Reply #17: It's also used as a "Booster" in ordinary fission bombs.

[Tesha]

The big deal in fission bombs is getting a the reaction to run as far
as it can before the bomb "disassembles" itself. You do this by getting
as many free neutrons as possible to stay in the core/be present in the
core therey causing more U235 nuclei to fission.

You can do that with a neutron reflector, but that's relatively
inefficient. Adding tritium works better; it undergoes a relatively
low-intensity fusion reaction but in the process, it cranks out lots
of free neutrons which "boost" the main fission reaction.

Most of our small nukes are tritium-boosted fission bombs.

Tesha