5 ms·

Woah, looks like this article has a major error in it right up front: "The project follows a 2-MW experimental version completed in 2021 and operated since the

Woah, looks like this article has a major error in it right up front: "The project follows a 2-MW experimental version completed in 2021 and operated since then. " They completed the TMSR-LF1 back then, and got authorization to turn it on, but have never announced startup or operation, as far as I'm aware. I've actually been bracing for the headline since 2021 because it would be the first time we operated a molten salt reactor since Oak Ridge's MSRE shut down in 1969. For all its purported benefits, fluid nuclear fuel has major challenges because the extraordinarily radioactive fission products are no longer held up inside the fuel pins, but rather are flowing around the entire primary system, coming into intimate contact with (and plating out on) pumps, heat exchangers, the vessel wall, instruments, valves, etc. etc. My guess is that they ran into some trouble with containing this, or remotely maintaining the primary equipment. FWIW, the US started up a commercial thorium-fueled reactor back in 1961 at Indian Point 1 [1] (previously known as the Consolidated Edison Thorium Reactor [2]). We replaced the thorium with enriched uranium in the second core, and all subsequent cores, because it was a lot more economical. [1] https://www.youtube.com/watch?v=1sWqmPyoYxw https://www.youtube.com/watch?v=1sWqmPyoYxw [2] https://babel.hathitrust.org/cgi/pt?id=mdp.39015086582338&seq=33 https://babel.hathitrust.org/cgi/pt?id=mdp.39015086582338&se...

AnthonyMouse 2y ago
What makes uranium more economical, fuel production or some aspect of operation? And if it's the first one, is that just lack of scale for thorium or something else?
- godelski 2y ago
  Uranium is pretty abundant. The US has a lot, China twice as much, Kazakhstan a lot more, and Australia puts everyone to shame. Thorium isn't ready to be fuel and must be enriched (granted, you need to do this for uranium too but some is naturally in a fissile state). So there's things like breeder reactors that enrich during the cycle but this is challenging and presents other issues such as turning it into weapons manufacturing (increase proliferation concerns). There's a lot of small details that matter a lot. Fwiw, the parent has written a fair amount on this and runs a website with a lot of useful information for anyone curious. You can check their comments too as they usually participate anytime nuclear comes up https://whatisnuclear.com/thorium.html https://whatisnuclear.com/thorium.html
  - AnthonyMouse 2y ago
    Isn't thorium also pretty abundant? Judging by this, the US has around six times as much thorium as uranium: https://en.wikipedia.org/wiki/List_of_countries_by_uranium_reserves https://en.wikipedia.org/wiki/List_of_countries_by_uranium_r... https://en.wikipedia.org/wiki/List_of_countries_by_thorium_resources https://en.wikipedia.org/wiki/List_of_countries_by_thorium_r... I've also never really gotten the proliferation concern. I mean, sure, you don't want to sell a breeder reactor to Iran. But why can't you sell one to PG&E? Are we that concerned that California could get the bomb? Plus, isn't the proliferation thing supposed to be one of the advantages of thorium, since you can't feasibly make a bomb out of the uranium-233 it gets bred into?
    - lazide 2y ago
      Yup. The big issue with Thorium is it isn’t fissile at first, and requires an existing nuclear reactor and careful fuel management to actually be usable in a reactor.
    - tim333 2y ago
      >A declassified 1966 memo from the US nuclear program stated that uranium-233 has been shown to be highly satisfactory as a weapons material (wikipedia https://en.wikipedia.org/wiki/Uranium-233#Weapon_material https://en.wikipedia.org/wiki/Uranium-233#Weapon_material)
      - AnthonyMouse 2y ago
        From the same article, apparently the infeasiblity is that pure uranium-233 could work, but a normal breeder reactor would also produce a small amount of uranium-232, which is fine for power reactors but not bombs. If you have the resources of the US DoD then you can design a special breeder reactor that uses special thorium, but by that point you could just make one that breeds plutonium out of uranium too.
        credit_guy 2y ago
        Although in theory a U-233 bomb would work just fine, the fact is that very few U-233 bombs were ever made. I don't think that more than 10, by all the nuclear powers combined. One way or another U-233 is not as good a bomb-making material in practice as it is in theory.

AnthonyMouse 2y ago

What makes uranium more economical, fuel production or some aspect of operation? And if it's the first one, is that just lack of scale for thorium or something else?

godelski 2y ago
Uranium is pretty abundant. The US has a lot, China twice as much, Kazakhstan a lot more, and Australia puts everyone to shame. Thorium isn't ready to be fuel and must be enriched (granted, you need to do this for uranium too but some is naturally in a fissile state). So there's things like breeder reactors that enrich during the cycle but this is challenging and presents other issues such as turning it into weapons manufacturing (increase proliferation concerns). There's a lot of small details that matter a lot. Fwiw, the parent has written a fair amount on this and runs a website with a lot of useful information for anyone curious. You can check their comments too as they usually participate anytime nuclear comes up https://whatisnuclear.com/thorium.html https://whatisnuclear.com/thorium.html
- AnthonyMouse 2y ago
  Isn't thorium also pretty abundant? Judging by this, the US has around six times as much thorium as uranium: https://en.wikipedia.org/wiki/List_of_countries_by_uranium_reserves https://en.wikipedia.org/wiki/List_of_countries_by_uranium_r... https://en.wikipedia.org/wiki/List_of_countries_by_thorium_resources https://en.wikipedia.org/wiki/List_of_countries_by_thorium_r... I've also never really gotten the proliferation concern. I mean, sure, you don't want to sell a breeder reactor to Iran. But why can't you sell one to PG&E? Are we that concerned that California could get the bomb? Plus, isn't the proliferation thing supposed to be one of the advantages of thorium, since you can't feasibly make a bomb out of the uranium-233 it gets bred into?
  - lazide 2y ago
    Yup. The big issue with Thorium is it isn’t fissile at first, and requires an existing nuclear reactor and careful fuel management to actually be usable in a reactor.
  - tim333 2y ago
    >A declassified 1966 memo from the US nuclear program stated that uranium-233 has been shown to be highly satisfactory as a weapons material (wikipedia https://en.wikipedia.org/wiki/Uranium-233#Weapon_material https://en.wikipedia.org/wiki/Uranium-233#Weapon_material)
    - AnthonyMouse 2y ago
      From the same article, apparently the infeasiblity is that pure uranium-233 could work, but a normal breeder reactor would also produce a small amount of uranium-232, which is fine for power reactors but not bombs. If you have the resources of the US DoD then you can design a special breeder reactor that uses special thorium, but by that point you could just make one that breeds plutonium out of uranium too.
      - credit_guy 2y ago
        Although in theory a U-233 bomb would work just fine, the fact is that very few U-233 bombs were ever made. I don't think that more than 10, by all the nuclear powers combined. One way or another U-233 is not as good a bomb-making material in practice as it is in theory.