Civilian vs Military: Power, Proliferation, and Pandora

I never wanted to write this article. There is already way too much conflation of nuclear energy with nuclear weapons, and even writing with the best of intentions and clearest of language I guarantee that someone will attempt to use this article as proof that nuclear is too dangerous because Bombs!

I ignore these people like I ignore anti-vaxxers, flat-earthers, and similar purposefully ignorant people because the method of producing nuclear weapons is completely separate from the production of electricity from nuclear reactions.

I understand that the thought of nuclear weapons is terrifying. They held and even still hold our world in the grip of fear that we might destroy ourselves with them. And I can’t stop that fear. No one can until either nuclear weapons are themselves removed from our abilities, or we succeed in building a world that Everyone agrees is not worth destroying.

First things first. Only fissile materials can be used to make a nuclear explosive. That basically means that U235 is the easiest to use because it occurs naturally in fairly large quantities. Using anything else like Pu-239 or U-233 really is just showing off.

One difference between making a fission weapon and a fission reactor is how pure the fissionable material you need is. A light water reactor needs between 3-7% of the input uranium to be the fissionable U-235 rather than the non-fissionable U-238, where a weapon needs at least 50% U-235 but the higher the better. But how do you enrich uranium?

It’s not the Indiana Jones warehouse but it’s not that far off

This is a warehouse full of operational gas centrifuges. The difficulty with enrichment is that you are trying to separate two things that are chemically identical and only differentiated by a 1% mass difference. So the way you separate them is to make a gas, usually Uranium hexafluoride, and then you spin the gas inside these centrifuges really really fast to take advantage of centripetal force to draw the heavier U-238 to the edge and bottom of the centrifuge while the lighter U-235 gets “floated” to the center and top.

This is not a quick process. Made less so because adding the 6 fluorine atoms to the uranium reduces the mass difference to 0.8%, so it either takes a very long time to purify a single centrifuge, or you cascade it like shown in the picture. Pull the gas with the slightly higher U235 concentration out of the top, and the slightly lower concentration out of the bottom. The top goes on to the next centrifuge in line and the bottom goes back to the beginning to hopefully pull out some more of the stuff that’s left. Each centrifuge increases enrichment by usually less than 0.1%. And even that is only if you are being incredibly aggressive about it.

Now before someone starts going off about breeding plutonium in a reactor to use as a bomb, there is a slight problem with that line of logic. Plutonium-239 is a very good bomb material, Plutonium-240 is Too good of bomb material. The presence of too much Pu-240 can actually cause a plutonium-based bomb to spontaneously explode.

Not ideal in something that is meant to be a strategic deterrent I’m sure you will agree. And Plutonium 240- is made in the same process that breeds Plutonium-239 so if you want to make a bomb that doesn’t get too excited about its job, then you have to centrifuge your material anyways. And since the mass difference is less than 1/3rd that of uranium separation it takes that much longer and costs that much more.

So how do we keep an eye on people who might be trying to develop nuclear weapons with or without a civilian nuclear program? Well here’s where I get to flex my degree credentials. What do nuclear weapons and Olympic fencers have in common?

Other than the belief that the best defence is a good offence.

They both use a really interesting kind of steel called maraging steel. Fencers use it because it is extremely crack resistant, flexible, tough, and strong. Gas centrifuges use it for exactly those same reasons. The efficiency of a centrifuge depends on really only one thing, the speed at which it rotates. Speed it up and the forces get drastically increased, which improves the speed of the process and the efficiency of the separation. Gas centrifuges for nuclear weapons production can rotate at tens to hundreds of thousands of RPM. No one really knows the exact speeds except the people actually designing and operating them because… well Top Secret national defence kinda stuff.

The problem is is that very few materials can withstand those kinds of forces being exerted on them for long periods of time and are also corrosion resistant because the hexafluoride gases used in them are viciously corrosive. So what international organizations do is they monitor countries for their imports of materials that can be used to produce maraging steel. As amazing a material as it is, there aren’t many economic uses for it, so it’s hard to cover up a paper trail for it.

I know nuclear weapons are awful, terrifying, and generally just a bad idea. But trying to lump civilian applications of nuclear energy in with them is counterproductive and ignorant. You can’t put the genie back in the bottle and other such assorted clichés, and being childish by saying that all nuclear is bad because it’s possible to make bombs is neither productive nor true.

6 thoughts on “Civilian vs Military: Power, Proliferation, and Pandora

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  1. Nuclear power fuel, new or used, cannot be made into bombs. That’s the point of it being ~95% U238 on the way in and on the way out. The little bit of Plutonium made while it’s in reactor is a mix of Pu isotopes that I encourage any bad folks to try to make into a bomb — Pu240 fissions unpredictably.

    And the purpose of centrifuging natural Uranium is to bring its U235 content back up to the ~5% it was ~2 billion years back, when Ma Nature had her own reactors in the mountains of Oklo Gabon — look it up. Was the planet, or even Africa, ruined by that reality?


    1. I agree with all your points, I even make the same point about Pu240 being unwanted due to its rapid fission rate. I also pointed out quite specifically that you would have to centrifuge any fuel to enrich it to bomb levels too. The whole point being to show that using nuclear reactors as sources of bomb materials is inefficient and needlessly complicated compared to simply refining raw uranium. I also don’t understand why you seem to be insinuating that I thought that the natural reactor in Gabon was a bad thing?

      Liked by 1 person

    1. Just because first bomb was implosion type, does not mean it is easy.
      Testing gun-type was not necessary because it was easy.
      “field tests performed with uranium-235 prototypes in late 1944 eased doubts about the gun-type method to be employed in the uranium bomb.”, “the gun-type bomb design seemed so simple and practical” & “there was only enough weapons-grade uranium available for one bomb, and confidence in the gun-type design was high,”
      The Uranium-235 gun-type design was the focus of early efforts 1942-1945

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  2. The ultimate proliferation resistant reactor does not need enrichment plants and it does not produce plutonium. Such a reactor do not exists and IAEA safeguards are necessary.
    LWR needs inspectors continuously monitoring enrichment facilities. But, at the reactor site inspectors are needed only during refuelling.
    CANDU does not need enrichment facilities. But at the reactor site CANDU needs more frequent IAEA inspection because of continuous refuelling.
    IAEA safeguards make sure that everything remains “reactor grade” throughout the fuel cycle.
    There is a notion that CANDU spent fuel has more Pu239 content. This is not true.
    (Reference: CANDU Non-Proliferation and Safeguards: “A Good Story Seldom Told”

    Liked by 1 person

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