Great idea 🙂
After a bit of a think I’m not sure that it’s feasible though. Beta plus decay uses energy to convert a proton into a neutron, a positron and a neutrino. If the process takes energy (rather than releasing it) then it’s kind of the opposite of nuclear power, which releases energy in the fission reactions.
Something cool though which you might not have seen is tritium illimination – taking tritium gas and putting it inside something phosphorous. It emits electrons because of beta decay which then light up the phosphor – so you can use it for glow-in-the-dark things! I think it is even still used a bit…
If you could find something that was fairly naturally abundant and readily decayed via beta+, sure, although off the top of my head I can’t think of anything in nature – but I’m sure you could maybe create something in a breeder reactor of some sort. The energy would be released would be difficult, but not impossible to stop in a material to convert it to heat – something like a molten salt would work quite well (and I’m sure it’s been employed on submarines), but then you start adding in alsorts of other issues like, how do you stop highly corrosive molten salt from destroying the inside of your reactor? Another massive issue is containment. Youd need a hellish amount of annihilations going on in your reactor…even if you could confine it (would be annoying confining two things of opposing charges with magnetic and electric fields!), if you lost coninement, you’re going to have a pretty nasty situation on your hands with the vapourisation of a large area, as well as irradiating the surrounding area with gamma rays…I’m sure people wouldn’t feel safe having one of these theoretical power plants on their doorstep!