| $ | Dollar |
| ¥ | Yen |
| 1D | One-dimensional |
| 2D | Two-dimensional |
| 3D | Three-dimensional |
| A | Area |
| A0 | Flow-passage area |
| AC | Alternating current |
| ACRS | Advisory Committee on Reactor Safeguards |
| AEC | Atomic Energy Commission |
| AFM | Army Field Manual |
| ANS | American Nuclear Society |
| AP (reactor) | Advanced passive |
| ASME | American Society of Mechanical Engineers |
| B.5.b | Section B.5.b of Order EA-02-026 |
| BAF | Bottom of active fuel |
| BNL | Brookhaven National Laboratory |
| BWR | Boiling water reactor |
| °C | Degrees Celsius |
| CARVER | Criticality + Accessibility + Recuperability + Vulnerability + Effect + Recognizability |
| Cf | Pressure drop coefficient |
| CFD | Computational fluid dynamics |
| CFR | Code of Federal Regulations |
| CI/KR | Critical Infrastructure and Key Resources |
| Cm | Centimeter |
| CNN | Cable News Network |
| COMSECY | Commission Action Memoranda, the Office of the Secretary (SECY) |
| CP | Water specific heat capacity |
| CRS | Congressional Research Service |
| Cs | Cesium |
| D | Mass diffusivity of water vapor in air |
| DBA | Design-basis accident |
| DBT | Design-basis threat |
| DC | Direct current |
| DCLG | Department for Communities and Local Government (United Kingdom) |
| DHS | U.S. Department of Homeland Security |
| Diet | National Diet of Japan |
| DOE | U.S. Department of Energy |
| DPR | Decommissioning Planning Rule |
| DS | Dryer-separator |
| EA | Enforcement Action |
| EPRI | Electric Power Research Institute |
| °F | Degrees Fahrenheit |
| FLEX | Diverse and Flexible Coping Strategies |
| FOIA | Freedom of Information Act |
| FPC | Fuel Pool Cooling and Cleanup |
| ft | Feet |
| g | Gravity |
| GAO | U.S. Government Accountability Office |
| GE | General Electric |
| gpm | Gallons per minute |
| GTD | Global Terrorism Database |
| H | Hydrogen |
| ΔHfg | Heat of vaporization |
| hm | Mass transfer coefficient |
| hr | Hour |
| HRA | Human reliability analysis |
| IAEA | International Atomic Energy Agency |
| INMM | Institute of Nuclear Materials Management |
| ISFSI | Independent spent fuel storage installation |
| ISG | Interim Staff Guidance |
| J | Joules |
| JLD | Japan Lessons-Learned Division |
| K | Kelvin |
| kg | Kilogram |
| kJ | Kilojoule |
| km | Kilometer |
| L | Length |
| LCF | Latent cancer fatality |
| LOCA | Loss-of-coolant accident |
| m | Meter |
| M | Mass |
| MACCS2 | MELCOR Accident Consequence Code System, version 2 |
| MCi | Megacuries |
| MELCOR | Methods for Estimation of Leakages and Consequences of Releases |
| mi | Miles |
| MJ | Megajoules |
| mm | Millimeter |
| MOE | Japan Ministry of the Environment |
| MOX | Mixed oxide |
| mrem | Millirem |
| mSv | Millisievert |
| MUWC | Make-Up Water Condensate |
| MW | Megawatt |
| NAIIC | Nuclear Accident Independent Investigation Commission (Japan) |
| NAP | National Academies Press |
| NARAC | National Atmospheric Release Advisory Center |
| NAS | National Academy of Sciences (United States) |
| NEA | Nuclear Energy Agency (Organisation for Economic Co-operation and Development) |
| NEI | Nuclear Energy Institute |
| NIPP | National Infrastructure Protection Plan |
| NISA | Nuclear and Industrial Safety Agency (Japan) |
| NRA | (Japan) Nuclear Regulation Authority |
| NRC | National Research Council |
| NSIR | Nuclear Security and Incident Response |
| NTTF | Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident (U.S. Nuclear Regulatory Commission) |
| NUREG | (US)NRC technical report designation |
| O | Oxygen |
| OCP | Operating-cycle phase |
| OE | Office of Enforcement (USNRC) |
| OECD | Organisation for Economic Co-Operation and Development |
| OMB | U.S. Office of Management and Budget |
| ORNL | Oak Ridge National Laboratory |
| P | Pressure |
| P | Probability |
| PCT | Peak cladding temperature |
| PGA | Peak ground acceleration |
| PL | Public Law |
| PRA | Probabilistic risk assessment |
| PWR | Pressurized water reactor |
| Q. | Thermal power |
| QHO | Quantitative health objective |
| ρ | Fluid density |
| RAMCAP | Risk Assessment and Management for Critical Asset Protection |
| rem | Roentgen equivalent man |
| RISR | Risk Informed Security Regulation |
| RJIF | Rebuild Japan Initiative Foundation |
| RPG | Rocket-propelled grenade |
| s | Second |
| SAMG | Severe accident management guideline |
| SECY | Secretary of the Commission |
| SFP | Spent fuel pool |
| SFPS | Spent fuel pool study |
| Sh | Sherwood number |
| SNL | Sandia National Laboratories |
| SNM | Special nuclear materials |
| SOARCA | State-of-the-Art Reactor Consequence Analyses |
| SSP | Sector-Specific Plan |
| Sv | Sievert |
| t | Time |
| T | Temperature |
| TAF | Top of active fuel |
| TEPCO | Tokyo Electric Power Company |
| TMI | Three Mile Island |
| U | Uranium |
| UNSCEAR | United Nations Scientific Committee on the Effects of Atomic Radiation |
| USNRC | U.S. Nuclear Regulatory Commission |
| W | Width |
| WWII | World War II |
| yr | Year |
| Zr | Zirconium |
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