10 CFR Part 50 – The NRC’s traditional licensing framework for commercial nuclear reactors, built around a two-step approach: a construction permit followed by an operating license. Many existing U.S. plants were licensed under Part 50, and it remains available for new and advanced reactor applicants.
10 CFR Part 52 – The NRC’s newer licensing framework designed to streamline approvals through standardization and a more predictable one-step approach. Part 52 supports pathways such as Early Site Permits (ESPs), Standard Design Certifications, and Combined Licenses (COLs).
10 CFR Part 53 – A developing NRC rulemaking intended to provide a risk-informed, performance-based, technology-inclusive regulatory framework specifically suited to advanced reactors (beyond traditional light-water designs).
Advanced Manufacturing Technologies (AMT) – Modern manufacturing approaches—such as additive manufacturing (3D printing), advanced machining, robotics, and digital inspection—that can reduce lead times and improve repeatability.
Agreement State – A state that has entered into an agreement with the NRC to license and inspect certain radioactive materials (commonly byproduct, source, or special nuclear materials) used or possessed within that state.
ALARA (As Low As Reasonably Achievable) – An NRC-defined radiation protection principle requiring licensees to make every reasonable effort to keep exposures to ionizing radiation as far below regulatory dose limits as practical.
Alpha Particle – A heavy, positively charged radiation particle (two protons and two neutrons). Alpha radiation does not penetrate skin, but is hazardous if alpha-emitting material is inhaled or ingested.
ARDP (Advanced Reactor Demonstration Program) – A U.S. Department of Energy funding program created to accelerate advanced reactor demonstrations through cost-shared partnerships, de-risking first-of-a-kind deployment and strengthening domestic supply chains.
ASME N-Stamp – A certification under the ASME Boiler & Pressure Vessel Code that authorizes an organization to manufacture or repair certain nuclear safety-related components under strict quality and documentation controls.
Atomic Energy Act (1954) – The foundational U.S. law governing civilian use of nuclear materials and nuclear energy, including the regulatory authority that underpins the NRC’s oversight framework.
Baseload Power – Electricity generation that runs consistently to meet the grid’s minimum, always-present demand. Nuclear plants are often used as baseload because they operate reliably for long periods between refueling outages.
Becquerel (Bq) – The SI unit of radioactivity equal to one nuclear decay per second. It measures activity (how many atoms are decaying), not radiation dose to people.
Beta Particle – A fast-moving electron (or positron) emitted by certain radioactive materials. Beta radiation can penetrate skin to some extent and can be blocked by plastic, glass, or thin metal.
Binding Energy – The “glue energy” that holds the nucleus together. Nuclear fission and fusion release energy by moving nuclei toward more stable configurations with higher binding energy per nucleon.
Burnup – A measure of how much energy has been extracted from nuclear fuel, typically expressed as gigawatt-days per metric ton of uranium (GWd/MTU).
Capacity Factor – The percentage of time a power plant produces electricity at its maximum possible output over a period. Nuclear plants commonly achieve high capacity factors because they operate continuously except during planned refueling.
Central Processing Plant (CPP) – In uranium in-situ recovery (ISR), a facility where uranium-bearing solutions are processed to extract uranium, concentrate it, and produce a dried product (often yellowcake).
Chain Reaction – A self-sustaining sequence where fission events release neutrons that trigger additional fission events. Reactor control systems keep the chain reaction steady at the desired power level.
CISF (Consolidated Interim Storage Facility) – A proposed centralized location designed to store spent nuclear fuel temporarily—typically in dry casks—until a permanent geologic repository is available.
Coal-to-Nuclear – The redevelopment of retired coal plant sites for nuclear generation, often leveraging existing transmission infrastructure, cooling water access, industrial zoning, and a local workforce with relevant skills.
Containment Structure – A robust, leak-tight structure (often reinforced concrete with a steel liner) designed to prevent or significantly reduce the release of radioactive material during severe accidents.
Control Rod – A neutron-absorbing device (made from materials such as boron, hafnium, or silver-indium-cadmium alloys) inserted into or withdrawn from the core to regulate power or shut down the reactor.
