Systems and methods are presented for regulating electrical power generated from a decay of radiation-emitting isotopes. The systems include a diode formed of a semiconductor material capable of mitigating radiation damage by operating at temperatures greater than 300° C. In some embodiments, the semiconductor material includes uranium oxide, UO2±x, where 0≦x≦0.5. The systems also include a fluid comprising an isotope emitting alpha particles. The systems additionally include a closed circuit having the fluid disposed therein and configured to bring the fluid in contact with the diode. The methods involve flowing a fluid across a surface of a diode and generating electrical power from the diode in response to radiation absorbed therein. The fluid includes an isotope that emits alpha particles. The surface of the diode defines a portion of a closed circuit in which the fluid flows. The methods additionally involve extracting, from the fluid, decay products of the isotope. Other systems and methods are presented.