Scientists at the UK Atomic Energy Authority have made a significant breakthrough with the country’s central nuclear fusion experiment that takes the prospect of practically limitless clean energy one step closer. The Mast Upgrade, as the project is known is taking place at a reactor facility in Culham in Oxfordshire, could one day lead to active nuclear fusion, as opposed to today’s nuclear fission, powerplants capable of powering the whole of the country.

Nuclear fusion differs from nuclear fission in that it joins rather than splits atoms. It’s the same process that generates the sun’s heat and the reverse technique means that the process results in almost no radioactive waste.

The tricky part is that making nuclear fusion work means maintaining temperatures at over 100 million degrees. Superheated plasma is created which, if a meltdown is to be avoided, has to be given an escape route. The problem is escaping fumes are so hot they obliterate anything they touch.

The Mast Upgrade scientists now believe they have demonstrated they can now cool the fumes quickly enough to be allowed to dissipate. That would allow for a much smaller reactor than those currently used in nuclear fusions experiments. Smaller powerplants would be much cheaper to build which would, in turn, make the energy technology much more commercially viable.

Professor Ian Chapman, chief executive of the UK Atomic Energy Authority, referred to the development as “a success in one of fusion’s biggest challenges”.

The main prototype fusion reactor in existence today is the Iter, located in southern France. The site is spread over 42 hectares and needs to be so big to allow the fumes from the superheated plasma created by the fusion process enough time to cool before being allowed to dissipate.

Despite issues with nuclear fusion still to be resolved, scientists are quietly confident Iter will produce around 10 times more energy than it consumes within the next ten years. But the expense of building the reactor and supporting facilities means the energy produced would still be commercially unviable.

Mast Upgrade in Culham may now have solved that issue. One of the main savings of smaller nuclear fusion reactors would be that smaller magnets would be needed to contain the plasma. Until now the issue with smaller reactors is that they can’t contain an exhaust long enough to allow the plasma fumes to sufficiently cool before being released.

That’s the bottleneck the Culham team believe they have now solved. Their reactor, the Super X diverter, uses more magnets to direct the exhaust along a widening spiral. That gives it 20 metres over which to lose heat, which is enough for the power output of the dissipating fumes to fall from comparable to a rocket thruster to those coming out of a car engine.

There are still plenty of other challenges to be solved before prototype fusion power plants can evolve into commercially operating models. Not only safely confining the plasma, generating their own fuel and maintained by robots because humans will not be able to enter, they will be among the most complex collection of machines and facilities ever created.

But Chapman believes his industry’s mission to achieve commercial fusion power plants has to be successful if the world is to achieve its climate change goal of zero carbon dioxide emissions by 2050, stating:

“We radically underestimate the scale of that challenge. It’s just the most colossal challenge.”