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.

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).

An optional NRC licensing framework for commercial nuclear plants that uses risk-informed, performance-based, technology-inclusive requirements. It provides an alternative to the licensing pathways in Parts 50 and 52.

A group of chemical elements with atomic numbers 89 through 103, including uranium and plutonium. Several actinides are important in nuclear fuel and radioactive waste management.

Modern manufacturing approaches—such as additive manufacturing (3D printing), advanced machining, robotics, and digital inspection—that can reduce lead times and improve repeatability.

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.

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.

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.

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.

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.

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.

A fast fission 'powerhouse' microreactor developed by Oklo Inc. that uses heat pipes to transport heat and is designed to run on HALEU or recycled nuclear fuel.

BWXT Advanced Nuclear Reactor. A transportable 50MWth high-temperature gas-cooled microreactor that uses TRISO fuel for industrial and power applications.

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.

An engineering, procurement, and construction company involved in large infrastructure and energy projects, including nuclear projects. Project-specific contractor roles can change over time.

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.

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.

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.

The ratio of fissile material produced to fissile material consumed in a reactor. Fast reactors can be designed to have a breeding ratio >1, creating more fuel than they use.

A measure of how much energy has been extracted from nuclear fuel, typically expressed as gigawatt-days per metric ton of uranium (GWd/MTU).

BWX Technologies, Inc., a manufacturer and supplier of nuclear components and fuel, including work on advanced reactor technologies.

The electricity a plant actually produces over a period divided by the electricity it could produce if it ran continuously at its rated capacity over that period, expressed as a percentage.

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).

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.

A proposed centralized location designed to store spent nuclear fuel temporarily—typically in dry casks—until a permanent geologic repository is available.

The outer layer of a fuel rod (often made of Zircaloy or specialized steel) that physically contains the fuel pellets and prevents radioactive fission products from escaping into the coolant.

The redevelopment of retired coal plant sites for nuclear generation, often leveraging existing transmission infrastructure, cooling water access, industrial zoning, and local workforce skills.

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.

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.

A chemical process that converts uranium concentrates (yellowcake) into forms usable for enrichment—most commonly uranium hexafluoride (UF₆)—after refining and purification steps.

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, and molten salts.

The central region of the reactor containing nuclear fuel and where the controlled chain reaction produces heat.

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.

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.

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.

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.

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.

A safety philosophy using multiple independent and redundant layers—physical barriers, engineered systems, and procedural controls—to prevent accidents and mitigate consequences.

Neutrons released seconds to minutes after fission by certain fission products. Delayed neutrons make reactor control practical by slowing the timescale of reactivity changes.

Department of Environmental Quality. The Wyoming state agency responsible for environmental oversight and permitting (air, water, land) in conjunction with federal regulations.

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.

Electric generation that can be turned on/off or ramped up/down on demand to balance the grid.

A wearable device (badge or electronic unit) used to measure a worker’s radiation dose over time, supporting compliance with NRC limits and ALARA practices.

A method of storing spent nuclear fuel in sealed steel canisters with concrete and/or additional shielding, typically located on-site at nuclear plants.

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.

An area around a nuclear facility for which emergency protective actions are planned. For many large commercial reactors, planning traditionally covers approximately 10 miles for plume exposure and 50 miles for ingestion pathways; requirements can differ for advanced reactors.

The non-nuclear portion of a plant that typically includes thermal energy storage, turbines, and generators. It is regulated differently than the nuclear island.

A Wyoming incentive approach used to attract energy and industrial investments by sharing early-stage costs, supporting feasibility work, or infrastructure.

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.

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.

Material that is not fissile itself but can be converted into fissile material through neutron capture and subsequent decay (e.g., U-238 can become Pu-239).

Material capable of sustaining a nuclear chain reaction by fission with thermal (slow) neutrons, such as U-235 and Pu-239.

The splitting of a heavy atomic nucleus (like uranium) into smaller nuclei, releasing energy, neutrons, and radiation.

