Thorium Plug

As I emerged from my slumbers this morning, I absorbed the latest radio chatter about British Gas – investing wisely, or fleecing the consumer ? All a bit sensitive because of the Government “dash for gas”, what with those EDF Frenchies sueing protesters and so on. (See this Monbiot article). Contrast yesterday morning, when Sue Ion was featured on the rather wonderful Life Scientific. I came across her on PPARC Council when I did my tour of duty – she was a sane and useful voice. (Wommers – get her back !)   She is a stalwart of BNFL, and made a strong case for a mixed energy strategy, with off-shore wind accompanying nuclear. Many greenies are reluctantly backing nuclear – despite its problems,  a window is closing, and we may have no choice.

Meanwhile I am finally reading a book I got for Christmas – Physics of the Future by Michio Kaku. Mostly this is about nanobots and tricorders and ubiqitous computing in our socks and so on, but there is also a chapter about energy, which is distinctly less upbeat than the rest of the book, and indeed may make the rest of the book pointless as civilisation collapses. Kaku is a fan of the hydrogen economy, and that may cure us of our oil addiction,  but of course you need an energy source behind it. Kaku assumes that it pretty much has to be nuclear, but starkly spells out the problems – dealing with waste, and nuclear weapons proliferation.

So what puzzles me is – why does nobody ever mention Thorium? Since the 1940s we have known two things. (1) Molten salt reactors have many advantages over fuel rods – no meltdown problem, no high pressures, basically far safer. (2) Using the Thorium fuel cycle has to be the best way to go. You bombard  Th-232 with neutrons and get U-233, which is the fissile material. Thorium is much more abundant than uranium, there is much less waste, the lifetime is much shorter, and there is no weapons grade material for terrorists to steal.

So now we get to the depressing part. That last advantage is why governments are not interested – there is no weapons grade by-product. It seems to be why the US government abandoned this technology in the 1970s. We are ignoring the technology that will save civilisation because we want bombs. Hey, wouldn’t it be easy to solve the Iran dilemma ? “We only want nuclear technology for peaceful purposes”. “Okey dokey – here, have this LFTR design. Its dead easy, You don’t need any of those tricky centrifuges! Our guys can come over and help you build it.”

Here is a wikipedia page about the Thorium fuel cycle, and here are two useful web sites about sane nuclear energy : here, and here

Interestingly, the two governments that are investing in this technology are China and India. I feel the future-train whistling past our ears.

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22 Responses to Thorium Plug

  1. Nick Cross says:

    The Thorium reaction can also clean up some of the waste from Uranium reactions. It wasn’t popular in the ’50s and ’60s because it wouldn’t lead to weapons, but it seems stupid not to have invested in it over the last few decades.

  2. Solar power from satellites. Bring it down to Earth with a cable. Or fusion.

  3. shiroboshi says:

    As far as I understand things, the “no proliferation” argument is often cited but not really that substantiable. If you want to, you can breed appropriate grade isotopes from a Th fuelled reactor, so no, it isn’t “governments want WG fissile materials, therefore they don’t do Thoriium”.

    To my understanding the Thorium fuel cycle is nowhere near as simple as some people make out it is. Uranum was used because the fuel refinement technology was developed with the first reactors (i.e. Chicago pile) and it was a lot easier to build on long standing work from this than to start from scratch, similar to moving from e.g. petrol to pure ethanol.

    While salt reactors have intrinsic safety advantages (but so do all GenIV systems e.g. pebble bed or PRISM systems) there is an array of other problems involved with the running of the systems.

    To my knowledge, Thorium has a number of advantages, not the least its abundance in the earths crust. However, if you can run Thorium fuelled reactors you could as well run breeder reactors which burn up reprocessed fuel from existing stocks. The problem isn’t really that we are running out of U based fuel. India and China are looking into Th because they do not have part depleted stocks of U based fuels that cold be reprocessed or used in breeders.

  4. Joel Turner says:

    Thorium is over-rated, in hundreds of comments just like this. The overwhelming majority of advantages suggested here are almost completely unproven (two MSR research reactors operated at ORNL in the 1950s/60s, but nothing that has ever even produced power).

    The waste reduction from MSRs relies on chemical processes which have never been successfully completed, and involves the handling of fission products with 0-day decay time (to contrast this, ‘normal’ fuel waste is left for a period of up to a decade before it is handled).

