Canadian Nuclear Scientist: Another, even more dangerous possibility than fire at Spent Fuel Pool No. 4 — Re-initiation of chain reaction can occur if fuel rods move slightly, an “accidental criticality”

Published: April 29th, 2012 at 1:23 pm ET


Title: Why Nuclear Scientists Have Missed the Danger of Spent Fuel Pools
Source: Akio Matsumura
Author: Gordon Edwards
Date: Jan. 23, 2012

Dear Akio,

You asked me why there has been so little warning from the “nuclear establishment” (TEPCO and the regulatory agency) about the potential for catastrophic accidents involving the spent fuel pool in reactor number 4.


In addition to the possibility of zirconium fires (which have for a long time been almost completely overlooked by nuclear engineers and regulators) there is another, even more dangerous possibility. An alteration in the geometry of the spent fuel in the pool, by which the separation between the spent fuel rods is slightly but significantly reduced, can lead to re-initiation of the chain reaction in the pool.

This “accidental criticality” will not only drive the temperature up rapidly, but will also replenish the supply of short-lived heat-producing fission products, accelerating the damage to the fuel, magnifying the heat loading, increasing the probability of a fuel pool meltdown, and vastly increasing the atmospheric releases of radioactivity.

It has been a standard practice in the nuclear industry to avoid consideration of all of these possibilities, based on the assumption that there will be “lots of time” to react to any emergency involving the spent fuel pool, as it will normally take days for the spent fuel to reach the melting point and it will be a “simple matter” to refill the pools with water if necessary.

This ignores the fact that major structural damage may make it impossible to approach the spent fuel pool due to the lethal levels of gamma radiation emanating from the spent fuel once the protective shielding of the water is gone.

Read the report here

h/t Anonymous tip

Published: April 29th, 2012 at 1:23 pm ET


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  2. Ex-Fukushima Worker: High risk they’ll break fuel rods in Unit 4 pool — Gundersen: Moving fuel risks nuclear chain reaction; You can’t stop it, no control rods to control it August 14, 2013
  3. Nuclear Expert: Iodine-131 in No. 4 pool suggests that “spent fuel has started its own chain reaction” April 15, 2011
  4. Tepco checking debris fallen to bottom of Reactor No. 4 — May move control rods — ROV to be sent into Spent Fuel Pool March 12, 2012
  5. Source: First try to remove spent fuel from Unit 4 could be next week — Nuclear Engineer: Everyone’s nervous about pulling out used rods that are corroding; Will zircoloy tubes break and spill fuel pellets, leading to a criticality? (AUDIO) November 23, 2013

23 comments to Canadian Nuclear Scientist: Another, even more dangerous possibility than fire at Spent Fuel Pool No. 4 — Re-initiation of chain reaction can occur if fuel rods move slightly, an “accidental criticality”

  • Bobby1

    Iodine-131 levels have risen to 250 Bq/kg in Gunma prefecture sewage sludge.

  • norbu norbu

    So are we talking about sooner than later there will be a melt down of this pool[#4]? I am not sleeping well at night, cant stop thinking we should get out of California very soon. There wont be any food to eat our bee's will be polluted, what to do. This article should be in the main stream media, but wont be. Very sad. Tears on my face.

  • "alteration in the geometry of the spent fuel in the pool"

    How much? Like having a 35 ton crane fall on it? Moderate to strong earthquake? Are we talking feet, yards, inches?

    I was unaware of the flammability of zirconium until I read it on ENENEWS. How stupid were the designers? It is like designing something using gunpowder and gasoline to contain nitroglycerin.

  • norbu norbu

    They new what they were doing. population control. They new it would happen at some point. They are stupid. What is this little red switch, oop's wrong button…….

