The US Department of Energy (DOE) has completed an environmental assessment clearing the way for the fabrication of high-assay low-enriched uranium (HALEU) fuel for advanced nuclear reactors at the Idaho National Laboratory (INL). Meanwhile, the US Department of Defense (DOD) has issued a Request for Information (RFI) for a small mobile reactor using HALEU fuel to provide electrical power in rapid response scenarios.
The DOE’s HALEU is from used fuel from the Experimental Breeder Reactor-II (EBR-II), which operated at the site from 1964 to 1994. Since 2000, DOE has employed an electrometallurgical treatment process at the MFC to refine and downblend the used high-enriched uranium fuel from the now-decommissioned reactor. About 10 tonnes of HALEU has been produced as a result of this process and is currently stored at INL.
Many advanced reactor designs currently under development will require HALEU fuel, enriched to between 5% and 20% in fissile uranium-235 (U235). The low-enriched uranium fuel used in today’s nuclear power plants typically contains less than 5% U235. There are at present no commercial facilities in the US that are immediately capable of producing HALEU.
The decision means the federal government can fabricate HALEU fuel at INL from the lab’s existing HALEU feedstock – mostly from the treatment of EBR-II fuel but also from some other small quantities of HALEU stored at the site – to support the near-term research, development and demonstration needs of private-sector developers and government agencies, including advanced reactor developers.
The mobile nuclear reactor is required to produce a threshold power of 1-10 MWe of generation, which it must be able to produce for at least three years without refuelling. It must weigh less than 40 tonnes and be sized for transportability by truck, ship, and C-17 aircraft. Designs must be “inherently safe”, ensuring that a meltdown is “physically impossible” in various complete failure scenarios such as loss of power or cooling, and must use ambient air as their ultimate heat sink, as well as being capable of capable of passive cooling.
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