SPECIAL REPORT | LEARNING FROM FISSION V According to the ITER Organisation:
● “Fusion is a potential source of safe, non-carbon emitting and virtually limitless energy.”
● Per unit mass fusion can release nearly four times as much energy as nuclear fission reactions.
● Fusion fuels are widely available and are nearly inexhaustible. Deuterium (D) can be recovered from all forms of water, while tritium (T) may be produced during the fusion reaction as fusion neutrons interact with lithium.
● Like fission, fusion does not emit carbon dioxide or other greenhouse gases – its major by-product is helium, an inert, non-toxic gas.
● Unlike fission, nuclear fusion reactors produce no high- level activity or long-lived nuclear waste and there are no enriched materials in a fusion reactor that could be exploited to make nuclear weapons. A Fukushima-type nuclear accident is not possible in a tokamak fusion device.
● Crucially, the average cost per kilowatt hour of electricity is also expected to be similar too fission – slightly more expensive at the beginning, when the technology is new, and less expensive as economies of scale bring the costs down.
This list relates mainly to fusion produced by a tokamak device, such as that being built by ITER in southern France. Construction began in 2005 – based on a first-of-a-kind global collaboration. Europe is contributing almost half of the costs of its construction, while the other six members to this joint international venture (China, India, Japan, South Korea, Russia and the USA), are contributing equally to the rest. Tokamaks are the most common approach to confining the plasma needed for this type of fusion device. They use powerful superconducting magnets to hold the plasma in a ring-shaped (toroidal) vessel. The flow of the electrically charged plasma particles themselves also generates a magnetic field that helps to confine the plasma. However, there are other key fusion methods. In the
Below: TAE is a privately- funded fusion technology venture
1950s, US astrophysicist Lyman Spitzer showed that magnetic fields could also be configured in a twisted loop – a device known as a stellarator. Initially tokamaks, developed by the USSR in the 1960s were deemed
less complex until recently. Now the Wendelstein 7-X experimental stellarator has been built in Greifswald, Germany, by the Max Planck Institute for Plasma Physics (IPP) at a cost of $1.15bn It was completed in 2015. Then there is also inertial confinement, an idea which has also been around since the 1950s where the fusion plasma is not confined by magnetic fields. Instead, a shock wave compresses it to the immense densities needed. Among others, this approach is being studied at the US National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, where small capsules of D–T fuel are imploded using pulses of laser light.
A lot of work is being done at the UK Atomic Energy
Agency’s (UKAEA’s) Culham Centre for Fusion Energy (CCFE), where several major projects are underway. These include the Joint European Torus (JET) which is currently the world’s biggest and most powerful tokamak. It is the focal point of the European fusion research programme which feeds into ITER. CCFE’s MAST (Mega Amp Spherical Tokamak) Upgrade is an advanced tokamak experiment trialling a design for compact fusion devices known as spherical tokamaks. Finally, the Spherical Tokamak for Energy Production (STEP) is an ambitious programme which aims to deliver an integrated design for a commercially-viable fusion power plant based on the spherical tokamak concept. Other government supported projects include South
Korea’s Korean Superconducting Tokamak Reactor (KSTAR) at the National Fusion Research Institute (NFRI) in Daejeon and China’s Experimental Advanced Superconducting Tokamak (EAST) both of which, like JET, will feed into ITER. All these projects aim to produce a sustained fusion reaction and most have achieved various levels of fusion and over periods measured in seconds. There are several ambitious plans for follow-on devices (post-2050) that will demonstrate commercial fusion energy production. These include EuroFusion’s planned successor to ITER – DEMO; South Korea’s K-DEMO (in collaboration with US Department of Energy’s Princeton Plasma Physics Laboratory) and China’s Fusion Engineering Test Reactor.
Private enterprise pile on On top of these government initiatives, the number of private companies developing fusion concepts has grown rapidly in recent years. A survey earlier in 2022 by the Fusion Industry Association showed that investment in private fusion companies had more than doubled in the past year with eight new companies being founded, bringing the total to around 33. According to the survey, fusion companies declared more than $4.8bn of funding, up by 139% on 2021 and for the first time, private investment into fusion energy outstripped government funding. Some private fusion companies are developing scaled
down tokamak designs such as Tokamak Energy which is looking at spherical tokamaks. Commonwealth Fusion Systems (CFS) – spun out of the Plasma Science and Fusion Centre of the Massachusetts Institute of Technology (MIT) – is developing high temperature superconducting magnets for the SPARC tokamak. Another university spin out, First Light Fusion from the UK’s University of Oxford, is developing inertial confinement using an electromagnetic projectile gun instead of lasers to compress the target. Canada’s General Fusion and UKAEA have initiated
projects to advance the commercialisation of magnetised target fusion with the aim of building a demonstration
24 | April 2023 |
www.neimagazine.com
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