18 thoughts on “Thorium”

  1. To be fair, I think *burning* thorium sounds like a terrible, awful, bad plan.

    How about just fissioning it?

  2. Among the hazards one of the interviewed detractors mentions about molten salt is the risk of toxicity from inhaled beryllium. The beryllium is in the core salt, and being exposed to it means a worker is breathing vapors from the core of a nuclear fission reactor. Isn’t there an even greater risk that a worker in a conventional light water reactor will start huffing steam out of the primary loop to clear his sinuses?

    You’d think that power plant workers would have enough sense not to do either one, but then we live in a world were teens lick Tide pods.

  3. On the supposed severe health risks from Be in a molten salt reactor, my BS meter is twitching a bit. First, there is experience from the prototype reactor from the 60’s. Second, I doubt very much that the vapor pressure of ANYTHING (including Be) is very high with a molten F salt. F is pretty tenacious chemically. Finally, there is a lot of experience dealing with Be glasses with high power lasers. Yes, you have to be careful. Don’t break the plasma tube. Don’t breath in any glass shards. Compared to hazards involved in the petrochemical industry or the LWR industry, I think this is something that could be handled pretty easily.

    And with respect to tritium, give me a break. Remember, Li breeding T is vital for most fusion reactor schemes. Fusion is like biofuel from algae and peak oil, always 3 decades in the future.

    1. And any tritium will boil off with the other short half-life radioactive volatiles like xenon-135. It will probably form tritium fluoride (radioactive hydrofluoric acid), which would boil at room temperature. All those vented decay products are automatically tapped off for further processing and possible long-term storage.

      Anyway, a few years ago on Kirk’s thorium reactor website I suggested a further safety improvement for a LFTR. The conventional design is that the molten salt sits in a reactor vessel, essentially a large drum with a freeze plug at the bottom that, when allowed to melt, drains all the fuel into a series of narrow storage reservoirs whose shape won’t support continued fission and whose surface area allows plenty of cooling.

      My idea took advantage of having a liquid fuel whose overall volume and shape is a requirement for sustaining a reaction, and if you pump liquids through vertical nozzles you can make all sorts of sustained but dynamically unstable shapes, just as we do with decorative fountains.

      I focused on how you can hold the output hose of a pond pump slightly under a pond’s surface and form a large mound of flowing water. You sometimes see that technique used in sewage treatment plants.

      You could do the same to make a perpetually overflowing hemispherical kitchen sink, where the basin itself lacks the size to sustain a fission reaction without an extra half-ball of flowing water above the sink, since that turns the hemisphere into a roughly spherical shape with twice the liquid volume. The spillage of course constantly overflows the sink and flows down across heat exchanges to the recirculation pumps below, just like the decorative disappearing fountains that people put in their gardens.

      Of course with multiple nozzles you could make all kinds of dynamically unstable shapes, and you could probably even use bimetallic strips to automatically adjust the nozzle orientation with temperature. And of course multiple nozzles running off multiple pumps provides even more control over the critical mass and fission rate. It’s an extremely throttleable power source.

      Anyway, the spillage flows out, away, and down across the heat transfer pipes before getting recirculated by the pumps. If the pumps stop, the critical mass collapses into drips and puddles. If the reaction got to hot, the fountain of liquid should expand or froth, almost instantly limiting the reaction rate.

      But heck, that will have to come after someone gets a more conventional design up and running. There are plenty of existing hurdles to overcome before we get really creative.

    2. || And with respect to tritium, give me a break. Remember, Li breeding T is vital for most fusion reactor schemes.

      I consider tritium leakage a very serious likely showstopper for fusion (not the only one, though). A 1 GW fusion reactor will burn 55 kilograms of tritium per year. That would be enough tritium to cause two months of river mouth flow of the Mississippi River to exceed EPA limits on tritium concentration.

    3. The issue isn’t so much that Be is toxic, it’s that Be is rare. Annual global mine production of Be is just 220 tonnes. Fortunately there are MSR designs that avoid Be. My favorite is the Stable Salt Reactor from Moltex Energy.

