Will Fusion or Fission power the world?

Civilisation needs a long term reliable power source if it is to avoid eventual collapse. Renewable energy cannot achieve this because a) it is inherently unreliable and requires gas backup,  b) lasts less than 20 years yet requires huge areas of land/sea, and c) its renewal depends on steel, tarmac, plastics and heavy machinery.  Nuclear Energy on the other hand  is truly Zero Carbon neutral, lasts over 60 years and can if needed produce hydrogen, biofuel and recharge batteries at night.

The development of Nuclear Energy in the UK was damaged by a bad press, Chernobyl,  and Three Mile Island. The only known fatalities from these incidents were 28 deaths among Fire Fighters in Chernobyl who  extinguished the fire from the roof. Another Chernobyl style accident is impossible in modern PWRs which have an excellent safety record. The Accident at Fukushima was due to a large Tsunami that killed no-one and could have been easily been avoided if the emergency generators had been sited on the roof of the reactor building. Nuclear France has a very good safety record whereas fossil fuels and off-shore wind have far worse fatality rates. France also has the lowest carbon emissions per capita in Europe.

Nuclear Energy comes in two flavours. Fission and Fusion.

  1.  The first Fission chain reaction using natural uranium and a graphite moderator was achieved in a Chicago Squash court 83 years ago by a team led by Enrico Fermi. It was literally a “pile” of Uranium and Graphite bricks arranged to achieve a chain reaction . Luckily the power generated was low (~1watt) since there was no shielding. All the natural Uranium occurring on earth was produced from the dust from a supernova of a first generation massive  star. Modern Fission reactors use enriched Uranium fuel rods in a pressurised water reactor (PWR). France is the leader in deploying low carbon nuclear energy and it’s commercial arm EDF is building Hinkley C and runs Sizewell B Fission Reactors which maintain power for up to 2 years before refuelling.
  2. Nuclear Fusion is the fusion of light elements (mainly Hydrogen) in stars to generate heavier elements up to Iron until the star runs out of hydrogen. The largest stars then explode in a supernova producing heavier elements including Uranium. The quest to exploit fusion on earth to generate electricity began in Harwell  in the 1950s and is still ongoing today. Why is it so hard? To make Fusion work you need to heat and contain a burning plasma of hydrogen isotopes (Deuterium and Tritium) and then extract the heat energy to drive turbines and generate electricity. The  power cycle must also breed new Tritium fuel to maintain  a steady state operational cycle lasting many months of operations. Tokamaks are the leading design for future fusion reactors if they can demonstrate steady state electricity generation like Fission.  ITER  (International Thermonuclear Experimental Reactor) is being constructed in France.  However other designs have emerged in recent years such as Spherical Tokamacs and Inertial fusion. The UK is no longer a direct member of ITER and has announced plans to build a Fusion power station STEP (Spherical Tokamak for Energy Production) on the site of an old coal power station in Nottinghamshire and to be connected to the grid by 2040.
  3. Inertial  fusion implodes small DT samples with lasers or projectiles to release energy and recently the Lawrence Livermore National Laboratory achieved ignition through laser implosion of a DT  pellet with a small energy gain. A UK company First Light Fusion PLC uses extreme electromagnetic pulses to focus energy onto a DT target
  4. Commercial Fusion. An interesting development is the increase in  privately funded companies looking to try alternative approaches to the large international efforts. The potential pay-off if successful of a new energy source is immense. In the UK Tokamak Energy is developing spherical Tokamaks with High Temperature Superconductors.
  5. The design of a Tokamak Fusion Reactor is rather complicated. These currently run as a series of energy pulses. The energy produced through the fusion of atoms is absorbed as heat in the walls of the vessel. Just like a conventional power plant, a fusion power plant will use this heat to produce steam and then electricity by way of turbines and generators. Any damage to the walls or the cooling system by disruptions must be avoided.

The JET Closing ceremony was held 28th March after a successful DT campaign which beat the word record fusion energy


I was recently involved in an on-line discussion about Fusion prospects compared to Fission with John Carr (an ex CERN colleague) and Michel Claessens from ITER.

What is clear is that in the short term ( next 10 – 15 years) we need to build several EPR Fission reactors. There are 8 nuclear sites in the UK and so far just 2 of these sites will host EPRs (Hinkley and Sizewell) providing a baseload power of 6GW.  The UK will need at least double this value to maintain energy security.

It was just announced today (12/03/24)  that the UK  will have to build several new gas powered stations because of the reliability shortfalls in renewable energy supply!

