Modeling Ionizing Radiation for Spaceflight Dynamic Radioisotope Power Systems

This paper presents methods, simulations, and analyses for spaceflight ionizing radiation exposures to three dynamic radioisotope power systems (DRPSs). The specific systems being investigated are part of an open solicitation by the National Aeronautics and Space Administration (NASA) and the US Department of Energy (DOE) to develop DRPS convertor technologies. The analyses include ionizing radiation sources from PuO
2
(and associated isotopes) and galactic cosmic rays (GCRs) over notional 20-year mission architectures with optional 10-year exposures from Jovian radiation environments. Total integrated doses to various components are calculated and compared to known material degradation thresholds in the open literature. Based on the findings, certain material trades are recommended for Jovian and non-Jovian mission architectures based solely on ionizing radiation. However, consideration is given to known and unknown synergistic degradation effects (l.e., radiation in combination with heat, pressure, or outgassing) that may be relevant to these systems and are not captured in these analyses.