There’s an argument to be made that we should do a much better job of directing those neutrons to make tritium, since fission isn’t even something to discuss until we know how to make abundant tritium.
Yes. But fusion is not quite here yet. It's a difficult business proposition to store large quantities of tritium in the hope that you'll be able to sell to an operator of a fusion reactor three decades down the road (after about 80% of it has decayed).
On the other hand, when fusion is ready for prime time, one could use liquid lithium in a reactor. Liquid lithium has quite a number of advantages over sodium: in that temperature range it has more specific heat capacity than any metal, higher even than water. It has excellent conductivity.
And if it captures a neutron, it splits in helium and tritium plus energy. It could increase the energy production of a fission reactor by more than 5%. And you get that tritium for free, and ultra-rare helium-3 if you fancy some aneutronic fusion at some point.
