| Abbreviation | Definition |
|---|---|
| RDD | Reactor Development and Demonstration |
| RDQ | Rate Distortion Quantization |
| RDTP | Restricted Delay Test Pair |
| R-E/i | Ohms Law (not an acronym) |
| REA | Rod Ejection Accident |
| REB | Relativistic Electron Beam |
| REBA | Relativistic Electron Beam Accelerator |
| REBA | Restricted Bandwidth |
| REBAT | Restricted Bandwidth Technique |
| RECAN | Regional European and Central Asian ALARA Network |
| red | reverse electrodialysis |
| REIXS | Resonant Elastic and Inelastic Xray Scattering |
| REL | Recommended Exposure Limit |
| REM | Roentgen Equivalent Man |
| REMPI | Resonance-Enhanced MultiPhoton Ionization |
| REPM | Rare Earth Permanent Magnets |
| REST | REpresentational State Transfer |
| REV | Reversible |
| REXS | resonant elastic x-ray scattering |
| RF | Range Folding |