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ReCore is an integrated engineering concept for closed fuel cycle nuclear power project. It is not a claim that all challenges have been solved. Its purpose is to investigate whether commercially demonstrated technologies, combined in a different architecture, could deliver firm low-carbon power, close the nuclear fuel cycle, and improve manufacturability without relying on speculative materials or fuel forms. Individual subsystems have different Technology Readiness Levels (TRL), and commercial deployment would require significant engineering, qualification, licensing, and economic validation.
The plant class under study is a modular sodium fast reactor of about 720 MWth (~300 MWe class at a ~45% net Brayton target), a closed nitrogen power cycle, and a pyroprocessing path for metallic fuel. First-principles screening of the cycle and heat exchangers currently shows about 43.9% / ~316 MWe. That is under the 45% target, not above it, and it is not a guaranteed plant rating.
Most advanced-reactor proposals start from physics or peak efficiency. ReCore starts from a systems question: what could actually be manufactured, fuelled, and licensed at scale?
Beyond safety and economics, ReCore-Reactor, ReCore-Power, and ReCore-Processing are shaped by supply chains and construction constraints. First-principles design asks what can be built with industrial materials and modular factory content, and with fuel paths that do not wait on scarce enrichment, specialised particle fuels, or ultra-heavy vessel forgings — detailed under Fuel Science and Supply Chain.
Maturity is discussed as component TRLs on each technology page — not as a single score for the whole plant. Building blocks draw on demonstrated SFR, metal-fuel, closed gas-cycle, and pyro programmes. What is largely open is integration: FOAK plant engineering, a commercial pyro hub, safeguards, and licensing. The novelty is less “new physics” than better arrangement of existing technology classes.
Today’s light-water fleets still run largely once-through. They extract only a small fraction of uranium’s energy, leave spent fuel with long-lived actinides that dominate radiotoxicity for on the order of 300000 years, and hold plutonium and depleted uranium inventories with limited productive use. Grids also need dispatchable low-carbon power when wind and solar fall. ReCore explores whether a modular SFR, nitrogen Brayton plant, and metal-fuel recycle pathway could address that set of needs without unobtainium.
Many advanced reactor proposals depend on scarce fuel supply chains — continuous enrichment capacity, HALEU, or specialised fuels such as TRISO — and on a few global forges for ultra-heavy reactor pressure vessels. Those bottlenecks can constrain schedule, cost, and independence. ReCore is aimed the other way: metallic fuel from existing civilian Pu, DU, and recycled actinides, plus a near-atmospheric sodium vessel as modular plate-and-sector work. More detail: Supply Chain, Fuel Science.
The concept intends to recover energy from spent fuel, recovered actinides, depleted uranium, and (for early cores) separated civilian plutonium — after processing, not by “burning waste” as a slogan. Early cores are metallic U-Pu-Zr from existing civilian plutonium and depleted uranium. That fuel has to be cast in a glovebox or hot-cell line; an oxide MOX plant does not make it. Later cores are intended to draw on recycled U-TRU-Zr. The pyro plant is that later step. It is not required before the first core, and it does not by itself make fresh plutonium fuel easier to guard. See Fuel Science and ReCore-Processing.
Multi-recycling of transuranic elements is intended to substantially reduce the long-term radiotoxic inventory that motivates multi-hundred-thousand-year isolation arguments, leaving a residual stream dominated by fission products (often discussed on the order of centuries, e.g. ~500 years in simplified literature comparisons). That is a fuel-cycle goal, sensitive to recovery fractions, losses, multi-recycle operation, and waste-form performance — not an automatic outcome of a single plant.
Metallic fuel in sodium has high thermal conductivity and strong negative temperature feedback. As temperature rises, reactivity tends to fall — a physics-based assist to safety under many overpower or undercooling sequences. This does not mean the reactor cannot melt or that engineered systems are optional. Shutdown systems, decay-heat removal, barriers, and a full licensing safety case remain essential; see Risks & Potentials.
Pyroprocessing for metal fuel can co-recover plutonium with other actinides, rather than isolating a pure Pu product stream as in classical aqueous recycle. That is safeguards-by-process design, not a substitute for formal safeguards, material accountancy, or institutional control.
The reactor island is not the only — or even the largest — uncertainty. A complete industrial fuel cycle needs remote fabrication, pyroprocessing throughput, economics, safeguards, material accounting, and licensing of recycle facilities. Those challenges are as central as core physics; see ReCore-Processing and the open-work notes there.
A closed nitrogen Brayton cycle can vary electrical output through gas inventory control while holding temperatures relatively steady. That approach is potentially well suited to supporting variable renewable generation through flexible operation — if control, economics, and coupling to the nuclear island are demonstrated. It is not claimed as a proven commercial load-following product.
Nitrogen is chemically inert toward sodium, so a Na–H₂O reaction at the power-conversion interface is not the design driver it is for steam SFR plants. ReCore keeps Na and N₂ on opposite sides of the primary heaters, not in a circulating secondary-sodium loop.
The FOAK heater is a set of vertical shrouded bayonet-tube modules with removable swirl cartridges — six identical modules, one 120 MWth unit on each loop (720 MWth plant). The pressure boundary is a straight, smooth tube, closed at the bottom and hung from a single top tubesheet. The screening reference alloy is Alloy 709. Alloy 800H is the commercial alternative; higher nickel means sodium mass transfer is still an open test, so it is not selected. That tubesheet sits in the dry argon cover-gas plenum, above the sodium free surface.
The plenum location is defense in depth against gas entrainment, not a finished safety case. In a tube-shear event, buoyancy of the escaping ~80 bar nitrogen is intended to drive gas up into the argon plenum and its rupture-disk relief path. An intermediate sodium loop still answers things this geometry does not yet prove: isolation of activated sodium and tritium from the turbine, and a break case a regulator will accept. Fast nitrogen isolation valves and a side-stream gas cleanup are candidates around the direct boundary. They are not that proof. The secondary sodium loop stays a licensing fallback.
Primary sodium at about 1 bar is intended to avoid thick high-pressure primary vessels. Combined with modular external loops, the plant aims for a compact industrial footprint without ultra-heavy LWR/PWR-class pressure-vessel forgings.
Construction risk is one of nuclear’s central problems today. ReCore is intended to shift work from a single mega-build toward factory-oriented modules:
Capacity is intended to scale by multiplicity (more identical modules or units) rather than unique mega-projects. That is a construction hypothesis — FOAK schedule still has to be earned.
Core components use industrial practice where possible (316LN vessel and piping, a straight bayonet heater with a removable swirl cartridge, HT9 cladding, ALIP pumps). The heater tube in the screening model is Alloy 709; Alloy 800H is the available alternative and is not adopted until sodium mass transfer is shown to be acceptable. The Brayton recuperator is a diffusion-bonded printed-circuit class. The coolers are catalog gas-to-water exchangers. Printed lattices are a cooler candidate only. Decay heat in a blackout needs always-open sodium-to-air loops. Guard-vessel air cooling on the screening vessel is short of area, and dip coolers do not fit it. What is open is the integration: cartridge withdrawal, argon-plenum seals, seismic tube guides, the tube alloy, the unsized decay-heat loops, and a fuel-fabrication line. Estimated TRLs: ReCore-Reactor, ReCore-Power, ReCore-Processing.