Last December, Energy minister Greg Hands told the Nuclear2021 conference organised by the Nuclear Industry Association that the government was backing high-temperature gas-cooled reactors (HTGR) as the centrepiece of its £170m Advanced Modular Reactor (AMR) Research, Development & Demonstration Programme. That’s not much money of course, but Paul Howarth, CEO of the National Nuclear Laboratory, saw the announcement as ‘a further signal of the resurgence of nuclear’.
The goal of the AMR programme is to ‘prove the potential’ of advanced reactors and have a demonstration unit in operation ‘by the early 2030s, at the latest’. The aim was to develop technology to produce high temperature heat which could be used for hydrogen production, to supply industrial processes and potentially district heating, as well as electricity generation. After a consultation, the HTGR was confirmed as the preferred choice for this, but the government said it would continue to support other ‘advanced’ reactors, including the lead-cooled fast reactor, molten salt reactor, supercritical water-cooled reactor, sodium-cooled fast reactor and very-high-temperature gas reactor, in addition to high temperature gas reactors.
The USA is also developing a High Temperature reactor, the Xe-100, which in 2020 got support via the US Department of Energy’s Advanced Reactor Demonstration Program, while China has been developing a High Temperature helium gas-cooled reactor for some time. It recently started up its first small test unit. So the UK is bit behind, although actually the UK did test one small unit, the 20MW Dragon, at Winfrith in Dorset, from 1965 until 1976. But it was not followed up. Instead the UK persevered with its carbon dioxide gas-cooled plants and then shifted to Pressurised Water Reactors, including most recently the EPR at Hinkley- still under construction. And there is also talk of another EPR at Sizewell, as well as Rolls Royce’s mini-PWR system, as the UK’s first UK Small Modular Reactor.
Some of the other AMR options do go beyond that and include high temperature molten salt/thorium reactors and liquid sodium cooled fast reactors, of the sort being considered in the USA. And looking even further ahead, there’s nuclear fusion, which the UK is looking at quite seriously, with its STEP programme, and Tokomak Energy, developing on the MAST spherical Tokamak, along with First Light Fusion’s inertia confinement system, and Canadian company General Fusion's demonstration Magnetised Target fusion reactor, to be built at Culham.
Fusion- really high temperatures
Some say nuclear fusion, a really high temperature (2 million degrees) option, will replace fission of whatever sort - one advantage being that that fusion would allegedly be cleaner, with no wastes. However, that may not be completely true. In its preliminary review of the implications for decommissioning, radioactive waste management, & radioactive waste disposal associated with fusion, the UK Committee on Radioactive Waste Management notes that, while ‘nuclear fusion technology is advocated as not being compromised by the burden of generating long lived nuclear wastes…it is evident that this claim is challenged by the expected generation of some significant volumes of LLW [low level waste] and likely ILW [Intermediate level waste] arisings’. It says, ‘although nuclear fusion does not produce long lived fission products & actinides, neutron capture by the fusion reactor structural materials & components forms short, moderate and some long-lived activation products. Thus in addition to tritium emissions and contaminated materials, it is clear that there will be a need to manage radioactive materials and wastes produced by neutron activation, within regulatory controls, over the whole life cycle of a fusion reactor.’
It noted that ‘the technological approach to nuclear fusion was historically predicated on avoiding the generation of long lived activation products’, and pointed out that the giant International Thermonuclear Experimental Reactor project (ITER) being built in France ‘continues to express this aim’, saying on its web site that it produces no long-lived radioactive waste: ‘Nuclear fusion reactors produce no high activity, long-lived nuclear waste. The activation of components in a fusion reactor is low enough for the materials to be recycled or reused within 100 years’. CoRWM also noted that, in the UK, ‘the recent call for expressions of interest to accommodate siting the STEP facility makes no mention of management of the arising radioactive waste. Future dialogue with local communities needs to ensure it is as open & transparent as possible on such matters.’
There are also other issues with fusion. It is usually said that, whereas there are relatively limited reserves of uranium and not that much more thorium, the fuel for fusion is far less constrained- deuterium can be obtained from the sea and tritium can be made from lithium. However, there are other calls on the relatively limited lithium reserves. Lithium is used for electric vehicle batteries and in many other batteries. So we may run short of cheap supplies . The volumes needed for fusion would not be huge, so that may not be a problem for while, but processing sufficient to make tritium may prove to be an issue soon. The ITER web site says that, at present, ‘the world supply of tritium (used with deuterium to fuel the fusion reaction) is not sufficient to cover the needs of future power plants. ITER will provide a unique opportunity to test mockup in-vessel tritium breeding blankets in a real fusion environment’.
No help with climate change?
That is a little sobering: we might be able to breed tritium from lithium, but longer term we may have a potential basic lithium resource limitation. Sounds like renewables would be a better bet- with no fuel resource limits and no active or other wastes either. Some of them do need some rare materials, but these are not consumed as fuel and they can be recycled when the plant is retired. Moreover, while renewable energy systems already exist and work well, fusion looks some way off. ITER is just a very expensive prototype and even if all goes well in tests, we could not expect a commercial-scale follow-up until maybe 2050. It’s also worth noting that it is very energy and carbon intense, with vast power-hungry superconducting magnets and the like, and although the fusion energy released may balance the energy fed in to sustain the plasma, ITER wont generate net power. It’s only the core fusion reaction that will hopefully be net positive in energy terms. Indeed ITER, and also First Light, have been taken to task for seeming to claim otherwise. In reality, it has been argued, there will be large energy requirements for running the rest of the plant, with that, and the extra systems need for cooling and (crucially) power extraction, adding a lot to the cost (and carbon debt) of any eventual power producing plant.
However, rather optimistically, given that at present we don’t have detailed plans for power extraction, ITER’s web site says that, eventually, the average cost per kilowatt of electricity for fusion is expected to be similar to that from a nuclear fission plant ‘slightly more expensive at the beginning, when the technology is new, and less expensive as economies of scale bring the costs down’. Even more bravely, First Light Fusion has claimed that inertial confinement systems may eventually be able to deliver power at $25/MWh, competitive with renewables.
When faced with claims like that, it may be wise to be cautious. While renewable like wind can and do deliver cheap clean power now, there is still a way to go with fusion of whatever type, so it cannot help with the urgent response needed to climate change. To be fair, some of the new fusion developers, like CFS in the USA, do rather bravely claim that they can get their systems running ‘in the early 2030s’, and, somewhat provocatively, a recent Nature article quoted the view that ‘Fusion is the vaccine for climate change’. But it also relayed an update of the old joke that fusion was always 40 years away: now the view from the private sector fusion enthusiasts was that it was ten years away, and they may continue to say that year by year!
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