US and UK Sign Fusion Energy Partnership to Accelerate Commercial Deployment

The US Department of Energy's Princeton Plasma Physics Laboratory and the United Kingdom's Atomic Energy Authority have signed a memorandum of understanding to strengthen cooperation on fusion energy, allowing the two governments to advance the physics and technology basis for future commercial fusion power plants through joint development projects and sharing of key technical data. The agreement builds on King Charles's April 2026 address to a joint session of Congress underscoring the need for continued British and American cooperation on fusion, with both the DOE and UK government having released fusion energy roadmaps in 2026 to guide the technical achievements needed to accelerate commercial deployment. The UK roadmap focuses on delivering a commercial fusion machine by 2040 through the Spherical Tokamak for Energy Production prototype at West Burton in Nottinghamshire, while the US strategy lays out a more aggressive timeline for commercialising fusion energy by the 2030s leveraging private sector investment from companies including Helion Energy, which began construction of its Orion fusion power plant complex in Malaga, Washington in July 2025.

 

The UK STEP Programme and 2040 Delivery Timeline

 

The UKAEA established UK Fusion Energy as a subsidiary company to deliver the STEP spherical tokamak fusion power plant prototype, with a construction and fusion integration team expected to be assembled by October 2026 and the development consent order for the STEP plant to be submitted by March 2029, paving the way for government permit approval to commence construction. The STEP programme at West Burton in Nottinghamshire represents the UK's primary public sector fusion delivery vehicle, combining UKAEA's decades of fusion research expertise with private sector integration partnerships to produce a complete commercial fusion product by 2040. The 2040 target reflects the technical complexity of delivering a first-of-kind commercial fusion power plant from current technology readiness levels, requiring sustained progress across plasma physics, materials science, tritium breeding, superconducting magnet development and power conversion engineering simultaneously.

Berzak Hopkins, PPPL's Associate Lab Director for Strategy and Partnerships, said the strategic partnership allows the two nations to unite capabilities and deliver on the shared mission of bringing fusion from the lab to the grid, describing global partnerships as the mechanism through which PPPL amplifies its impact and pushes the boundaries of fusion science. The MOU structure, enabling participation in joint development projects and sharing of key technical data, provides a framework for collaboration that avoids the intellectual property and national security constraints that can complicate deeper commercial partnerships while still enabling the scientific and technical exchange needed to accelerate both nations' programmes. The fusion cooperation announcement reflects a broader pattern of US-UK scientific and technology partnership intensification across AI, nuclear and advanced energy technologies that has characterised bilateral relations in 2026.

 

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US Private Sector Fusion Progress

 

Helion Energy marked one year since beginning construction of its Orion fusion power plant complex in Malaga, Washington in July 2025, receiving both a Radioactive Materials License and Radioactive Air Emissions License from Washington State in June 2026, confirming the plant is ready to operate once construction is complete with the generator building's initial earthwork having begun in spring 2026. The US fusion strategy's more aggressive commercialisation timeline relative to the UK's 2040 target reflects the substantially larger private sector investment flowing into American fusion companies, where venture capital and strategic corporate investment has funded multiple companies pursuing diverse fusion technology approaches across magnetic confinement, inertial confinement and field-reversed configuration concepts. TAE Energies entered a joint venture with UKAEA on May 2026, creating TAE Beam UK to commercialise particle accelerator technology for fusion and non-fusion applications, with neutral beam technology described as critically enabling for heating and sustaining fusion reactions in a power plant design TAE describes as smaller, more efficient and more cost-effective than competing concepts.

TAE is in the process of selecting a site for its first US power plant, with plans to begin construction of a first 50-megawatt plant by end of 2026 following completion of its merger with Trump Media and Technology, with future fusion plants planned at 350 to 500 megawatts. The TAE Beam UK joint venture with UKAEA demonstrates that the US-UK fusion partnership extends beyond government-to-government laboratory cooperation into commercial technology development and deployment, with American fusion companies establishing British subsidiaries to access UKAEA expertise and position for European market development alongside their primary US focus.

 

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G20 and International Fusion Policy Context

 

The US will host the G20 summit in Miami in December 2026 with fusion power and small modular reactors expected to be core focuses, with the three summit themes of reducing regulation, unlocking reliable energy supply chains and pioneering technology innovation providing a policy framework within which fusion commercialisation can be advanced at the multilateral level. Jarrod Agen, Executive Director of the White House's National Energy Dominance Council, described planned discussions on modernising regulations across countries to better incorporate newer nuclear technologies including small modular reactors, advanced reactors and fusion power reactors, with harmonisation among the US Nuclear Regulatory Commission and other G20 nuclear regulators identified as a mechanism for encouraging greater innovation and technology sharing. The presence of Westinghouse, X-Energy, Last Energy, Rolls-Royce, GE Vernova, TAE Technologies and Tokamak Energy at preparatory G20 fusion discussions illustrates the breadth of the commercial fusion and advanced nuclear ecosystem that is seeking regulatory modernisation as a prerequisite for accelerated deployment.

Sustained progress on the STEP programme construction consent timeline, Helion's Orion plant completion and TAE's first plant construction commencement over the next two to three years would provide the concrete commercial milestones needed to validate the fusion energy timelines that the US and UK roadmaps project, moving the technology from a credible long-term clean energy prospect to an imminent commercial reality with direct implications for power sector decarbonisation planning.

 

Source: S&P Global Inc