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Tritium is a natural byproduct of CANDU fusion reactors, of which there are some 25 or so in operation globally, mostly in Canada. CANDUs use heavy water as a

Tritium is a natural byproduct of CANDU fusion reactors, of which there are some 25 or so in operation globally, mostly in Canada. CANDUs use heavy water as a neutron moderator (D20 instead of H2O), making T2O a natural byproduct. Though most of the reactors do not harvest the tritium, a small number do. CANDU operators have long been ready to make the capital investments in tritium harvesting, once demand materializes. ITER has long been seen as a potential major source of tritium demand.

anonuser123456 5y ago
I think the SPARC guys are going to eat all the CANDU tritium before ITER ever gets a chance light up. If we have to scale up fission reactors to produce enough tritium to scale fusion reactors, then don't need the fusion reactors.
- mlindner 5y ago
  Tritium only has a half life of 12 years. It's not like there's stockpiles of the stuff. It's constantly being produced. Also as mentioned up thread, they'll breed their own Tritium.
codesnik 5y ago
(you probably meant to write "CANDU fission reactors")
snek_case 5y ago
I'm wondering, fusion reactors themselves produce neutron radiation as a byproduct. Once you have a fusion reactor running, could you use the fusion reactor itself to breed tritium? Also thinking, we target deuterium + tritium fusion because it's the least energy intensive. However, once we have working proof of concept reactors, could we just make them slightly bigger and fuse more abundant molecules/isotopes instead?
- carbonguy 5y ago
  > Once you have a fusion reactor running, could you use the fusion reactor itself to breed tritium? I'll have to find the citation, but IIRC the answer is "theoretically, yes" - the concept is that molten lithium could be used in a tokamak to absorb neutrons and produce tritium at the same time. EDIT: Here are two citations I was able to find quickly - it looks like one of the ITER experiments will be to validate the concept [1] and that this could also be the way that heat is removed from the reactor. [2] [1] iter.org/mach/TritiumBreeding [2] https://www.euro-fusion.org/faq/top-twenty-faq/what-is-a-lithium-blanket-and-how-does-it-work/ https://www.euro-fusion.org/faq/top-twenty-faq/what-is-a-lit...
- anonuser123456 5y ago
  While not listed in the article, this is the design goal of the SPARC reactor. Their plan is to use FLiBe (Google it) blanket to breed tritium. The Be acts as a neutron multiplier. As for non D-T fusion, the next best candidate is D-He3. Unfortunately, the only large scale source of He3 is on the surface of the moon and it would have to be mined, on the moon, and sent back to Earth.
  - dmix 5y ago
    A study on feasibility of lunar He3 mining https://ui.adsabs.harvard.edu/abs/2014cosp...40E1515K/abstract https://ui.adsabs.harvard.edu/abs/2014cosp...40E1515K/abstra... Not as bad as I expected but not yet feasible economic wise. Assuming the fusion part exists.
  - snek_case 5y ago
    According to wikipedia: "Fusing two deuterium nuclei is the second easiest fusion reaction." "The optimum energy to initiate this reaction is 15 keV, only slightly higher than that for the D-T reaction." https://en.wikipedia.org/wiki/Fusion_power#Fuels https://en.wikipedia.org/wiki/Fusion_power#Fuels

anonuser123456 5y ago

I think the SPARC guys are going to eat all the CANDU tritium before ITER ever gets a chance light up. If we have to scale up fission reactors to produce enough tritium to scale fusion reactors, then don't need the fusion reactors.

mlindner 5y ago
Tritium only has a half life of 12 years. It's not like there's stockpiles of the stuff. It's constantly being produced. Also as mentioned up thread, they'll breed their own Tritium.

codesnik 5y ago

(you probably meant to write "CANDU fission reactors")

snek_case 5y ago

I'm wondering, fusion reactors themselves produce neutron radiation as a byproduct. Once you have a fusion reactor running, could you use the fusion reactor itself to breed tritium? Also thinking, we target deuterium + tritium fusion because it's the least energy intensive. However, once we have working proof of concept reactors, could we just make them slightly bigger and fuse more abundant molecules/isotopes instead?

carbonguy 5y ago
> Once you have a fusion reactor running, could you use the fusion reactor itself to breed tritium? I'll have to find the citation, but IIRC the answer is "theoretically, yes" - the concept is that molten lithium could be used in a tokamak to absorb neutrons and produce tritium at the same time. EDIT: Here are two citations I was able to find quickly - it looks like one of the ITER experiments will be to validate the concept [1] and that this could also be the way that heat is removed from the reactor. [2] [1] iter.org/mach/TritiumBreeding [2] https://www.euro-fusion.org/faq/top-twenty-faq/what-is-a-lithium-blanket-and-how-does-it-work/ https://www.euro-fusion.org/faq/top-twenty-faq/what-is-a-lit...
anonuser123456 5y ago
While not listed in the article, this is the design goal of the SPARC reactor. Their plan is to use FLiBe (Google it) blanket to breed tritium. The Be acts as a neutron multiplier. As for non D-T fusion, the next best candidate is D-He3. Unfortunately, the only large scale source of He3 is on the surface of the moon and it would have to be mined, on the moon, and sent back to Earth.
- dmix 5y ago
  A study on feasibility of lunar He3 mining https://ui.adsabs.harvard.edu/abs/2014cosp...40E1515K/abstract https://ui.adsabs.harvard.edu/abs/2014cosp...40E1515K/abstra... Not as bad as I expected but not yet feasible economic wise. Assuming the fusion part exists.
- snek_case 5y ago
  According to wikipedia: "Fusing two deuterium nuclei is the second easiest fusion reaction." "The optimum energy to initiate this reaction is 15 keV, only slightly higher than that for the D-T reaction." https://en.wikipedia.org/wiki/Fusion_power#Fuels https://en.wikipedia.org/wiki/Fusion_power#Fuels