Conversion (Uranium) – A chemical process that converts uranium concentrates (yellowcake) into forms usable for enrichment—most commonly uranium hexafluoride (UF₆)—after refining and purification steps.
Coolant – The fluid that removes heat from the reactor core and transports it to systems that generate electricity or provide useful heat. Examples include water, liquid sodium, helium, molten salts, and lead-based coolants.
Core – The central region of the reactor containing nuclear fuel and where the controlled chain reaction produces heat. The core includes fuel assemblies, control components, and structural supports.
Criticality – The condition where a nuclear chain reaction is self-sustaining at a steady level. In a power reactor, “critical” does not mean dangerous—it means neutron production and losses are balanced.
Curie (Ci) – A traditional unit of radioactivity equal to 3.7 × 10¹⁰ decays per second. It is larger than a becquerel and still commonly used in U.S. regulatory and industrial contexts.
Decay Heat – Heat that continues to be produced after a reactor is shut down, primarily from the radioactive decay of fission products. Decay heat is a major driver of safety system design.
Decommissioning – The process of permanently shutting down a nuclear facility, removing radioactive materials, dismantling structures as appropriate, and remediating the site to meet regulatory release criteria.
Deconversion – The chemical process of converting depleted UF₆ (a stable storage form for enrichment tails, but reactive with moisture) into a more stable solid compound suitable for long-term storage and handling.
Defense-in-Depth – A safety philosophy using multiple independent and redundant layers—physical barriers, engineered systems, and procedural controls—to prevent accidents and mitigate consequences if an accident occurs.
Delayed Neutrons – Neutrons released seconds to minutes after fission by certain fission products. Delayed neutrons make reactor control practical by slowing the timescale of reactivity changes.
Design-Basis Accident (DBA) – A set of legally defined accident scenarios and conditions that a nuclear plant must be designed to withstand while meeting regulatory limits for public safety.
Dispatchable Power – Electric generation that can be turned on/off or ramped up/down on demand to balance the grid.
Dosimeter – A wearable device (badge or electronic unit) used to measure a worker’s radiation dose over time, supporting compliance with NRC (or Agreement State) limits and ALARA practices.
Dry Cask Storage – A method of storing spent nuclear fuel in sealed steel canisters with concrete and/or additional shielding, typically located on-site at nuclear plants.
EBR-II (Experimental Breeder Reactor II) – A historic sodium-cooled fast reactor project in Idaho that demonstrated key fast-reactor concepts and contributed to the technical lineage of later SFR designs.
Emergency Planning Zone (EPZ) – NRC-required planning areas around nuclear power plants. The NRC describes two primary EPZs: a plume exposure pathway zone (approx 10 miles) and an ingestion pathway zone (approx 50 miles).
Energy Island – The non-nuclear portion of a plant that typically includes thermal energy storage, turbines, generators, and associated equipment. It is regulated differently than the nuclear island.
Energy Matching Funds – A Wyoming incentive approach (policy/finance tool) used to attract energy and industrial investments by sharing early-stage costs, supporting feasibility work, infrastructure, or siting.
Enrichment – The process of increasing the concentration of the fissile isotope U-235 in uranium from its natural level (~0.7%) to higher levels suitable for reactor fuel.
Export of Energy – Wyoming’s long-standing role as a major net energy exporter, producing substantially more energy than it consumes and sending electricity and fuels to other states.
Fertile – Material that is not fissile itself but can be converted into fissile material through neutron capture and subsequent decay, such as U-238, which can become Pu-239 in a reactor.
Fissile – Material capable of sustaining a nuclear chain reaction by fission with thermal (slow) neutrons, such as U-235 and Pu-239.
Fission – The splitting of a heavy atomic nucleus (like uranium) into smaller nuclei, releasing energy, neutrons, and radiation. Nuclear power plants generate heat primarily from controlled fission.
Fuel Cycle (Nuclear Fuel Cycle) – The end-to-end system for producing, using, and managing nuclear fuel: mining/recovery → milling → conversion → enrichment → fuel fabrication → reactor use → spent fuel storage/disposal.
Fuel Pellet – A small ceramic cylinder (commonly uranium dioxide, UO₂) that contains enriched uranium and forms the basic fuel unit in most reactors. Pellets are stacked into fuel rods.
