Holtec International and EDF Energy have submitted a joint proposal to the UK Government for the deployment of Holtec’s SMR-300 small modular reactors (SMRs) at Cottam in Nottinghamshire. The companies have also signed Heads of Terms to establish a joint venture to advance the project’s development.
The submission was made under UK’s Advanced Nuclear Framework, which was established in February to accelerate deployment of advanced nuclear technologies and encourage greater private sector participation in new nuclear development. Holtec and EDF Energy aim to deliver new nuclear generation by leveraging private investment, proven technology, existing infrastructure, and decades of UK operational experience.
The SMR-300 design is an advanced, passively safe, pressurised light water with a capacity of 300 MWe / 1050 MWt and a design life of 80 years. It uses a single heat transfer circuit and houses a core of 69 Framatome GAIA fuel assemblies. Each assembly uses standard ceramic pellets containing up to 5% enriched uranium dioxide avoiding the need for specialised, hard-to-source fuels. The used fuel pool is located entirely inside the fortified containment structure. The SMR-300 has already advanced past foundational phases of the UK’s Generic Design Assessment (GDA).
In September 2025, Holtec signed a memorandum of understanding with EDF Energy and real estate partner Tritax Management to use SMR-300s at Cottam, a former decommissioned coal-fired power station, to provide power to new data centres on the site. The project will deploy up to four SMR-300 units, which combined would generate around 1.3 GWe. The project would also enable foreign direct investment into the UK, including nuclear fuel fabrication and by Framatome and turbine manufacture by Arabelle Solutions. The 1 GW data centre project is targeted to come online by 2030, with the SMRs beginning operation in the following decade. Completion of the GDA has set the regulatory foundation to build at Cottam.
“Our long-standing partnership with EDF, combined with the opportunity created by the UK’s Advanced Nuclear Framework, provides a strong foundation for advancing SMR-300 deployment at Cottam,” said Dr Rick Springman, President of Holtec International. “This submission represents an important milestone for the project and for advanced nuclear energy in Great Britain. Holtec plans to substantially expand its presence in the UK with a significantly larger operation centre and is evaluating a manufacturing plant to build nuclear equipment in the country.”
Cottam will host second-of-a-kind (SOAK) SMR-300s. First-of-a-kind (FOAK) units are under construction at the Pioneer project at Holtec’s Palisades Energy site in Michigan. This is being executed as a joint venture alongside Hyundai Engineering & Construction. Active pre-construction activities are underway on-site while safety and environmental impact evaluations are conducted. The two SMR units are scheduled to come online in the early 2030s. Pioneer will establish the operational framework, supply chain logistics, and licensing maturity needed to export the reactor technology globally.
Holtec’s construction permit application for the twin Pioneer units is currently under review by the US Nuclear Regulatory Commission, Both the Cottam and Pioneer projects will benefit from growing cooperation between the UK’s Office for Nuclear Regulation and the US Nuclear Regulatory Commission – with the aim of regulators working collaboratively to deliver benefits across both projects.
