Spent fuel rod pools at Daichi and one good source

Posted in Imminent Catastrophe at 8:26 pm by George Smith

Like most I’ve been watching US television for news on the reactor disasters at Fukushima.

The one source, outstanding above all, has been ol’ Frank von Hippel, director of the Program for Science and Global Security at Princeton.

I remember von Hippel from a time, many years ago, when I subscribed to the Bulletin of the Atomic Scientists.

Von Hippel has been on Rachel Maddow and for tonight’s show he gave the clearest-for-the-layman explanation of what one of the primary threats is at Daichi.

Any mistakes in this interpretation are mine.

It centers on the spent fuel rods pool at, I think, Daichi 4. They need constant circulative cooling and no longer have it so their radioactive decay heat, which is no longer dissipated, boils off or splits what water covering remains or that which is added in insufficient volume in an emergency.

As it happens (or when it happens), the temperature of the rods rises even more intensely, destroying their cladding, blistering and blowing it off. Explosions occur because of the generation of quantities of hydrogen gas, leftover from the oxidation of the hot zirconium metal fuel cladding.

According to von Hippel there is now no easy way to determine the state of the infrastructure and the rods because intense gamma radiation — which means some large quantity of radioactive metal has actually been uncovered — and the destruction of sensors and cameras at the site.

When the rods are uncovered by the water mediator/shield and the cladding perforated or destroyed, the heat also drives off the spent fuel’s volatile radioisotopes. And that process is the spraying of radioactive waste into the prevailing winds. Unless it’s contained by intact walls.

Each Daichi reactor contains between 60 and 80 tons of fuel rod assemblies.

Spent fuel rod pools concentrate exhausted fuel rod assemblies.

Von Hippel said he had heard estimates of anywhere between 2 and 8 reactor cores being present in the spent fuel rod pool in question.

And so the problem of catastrophe, in terms of raw numbers, is rendered quite clearly.

It’s incomprehensible to me (well, cynically, no it’s not) that a significant number of Americans would think this disaster is about them and commence a hoarding rush on potassium iodide and Geiger counters.

But that’s the way it is.

“Ask a GE Technician” reads one of the evil AdSense ads on one of my posts at SITREP GlobalSec. Sometimes it disappears, so you have to get quick and lucky.

The catastrophically failed reactors at Daichi are all GE’s.


  1. Major Variola (ret) said,

    March 16, 2011 at 7:38 am

    “intense gamma radiation — which means some large quantity of radioactive metal has actually been uncovered”

    Because the 30 feet of (borated) water normally absorbs it.
    Boron was necessary ?! to keep neutron reactivity down.
    Apparently real estate is too tight for simple geometric
    controls. Fissile materials in barrels in warehouses are subject to this,
    (look up “criticality control”)
    though they don’t need expensive cooling, which motivates
    saving real estate for spent fuel.

    Once the borate sinks down as the water uncover the rods you get the
    spontaneous fission neutrons getting amplified by all that fissile
    material. Generating more heat. (Reactors are neutron amplifiers
    driven by delayed neutrons; bombs are neutron amplifiers driven
    by prompt neutrons. That BTW is why reactors can be controlled with
    mechanical absorbing rods (msec response times).)

    Anyway, the problem is once the Zirconium is burning you now have the worst case RDD scenario you can imagine. Magnesium-class
    pyrotechnics surrounding a stick of nasty. The phrase
    “whichever way the wind blows” comes to mind…

    Yep, 10 reactor’s worth of fuel, some quite reactive, all of it full of long lasting isotopes. Cesium volitilizes quite easily being the most extreme in that column.. yet tastes like potassium!

    Thing is, commandos (aka terrorists) could never have done this,
    even if they drained a pool and shut off the power locally.

    And a 9.0 plus wave was not “in the spec”. And then the reactors themselves were distractions. Because they are robust than modern designs. The hydrogen explosions are nice touches.

    That some of the fuel is MOX (Pu enriched) it is more reactive than regular enriched U would be. Gasoline vs. kerosine.

  2. A. Benway said,

    March 16, 2011 at 8:51 am

    read “los alamos primer” and smyth’s “atomic energy” both online, I think. It’s sad that people know so little about the important things…

    the fubar was easily foreseeable.

  3. Major Variola (ret) said,

    March 17, 2011 at 11:53 am

    A. Benway,
    The Primer was recently put on line, I have also read the paper version
    which Serber annotated, correcting some hilarious mistakes
    (which sometimes cancelled so he got the right answer!) and
    explaining the physics a bit more.

    Sublette’s Nuke weapons FAQ is also a great lay resource.
    I’d suggest that, then Symth, then LAP.

    I once made yellowcake from tailings from an abandoned mine,
    drain cleaner, and ammonia. Its trivial, and harmless, but was amusing during the Iraq build up, to do in suburbia. I have a GC as a scientific
    hobbyist so I could track the activity, plus when it precipitates from dilute green to orange its completely obvious.

    This weekend Japan gets a new National Park, when the wind blows from the east and the zirconium catches fire.

    The answer, my friend, is blowin in the wind

  4. Elbert said,

    March 28, 2011 at 2:17 pm

    It’s too late to laugh. This is now the entire planet’s problem. get the iodine pills ready… http://www.informationclearinghouse.info/article27778.htm

  5. 10 reactor’s worth of fuel in Unit 4 (!!!) « flying cuttlefish picayune said,

    April 20, 2011 at 7:40 am

    […] http://dickdestiny.com/blog1/2011/03/15/spent-fuel-rod-pools-at-daichi-and-one-good-source/  […]

  6. Cryptome Nuclear Power Plants and WMD Series said,

    September 19, 2011 at 1:21 am

    […] NGO (offsite) Japan Nuclear Energy Safety Organization March 17, 2011 GE Hot Rods (offsite) General Elctric Spent Nuclear Fuel Rods Threat March 16, 2011 DG JP (offsite) Digital […]