...AND CHEAPER...:

However, Iter is vastly different to the design for the UK's Step reactor. Iter uses a doughnut-shaped reactor design, but Step will use a spherical tokamak design, which is more compact. This reduction in size will mean that the magnets can be much smaller, potentially saving millions of pounds.

Part of the plan to support the building of the Step reactor is the new fusion research facility to be constructed alongside the Nuclear AMRC in Rotherham. This will take the concept design for the reactor and transform it into buildable components that are ready for use in industry.

One of the main advances in fusion research that makes Step viable is the Super-X divertor. As fusion involves temperatures as hot as the Sun, this heat has to go somewhere. If the vessel's walls experience this thermal load, they would instantly melt, causing the fusion to fail. Instead, this plasma exhaust, is directed towards the divertor.

"Plasma exhaust is one of the key technical challenges facing fusion. Byproducts and excess heat from the plasma will need to be removed, without damaging the surrounding surfaces. We do this with an exhaust system known as a divertor," says Chapman. "The new system we're trialling at the Mast Upgrade should reduce the heat to manageable levels, such as that found in a car engine."

The divertor allows the waste material created during the fusion process to be removed as the reactor is working. As the high-energy plasma particles strike the targets, their kinetic energy is transformed into heat, which is removed by various cooling methods.

One way to make the 2040 date more achievable could be to use part of an existing power plant, with the old power-generation system replaced with the new Step reactor. The benefit of this is that the energy conversion process, for creating electricity, remains the same.

"If the decision is made to build the Tokamak, but to utilise an existing site with an existing turbine building, then it becomes a lot more feasible to me," says Storer. "All that time and cost has already been sunk."

The main hurdle will be the interface between the new fusion reactor and existing power plant. Sadly, there is no such thing as a USB port for power plants. However, the time and cost of having to build an entirely new power plant is significant. The comparatively small size of the Step reactor is also advantageous.

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