NuScale study confirms suitability of SMR design to use MOX fuel

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The UK's plutonium stockpile could be used to fuel a new design of small modular reactor proposed by US company NuScale

NuScale Nuclear power, the Oregon-based nuclear hardware specialist which last autumn unveiled small modular reactor (SMR) technology that it hopes to use in the UK market, has now revealed that its design has been evaluated for partial or full fuelling with mixed uranium and plutonium oxide (MOX) fuels. The company commissioned a study from the UK National Nuclear Laboratory to evaluate whether the reactors could be used to run with the fuel, which can be formulated to use up a stockpile of civil (ie, non-weaponised) plutonium.

The SMR technology, currently untried but slated to come into service in the US in 2023 consists of 50MW pressurised water reactor units designed to be installed in a cluster of up to 12 units within single power stations, to give an option for flexible-output stations whose output could be varied quickly, for example to balance intermittent renewables. Like all SMRs, they could be built in relatively small factories from components cast in conventional foundries, thereby reducing the cost and difficulty of building nuclear reactors.

The NNL study looked at both partial and full loading of the reactor core with MOX, and confirmed that neither scenario would affect the reactor’s design or operation. It also showed that a 12-unit power station running on full MOX would consume a 100-tonne stockpile of plutonium – similar to the size of the UK’s plutonium holding, which is stored at Sellafield – in about 40 years; this would generate 200million MWhr of electricity, while degrading the isotopic content of the plutonium to make it unusable for nuclear weapons.

"The National Nuclear Laboratory has been pleased to work with NuScale on a commercial basis to help demonstrate the capability of their SMR in relation to MOX fuel,” said NNL Business Leader for Fuel and Reactors, Dan Mather. “Reuse of the plutonium for low carbon power generation could be a valuable way forward for dealing with the UK's nuclear legacy." One option currently being considered for the UK’s plutonium stockpile is conversion to MOX by a process used by Areva on France: Areva already has an important foothold in the UK with its plan to build its EPR reactor design at Hinkley Point in Somerset.

Chancellor of the exchequer George Osborne announced in December’s Spending Review that the Treasury had earmarked at least £250m to be spent on SMR technologies by 2020, and indicated that there would be a competition to identify the best-value design from prospective vendors with a view to building power stations in the 2020s