The end-to-end system for producing, using, and managing nuclear fuel: mining → conversion → enrichment → fuel fabrication → reactor use → storage/disposal.

A small ceramic cylinder (commonly uranium dioxide, UO₂) that contains enriched uranium and forms the basic fuel unit in most reactors.

A metal tube (cladding) containing stacked fuel pellets. Cladding must withstand heat, pressure, corrosion, and radiation.

An advanced reactor safety concept where containment is achieved through a combination of high-integrity fuel forms (like TRISO) and engineered barriers rather than solely a large building.

The joining of light nuclei (such as hydrogen isotopes) to release energy. Fusion is an active research field but not yet commercially proven for grid power.

High-energy electromagnetic radiation emitted by radioactive materials. Gamma radiation is highly penetrating and requires dense shielding such as lead or thick concrete.

The dominant modern method for uranium enrichment where UF₆ gas is spun at high speeds to separate lighter U-235 from heavier U-238.

A key technology partner in the Natrium project, providing expertise in sodium-cooled reactor design and fuel handling.

A portable instrument commonly used to detect and measure ionizing radiation (especially beta and gamma).

A permanent underground facility designed for long-term isolation of high-level radioactive waste, relying on geology and engineered barriers.

A description of an energy storage system whose power output is measured in gigawatts. Energy capacity and how long that output can be sustained are measured separately, commonly in gigawatt-hours.

The SI unit for absorbed dose: 1 joule of radiation energy absorbed per kilogram of material.

A major geologic and industrial region in Wyoming associated with uranium resources and ISR development.

The time required for half the atoms in a radioactive sample to decay.

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.

A DOE initiative aimed at establishing a domestic U.S. supply chain for High-Assay Low-Enriched Uranium to reduce reliance on foreign imports.

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.

A passive heat transfer device used in microreactors (like Aurora and Kaleidos) that uses a vacuum-sealed tube and fluid to move heat without pumps or moving parts.

Highly radioactive waste, primarily spent nuclear fuel or waste from reprocessing. HLW requires robust shielding and long-term isolation.

A reactor type that uses an inert gas—typically helium—as coolant and operates at high temperatures, suitable for electricity and industrial heat.

A process where metals (like certain steels or zirconium) become brittle and susceptible to cracking due to the absorption and diffusion of hydrogen, a long-term concern for reactor vessels.

A classification describing systems that contribute to preventing or mitigating accidents, though they may not meet the strict regulatory definition of “safety-related.”

A Wyoming state-level body that reviews and permits major industrial facilities based on local impacts like socioeconomics and infrastructure.

Intermountain West Nuclear Energy Corridor. A designated regional technology hub (spanning Wyoming and Idaho) focused on the development and scaling of advanced nuclear technologies.

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.

A critical component in sodium-cooled reactors that transfers heat from the radioactive primary sodium loop to a non-radioactive secondary sodium loop.

Radiation energetic enough to remove electrons from atoms, potentially causing chemical changes in living tissue (e.g., alpha, beta, gamma, X-rays).

A 1MWe portable, high-temperature gas-cooled microreactor developed by Radiant, designed to replace diesel generators in remote locations.

The project designation for the Natrium nuclear unit planned at the Kemmerer site; Wyoming’s first planned commercial nuclear unit.

The host community for Wyoming’s Natrium demonstration project and a focal point for coal-to-nuclear transition.

A 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.

Uranium enriched above its natural U-235 concentration but to less than 20% U-235. Conventional light-water reactor fuel commonly uses approximately 3–5%; HALEU is the portion above 5% and below 20%.

In ISR uranium recovery, the leaching solution (typically oxygenated water) injected into the ore zone to dissolve uranium minerals.

Operating a power plant in a way that adjusts output up or down in response to grid demand.

An accident scenario involving loss of reactor coolant flow or inventory. A major design basis event for reactor safety.

A major ISR uranium project in Wyoming, representing the modern approach to uranium recovery.

