A company backed by Amazon's Jeff Bezos is set to build a large-scale nuclear fusion demonstration plant in Oxfordshire.
Canada's General Fusion is one of the leading private firms aiming to turn the promise of fusion into a commercially viable energy source.
The new facility will be built at Culham, home to the UK's national fusion research programme.
It won't generate power, but will be 70% the size of a commercial reactor.
General Fusion will enter into a long-term commercial lease with the UK Atomic Energy Authority following the construction of the facility at the Culham campus.
While commercial details have not been disclosed, the development is said to cost around $400m.
It aims to be operational by 2025.