The government is proposing a fusion reactor – the Spherical Tokamak for Energy Production (STEP) – for our energy needs. This would be a smaller version of the unsuccessful Tokamak prototype (JET) at Culham in Oxfordshire. Quite why the STEP project would be expected to work when its prototype has failed is unexplained in official documents. But the government is looking to develop an operational site for a STEP reactor. The plan is for the Business Secretary to choose a site for a prototype, following recommendations of UKAEA, by 2024
However the government’s new panacea has almost nothing to do with our energy needs and everything to do with Boris Johnson’s ill-considered techno-dreams. It will most likely join the long line of Boris’ flops after the Thames Gateway airport, the Emirates airline cable car, the bendy bus, the Thames Garden bridge etc, etc. But this time the taxpayer will have to pay £billions rather than £millions.
What is nuclear fusion?
It’s a dangerous process whereby radioactive hydrogen (tritium) is smashed into another form of hydrogen (deuterium) at massive temperatures and pressures inside a plasma to release much radiation and some heat. The same process occurs in our Sun ….. but the Sun is safely located 93 million miles away.
Formidable technical problems exist with fusion. First they have to get the deuterium-tritium reaction to work continuously: they’ve done this at the JET experimental facility at Culham…. for a few seconds. Then they have to get it to release more energy than used in producing the reaction. This has never successfully happened to date. Then they would have to capture the energy released. JET has never been close.
The plan is to surround the plasma chamber with molten lithium. But the engineering is really invidious: a high vacuum on one side, molten lithium on the other, and billions of high-energy neutrons bombarding the wall each second. They then have to run hot molten lithium through heat exchangers to raise steam for a turbine. Experience with such heat exchangers – molten metal on one side, water on the other – has been disastrous all over the world. The problem is that lithium is extremely flammable, indeed explosive in contact with water or air. And should it ever operate, vast amounts of radioactive gases and radioactive water vapour would be released to the local environment.
The government’s mooted fusion reactor comes with promises of cheap and clean energy to move to a zero-carbon economy, with little radioactive waste and no plutonium by-products for nuclear weapons. But this government has a bad track record with its promises ….how valid are these claims?
The reality is that a fusion reactor, if ever operated, would produce many radioactive by-products that are far from harmless. In addition, most (around 80%) of the output energy would be in the form of high-energy neutrons which would lead to structural damage, large amounts of radioactive waste and the need for much biological shielding to protect operators and the public nearby.
Fusion plants can also be viewed as gigantic exercises in tritium recycling. If the plant were ever constructed, large amounts of radioactive tritium (~1018 becquerels per year) would be routinely released into the atmosphere and via the cooling water. That’s 1,000,000,000,000,000,000 Bq each year – a great deal of radioactivity. It would contaminate all areas downwind and downstream. Some nuclear scientists think that tritium is a “weak” nuclide but the reality is the opposite: see The Hazards of Tritium – Dr Ian Fairlie. If an explosion and/or fire occurred (tritium and deuterium are both flammable), the amounts of radioactivity released would be even greater and would constitute a nuclear disaster.
Fusion reactors would also be subject to most of the major problems associated with fission reactors, including large-scale cooling demands, high construction and operational costs and lengthy construction times – stretching to decades. The structure, damaged by neutron bombardment, would need to be replaced regularly, resulting in large amounts of radioactive wastes for which there is no current solution in the UK.
What do experts say?
In the past, skeptical scientists opposed nuclear fusion as unworkable, including many US scientists. More recently, Dr Daniel Jassby who worked for 25 years on plasma physics and neutron production related to fusion energy at the Princeton Plasma Physics Laboratory, at Princeton university in the US has written two informative articles (see below) on the myriad problems with nuclear fusion for the Bulletin of Atomic Scientists (the US journal which gave us the Doomsday Clock). He concluded “When you consider we get solar and wind energy for free, to rely on fusion reaction would be foolish”.
“Fusion reactors: Not what they’re cracked up to be” – by Daniel Jassby, April 19, 2017: https://thebulletin.org/2017/04/fusion-reactors-not-what-theyre-cracked-up-to-be/
“ITER is a showcase … for the drawbacks of fusion energy” – by Daniel Jassby, February 14, 2018: https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-drawbacks-of-fusion-energy/
In short, nuclear fusion would not provide cheap, clean, safe or healthy energy and would reduce the funding available for safer and cheaper renewable energies.