Could Fusion eventually be the game changer ?



About Clive Best

PhD High Energy Physics Worked at CERN, Rutherford Lab, JET, JRC, OSVision
This entry was posted in Energy, nuclear, renewables. Bookmark the permalink.

15 Responses to Will Fusion or Fission power the world?

  1. Euan Mearns says:

    Hi Clive, I enjoyed the webinar, and I suppose not too surprised to see unanimity on the bleak prospects for fusion. I left a question rather late on the day about breeder reactors. No one mentioned them. Any reason?

  2. forbin says:

    maybe someone is listening ;-

    “The government today outlines plans for the biggest expansion of nuclear power for 70 years to reduce electricity bills, support thousands of jobs and improve UK energy security – including exploring building a major new power station and investing in advanced nuclear fuel production.”

    jus 300 million set for this which we all know will get canceled by the next Labour government.


  3. Dr Clive Best says:

    I think the seminar was maybe restricted to 2 hours which may explain why some comments were not heard. The speakers probably talked too much !
    Fast Breeder reactors seem to have been abandoned as there is no shortage of Uranium and the technology is more demanding.

  4. Dr Clive Best says:

    Hopefully Ed Miliband will not be in charge of Energy Policy.

  5. Thirty-five years ago Walter Marshall planned to build a fleet of PWRs around the country, based on the Sizewell B PWR (which, 30 years on, is still providing 1 GW for the national grid). Despite the recent Chornobyl accident, permission was given for a PWR at Hinkley Point C in 1990, following a public inquiry (some of which I attended). Unfortunately, the Thacher/Major electricity generation privatisation plans scuppered Marshall’s dream — nuclear power stations could not be privatised because decommissioning had not been costed (at least, properly). This oversight was a failure of successive governments, which did not want to face up to a proper costing regime for decommissioning (and some of the blame must be assigned to the nuclear industry for letting this issue drift over the years). So, instead of Marshall’s fleet of PWRs, which would have been supplying electricity today (as does Sizewell B), we had the “dash for gas” and the problems we face at the moment with a lack of baseload generation.
    Now, we are trying to catch up, with the EPR under construction at Hinkley Point and the planned EPR at Sizewell. This is a recognition of reality as far as baseload generation is concerned, but it is clear that there are problems that have to be overcome, both technical and financial. It is a great shame that the last 35 years have been wasted and we find ourselves in the present predicament.
    As for fusion energy, great potential but overoptimistic claims. One aspect that concerns me is the tritium fuel cycle. I have been pointing out for years (and will be doing so again next week in a lecture at the EU Tritium School in Marseille), that there is mischief to be made over kilogram quantities of tritium present at a commercial fusion reactor. There are those (e.g., Ian Fairlie — see his website) who claim that the health effects of tritium have been underestimated, and they are going motor on this issue unless a substantial evidence base to counter such claims is available. I’m hoping that the fusion community doesn’t continue to think that this issue will just go away. Chris Llewellyn-Smith recognised the problem getting on for two decades ago, but he has now left the scene.

  6. Clive Best says:

    Thanks for this Richard. You perfectly described how the UK lost its way through changing political dogma regarding Energy. This is still continuing. John Carr lives very close to Marseille and he has the similar opinions to yours !

    I believe we once shared an office at Liverpool University !


  7. Yes, Clive, we did indeed share Room 101 (!) in the Oliver Lodge Laboratory for a couple of years or so. When you went off to CERN I went to work for BNFL at Capenhurst, and stayed with BNFL in various roles until I took early retirement in 2006 and went to The University of Manchester. For the past 40 years I have been involved in assessing the risks of low-level exposure to ionising radiation (which is why I attended the Hinkley Point C public inquiry in 1989). During that time I have been involved with the risks of exposure to tritium, which is why I have a nasty feeling that fusion is going to run into trouble with the tritium fuel cycle if the fusion community doesn’t recognise the problem now (although several years back would have been even better). However, when I chaired the annual EU Scientific Seminar on fusion energy in 2022, I learnt of other radiological issues (https://energy.ec.europa.eu/topics/nuclear-energy/radiation-protection/scientific-seminars-and-publications/seminars_en#eu-scientific-seminar-2022). The fusion community needs to wake up to the potential problems ahead and learn from the difficulties that have been experienced by fission energy.
    Speaking of which, the ricocheting of energy policy over the decades is staggering to behold. The UK moved from gas-cooled reactors to light water reactors, and then abandoned these, only to latch onto them again in recent years (at a heavily increased cost). Now we are going to try to keep our second-generation gas-cooled reactors going for as long as possible before the EPRs are ready. What a shambles! I was largely kept in a job by significant investment in reprocessing at Sellafield (much of it courtesy of the Japanese), but the production of separated plutonium in this country (but not in France) ceased 20 years ago and now there are suggestions that the >100 t of Pu stored at Sellafield (worth a considerable sum of money) should be treated as waste! Now, I don’t want to fall into the trap of suggesting that the fission fuel cycle is free of technical problems (as some have wanted to believe in the past), but this dramatic veering of direction has got us to the sorry state of affairs that we see today. No wonder we need more gas-fired power stations to keep the lights on when the wind drops, but what a statement of failure of policy!

