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Initial results from UKAEA’s Mast Upgrade experiment in Culham, near Oxford, demonstrated the effectiveness of an innovative exhaust system that could keep fusion power plants operating for much longer.
Using a tokamak reactor, fusion power stations will heat a plasma to enable types of hydrogen to fuse together, releasing energy that can be used to generate electricity.
A key challenge in getting tokamaks on the electricity grid is removing excess heat produced during fusion reactions, however. Without an exhaust system that can handle the intense heat, materials will have to be replaced regularly – significantly affecting the amount of time a power plant can operate for.
The new system, known as a Super-X divertor, could allow components in future commercial tokamaks to last for much longer. This in turn would greatly increase the power plant’s availability, improving economic viability and reducing the cost of fusion electricity.
Tests at the 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 announced today (26 May).
The new design essentially gives the tokamak a longer ‘exhaust pipe’, the UKAEA said. The divertor works by ‘steering’ hot particles from the plasma out of the machine, and injects a gas to spread the heat out and help cool the plasma to manageable levels.
“These are fantastic results. They are the moment our team at UKAEA has been working towards for almost a decade,” said lead scientist Dr Andrew Kirk. “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.”
UKAEA plans to build a prototype fusion power plant – known as Step – by the early 2040s, using a compact machine called the spherical tokamak. The agency said the success of the Super-X divertor is a huge boost for engineers designing the Step device, as it is particularly suited to the spherical tokamak.
Mast Upgrade is funded by the government’s Department for Business, Energy & Industrial Strategy, the Engineering & Physical Sciences Research Council (EPSRC) and the EUROfusion consortium.
EPSRC executive chair, Professor Dame Lynn Gladden, 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.”
UKAEA will announce the results at today’s official opening of the Mast Upgrade facility. Guest of honour, British astronaut Tim Peake, will create his own artificial ‘star’ by running a plasma test on the machine.
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