Monday, May 1, 2017

Back to the future: old nukes for new

In 1965, Fred Lee, the UK’s then Minister of Power, famously told the House of Commons that 'we have hit the jackpot this time,' with the Advanced Gas-cooled Reactor (AGR). That was maybe a reference back to an earlier episode, when expansive claims were made that the ZETA nuclear fusion test plant heralded a global breakthrough- it didn’t.   Unfortunately, things also went very wrong as the AGR programme unfolded. The first station, on the south Kent coast, was Dungeness B. It was ordered in 1965, but did not start up until 1982, over 17 years later, by which time its cost had reached more than five times the initial estimate, and its output had been scaled down by over 20%. In 1985, two decades after the original order, the second reactor at the station had only just started up. Atomic Power Constructions, the company that won the Dungeness B contract in 1965, had by 1970 collapsed in total technical, managerial and financial disarray:
Project disasters like that might be seen as part of the learning process, though the UK seems hell bent on a repeat, with EDF’s £24bn Hinkley EPR project, to be followed perhaps by more, with a variety of new ‘first of kind’ reactors projects being proposed. As Peter Atherton put it in evidence to a Lords committee: we will be building four different reactor types, with at least five different manufacturers, simultaneously. That is industrial insanity’.  
While some nuclear enthusiasts hope that these Generation III reactors, like the EPR or its rivals, will be successful, there is also pressure to move on to new technology and so called Generation IV options, including liquid sodium-cooled fast neutron breeder reactors, helium-cooled high tempertutre reactors and thorium-fuelled molten salt reactors, at various scales.  As I describe in my new book Nuclear Power: Past, Present and Future, many of them are in fact old ideas that were looked at in the early days and mostly abandoned. There were certainly problems with some of these early experimental reactors, some of them quite dramatic. Examples include the fire at the Simi Valley Sodium Reactor in 1959, and 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 fast neutron  reactor projects around the world, for example in France, Japan and Russia.
For good or ill, ideas like this are back on the agenda, albeit in revised forms. That includes  the currently much promoted idea of scaling down to small modular reactors- SMRs. In theory they can be mass produced, so cutting costs. Not everyone is convinced:  scaling down doesn’t necessarily reduce complexity and it’s that that may be the main cost driver.  One cost offsetting option is to locate them in or near cities so that the waste heat they produce can feed into district heating networks. But given the safety and security risks, will anyone accept them in their backyard? And like all nuclear plants, they will produce dangerous long lived wastes that have to be dealt with.
Fast neutron breeder reactors can produce new plutonium fuel from otherwise unused uranium 238 and may also be able to burn up some wastes, as in the Integral Fast Reactor concept and also the Traveling Wave Reactor variant. Molten Salt Reactors using thorium may be able to do this without producing plutonium or using liquid metals for cooling. Both approaches are being promoted, but both have problems, as was found in the early days. Certainly fast breeder reactors were subsequently mostly sidelined as expensive and unreliable. And as heightening nuclear weapons proliferation risks. The US gave up on them in the 1970s, France and the UK in the 1990s. Japan soldiered on, but has now abandoned its troubled Monju plant. For the moment it’s mainly Russia that has continued, including with a molten lead cooled reactor, although India also has a fast reactor programme, linked to its thorium reactors plans.
Thorium was used as a fuel for some reactors in some early experiments and is now being promoted again- there is more of it available globally than uranium. But there are problems.  It isn’t fissile, but neutrons, fast or slow, provided by uranium 235 or plutonium fission, can convert Thorium 232 into fissile U233. However, on the way to that, a very radioactive isotope, U232, is produced, which makes working with the fuel hard. Another isotope, U234 is also produced by neutron absorption. Ideally, to maximise U233 production, that should be avoided, but experts are apparently divided on whether this can be done effectively.
The use of molten salts may help with some of these problems, perhaps making it easier to play with the nuclear chemistry and tap off unwanted by-products, but it is far from proven technically or economically. The economics is certainly challenging. Nuclear plants of any sort may not be competitive in the emerging electricity market, as renewables get ever cheaper and their market share expands, but some nuclear options might be able to compete in the heat and synfuel markets. However, even that is unclear- renewables may also be able to compete in meeting these end uses, with fewer side effects.   
Back in the 1950s, President Eisenhower launched Atoms for Peace initiative, promising US aid with the world-wide development of bountiful nuclear energy, and that idea has lingered on. In 2006, under the Global Nuclear Energy Partnership (GNEP) backed by President George W Bush, US Energy Secretary Samuel Bodman said that ‘GNEP brings the promise of virtually limitless energy to emerging economies around the globe’. After Fukushima and the economic challenges to nuclear presented by gas and renewables, GNEP was in effect abandoned and we don’t hear rhetoric like that so much: nuclear is on the defensive, only supplying 11% of global electricity as against 25% from renewables, with the cost of the later falling rapidly, while nuclear costs seem to be rising inexorable. Whether the new Generation of fission technologies will be able to resuscitate it remains to be seen.  It doesn’t seem a good bet: http://science.sciencemag.org/content/354/6316/1112.1  And if you still have hopes for fusion, see this: http://thebulletin.org/fusion-reactors-not-what-they’re-cracked-be10699
All this and more is covered in my new IOPP  book ‘Nuclear Power: Past, Present and Future’: http://iopscience.iop.org/book/978-1-6817-4505-3
*If you are a real devotee of nuclear history, take a look at this new long, partisan and somewhat overwhelmingly chaotic video selling thorium molten salt reactors: https://www.youtube.com/watch?v=H6mhw-CNxaE


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