    MSR safety is also completely unproven – based entirely on being able to thaw/freeze the salt at will, as and when required. This was an area that ORNL struggled with in their operation, and involved several outages for the MSRE research reactor.

    Thorium is indeed much more abundant than uranium (and therefore will probably be developed at some point) but it’s just not needed yet – known uranium stocks will last for centuries, even with the rapid expansion of conventional nuclear.

    Finally it has recently been proven that you could indeed generate high-purity fissile material from a thorium fuelled MSR. Given the amount of funding focussed on weapons development compared to civil development, if thorium had been more attractive at the time we would have had a U233 based weapon (it was actually dropped because of the lower breeding ratio potential shown in the MSR compared to liquid metal fast breeders, although the ability to generate plutonium quickly was attractive at the time).

    Civil nuclear is not used to get a weapons by-product. If it was the UK wouldn’t be building more nuclear, while sat on >200T of plutonium without a real clue of what to do with it.

    • andyxl says:

      What an interesting pair of comments ! Many thanks. I guess one retort is that MSR was not given a chance to be developed following the original Oak Ridge experiments. (Alvin Weinberg was fired). So from that point of view, the Indian and Chinese experiments are even more interesting.

      If you are right about Thorium being potentially just as weapons friendly, then we can all be depressed again. Back to covering Morocco with photo-cells I guess.

      • Joel Turner says:

        I wouldn’t quite say it’s cause for depression – there’s already so much plutonium in the world that new technologies are unlikely to allow the construction of more bombs, it just doesn’t work like that any more.

        I think the *idea* of MSRs is fantastic, I just think there’s an awful awful lot of lobbying to develop them, and it’s out of proportion to how much benefit they might actually offer. And that’s before you even start on the conspiracy theories that come up when you point out technical challenges – at one point I was accused of being a Chinese spy, somehow ingrained in the UO2 production industry, simply for pointing out that an ORNL calculation has been shown to contain some mistakes!!

  5. andyxl says:

    Joel – you make a good point about the abundance of plutonium. But then why do Iraq want their own nuclear programme ? Can they in practice just buy as much Plutonium as they need for bombs ? If not, the link between nuclear power technology and weapons still exists in at least some countries.

    While you are myth-busting … is it at least historically true that Nixon shut down the ORNL programme for weapons-related reasons, or is that Thorium-fan propaganda ?

    • Joel Turner says:

      You’re absolutely right – sorry I wasn’t particuarly clear there, I was referring to the way existing nuclear powers ‘hold on’ to the U-Pu fuel cycle – it’s certainly not because they need the Pu! Iran is a special case, I’m not sure there is a single answer to ‘why they want nuclear’, and I’m certainly not qualified to give one – you are absolutely right in that a major concern of the development is a source of Pu however.

      Again I’m not sure it’s a simple question. Probably part of the reason for it’s shutdown was that it was more troublesome to produce weapons grade material (but certainly not impossible), but another reason ofter given is (bizarrely) that of uranium abundance. At the time, the stocks of uranium identified as suitable for mining were a fraction of what they are now. Alongside the development of the MSR was a more conventional reactor – the liquid metal fast breeder (LMFR). Studies showed that this would be a more useful breeder potentially (effectively it could produce useable fuel more quickly) and this provided a technical benefit in a time when fuel was believed to be scarce. You’ll note that we’re not tripping over fast breeders either at the moment – these were cancelled when uranium stocks were identified as much larger than previously thought.

      • Sorry, I’ve come to this discussion a little late! Joel and Shiroboshi’s comments are absolutely right. Thorium fuel is certainly not the panacea it is often touted to be, and molten-salt reactors are unproven in any commercial sense. Right now, Thorium advocates are apt to point and say ‘look, the Chinese are building one at SINAP’, but forget that the Chinese have had a programme there for many years, and are currently only building a molten-salt *cooled* reactor (no fuel in the salt). Larger scale is a loooong way off.

        Quite apart from the additional technical difficulties of Thorium (it’s harder to process, both intrinsically because of its single oxidation state, and because the overall process is less well developed), the real question to ask about Thorium is: who is going to do it?

        Commercial nuclear power companies already have enough trouble getting standard PWRs off the ground (look at what’s happening in UK nuclear new build if you want an example). And BWRs have problems despite years of development (Fukushima, anyone?). There is no incentive to companies to use it, and plenty of reasons not to.

