Adding any heavy ion species into a plasma makes it cool rapidly due to bremsstralung radiation. This goes up as Z^2 where Z is the charge on the ion. So if you added in even a small amount of uranium and it became anywhere near full ionized, ie Z->92 then the rate of cooling would go up by ~8000x preventing the plasma ever achieving fusion temperatures. It’s bad enough trying to cope with boron with Z=5.
You could have a hybrid deuterium or D-T device where fissile material (or actinide waste product you want to get rid of) surrounds the DPF device to react with the neutrons. This would be similar in concept to various accelerator driven sub-critical reactor designs that are being proposed.