  • covelogibbs covelogibbs

    If the spent fuel pool at unit 4, and or common fuel pool at Daiichi releases massive radiation in the direction of Fukushima Daiini, could it potentially have to be abandoned? If so, how long can these nuclear reactors run autonomously or from a remote location? Is there still a possibility of the dreaded "demonic chain reaction of meltdowns" that Japanese experts thought might eat Tokoyo?

    • AGreenRoad AGreenRoad

      yes, and the news gets worse than that…

      Super Solar Storm To Hit Earth In 2013 'Carrington Effect'; 400 Nuke Plants Will Melt Down/Explode; via A Green Road Blog

      Nuclear power, radiation and humans do not mix well.

      • Fred

        More model fantasy from the grantosphere alarmists? They have no idea how the sun works, so, like AGW more funding alarmism….(sigh)

        I'm still looking for a true "believer" who's willing to sign over his property to me on Dec 31, 2012……no takers….

      • RutherfordsGhost

        Not a very accurate story my friend.
        Fukushima melted down for two reasons, firstly the loss of cooling water as the level went out before the tidal wave.
        Second, internal failures of fuel assemblies as they were shaken loose. We know this from operator alarms during the shake monitoring neutron fluence, and from the perimeter cameras showing the intakes being sucked dry.

        As for this solar effect shutting down reactors – probably unlikely. Many reactors operate from mechanical pumps from the turbine halls for providing coolant, and only certain types require electrical power – that's an American design. Although when not operating, nuclear submarines have the same cooling problem.
        Also, telegraph wires covered 100's of miles, so of course they arced. They do in storms anyway.
        Better luck next time.

  • Arizonan Arizonan

    Hi Cove,
    Yes, if the SFP4 collapses, it has the potential to create a catastrophe that might involve the evacuation of eastern Japan, all of Japan, if not all or part of the West Coast of the US, depending on which doomsday scenario the scientist is using. The SFP4 has been leaning oddly since the 3-11-11 earthquake, and has had numerous problems and releases of radioactivity already (search archive). Certainly no one would be able to work anymore at Fuku, thus eventually leading to six reactors buildings/plus fuel pools with no one to help get water onto them. TEPCO claims to have reinforced SFP4, but the photos make it look like they just threw up some aluminum scaffolding. It didn't look particularly earthquake-proof, and TEPCO has also said it will take them ten years to remove the fuel from the pool and "safely" put it into storage. This is probably yet another of TEPCO's wildly optimistic and unrealistic timelines. Still, it mean the world should be on the edge of its collective seat every time there is another earthquake in Japan. We can be pretty certain, though, that if uch an event were to happen in the future, both TEPCO and the Japanese government would try to downplay it, and the US would do its best to ignore it.

  • Arizonan Arizonan

    After all, the pronukers say, it is such a small amount of radiation it can hardly hurt you, just like eating a banana or a brazil nut or flying in an airplane. They will predictably respond with their usual lies, and they may even get away with it, as they seem to have so far with regards to even highly contaminated areas of Tokyo.

  • Arizonan Arizonan

    Gunderson's argument about SFP3 seems reflected in the above news article. I know there is still some debate about whether the obvious criticality at #3 occurred in the reactor or the SFP, but I believe Gunderson at one time suggested that the hydrogen explosion inside the outer containment might have been enough to reconfigure the geometry of the SFP3 enough to cause the criticality. Maybe the unique formation and radiosignature of the explosion at #3 was actually caused by BOTH a hydrogen explosion in the reactor and a prompt criticality in the SFP?? Thoughts, anyone?

  • norbu norbu

    They breath air just like us, drink water, eat food, it will catch up to them as well. There lies will get them soon……no-where to run or to hide for them, like the black death in Egypt when Moses was there, it will come for them who made the Nuclear power that destroy's the EARTH, the rest of us will be safe.

  • Radio VicFromOregon

    So, this puts the kibosh on my thoughts of building a new pool on the ground next to SFP4 building and transferring the fuel rods this short distance?