  4. Well the problem with using thorium as a nuclear fuel is many fold. For one someone has to fund the research and funding for nuclear power generation isn’t that abundant. Although the situation has improved in the last decade. Also AFAIK the process typically is like you need to breed U-233 from Thorium using neutrons. Then you burn that. This is more convoluted than just using Uranium or Plutonium. Then there is the other problem. Uranium just isn’t that expensive at all and we have more than enough of it as it is. Heck the Japanese have developed a feasible way to extract Uranium from seawater. That’s how much of a non-issue Uranium shortages are right now.

    Other than that the only supposed advantage Thorium has that Uranium does not is that it is supposedly proliferation resistant. But I have heard many people say it is not impossible to make a nuclear weapon with these materials. It is just that no one has tried to do one so the process is poorly understood.

    It is a shame we are not seeing more modern nuclear reactors being built though. Recently the US Secretary of Energy Rick Perry was at Vogtle and the US government provided some more funding to the project. That is good news since I guess that means the project is much more likely to reach completion. With all the work stoppages and delays the project cost has increased significantly. This is a major bug bear of nuclear power projects. Nuclear reactors do provide cost effective power but require tremendous capital raising and long construction times. It is similar to building a hydropower plant in terms of capital profile to be honest. That’s why they aren’t built more. With natural gas being as cheap and plentiful as it is now I expect more natural gas power plants to be built and nuclear to mostly stagnate unless you’re in some place where natural gas doesn’t come easy.

    1. A reason you see nuclear doing better in China than in the US is that skilled labor is cheaper there. An engineer in Shangai makes $20K/year.

      In the US, we can exploit this cheap labor by buying products that embody it. Photovoltaics, for example, where the cost of site specific design, and of installation, is smaller. We can’t at this time buy nuclear reactors from China and have them shipped here.

  5. The advantages of thorium are that thorium is 500 times more abundant than U-235, and the advantage of the molten salt reactor is that it’s inherently safe and doesn’t require a pressure vessel, much less one designed to the extremes of a modern commercial reactor vessel.

    A molten salt reactor was designed to power an airplane, and they are small, powerful, and simple enough that we could use them in Navy destroyers. The Chinese could to, which is a concern.

    1. This is not much of an advantage, since we have an abundance of uranium.

      The real advantage of MSRs is the lack of volatiles in the nuclear island, which can pressurize the containment structure in an accident. As a result, the containment structure can be much smaller and less expensive (a factor of 5 or so) vs. a LWR. This advantage has nothing to do with thorium.

      1. The thorium fuel cycles has a massive advantage regarding the waste stream, as it produces no transuranics and anywhere from 0.1% to 1% as much overall waste, and that waste doesn’t need to be contained nearly as long. CERN estimates that one ton of thorium would produce as much energy as 200 tons of uranium, as our normal reactors don’t consume much of the fuel.

        1. If your thorium reactor is producing no transuranics, that means it has no 238U in it. So, the 233U that IS present (it’s what the thorium is turned into in order to use it) is very high enrichment. This is unacceptable from a proliferation and diversion point of view.

  6. Cool, so I’ve basically been getting it right during my public Moon lectures. When pointing out the potential energy resources on the Moon I do mention Thorium, typically associated with mare materials, as a consideration, but since you can’t really weaponize it folks just haven’t done much research on it. So it’s kind of off there with helium-3, interesting but certainly nowhere near ready for prime time.

    1. The reason Kirk Sorensen was studying thorium molten salt reactors ws because he was working for NASA, researching potential power sources for extended deep space missions.

  7. This should be Trump’s response to the Green New Deal. Building a number of prototype thorium test reactors as a carbon free power source that doesn’t kill birds or blight the countryside with ugly windmills.

  8. I call bs on the guy’s analogy of salt and cars.
    There isn’t any water in the reactor design. Just a flouride salt. Flourine, when reacted with anything hangs on very strongly. I suspect the FUD here isn’t to do with any engineering issues.
    Besides they got thousands of hours of operation at Oak Ridge back in the 1960’s.
    Can we all let go of the proliferation issue? This was raised in the article after talking about the fizzer when U233 was tried in a bomb.
    Any government that wants nuclear weapons will get them regardless of whether it runs a civilian nuclear power program. The Manhattan project had nuclear reactors that didn’t produce power and the story of Stalin’s first bomb is very instructive.

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