  8. Incidentally, when I lecture on tritium, I always give this quote from a presentation made by Willard F. Libby (the 1960 Nobel Laureate in Chemistry) at a conference on tritium way back in 1971 (even before our postgraduate days).
    “If the controlled thermonuclear reactor is ever developed, we would be going through tritium on the way to the release of fusion energy. So I think this means we should think about what problems might come up when we are using tritium in quantities that make our present activities look miniscule…Therefore, we must come to understand how to live with tritium and really understand it.”
    Willard Frank Libby, “History of Tritium” In: Tritium. Conference held at Las Vegas, Nevada, August 28 – September 3, 1971. A. A. Moghissi & M. W. Carter (eds.), Messenger Graphics, Las Vegas, NV (1973) pp 3-11.

  9. Clive Best says:

    I remember that we also used to seek out real ale pubs in Liverpool! Looks like you had a very good career! After CERN, I worked at the Rutherford for a couple of years before joining JET.

    I agree about the Tritium Fuel Cycle. A Tokamak Fusion reactor will have to breed more tritium and containing it is a problem.

    It is such a shame that Walter Marshall didn’t realise that plan. Sizewell B was built on time and has worked perfectly with a minimal impact on the Norfolk coast, unlike the offshore wind farms which will need replacing in 15 years time. I suspect instead they may be left to rot with large environmental damage.

    I agree with everything else you say !

  10. Chris says:

    Many years ago, 1963/64 I visited Harwell atomic energy Authority in Oxfordshire, we went as school children to see the Atlas computer, at the time one of the world’s most powerful computer, although no where near as powerful as the phone I’m writing this on. We also saw technicians manipulating radio active isotopes, all very exciting for us 13/14 year olds, at the end of the tour we were taken into a toilet wash room and asked to stick our hands into a machine on the wall, a Geiger counter, it promptly started to make that crackling noise we all now associate with radiation. We were then asked to wash our hands and put them in the Geiger counter, no noise.
    This we were told is how easy it is to get rid of radiation. It was of course years later that I realised it was not only on my hands but also my school uniform, my hair all over me in fact.
    Still 60 odd years later no apparent harm done, but I do hope that safety governance is better now, I acknowledge nuclear is needed now, but it is not zero emissions.

  11. Guy Leech says:

    It seems to me that spending taxpayers’ money on trying to develop electricity generation from fusion is as pointless and wasteful as spending it on Net Zero, and should be completely stopped.

    On fission, aren’t the elephants in the room cost and safety, which are closely linked. Wade Allison’s GWPF paper and talk last year were eloquent about this. If these issues were reassessed objectively, fission could really produce electricity that is “too cheap to meter”. Isn’t it time to start again from scratch on fission design using sensible safety criteria, not excessive ones.

    • Clive Best says:

      I agree. Fission reactors are well proven, safe and 100% reliable. Renewable energy is less safe, unreliable and needs 100% backup from gas.

      What a shame our politicians are totally ignorant of basic physics.

  12. Richard WAKEFORD says:

    I see

  13. Richard WAKEFORD says:

    I see that the latest issue of Physics World addresses the interesting issue of the production of tritium via the lithium blanket round a fusion reactor.
    The subject of lithium enrichment is raised. When I first went to Capenhurst from Liverpool I learnt of a lithium enrichment plant that had operated there in earlier years. I assume that this still goes on somewhere, but I don’t know where. It is an interesting question that I had not thought about in the context of fusion reactors. Good to see these matters being discussed — there has to be an honest discussion that includes problems (such as the need for large quantities of tritium) or politicians and the public will conclude that they are being misled (and they may well be right).

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