The site of a former coal-fired power plant in Nottinghamshire has been selected by the U.K. Atomic Energy Authority as the site for a prototype nuclear fusion power station, which could pave the way for a new form of low-carbon power in the U.K.

The West Burton A power station is slated for closure by its owner, French energy giant EDF, in March 2023. Following development and acceptance of a concept design by 2024, the site will then host the Spherical Tokamak for Energy Production (STEP) fusion power station, which is expected to be built by 2040.

The planned fusion facility is based on a tokamak design that uses magnetic fields to confine a plasma of heavy isotopes of hydrogen, tritium and deuterium, which fuse under extreme heat and pressure. STEP would be a variant on the basic tokamak, a spherical tokamak that holds the plasma in a cored-apple shape. Data gleaned from the Mega Amp Spherical Tokamak-Upgrade spherical tokamak device, which began operating in October 2020, will heavily inform the STEP design.

With a total diameter of only around 10 m, STEP will be relatively small in comparison to the International Thermonuclear Experimental Reactor. The design will reduce costs but will not allow for tritium breeding.

The STEP program will demonstrate the ability to generate net electricity from fusion, determine how the plant will be maintained through its operational life, and prove the potential for the plant to produce its own fuel.