Amentum has secured a new engineering services framework to support critical infrastructure and platforms in the UK nuclear sector. The agreement further consolidates the American company’s position in one of Europe’s most active nuclear markets, where it already operates across three distinct and complementary fronts.
The full scope of Amentum’s commitment in the country is substantial. Hinkley Point C, Sizewell C, and Sellafield form the three pillars of an industrial strategy built over many years. At Hinkley Point C, Amentum is the partner responsible for programme, project, and construction management. At Sizewell C — the new nuclear power station given final government approval in June 2025 — the company was selected as the sole partner for programme and project management. The contract will run through to the plant’s commissioning, expected in the mid-2030s. At Sellafield, the role covers engineering design, safety cases, and project management across multiple nuclear decommissioning sites.
The Sizewell C agreement dates back to March 2025. Sizewell C Ltd is 76% owned by the UK government, which has committed £2.5 billion to the project. The reactor design mirrors that of Hinkley Point C — a deliberate choice aimed at transferring efficiencies already gained in practice. At Hinkley, lessons learned between the construction of the first and second units have generated estimated savings of over 20%. Bringing those improvements to Sizewell is one of the explicit goals of the mandate awarded to Amentum.
At Sellafield, the scope is different but no less significant. Under the Decommissioning and Nuclear Waste Partnership, a fifteen-year framework, Amentum has secured leading positions for remediation work within the site’s high-security area. A joint venture called The Decommissioning Alliance — formed by Amentum, AtkinsRéalis, and Westinghouse — has been selected as the partner for retrieving materials from legacy storage ponds. The total value of work attributable to Amentum is estimated at up to £1.4 billion. The company also operates the country’s largest private complex of nuclear laboratories and engineering test facilities, based in Warrington.
The new engineering services framework fits naturally into this already well-structured picture. With more than 6,000 people employed across the UK and a presence covering both new build and decommissioning, Amentum is positioning itself as a cross-cutting supplier across the entire plant lifecycle. A Lifetime Enterprise Agreement with EDF also provides ongoing support to the country’s existing nuclear fleet. The ability to operate simultaneously across contracts of this scale reflects an organisational capacity that few players in the sector can match.
The UK aims to significantly expand its nuclear capacity by 2050. In this context, Amentum’s comprehensive footprint — spanning project engineering, safety, construction management, and decommissioning — makes it a difficult actor to bypass for anyone seeking to operate in the sector. If Sizewell C delivers on schedule, it will also serve as a real-world test of the ability to replicate industrial efficiencies from one construction site to the next: a model that, if proven, could reshape the economics of new nuclear across Europe.