Fuel Rod – A metal tube (cladding) containing stacked fuel pellets. Many rods form a fuel assembly. Cladding must withstand heat, pressure, corrosion, and radiation.
Functional Containment – An advanced reactor safety concept where the “containment function” is achieved through a combination of high-integrity fuel forms (such as TRISO), sealed systems, and engineered barriers rather than solely a large building.
Fusion – The joining of light nuclei (such as hydrogen isotopes) to release energy. Fusion is not yet commercially proven for grid-scale electricity but remains an active R&D field.
Gamma Ray – High-energy electromagnetic radiation emitted by radioactive materials. Gamma radiation is highly penetrating and requires dense shielding such as lead, steel, or thick concrete.
Gas Centrifuge – The dominant modern method for uranium enrichment. UF₆ gas is spun at very high speeds; slightly heavier U-238 molecules separate from slightly lighter U-235 molecules.
Geiger Counter – A portable radiation detection instrument commonly used to detect and measure ionizing radiation (especially beta and gamma).
Geologic Repository – A permanent underground disposal facility designed for long-term isolation of high-level radioactive waste, relying on geology plus engineered barriers.
Gigawatt-scale Storage – Energy storage capacity measured at the gigawatt level, indicating the ability to deliver very large amounts of power.
Gray (Gy) – The SI unit for absorbed dose: 1 joule of radiation energy absorbed per kilogram of material.
Great Divide Basin – A major geologic and industrial region in Wyoming associated with uranium resources and ISR development.
HALEU (High-Assay Low-Enriched Uranium) – Uranium enriched to greater than 5% and less than 20% U-235. Many advanced reactors require HALEU to achieve compact core designs.
Half-life – The time required for half the atoms in a radioactive sample to decay. Half-life determines how quickly radioactivity decreases and is crucial for waste management.
Header House – In ISR uranium operations, a small field facility that manages the flow of lixiviant into injection wells and uranium-bearing solution out of production wells.
High-Level Waste (HLW) – Highly radioactive waste, primarily spent nuclear fuel or waste from reprocessing. HLW requires robust shielding and long-term isolation.
High-Temperature Gas Reactor (HTGR) – A reactor type that uses an inert gas—typically helium—as coolant and operates at high temperatures.
Important to Safety – A classification used in safety analysis describing systems, structures, and components that contribute to preventing or mitigating accidents, though they may not meet the strict definition of “safety-related.”
Industrial Siting Council (ISC) – A Wyoming state-level body that reviews and permits major industrial facilities based on local impacts (e.g., socioeconomics, infrastructure).
In-Situ Recovery (ISR) – A uranium recovery method where a leaching solution is circulated through an underground ore zone to dissolve uranium, which is then pumped to the surface.
Ionizing Radiation – Radiation energetic enough to remove electrons from atoms, potentially causing chemical changes in living tissue. Includes alpha, beta, gamma, neutron radiation, and X-rays.
Kemmerer Power Station Unit 1 – A project designation used to identify the Natrium nuclear unit at the Kemmerer site; Wyoming’s first planned commercial nuclear unit.
Kemmerer, WY – The host community for Wyoming’s Natrium demonstration project, a major focal point for coal-to-nuclear transition discussions.
LCOE (Levelized Cost of Electricity) – A standardized metric for comparing generation sources by calculating the average total cost of building and operating a plant over its life divided by total electricity produced.
LEU (Low-Enriched Uranium) – Uranium enriched up to 5% U-235, commonly used in today’s light-water reactors.
Lixiviant – In ISR uranium recovery, the leaching solution (typically oxygenated water with a chemical agent) injected into the ore zone to dissolve uranium minerals.
Load-Following – Operating a power plant in a way that adjusts output up or down in response to grid demand.
LOCA (Loss-of-Coolant Accident) – An accident scenario involving loss of reactor coolant flow or inventory. A major design basis event.
Lost Creek Project – A major ISR uranium project in Wyoming, representing the modern ISR approach to uranium recovery.
Low-Level Waste (LLW) – Radioactive waste that is not spent fuel, HLW, or transuranic waste. Includes contaminated clothing, filters, tools, resins.
