Nuclea agrees to buy molten-salt reactor designs built to burn nuclear waste

At the moment when spent nuclear fuel is usually treated as a liability, Nuclea Energy has agreed to buy a portfolio designed to turn part of it back into reactor fuel. The deal brings Moltex Energy’s technology assets—including the 300 to 500 MWe Stable Salt Reactor–Wasteburner, or SSR-W—into the same program as Nuclea’s lead-cooled microreactors.

WATSS, short for Waste to Stable Salt, connects the spent-fuel chemistry to the reactor design. The process extracts transuranic actinides from spent fuel assemblies and mixes them into liquid chloride salts, avoiding pure plutonium streams. Canadian Nuclear Laboratories tested the chemical separation with actual irradiated fuel, under a framework involving Canada’s nuclear regulator. Those results support the fuel concept, but they are not a demonstration of a commercial reactor.

The SSR-W is built around a different arrangement from many historical molten-salt designs. Instead of pumping radioactive fluid through external pipes, it keeps the molten fuel inside stationary tubes submerged in a separate pool of coolant salt at atmospheric pressure. A fast-neutron core is then intended to split the long-lived actinides recovered by WATSS, while natural convection carries away decay heat without emergency electrical power.

The acquisition also adds FLEX, a thermal-neutron reactor that uses graphite blocks to slow neutrons and low-enriched uranium fuel salt held in the same kind of static pins. Its coolant is designed to reach around 750 degrees Celsius, a temperature suited to synthetic-fuel synthesis and heavy manufacturing. Nuclea’s existing Morpheus microreactor, by contrast, targets 3.5 to 50 megawatts and is intended for factory assembly and shipment to remote mining operations, island grids, or defense sites.

So what changes, concretely? Nuclea gains a route connecting spent-fuel chemistry to a reactor designed for large electricity output, alongside a separate high-temperature system for industrial heat. The portfolio includes 80 granted patents across nine technical categories and nine pending fuel-reprocessing patents, refined through more than a decade of collaborative research. The technology is still at the design and testing stage: closing the purchase depends on statutory screening under the UK’s National Security and Investment Act, and the companies have set a three-month deadline to meet the remaining conditions.