  • glowfus

    have they found the melted cores yet? they were lost sometime around march 11, 2011. it is now april 28, 2012. how long does it take to find 180 tons of purified melting uranium and plutonium? they know exactly where that little mars rover is, on mars which is another planet (not here on earth). but those pesky, pesky melting lost huge reactor cores,,,

  • norbu norbu

    They know where it is. It's classified info. They do not want us to know because it could cause a Revolution. It is like a giant purse," I know the keys are down there somewhere" it is so deep…


    The world would be well advised to heed this man's projected scenario. Once those rod-bundles collapse into one-another, all bets are off.

    I'm also impressed by his (Gordon Edwards) discerning between what they (nuclear power industry) know of worst-case-scenarios for the reactors themselves and what they haven't bothered to prepare for, in the event of a problem with spent-fuel-pools. He caps off the nightmare by pointing out, there's a lot more fissionable material within the pools than there is within the reactor.

    Everyone should make a point of drilling-down to the full article and reading it. Not that any who frequent this site don't know it, but this is scary stuff…

  • stopnp stopnp

    Haven't they been having recriticalities over there this whole time? Oh yeah, they dont know where the Iodine 131 is coming from. There are too many ways for this to happen. Is it one of it the fuel pools, maybe it's the coriums, or maybe it's Diani…

    They need to get the spent fuel out.

  • Concreteman99

    If you want to know just how crazy it is, read the incredible book by Martin Cohen and Andrew McKillop, The Doomsday Machine: The high price of nuclear energy the world's most dangerous fuel. Because in space, no one can hear you scream. A must read book folks….

  • Sickputer

    If the precarious spent fuel pond of Unit 4 overheats into a dirty bomb explosion, the most likely consequence is that reactors 1, 2, 3, 5 and 6 get out of control. Dainii follows. Being on the same parallel of latitude the USA will be severely contaminated.

    The re-racking of spent fuel rods (allowed in America by the NRC) is a double stack method to store the hot rods and was developed as a cheap alternative to removing rods to secondary waste sites (since there is not a single final storage waste site in Japan or America to accept rods it was just a matter of time before an accident occurred).

    The re-racked rods at Fukushima Daiichi are high odds candidates for a dirty bomb explosion. The result will be devastating for Japan and America. Get your emergency supplies and water ready for the possibility if sheltering inside for several weeks at a minimum. Escape to the Southern Hemisphere for averagd citizens will be virtually impossible after Unit 4 blows into the Jetstream wind. Billionaires and bureaucrats with private jets may escape with their families. Everyone else will be collateral damage. The National Guard will be sorely tested because 70,000 are overseas in combat operations and will be stranded and unable to return to America after an extended Northern Hemisphere fallout event.

  • sunpower

    Arizonan, I don't think Gundersen's idea is correct re the SFP at no. 3 blowing up. I think the explosion was in the reactor vessel, which shot the blowoff straight up in the air, pretty much as happened at Chernobyl and SL1. It was probably more of the same old zirconium ignition of hydrogen during meltdown. I think the no. 3 SFP got blasted by the reactor explosion shock wave. Any way you look at it there is alot of plutonium blown all over the site. TEPCO's talking about how to retrieve all this crap from a permanently doomed site is absurd. They cannot begin. If they could, where would they put it? This six sigma fallout needs to be permanently buried in situ, ASAP.
    I would even say bury the entire no. 4 SFP fuel load in situ, two hundred feet or more under. Set up a quarry conveyor and let dump trucks feed it sand. You could have the entire site under sand mountain in two weeks. Sure, the SFP fuel will melt, if it hasn't already, but with all the sand, the corium will take care of vitrifying the six sigma. With the thing buried and capped under a final layer of reinforced concrete, I would pretty much guarantee your problems in North America would be over, at least so far as those 'going out in the rain' rashes seen in Michigan.
    I am just really surprised how few of the so called nuclear experts has advocated burial of the site, which is all that will be done in the end anyway, once they stop being in denial about what has…