Manhattan Project – The WWII-era program that developed the first nuclear weapons and early nuclear technology. It shaped the early U.S. nuclear industry and western uranium development.
Microreactor – A very small nuclear reactor, often in the 1–20 MW range, designed for remote communities, military bases, mines, or industrial sites.
Moderator – A material that slows down fast neutrons to thermal energies where fission in U-235 is more likely. Water and graphite are common moderators.
Molten Salt Energy Storage (Thermal Storage) – A non-nuclear heat storage system using molten salt to store thermal energy at high temperature, allowing variable electrical output.
Natrium™ Reactor – A 345 MWe sodium-cooled fast reactor coupled with molten-salt thermal energy storage designed to increase output to roughly 500 MWe for peak demand.
Neutron Cross-Section – A measure of the probability that a neutron will interact with a nucleus (causing fission, capture, or scattering).
Neutron Radiation – Radiation consisting of free neutrons. Neutrons are highly penetrating and are best attenuated by hydrogen-rich materials like water, polyethylene, or concrete.
NQA-1 – A widely used nuclear quality assurance standard defining requirements for design control, procurement, documentation, inspection, and testing in nuclear projects.
NRC (Nuclear Regulatory Commission) – The independent U.S. federal agency that regulates civilian nuclear reactors, fuel cycle facilities, and radioactive materials.
Nuclear “Hub” – A strategic economic concept describing Wyoming as a center for nuclear development—reactor deployment, uranium production, fuel manufacturing, and supply chains.
Nuclear Island – The portion of a plant containing the reactor core and primary nuclear systems, with the highest levels of nuclear safety regulation and security.
Open Fuel Cycle – The U.S. approach in which nuclear fuel is used once in a reactor and then managed as spent fuel for storage and eventual disposal, without reprocessing.
Passive Safety – Safety features that rely on natural physical forces—such as gravity, natural circulation, or convection—rather than powered equipment or operator action.
Pebble Bed Reactor – A subtype of HTGR that uses tennis-ball-sized graphite “pebbles” containing TRISO fuel kernels.
Plume Exposure Pathway EPZ – The NRC’s primary EPZ (about 10 miles) where emergency plans focus on protecting the public from direct exposure and inhalation of radioactive materials.
Pore Volume – In ISR, a measure of the water volume contained in the pore spaces of the ore-bearing formation, used to track circulation progress.
Powder River Basin – A region famous for coal production but also associated with uranium resources in sandstone-hosted roll-front deposits, reinforcing Wyoming’s combined coal-and-uranium energy identity.
Price-Anderson Act – A U.S. law establishing a nuclear liability insurance framework that ensures funds are available in the event of a nuclear incident.
Prompt Neutrons – Neutrons released immediately during fission, making up most of the neutron population that sustains the chain reaction.
Radioactivity – The spontaneous decay of unstable atomic nuclei, releasing particles and/or electromagnetic radiation.
Reactor Core – The active region where fuel is arranged and fission occurs. Core design governs power density, cooling requirements, and safety margins.
Rem – A U.S. unit for equivalent or effective dose (biological impact). 100 rem = 1 sievert.
Reprocessing – A chemical process that separates usable uranium and plutonium from spent nuclear fuel for potential reuse, while isolating high-level waste streams.
Resin Beads – Small polymer beads used in ion exchange columns during ISR processing to capture dissolved uranium from solution.
Roll Front – A curved, moving zone in sandstone where uranium precipitates due to changes in groundwater chemistry, forming the classic “roll-front” ore bodies common in Wyoming.
Roll-Type Deposit – A sandstone-hosted uranium deposit model characterized by roll fronts formed by ancient groundwater flow and redox chemistry.
Safety-Related (SR) – The highest safety classification for structures, systems, and components that are required to prevent or mitigate accidents.
Sandstone-hosted Deposit – A uranium deposit type occurring in porous sandstone where groundwater movement and chemical conditions concentrate uranium. Ideal for ISR.
School of Energy Resources (SER) – A University of Wyoming entity involved in energy research, workforce development, and policy-relevant studies supporting nuclear development.
SCRAM – A rapid emergency shutdown of a nuclear reactor by quickly inserting control rods to halt the chain reaction.
Separative Work Unit (SWU) – A standard measure of the effort required to enrich uranium.
