| AC | alternating current |
| AEPS | Advanced Electric Propulsion System |
| ANL | Argonne National Laboratory |
| ARDP | Advanced Reactor Demonstration Program |
| B4C | boron carbide |
| BeO | beryllium oxide |
| cercer | ceramic-ceramic |
| cermet | ceramic-metal |
| DARPA | Defense Advanced Research Projects Agency |
| DC | direct current |
| DoD | Department of Defense |
| DOE | Department of Energy |
| DOE-NE | DOE Office of Nuclear Energy |
| EP | electric propulsion |
| FSP | Fission Surface Power program |
| HALEU | high-assay, low-enriched uranium (i.e., uranium enriched to contain from between 5 and 20 percent uranium-235) |
| HEU | highly enriched uranium (i.e., uranium enriched to contain from more than 20 percent uranium-235) |
| Isp | specific impulse |
| JIMO | Jupiter Icy Moons Orbiter |
| kWe | kilowatt-electric |
| LH2 | liquid hydrogen |
| LiH | lithium hydride |
| LOX | liquid oxygen |
| M&S | modeling and simulation |
| Mo | molybdenum |
| MPD | magnetoplasmadynamic |
| MWe | megawatt electric |
| MWt | megawatt thermal |
| NbC | niobium carbide |
| NEP | nuclear electric propulsion |
| NERVA | Nuclear Engine for Rocket Vehicle Application program |
| NEXT-C | NASA’s Evolutionary Xenon Thruster–Commercial |
| NextSTEP | Next Space Technologies for Exploration Partnerships |
| NRIC | National Reactor Innovation Center |
| NSTAR | NASA Solar Technology Application Readiness |
| NTP | nuclear thermal propulsion |
| PMAD | power management and distribution |
| PMS | propellant management system |
| PPU | power processing unit |
| SEP | solar electric propulsion |
| SNAP | Systems for Nuclear Auxiliary Power |
| SNTP | Space Nuclear Thermal Propulsion program |
| Ta | tantalum |
| TFE | thermionic fuel element |
| TOPAZ | Thermionic Operating Reactor Active Zone |
| UC | uranium carbide |
| UC2 | uranium dicarbide |
| UCO | uranium oxycarbide |
| UN | uranium nitride |
| UO2 | uranium dioxide |
| W | tungsten |
| WUO2 | tungsten uranium dioxide |
| ZPC | zero-power critical |
| ZrC | zirconium carbide |
| ZrH | zirconium hydride |