Likewise, for fusion experiments. I see assertions in planning documents that the supply of tritium on hand is wholly inadequate for planned research operation

Likewise, for fusion experiments. I see assertions in planning documents that the supply of tritium on hand is wholly inadequate for planned research operations on ITER, never mind its successor imagined to be built in such a way as to be able to drive a steam turbine, or likewise SPARC or its imagined successor. I.e. there is not enough for either program, never mind both. And Helion's D-3He reactor would need lots of 3He, and be utterly dependent on making more, itself. It takes 12 years for half of your stock of tritium to spontaneously become the needed 3He, and no possibility of hurrying it along.