One could obviously breed, separate, and accumulate U233 and use that to build a bomb.
According to Wikipedia, some experiments have been done with U233 as a bomb material, though it is not clear if a pure U233 bomb has ever been tested.
A matter of semantics whether you would call that a Thorium bomb, though?
No, it would be a Uranium bomb. Even if the 233U was bred from Thorium feedstock. Otherwise a Plutonium fission weapon would also be called a Uranium bomb, since its fissile material is also bred from a Uranium mother.
Your suspicion is correct. Breeding of U-233 from Th-232 is a slow process. First the thorium has to absorb a neutron to become Th-233. Thorium-233 is fissile, meaning it likes to absorb slow themal neutrons, not the fast ones you get in a nuclear bomb explosion. Once it has absorbed the neutron it spontaneously decays twice before it become U-233: first from Th-233 to Pa-233 (half life of around 20 minutes) then from Pa-233 to U-233 (half life of almost a month). There’s a reason that slow breeder reactors are called that, because slow is the only way you can breed U-233.
True. As a tamper, it would exist long enough for its mass to provide decent inertial confinement to the primary detonation, but not long enough for the dual beta decay to finish to provide further fissile fuel in an organized fashion.
Unlike a 238U tamper, which can be directly driven to usable fission by the neutron or gamma flux of the primary. The Fat Man device was estimated to have gotten 30% of its yield from the natural uranium tamper contribution.
I guess there is no logical reason to suppose that. I seem to recall reading it somewhere, but can’t remember the source now, so no idea how authoritative it might have been.
A stable diproton would surely have some major implications for nucleosynthesis pathways, though?
I would not even try to speculate on the details. Any real nuclear physicists in the house?
I would have guessed that if it were stable just about everything else would be too. That would have pretty wide reaching implications about the nature of the universe. It would sure be a very different place. The Big Bang would likely have directly created most of the elements in significant quantities. Stars might not even form in the manner we see, and nuclear processes would have very different energies. Nucleuogenises would certainly be very different.
Really, to make the diproton stable, you’d need to completely change the nature of the Strong Force. It’s not just “make the Strong Force stronger than the electromagnetic, so they stick together”: Remember, the dineutron also doesn’t hold together, and it’s the Strong Force that blows it apart. And would do the same thing to a diproton. Meanwhile, He-3 is stable, but H-3 isn’t.