Shielding – Materials placed between radioactive sources and people to reduce radiation exposure (e.g., lead, concrete, water).
Shirley Basin – A historically significant uranium district in Wyoming often associated with early ISR development and renewed interest.
Sievert (Sv) – The SI unit for radiation dose (biological effect). It reflects the health risk from exposure.
Small Modular Reactor (SMR) – A reactor generally producing about 50–300 MWe, designed for factory fabrication and modular construction.
Social License – The long-term acceptance and trust of a project by the local community and stakeholders. Social license is earned through transparency and engagement.
Sodium-Cooled Fast Reactor (SFR) – A fast-spectrum reactor using liquid sodium as coolant. Sodium’s high boiling point enables operation at high temperatures and low pressure.
Source Material – A legal term typically referring to uranium or thorium in any physical or chemical form subject to regulatory control.
Spent Fuel Pool – A deep, heavily shielded water pool used to store spent nuclear fuel after removal from the reactor for cooling and shielding.
Spent Nuclear Fuel (SNF) – Used reactor fuel that no longer efficiently sustains power production but remains highly radioactive and heat-generating.
Station Blackout (SBO) – A condition where a plant loses offsite power and onsite backup power, severely challenging cooling and safety systems.
Steam Generator – A heat exchanger that transfers heat from the reactor coolant (or an intermediate loop) to water to produce steam for the turbine.
Subcritical – A reactor condition where the chain reaction is decreasing over time because neutron losses exceed production.
Supercritical – A reactor condition where the chain reaction is increasing over time because neutron production exceeds losses.
Supply Chain Resilience – The capacity of local and national industries to supply the specialized components, services, and skilled labor needed for nuclear projects reliably.
Tails (Enrichment) – The depleted uranium output stream from enrichment where U-235 concentration has been reduced.
TerraPower – The company leading development of the Natrium advanced reactor and its demonstration project in Wyoming.
Transuranic Waste (TRU) – Waste containing man-made elements heavier than uranium (such as plutonium), typically from defense-related activities.
TRISO Fuel – “Tri-structural isotropic” fuel consisting of tiny uranium kernels coated in multiple ceramic layers, creating a highly robust containment system at the particle level.
Turbine – A rotating machine driven by steam to spin a generator and produce electricity.
U-235 – A fissile isotope of uranium (~0.7% in natural uranium) that readily fissions and is the primary driver of today’s nuclear power fuel.
U-238 – The most common uranium isotope (~99.3% in natural uranium). It is fertile but not fissile.
Underfeeding – An enrichment market strategy where operators use more separative work (SWU) to extract more U-235 from the same amount of feed uranium.
Uranium Energy Corp (UEC) – A uranium company with significant U.S. interests, including Wyoming, involved in the domestic uranium supply chain through projects and asset holdings.
Uranium Hexafluoride (UF₆) – The chemical form of uranium used in gas centrifuge enrichment because it becomes a gas at practical temperatures.
Uranium Recovery – A term often used for ISR operations emphasizing chemical extraction and restoration, distinguishing it from conventional excavation-based mining.
Ur-Energy – A uranium producer active in Wyoming ISR, notably operating the Lost Creek project and associated facilities.
Vitrification – The process of immobilizing high-level liquid radioactive waste by incorporating it into glass, producing stable “glass logs.”
Waste Isolation Pilot Plant (WIPP) – A deep geologic repository in New Mexico used for defense-related transuranic (TRU) waste disposal.
Wellfield – In ISR uranium recovery, the network of injection and production wells installed across an ore zone to circulate lixiviant.
Wyoming Energy Authority (WEA) – A Wyoming state agency involved in energy strategy development, policy planning, and coordination to support energy infrastructure.
Yellowcake (U₃O₈) – A concentrated uranium product (typically a powder) produced from uranium recovery operations and shipped to conversion facilities.
Yellowcake Capital – A nickname reflecting Wyoming’s long-standing status as a leading U.S. uranium-producing state.
Yellowcake Milling – The historic process of crushing and chemically processing ore to produce uranium concentrate.
Zircaloy – A zirconium alloy commonly used as cladding for light-water reactor fuel rods because it resists corrosion in hot water.