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Westinghouse accident tolerant fuel in US licensing 'first'

Monday, 19 August 2024

In a first for the USA, the country's nuclear regulator has approved an increase in the burnup limit for Westinghouse's Encore accident tolerant fuel design, paving the way for longer and more economic fuel cycles.

Westinghouse accident tolerant fuel in US licensing 'first' — Developing core designs with higher burnup brings value to utility customers (Image: Westinghouse)

The US Nuclear Regulatory Commission (NRC) approval means that for the first time, nuclear fuel batch reloads in the USA will be able to exceed a burnup limit of 62 gigawatt days per metric tonne of uranium.

Burnup is a measure of the thermal energy released by nuclear fuel relative to its mass - how much uranium is "burned" - or consumed - before the fuel is removed from a reactor when it can no longer economically keep a chain reaction going. Pressurised water reactors in the USA currently operate on 18-month fuel cycles. Higher burnups mean that fuel can stay inside the reactor for longer, which can lead to more economic operation.

"We are very pleased to receive approval from the Nuclear Regulatory Commission for incremental burnup in our nuclear fuel," Westinghouse President of Nuclear Fuel Tarik Choho said. "This milestone marks the start of production of nuclear fuel with increased capacity for pressurised water reactors, vastly improving fuel costs for US utility customers."

Westinghouse is one of three US nuclear fuel suppliers working with the US Department of Energy (DOE) to develop new accident tolerant fuels - or ATFs - for US reactors. ATFs use new fuel and cladding mixtures that could help improve the overall economics and performance of today’s reactors as well as allowing for longer response times at high temperatures in severe, beyond design basis, accident situations.

The initial phase of Westinghouse's EnCore programme focuses on chromium coated cladding (fuel rods) loaded with ADOPT (Advanced Doped Pellet Technology) fuel pellets coupled with higher enrichment and higher burnup.

Earlier this month, the company announced the production of its first fuel pellets containing higher enrichment levels than the 3-5% enrichment currently used in fuel for commercial reactors. LEU+ ADOPT pellets containing up to 8% by weight uranium-235 were pressed at the company's Springfields fuel manufacturing facility in the UK using a higher enriched uranium oxide powder prepared by DOE's Idaho National Laboratory, and will be fabricated into lead test assemblies to be shipped back to the USA for irradiation testing at unit 2 of Southern Nuclear's Vogtle plant in Georgia next year.