Radioactive waste that is not spent fuel, HLW, or TRU. Includes contaminated clothing, filters, tools, and resins.

The WWII-era program that developed the first nuclear weapons and early nuclear technology, shaping the U.S. uranium industry.

A very small nuclear reactor (1–20 MW) designed for transportability and use in remote communities, military bases, or industrial sites.

A material (like water or graphite) that slows down fast neutrons to thermal energies where fission in U-235 is more likely.

A non-nuclear heat storage system using molten salt to store thermal energy, allowing a plant to boost electrical output during peak demand.

A 345 MWe sodium-cooled fast reactor coupled with molten-salt thermal energy storage, designed to increase output to ~500 MWe for peak demand.

National Environmental Policy Act. A federal law requiring agencies to assess the environmental effects of their proposed actions prior to making decisions.

A measure of the probability that a neutron will interact with a nucleus (causing fission, capture, or scattering).

Radiation consisting of free neutrons. Neutrons are highly penetrating and require hydrogen-rich shielding like water or concrete.

A widely used nuclear quality assurance standard defining requirements for design, procurement, and inspection in nuclear projects.

The independent U.S. federal agency that regulates civilian nuclear reactors, fuel cycle facilities, and radioactive materials.

A strategic economic concept describing Wyoming as a center for reactor deployment, uranium production, fuel manufacturing, and research.

The integrated pathway of nuclear fuel: mining/recovery → conversion → enrichment → fuel fabrication → reactor use → storage/disposal.

The portion of a plant containing the reactor core and primary nuclear systems, subject to the highest safety and security regulations.

A nuclear technology company developing the Aurora 'powerhouse' fast reactor, focusing on using recycled nuclear fuel.

The U.S. approach where nuclear fuel is used once in a reactor and then managed as spent fuel for storage/disposal without reprocessing.

The utility partner (operating as Rocky Mountain Power in WY) collaborating with TerraPower to integrate the Natrium plant into the grid.

Safety features that rely on natural physical forces (gravity, convection) rather than powered equipment or operator action to maintain safety.

A subtype of HTGR that uses graphite “pebbles” containing TRISO fuel kernels, allowing continuous fuel circulation.

An emergency planning area focused on exposure to a radioactive plume, including direct radiation and inhalation. Traditionally about 10 miles for large commercial power reactors, its size can differ under other applicable rules.

In ISR, a measure of the water volume contained in the pore spaces of the ore-bearing formation, used to track circulation and recovery progress.

A region famous for coal production but also containing significant uranium resources in sandstone roll-front deposits.

A U.S. law establishing a nuclear liability insurance framework to ensure funds are available in the event of an incident.

Neutrons released immediately during fission, making up most of the neutron population sustaining the chain reaction.

A nuclear technology startup founded by former SpaceX engineers, developing the Kaleidos portable microreactor.

The spontaneous decay of unstable atomic nuclei, releasing particles and/or electromagnetic radiation.

The chemical decomposition of materials (like water splitting into hydrogen and oxygen) induced by ionizing radiation.

The active region of the reactor where fuel is arranged and controlled fission occurs.

A U.S. unit for equivalent dose (biological impact). 100 rem = 1 sievert.

A chemical process that separates usable uranium and plutonium from spent nuclear fuel for reuse, isolating high-level waste.

Small polymer beads used in ion exchange columns during ISR processing to capture dissolved uranium from solution.

A curved zone in sandstone where uranium precipitates due to groundwater chemistry changes, creating the ore bodies common in Wyoming.

A sandstone-hosted uranium deposit model formed by ancient groundwater flow, explaining why Wyoming contains large, ISR-friendly resources.

The highest safety classification for structures and systems required to prevent or mitigate accidents and maintain reactor safety functions.

A uranium deposit type occurring in porous sandstone where groundwater movement concentrates uranium. Ideal for ISR mining.

A University of Wyoming entity conducting energy research, workforce development, and studies supporting nuclear supply chain readiness.

