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Nuclear Power: Past, present and future

By Dave Elliott

I have been looking at some early, novel, nuclear ideas and how some of them are being re-explored. Thorium, molten salt reactors, high temperature reactors, fast neutron reactors- they have all been tried earlier on, with mixed results. In a new book for IOPP I ask, will the revamped variants, including smaller versions, do any better? And more radically, do we actually need any of them- has nuclear really got a future?

Nuclear fission produces heat which has been used for electricity generation in a range of power plants, with a varying degree of success. Early hopes were that nuclear power would become a major energy source. However, the initial quite rapid expansion in the 1960s and 70s was slowed by increasing competition from cheaper alternatives, including natural gas, and by major nuclear disasters, notably Chernobyl in1986. An attempt at a nuclear renaissance, based in part on improved reactor designs and the argument that nuclear power could play a role in responding to climate change, was stymied by the Fukushima disaster in 2011. While some new nuclear projects are going ahead, many old plants are being shut as uneconomic, often well before their expected retirement dates, leaving nuclear in effect stalled at around a 11% global electricity share. By contrast, by 2016, renewables had reached 24% globally, and, with prices falling fast, they seem likely to dominate in the years ahead:

Although some nuclear energy enthusiasts hope that better progress will be made with the current upgraded Generation II designs, the so-called Generation III reactors, there have been continuing technical, economic and project delivery problems, and some say the future for nuclear, if there is to be one, will lie in developing a new set of technologies, Generation IV. However, many of these are not new- they were looked at in the early pioneering days of nuclear power development, and in most cases abandoned. If some of them are to play a major role, they will have to overcome whatever problems led to their demise then, and also the problems that have faced subsequent designs.

The early days of nuclear power development was typified by a burst of optimistic, open ended experimental exploration of options, with a wide range of designs and types of reactor system being tested in the USA and elsewhere.  Some look back to that as a golden era:

However, there were some dramatic failures and disasters, like the fire at the Simi Valley Sodium Reactor in 1959, the explosion at the 3MW experimental SL-1 reactor at the US National Reactor Testing Site in Idaho in 1961, which killed three operators. Better known perhaps was and the core melt down of the Fermi Breeder reactor near Detroit in 1966. Sodium fires have been a major problem with many of the subsequent projects around the world, for example in France, Japan and Russia:

Fast breeder reactors had initially been seen as a vital new option, in the USA especially, given concerns about long term uranium resources, but work on breeders was halted in the USA in 1977, mainly due to concerns about plutonium proliferation. The UK and France soldiered on with their breeder programmes until the 1990s, but now, with Japan finally closing its troubled Monju project, only Russia, China and India have significant fast reactor programmes. However, that may now change, with some of the basic ideas being re-explored, with one contender being the Integral Fast Reactor concept developed in the USA in 1970s.  It’s the same with some of the other earlier, less developed, US ideas, such as the use of fuel in the form of molten flouride salts, rather than solid rods, as was explored at Oak Ridge National Laboratory in the 1960s, and the development of small modular reactors- there had been many test of small reactors in the USA in the the 1950s and 1960s:

High temperature helium gas cooled reactors are also being looked at again- they were first tested in the UK (Dragon at Winfrith), the US and Germany in the 1960s, but met with problems are were not followed up. But now the ‘Pebble Bed’ variant, initially being looked at by South Africa, is being developed by China.

The context now is of course very different, with tighter economic, environmental, safety and security constraints, and renewables are presenting a major challenge, but some are hopeful that updated Generation IV variants of these early ideas can win through, offering higher fuel efficiency and reduced waste production. Fast neutron breeder reactors can produce new plutonium fuel from otherwise unused uranium and may also be able to burn up some wastes, as in the Integral Fast Reactor concept: That may also be possible with another old ‘breed-burn’ idea (first mooted in 1958), the Traveling Wave Reactor, now being backed by Bill Gates:

Molten Salt Reactors (MSRs), perhaps using thorium, may be able to do this without producing plutonium or using liquid metals (or water) for cooling. MSRs will still produce some wastes, but it is claimed that waste handing is easier, since, whereas in solid-fuelled reactors, fission products accumulate within the fuel rods, in MSRs, fission products can be continuously removed, and there may also be fewer of them:

Both approaches, breeders of various types and MSRs, including Liquid Flouride Thorium Reactors, are being promoted, but both have problems, as was found in the early days, for example, sodium fires with breeders and molten salt corrosion issues with MSRs. With thorium based systems, there are also high radiation levels from one of the thorium decay products, U232, a powerful gamma emitter.  So more shielding has to be built.

The costs for all these systems are uncertain, but it is argued that scaled-down versions of some of them, ‘Small Modular Reactors’ (SMRs), much promoted at present, should be faster to build and easier to finance, and so may be more economic. However, even with mass production giving economies of scale, that is far from certain: complexity may be the main driver of cost/kWh, and that may not be reduced by going to multiple smaller-scale units. Their economic viability could be improved by using their waste heat to feed local heating networks, but given the safety and security risks, will SMRs be acceptable in or near cities?

The current Generation III projects, basically upgrades of the standard Pressurised Water and Boiling Water Reactors, may be able to sustain the nuclear programme for a while, but even the most optimistic observers accept that, longer-term, a move will have to be made to Generation IV, and then maybe fusion – if that can be made to work. Whether any of those options will be successful in enabling nuclear to expand remains to be seen: quite apart from safety and security risks and the yet to be resolved technical issues, there are plenty of non-technical problems and economic constraints. The market for electricity is now much tighter, given the advent of cheap renewables, and basically inflexible nuclear might only be able to play a limited role in backing up variable renewables. So, absent a major breakthrough, it may be that the future for nuclear, if it has one, will be to move into new markets and new end-uses for the energy it produces. That could include the production of hydrogen and synfuels for vehicle use and heat for industrial processes:

However, renewables may also be successful in these markets, with, arguably, fewer down-sides, and that seems to be the case overall- renewables are winning out.  Even so, it is early days. In some ways the Generation IV nuclear options are at the same stage as were many of the renewables twenty or so years ago- seeking to step beyond some historical precedents. Renewables of various types have managed that. It remains to be seen if Generation IV can. My new IoPP book ‘Nuclear power: past, present and future’, should be available next week at:

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  1. ChrisB

    Thanks for your assessment, I’m sure your book will have many interesting points.

    One item not often included is the increasing importance of carbon neutral energy. IMHO load-following needs to be addressed in the mix of energy sources. When wind & solar are on the grid, they should probably be linked with whatever backup source utilities utilize. This is increasingly methane gas. Hydro can also be used in many circumstances, but recent data strongly hints that some hydro has strong GHG emissions depending on on algae or other plant matter immediately upstream of a dam. Nuclear can load-follow, but this depends on the generator unit at each site.

    In the coming decade this GHG issue needs to be addressed in depth. The questions of what makes a clean grid and can both industry & transportation transition to clean energy (electricity) needs to be addressed.

  2. dave elliott

    Thanks for this, yes I agree on GHG, and there can be methane emisison problems with large hydro in some hot biomass-rich areas. But nuclear also has a GHG impact- from the (usually fossil) energy used for uranium mining and processing, which will get larger as lower and lower grade uranium ores have to be used- they are not making any more!
    Same for thorium.

  3. I agree about GHG. But nuclear is not GHG free- fossil energy is used to mine and process uranium and as uranium reserves dwindle, and lower grade ores have to be used, this energy (and carbon) debt wll rise.

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