb, detente is irrelevant then and we slip further down the slippery nuclear path to oblivion, sooner or later you will eliminate us, I'm luvin it being radiated.

  • weeman

    One third of the fuel assemblies damaged means that it was not a flaw in production of fuel assembly and was caused by external forces, is this why the SFP,s had prompt moderated criticality.
    No wonder I can imagine the forces on the fuel assemblies from water pressure from earthquake sloshing in pool, you have seen the affect of a earthquake on a swimming pool, the waves are huge and the energy they produce is tremendous, one gallon 10 pounds, do the math in a pool that size, squash them fuel assemblies like origami paper cranes.
    Am I wrong does it not need to be investigated and if found to be true, what position does that put us in, this is madness, suicide,pure dead brilliant, insanity runs in the nuclear family, paranoid, extremely angry and do not understand the logic cause there is none.

    • PavewayIII PavewayIII

      Asahi-Shimbun said the water tubes were damaged during manufacture. That would have been when they were slapping on the tie plates (either end) or when they were stuffing the bundles into the fuel channel (square tube surrounding each 8×8 bundle).

      I'm not sure why it took this long to see the damage. I guess they don't remove the fuel channel and inspect the bundle itself until after the 5-year cooling off period in the SPF. Anyone know?

  • markww markww

    I BET every Reactor in Japan has problems since TEPCO has no safety or heart for it's people only Greed.


  • Sol Man

    Blood power may lose it's entire client base.

  • razzz razzz

    These ABWR are bigger (more fuel rods) with the latest and greatest technology like automation and more safety redundancies. Even has a core catcher where the melted fuel can spread out like a big'ol radioactive pancake so cooling water can get to all of it. Claims it can shut down by itself and keep itself cool for three days before humans have to add more water.

    The weak point seems to be the spent fuel storage. I doubt the tech guy hit the manual override button to force an assembly into the rack so he could go to lunch sooner. If he didn't then all the individual spent fuel rods have to be inspected in all the plants until they figure out how and why what happened. The assemblies have rollers on them so the only way to screw up is get caught mid-insertion during an earthquake or the rods burned to hot and are now swelling due to a defect.

    One gallon of water weighs about 8.345 pounds.

  • Sickputer

    Naked apes worried about nuclear bomb attacks and World War III and it never happened.
    What did happen is the meltdowns of nuclear plants generating electricity will be the final war for some countries. Japan has lost their country. Nobody to blame but themselves. A one-sided nuclear war.

    Who will destroy their country next? China? India? Russia? France? USA?

    How many countries will have to be fatally contaminated before the remaining countries break up their own units? 1, 2, 3? Or maybe more?

    The Terminator movies had it right…the machines will decimate the earth.