MAST Upgrade internal view

Fusion power closer to viability with exhaust breakthrough

Image credit: EUROfusion

Fusion power plants could be on the brink of commercial viability thanks to a new exhaust system developed by scientists at the UK Atomic Energy Authority (UKAEA).

The body hailed the success of its ‘MAST Upgrade’ experiment, which is being conducted at Culham, near Oxford, UK.

Fusion energy is based on the same principle by which stars create heat and light. Using a machine called a ‘tokamak,’ a fusion power station will heat an ionised gas, or ‘plasma’, enabling two types of hydrogen nuclei (deuterium and tritium) to fuse together to release energy that can generate electricity.

But one of the key challenges in getting tokamaks on the electricity grid is removing excess heat produced during fusion reactions. Without an exhaust system that can handle this intense heat, materials will have to be regularly replaced – significantly affecting the amount of time a power plant could operate for.

The MAST Upgrade machine - exterior view

Exterior view of the MAST Upgrade machine

Image credit: EUROfusion

The new system, known as a ‘Super-X divertor’, would allow components in future commercial tokamaks to last for much longer; greatly increasing the power plant’s availability, improving its economic viability and reducing the cost of fusion electricity.

Tests at MAST Upgrade, which began operating in October 2020, have shown at least a tenfold reduction in the heat on materials with the Super-X system.

The UKAEA described the technology as a “game-changer” for achieving fusion power plants that can deliver affordable, efficient electricity.

A prototype fusion power plant is currently being planned for completion in the early 2040s, using a compact machine called the ‘spherical tokamak’. The Super-X divertor is particularly suited to the spherical tokamak, the body said.

UKAEA’s lead scientist at MAST Upgrade, Dr Andrew Kirk, said: “These are fantastic results. They are the moment our team at UKAEA has been working towards for almost a decade.

“We built MAST Upgrade to solve the exhaust problem for compact fusion power plants, and the signs are that we’ve succeeded.

“Super-X reduces the heat on the exhaust system from a blowtorch level down to more like you’d find in a car engine. This could mean it would only have to be replaced once during the lifetime of a power plant.

“It’s a pivotal development for the UK’s plan to put a fusion power plant on the grid by the early 2040s – and for bringing low-carbon energy from fusion to the world.”

Professor Dame Lynn Gladden, executive chair at The Engineering and Physical Sciences Research Council, said: “The UK has been a leader in the development of fusion energy for many years, strongly supported by EPSRC since the early 2000s. These first results from the MAST Upgrade project demonstrate that fusion as an energy source has the potential to radically change the world’s energy supply.”

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