UKAEA’s £55m device successfully takes a step closer to fusion power

Culham Centre for Fusion Energy

TAKING a step to achieving a fusion power plant, the UK Atomic Energy Authority’s (UKAEA’s) £55m (US$72.2m) Mega Amp Spherical Tokamak (MAST) Upgrade device has achieved “first plasma”, after a seven-year build.

Fusion power is a potential source of clean energy that would generate electricity using heat produced by nuclear reactions. In contrast to nuclear fission, which generates heat by splitting atoms, fusion releases energy when atoms are merged. Fusion is cleaner and has a nearly unlimited fuel supply. Additionally, the process is inherently safe, since if there are any abnormalities, the reaction immediately ceases. However, fusion power has yet to be proven at scale and work to develop it is ongoing. Once fusion power is commercially realised it could transform global power generation and help to achieve a lower carbon economy.

The MAST Upgrade can be used to achieve temperatures four times hotter than the centre of the Sun. It will be used to heat plasma to 100m^oC so that researchers can answer key questions for future fusion power plants.

When heated to extreme temperatures, electrons are separated from nuclei and a gas becomes a plasma – an ionised state of matter similar to a gas, composed of positive nuclei and negative electrons. Fusion plasmas are used to provide an environment in which light elements can fuse and yield energy.

Having achieved first plasma with the MAST Upgrade, UKAEA researchers now intend to use it to help tackle one of the biggest challenges in fusion research, which is extracting excess heat from plasma.

UKAEA scientists will now test a new exhaust system called the “Super-X divertor” at MAST Upgrade, which is intended to cool spent plasma down to manageable levels. The system is designed to channel plasma out of the machine at temperatures low enough for its materials to withstand, which means that the components can last longer. Super-X divertor enables an approximate tenfold reduction in heat arriving at the internal surface of the machine, which is a potential “game-changer” for the viability of future fusion power stations.

The success of the MAST Upgrade represents a step in the journey to designing future fusion power facilities.

MAST Upgrade will be the forerunner of the UK’s prototype fusion power plant, Spherical Tokamak for Energy Production (STEP), which is to be constructed by 2040. UKAEA is designing an initial £220m programme funded by the UK Government. The Government announced funding for the fusion power station last year. STEP will be based on MAST Upgrade’s spherical tokamak fusion concept. The machine has an innovative compact spherical design which offers a smaller, cheaper route to fusion power.

MAST Upgrade will also aid preparation for ITER. The magnetic fusion device, currently under construction in the South of France, is the world’s largest science megaproject and is intended to demonstrate fusion power on an industrial scale. First plasma is scheduled for December 2025.

Ian Chapman, CEO of UKAEA, said: “MAST Upgrade will take us closer to delivering sustainable, clean fusion energy. This experiment will break new ground and test technology that has never been tried before. It will be a vital testing facility on our journey to delivering the STEP fusion power plant.”

Amanda Solloway, UK Minister of Minister for Science, Research and Innovation, said: “We want the UK to be a world leader in fusion energy and to capitalise on its amazing potential as a clean energy source that could last for hundreds of years.

“Backed by £55m of government funding, powering up the MAST Upgrade device is a landmark moment for this national fusion experiment and takes us another step closer towards our goal of building the UK’s first fusion power plant by 2040.”