How do you get tritium out of the fission of uranium?
From lots of neutrons hitting water. Regular water yields some, heavy water (like the CANDU units) generate more.
It is a very rare fission product coming directly from U fission, but the quantity is negligible.
I think the US used to make it by bombarding lithium in reactors, we don’t any more.
Apparently, by going fission in the Connecticut River.