Glossary of Terms

Glossary: ReCore.One terminology

Terms used in the ReCore engineering concept (nuclear physics, materials, heat transport, pyroprocessing). Definitions support educational pages; they are not design guarantees.

Reactor & Physics

• SFR (Sodium Fast Reactor): A reactor that uses liquid sodium as a coolant and operates in the fast neutron spectrum, allowing for the burning of transuranic elements.
• Fast Spectrum: A neutron energy regime where neutrons have high kinetic energy, enabling them to fission heavy isotopes that build up as waste in traditional reactors.
• Negative Void Coefficient: A safety characteristic where the loss of coolant density (voiding) naturally reduces the reactor’s power level.
• Actinides: Heavy radioactive elements with atomic numbers 89 to 103. In the context of waste, it specifically refers to long-lived Transuranics.
• TRU (Transuranic Elements): Elements heavier than Uranium (e.g., Plutonium, Americium, Curium) that are the primary cause of long-lived nuclear waste radiotoxicity.

Engineering & Materials

• ALIP (Annular Linear Induction Pump): An electromagnetic pump with no moving parts that moves liquid sodium using travelling magnetic fields.
• Helix HX (Helical Heat Exchanger): Shell-and-tube unit with helical tubes designed for high heat-transfer rate and very low pressure drop. Internal fins and twisted-tape inlets enhance the gas side (e.g. high-pressure N₂). Used for primary Na→N₂ duty and for Brayton recuperator / precooler service.
• Alloy 709: Fe-20Cr-25Ni advanced austenitic stainless steel. Baseline tube/tubesheet alloy for the ReCore primary heater — higher creep strength at ~600 °C than 316LN/316H, thinner walls at 80 bar, and better formability for internally finned helical coils.
• Single-wall tube: One pressure boundary between N₂ and sodium. The FOAK ReCore heater uses this architecture; an 80 bar breach is mitigated by acoustic leak detection, fast isolation / blowdown, and cover-gas relief rather than a second wall.
• ALD (Acoustic Leak Detection): High-temperature ultrasonic hydrophones in sodium, intended to hear the cavitation signature of high-pressure N₂ entering liquid Na in milliseconds.
• Bonded Inserts: Fin or swirl inserts metallurgically fixed inside seamless tubes (drawn, tape, or bonded geometries) before or after helical forming.
• HT9: Ferritic–martensitic steel used as the baseline fuel cladding for ReCore metallic fuel; strong heritage in SFR metal-fuel programmes (e.g. FFTF / EBR-II class).
• P92 / NF616 / Grade 92: Advanced 9%Cr creep-resistant steels (power-plant pedigree). Optional cladding upgrades at fuel exchange when qualified for SFR metal-fuel duty — not required for FOAK cores.
• ODS Steel (Oxide Dispersion Strengthened): Oxide-dispersion alloys studied for high-flux cladding; not the ReCore baseline (kept only as a possible long-term R&D option outside the core concept).
• LVEB (Local Vacuum Electron Beam Welding): A precision welding technology that creates a localized vacuum over the weld seam, allowing for high-integrity joining of large structures on-site without a full vacuum chamber.

Recycling & Chemistry

• Pyroprocessing: A high-temperature, electrochemical recycling method for nuclear fuel that operates in molten salts rather than aqueous acids.
• LCC (Liquid Cadmium Cathode): A specialized component in an electrorefiner that co-deposits Plutonium and other actinides, ensuring they are never isolated in pure form.
• Electrorefiner: The heart of the pyroprocessing facility where electricity separates uranium and transuranics from fission products.
• Sodalite: A synthetic ceramic waste form used to permanently immobilize salt-based nuclear waste.

Strategy & Deployment

• TRL (Technology Readiness Level) {#trl}: A 1–9 maturity scale (NASA/EU-style) from basic principles to proven commercial systems. ReCore pages use estimated component TRLs and heritage notes; they are not official certified scores, and a full FOAK plant is not claimed as TRL 9.
• Iso-Breeder: A reactor design that produces exactly as much fissile material as it consumes, allowing for long-term operation without requiring fresh enrichment or fuel imports.
• FOAK (First-Of-A-Kind): The first full-scale deployment of a new technology or design.
• Bridge Fuel: A temporary fuel (e.g., U-Pu-Zr) used to start up the first reactors before the full closed-loop recycling facility is operational.
• EPZ (Emergency Planning Zone): The area around a nuclear plant with specific emergency planning requirements. EPZ size is a regulatory outcome, not something a concept document can assert; ReCore does not claim a site-boundary EPZ as achieved.