3 ms·
U238 isn't used in current designs because there's so much U235, and the input cost of using U235 is low enough relative to the value of the electricity generat
by arcticbull 5y ago
U238 isn't used in current designs because there's so much U235, and the input cost of using U235 is low enough relative to the value of the electricity generated that it's not worth using the U238 - generally speaking. It however can be used in fast neutron reactors or breeder reactors. [1]
[1] https://energyeducation.ca/encyclopedia/Breeder_reactor https://energyeducation.ca/encyclopedia/Breeder_reactor
- Retric 5y agoYour general point is correct, however both U238 and U235 are are consumed by commercial reactors right now. U238 > U239 decay into neptunium-239 which then decays into Plutonium-239. Essentially there is so much U238 in the reactor and so many neutrons flying around the above just happens.
- arcticbull 5y agoI was under the impression commercial reactors consumed like 1% of the available U238 vs the fast reactors which got closer to 70% (based on the article linked as [1]).
- Retric 5y agoYea, it depends on the fuel and design but in absolute terms the percentage of U238 fuel used is low. However the ratio of 238v235 consumed is much closer because there is so much more U238 than U235. To simplify if 4% of the fuel is U235 vs 96% U238. While spent fuel is say 1% U235 vs 95% U238/P239 then 3/(3 + 1) = 75% of the fuel used was U235 and 1/(3 + 1) = 25% of the fuel used was U238. Actual numbers are different, but you get the idea.
- arcticbull 5y agoThanks for the clarification!