I think there are a few different research groups working with different radioactive isotopes. (I think I already saw C14 anyway, I think they called it radioac

I think there are a few different research groups working with different radioactive isotopes. (I think I already saw C14 anyway, I think they called it radioactive diamond.) In al cases, they have very low power, so they are not practical. You will see a similar post again in 6-12 months.