4 ms·

I thought it was the other way around in fact. That they don't produce nuke-weapon-ready material meant that this avenue was not profitable from a security pers

I thought it was the other way around in fact. That they don't produce nuke-weapon-ready material meant that this avenue was not profitable from a security perspective. I may be recalling this incorrectly and I haven't re-checked but I think that's correct?

philipkglass 9y ago
No, that is incorrect, though it has often been repeated by less technically informed advocates of the thorium fuel cycle. The vast majority of the world's commercial nuclear reactors are light-water-moderated pressurized water reactors or boiling water reactors (PWR and BWR respectively). The actual military origins of these light water reactors is that they were originally researched for submarine and ship propulsion for the US Navy: https://en.wikipedia.org/wiki/Light-water_reactor https://en.wikipedia.org/wiki/Light-water_reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor#History https://en.wikipedia.org/wiki/Pressurized_water_reactor#Hist... https://en.wikipedia.org/wiki/Boiling_water_reactor#Evolution https://en.wikipedia.org/wiki/Boiling_water_reactor#Evolutio... The United States and other nuclear weapons states never produced their weapons plutonium from light water reactors. Weapons grade plutonium has typically been produced from uranium in dedicated plutonium-production reactors moderated with heavy water or graphite. (The United States once had a single reactor that also produced commercial electricity along with weapons plutonium, https://en.wikipedia.org/wiki/N-Reactor https://en.wikipedia.org/wiki/N-Reactor, but it wasn't a light water reactor either.) Since uranium fueled light water reactors weren't used to make plutonium for weapons in the first place, the thorium-myth claim that commercial power reactors stuck with uranium so as to make weapons material is ridiculous. The military's early sponsorship of light water reactors for naval propulsion did give uranium-fueled LWRs a significant historical path dependency advantage. I speculate that thorium advocates who continue to repeat the myth about how uranium LWRs became dominant do so because it makes the dominant technology's dominance sound more sinister, hence thorium sound more attractive by contrast.
- acidburnNSA 9y ago
  Oh my god thank you for understanding this and explaining it so well. I spend a lot of time trying to suppress the sinister-LWR myth. Real reasons MSRs declined include [1]: * The existing major industrial and utility commitments to the LWR, HTGR, and LMFBR. * The lack of incentive for industrial investment in supplying fuel cycle services, such as those required for solid fuel reactors. * The overwhelming manufacturing and operating experience with solid fuel reactors in contrast with the very limited involvement with fluid fueled reactors. * The less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept. [1] http://www.energyfromthorium.com/pdf/WASH-1222.pdf http://www.energyfromthorium.com/pdf/WASH-1222.pdf
- Recurecur 9y ago
  The issue wasn't "light water reactors" it was "uranium fuel cycle". Cheap uranium definitely benefited the US government.
  - igravious 9y ago
    And going back one step Recurecur, isn't a very large part of the the issue "fissionable plutonium" (because bombs) which motivates the "uranium fuel cycle" which means the "thorium fuel cycle" isn't half so interesting.

philipkglass 9y ago

No, that is incorrect, though it has often been repeated by less technically informed advocates of the thorium fuel cycle. The vast majority of the world's commercial nuclear reactors are light-water-moderated pressurized water reactors or boiling water reactors (PWR and BWR respectively). The actual military origins of these light water reactors is that they were originally researched for submarine and ship propulsion for the US Navy: https://en.wikipedia.org/wiki/Light-water_reactor https://en.wikipedia.org/wiki/Light-water_reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor#History https://en.wikipedia.org/wiki/Pressurized_water_reactor#Hist... https://en.wikipedia.org/wiki/Boiling_water_reactor#Evolution https://en.wikipedia.org/wiki/Boiling_water_reactor#Evolutio... The United States and other nuclear weapons states never produced their weapons plutonium from light water reactors. Weapons grade plutonium has typically been produced from uranium in dedicated plutonium-production reactors moderated with heavy water or graphite. (The United States once had a single reactor that also produced commercial electricity along with weapons plutonium, https://en.wikipedia.org/wiki/N-Reactor https://en.wikipedia.org/wiki/N-Reactor, but it wasn't a light water reactor either.) Since uranium fueled light water reactors weren't used to make plutonium for weapons in the first place, the thorium-myth claim that commercial power reactors stuck with uranium so as to make weapons material is ridiculous. The military's early sponsorship of light water reactors for naval propulsion did give uranium-fueled LWRs a significant historical path dependency advantage. I speculate that thorium advocates who continue to repeat the myth about how uranium LWRs became dominant do so because it makes the dominant technology's dominance sound more sinister, hence thorium sound more attractive by contrast.

acidburnNSA 9y ago
Oh my god thank you for understanding this and explaining it so well. I spend a lot of time trying to suppress the sinister-LWR myth. Real reasons MSRs declined include [1]: * The existing major industrial and utility commitments to the LWR, HTGR, and LMFBR. * The lack of incentive for industrial investment in supplying fuel cycle services, such as those required for solid fuel reactors. * The overwhelming manufacturing and operating experience with solid fuel reactors in contrast with the very limited involvement with fluid fueled reactors. * The less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept. [1] http://www.energyfromthorium.com/pdf/WASH-1222.pdf http://www.energyfromthorium.com/pdf/WASH-1222.pdf
Recurecur 9y ago
The issue wasn't "light water reactors" it was "uranium fuel cycle". Cheap uranium definitely benefited the US government.
- igravious 9y ago
  And going back one step Recurecur, isn't a very large part of the the issue "fissionable plutonium" (because bombs) which motivates the "uranium fuel cycle" which means the "thorium fuel cycle" isn't half so interesting.