A rapid emergency shutdown of a nuclear reactor by quickly inserting control rods to halt the chain reaction.

A legal agreement required under the Atomic Energy Act for significant transfers of nuclear material or technology from the U.S. to other nations.

A standard measure of the effort required to enrich uranium.

Materials (lead, concrete, water) placed between radioactive sources and people to reduce radiation exposure.

A historically significant uranium district in Wyoming associated with early ISR development and renewed production interest.

The SI unit for radiation dose (biological effect), reflecting health risk from exposure.

A reactor generally producing 50–300 MWe, designed for factory fabrication, modular construction, and flexible siting.

The long-term acceptance and trust of a project by the local community and stakeholders, earned through transparency and engagement.

A fast-spectrum reactor using liquid sodium as coolant, allowing high-temperature, low-pressure operation.

An NRC regulatory term generally covering uranium, thorium, and certain ores containing them. Its precise meaning and exemptions are defined in federal regulations.

A deep, heavily shielded water pool used to store spent nuclear fuel immediately after removal from the reactor for cooling and shielding.

Used reactor fuel that no longer efficiently sustains power production but remains highly radioactive and heat-generating.

A condition where a plant loses both offsite power and onsite backup power, severely challenging safety systems.

A heat exchanger that transfers heat from the reactor coolant to water to produce steam for the turbine.

A reactor condition where the chain reaction is decreasing over time (neutron losses exceed production).

A reactor condition where the chain reaction is increasing over time.

The capacity of industries to supply specialized components, services, and skilled labor needed for nuclear projects reliably.

The depleted uranium output from enrichment where U-235 concentration has been reduced.

The company leading development of the Natrium advanced reactor and its demonstration project in Wyoming.

The ratio of useful work output to heat input. High-temperature reactors (like HTGRs and SFRs) typically achieve higher thermal efficiency than traditional light-water reactors.

Waste containing man-made elements heavier than uranium (like plutonium), typically from defense activities. Managed separately from commercial fuel.

“Tri-structural isotropic” fuel consisting of tiny uranium kernels coated in ceramic layers, creating robust containment at the particle level.

A rotating machine driven by steam to spin a generator and produce electricity.

A fissile isotope of uranium (~0.7% in natural uranium) that readily fissions.

The most common uranium isotope (~99.3% in natural uranium). It is fertile (can breed plutonium) but not fissile.

An enrichment market strategy where operators use more work (SWU) to extract more U-235 from less feed uranium.

The technical term for 'Yellowcake' (U3O8) after it has been milled/processed but before it is converted into UF6.

A uranium company with significant U.S. interests, including projects in Wyoming.

The chemical form of uranium used in gas centrifuge enrichment because it becomes a gas at practical temperatures.

A term often used for ISR operations emphasizing chemical extraction and restoration rather than excavation.

A uranium producer active in Wyoming ISR, notably operating the Lost Creek project.

The process of immobilizing high-level liquid radioactive waste by incorporating it into stable glass logs.

A safety metric measuring how reactor reactivity changes as bubbles (voids) form in the coolant. A negative void coefficient is a critical safety feature.

A deep geologic repository in New Mexico used for defense-related transuranic (TRU) waste disposal.

The network of injection and production wells in ISR installed across an ore zone to circulate solutions.

A state agency involved in energy strategy development, policy planning, and supporting nuclear innovation.

A nuclear design firm developing the Xe-100 high-temperature gas-cooled pebble bed reactor.

An 80MWe high-temperature gas-cooled pebble bed reactor developed by X-energy, designed for modular deployment.

A concentrated uranium powder (U₃O₈) produced from uranium recovery and shipped to conversion facilities.

A nickname reflecting Wyoming’s long-standing status as a leading U.S. uranium-producing state.

The historic process of crushing and chemically processing ore to produce uranium concentrate.

A zirconium alloy commonly used as fuel rod cladding because it resists corrosion and absorbs few neutrons.