Great British Energy – Nuclear (GBE-N) has selected the Litmus Nuclear joint venture between Amentum and Cavendish Nuclear as Owner’s Engineer for its small modular reactor (SMR) project in the UK. The 14-year contract, with a maximum value of $406m, covers work to deploy GBE-N’s preferred reactor technology from Rolls-Royce SMR at the Wylfa site in North Wales.
In June 2025 Rolls-Royce SMR was selected as the UK government’s preferred technology for the first SMR project. In November 2025, the UK Government selected Wylfa on the island of Anglesey, North Wales, as the site to host the three Rolls-Royce SMR units with the potential to increase this to eight units. A final investment decision is expected to be taken in 2029.
Litmus Nuclear, led by US-based engineering and technology company Amentum, will provide essential independent assurance and expert technical advice including design, safety, engineering, construction and commissioning to support GBE-N’s goal of reaching a final investment decision for the Wylfa programme. The joint venture partners will ensure that the SMR programme is robust, meets regulatory requirements and can deliver reliable, low-carbon power for decades to come.
In January, Amentum, which has a solid presence in the UK, was selected as the programme delivery partner for the first deployments of the Rolls-Royce SMR. Rolls-Royce SMR and Amentum signed a collaborative agreement giving Amentum the programme delivery role responsible for integration, oversight and governance, construction management and execution of SMR deployment.
The Rolls-Royce SMR, a 470 MWe design based on a small pressurised water reactor, will is designed to provide consistent baseload generation for at least 60 years. Some 90% of the SMR will be built in factory conditions, limiting on-site activity to assembly of pre-fabricated, pre-tested, modules which has the potential to drastically shorten build schedules.
“This award recognises Amentum’s expertise in accelerating the global expansion and revitalization of nuclear energy and also underlines our central role in the UK’s nuclear ambitions, alongside our work at Hinkley Point C and Sizewell C,” said Loren Jones, Senior Vice President and head of Amentum’s Energy & Environment-International business. “We will draw upon our deep technical nuclear knowledge to provide independent technical and delivery assurance so that GBE-N can progress the SMR programme and make a vital contribution to strengthening energy security and the UK’s industrial base.”
GBE-N CEO Simon Roddy noted: “As we continue to bring together the coalition required to deliver the UK’s first SMRs, I’m pleased to welcome Amentum and Cavendish to the team. Their valuable expertise will be instrumental in assuring GBE-N’s project moves with pace and determination, and I look forward to working with them over the coming years.”
