On 14 September 2026, the UK Atomic Energy Authority (UKAEA) and the US Department of Energy's Princeton Plasma Physics Laboratory (PPPL) signed a Joint Declaration of Intent at the Global Fusion Policy Summit in London to explore linking their fusion supercomputing platforms. The proposed SUNRISE–STELLAR-AI Federation would connect UKAEA's SUNRISE supercomputer with PPPL's STELLAR-AI platform, allowing researchers on both sides of the Atlantic to train AI models on results from both laboratories.

The collaboration would draw on experiments from UKAEA's MAST Upgrade facility in Oxfordshire and PPPL's NSTX-U facility in New Jersey, both compact spherical tokamaks with similar designs. UKAEA said the federation aims to shorten the design cycle for future fusion power plants and support projects including the UK's STEP and US concepts such as PPPL's STAR. It builds on a memorandum of understanding signed in June.

UKAEA said SUNRISE is the UK's first AI supercomputer dedicated to fusion energy, backed by £45 million from the UK government. Following the summit, the two organisations said they had discussed possible next steps, including exploring digital twins of both facilities and moving computing jobs between platforms.