        Why don’t Govts do thorium? An easy one is that there is loads of fuel given the rate we’re using it, and everyone assumes that in the future we’ll be able to get it from seawater; later on either fusion will be working, we’ll have lots of renewables, or some other ‘magic’ solution will appear. Add to that, that the UK has invested enormously in fast breeder technology, and despite the hiatus sodium-cooled reactors are the most likely technology to be implemented.

        Another answer is that Govts don’t have the appetite at the moment to plan strategically like they did in the 50s; ‘let’s just leave it to the market, they’ll figure out the best way’, which of course is idiocy, but there you go. And which Govt. is going to go head-to-head with a populace in thrall to the Green movement and its knee-jerk views on waste and weapons? Not in this climate, even when the lights are about to go out because of the loss of coal stations. Voters and Govt. are alike – not rational.

        People promoting molten-salt reactors in the UK have a very hard sell. There is no commercial interest (witness the NNL report recently), plus there is the simple fact that MSRs are pretty much the only reactor technology that the UK has never worked on.

    • shiroboshi says:

      Andy, Pu isn’t exactly easily available on the open market. While there are some less than sensible politicians around, especially in nuclear capable FRS, most people aren’t stuid enough to sell WG isotopes to Iran…

      It is possible to build a thermonuclear device based on enriched Uraium (in fact the fist two devices were U based “slammers”) although IIRC Pu based weapons are smaller and more efficient. But on the simplest level, enriched Uranium can be used as fuel and for bombs….

      • The reason small states like breeding Pu is that it can be done in small facilities. Traditional enrichment plants are bigger, and need components (e.g. centrifuge technology) that are readily spotted. This is why Syria ‘imported’ a Pu-production reactor from North Korea.

  6. Toby Hoffman says:

    Joel what about Indian Point Thorium plant in 1962? Are you saying it never produced reliably?

    • Joel Turner says:

      No, I was talking about molten salt reactors, not thorium fuel (although the two are often discussed as if they are synonymous they are completely different concepts – the advantages ascribed to thorium are largely, but not entirely due to the MSR and not thorium, aside from the waste issue). Reading back, that’s certainly not clear in my comment and I apologise.

      The indian plant was a solid fuelled light water reactor that used thorium as a fuel and was later changed to use UO2 fuel. There are other examples of solid fuelled thorium plants, THTR-300 in Germany being a prime example. We know how to employ thorium, we just chose not to.

      • tobyhoffman says:

        Didn’t ORNL produce power for five years straight?

      • Joel Turner says:

        Toby – No, the MSRE operated for about 5 years, but discharged it’s heat through air-cooled heat exchangers, it was never power producing to my knowledge.

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  8. Jonathan Thornburg says:

    Unfortunately, the U-233 produced in a thorium fuel cycle is a pretty good atomic-bomb material. It has a low spontaneous fission rate, so it can readily be used in a gun-type bomb (the easiest kind for terrorists or other low-tech-bomb-makers to build). U-233′s one saving grace is that its radioactive decay chains include some nasty gammas, so radiation safety for people assembling or working near those bombs would be a problem.

    Overall, thorium fuel cycles still have major nuclear-weapon proliferation risks.

    Reference:
    Section 6.2 of Carey Sublette’s “Nuclear Weapons FAQ”,
    http://nuclearweaponarchive.org/Nwfa/Nfaq6.html#nfaq6.2

    • Joel Turner says:

      This is (slightly) incorrect. U-233 bred though the Th-U fuel cycle almost invariable contains U-232, which is the strong gamma emitter. It’s very recently been shown that it is feasible to produce pure U-233, but this is a recent development. Pure U-233 is actually readily handled I believe, but ppm concentrations of 232 will cause difficulties.

    • tobyhoffman says:

      Very informative – thank you Jonathan. My great Uncle Thornburg invented the Atomic Clock while at MIT. Might you be related?

  9. Jonathan Thornburg says:

    Oops, sorry, garbled url, that should be
    http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html#nfaq6.2

  10. [...] did I already already use that gag in an earlier post? Anyhoo. Two or so weeks ago commenters on my own nuclear blog post made me eat humble pie , liberally sprinkled with Thorium. Last week I was in Thurso, in the far [...]

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