Nuclear terms, defined simply.
Nuclear comes with its own vocabulary. Below are some acronyms and terms you'll see most often.
Yellowcake
Concentrated uranium powder produced by milling raw uranium ore. The starting material for reactor fuel.
Chemical process that turns yellowcake into uranium hexafluoride (UF₆) gas, which can then be enriched.
Enrichment
Increasing the proportion of uranium-235 relative to uranium-238. Required to make reactor fuel.
LEU
Uranium enriched to 3–5% U-235. Used in most commercial reactors worldwide.
HALEU
High-Assay LEU
Uranium enriched to 5–20% U-235. Required by some advanced reactor designs.
SMR
Small Modular Reactor
A smaller, factory-built reactor installed in modules. Safer and cheaper per-unit than traditional large reactors.
Microreactor
Even smaller reactor, typically under 20 megawatts. Designed for remote sites or specific facilities.
Reprocessing
Chemical separation of used reactor fuel to recover usable uranium and plutonium. Not currently done commercially in the U.S.
NRC
Nuclear Regulatory Commission
Chemical separation of used reactor fuel to recover usable uranium and plutonium. Not currently done commercially in the U.S.
DOE
Department of Energy
Chemical separation of used reactor fuel to recover usable uranium and plutonium. Not currently done commercially in the U.S.
RFI
Request for Information
A formal federal or state notice asking for input before commitment to a program. RFIs are non-binding commitments.
CUP
Conditional Use Permit
A local permit allowing a specific use only if certain protective conditions are met. Requires public review.
LLW
Low-Level Waste
Lightly contaminated materials (gloves, tools, filters). Managed at licensed disposal sites.
HLW
High-Level Waste
Highly radioactive material from used reactor fuel or reprocessing. Requires long-term deep geologic disposal.
Decommissioning
The regulated process of safely shutting down and dismantling a nuclear facility at end of life.
Isotope Production
Manufacturing of radioactive materials used in medical imaging, cancer treatment, industry, and national security.