Small Modular
Reactors (SMRs) of up to a few hundred megawatts capacity are being touted by
some as the way ahead for nuclear power since they are expected to be quicker
to build than large gigawatt scale plants and so less costly to finance, with
mass production also reducing unit costs. They might also be located in or near cities so that the waste heat they
produce could be fed to district heating networks, the use of this extra output
offsetting their cost further. It may also be possible, it is claimed, that
their power output could be more easily varied, so that they could play a role
in grid balancing, though, as with large nuclear plants, that would undermine
their economics- it is best to run them flat out.
There has certainly
been much enthusiasm expressed for the idea, with various vendors offering
their wares, for example http://www.westinghousenuclear.com/New-Plants/Small-Modular-Reactor Estimates
of costs vary, but in the US context it has been claimed by NuScale that ‘first
of kind’ SMRs might generate at around 101cents/MWh, falling to 90c/MWh on mass
production, cheaper than new large advanced nuclear plants at 96c/MWh, and also
cheaper that coal fired plants, but not competitive with unabated combined
cycle gas plants (64-66c) or wind plants (80c) or hydro (85c). http://www.nuscalepower.com/images/nuscale_smr_benefits/Right_Column/nuscale-operating-costs.jpg
Some of the designs
for SMRs are quite exotic, based on the use of fuel dissolved in molten salt
which then acts as both reaction medium/moderator and heat transfer /coolant
medium. Terrestial Energy amongst others is pushing this Molten Salt Reactor idea,
and is seeking US government backing: http://www.world-nuclear-news.org/NN-Terrestrial-Energy-to-complete-US-loan-guarantee-application-1409167.html
It may take a while to happen-
this is new ground. But some of the less radical ideas might be faster to
develop. The UKs Energy Technologies Institute says SMRs could be up and
running in the UK by 2030 if R&D work gets underway soon and should be
designed to be able to run in CHP mode, so that they can provide heat as well
as electricity: http://www.eti.co.uk/insights/the-role-for-nuclear-within-a-low-carbon-energy-system/
Although much work will have
to be done to modify the technology for civil power (and possibly heat), it is
claimed that civil SMRs can be based on existing nuclear submarine propulsion technology,
which is well established, with companies like Rolls Royce being well placed to
develop suitable units: www.telegraph.co.uk/business/2016/03/19/rolls-royce-could-power-britains-nuclear-future-with-mini-reacto/ However the submarine and civil contexts are very different,
with very different operational requirements and operating regimes. Safety and reliability is obviously a key issue in all
contexts, but even in the closely managed military environment things can go
wrong: www.theguardian.com/world/2011/mar/10/royal-navy-nuclear-submarine-reactor-flaws And spreading SMRs around in urban
areas could pose safety and security risks, with local public acceptability
potentially being a big issue.
In the USA however, the Tennessee Valley Authority
(TVA) claims
that SMRs could be put close to population zones and it is looking to reduce the risk of issues such as
emergency
planning evacuation zones slowing
operating project approval. They say that, given safety
upgrades, ‘based upon the preliminary information which we've received from
the four vendors, we are confident that all of them can be supported by a
two-mile emergency plan [zone] and at least one has capability of site [only] boundary’ i.e. no
safety zoning beyond the plant site. That compares with 10 miles typically
required for a large reactor. http://analysis.nuclearenergyinsider.com/us-operator-seeks-swift-smr-licensing-optimize-low-carbon-output
That seems a little provocative. Will anyone accept mini nukes
in their backyards? And what about security? SMRs will pressumably be sealed modular units,
making access to the fissile material hard, but, unless they are very carefully
guarded, they might still provide an enticing and convenient target for
terrorist attack. In terms of safety, the US Union for
Concerned Scientists says that ‘Multiple SMRs may actually present a higher risk
than a single large reactor, especially if plant owners try to cut costs by
reducing support staff or safety equipment per reactor.’ It adds that ‘some proponents have suggested siting SMRs
underground as a safety measure. However, underground siting is a double-edged
sword- it reduces risk in some situations (such as earthquake) and increases it
in others (such as flooding). It can also make emergency intervention more
difficult. And it increases cost.’
There are thus a range of technical, economic, safety and
security issues to face, not least the issue of social acceptance, with there
being no clear indication that they can be resolved: http://www.academia.edu/8114310/One_size_doesn_t_fit_all_Social_priorities_and_technical_conflicts_for_small_modular_reactors
From the industry side however, enthusiasm remains strong, and
there is much debate about exactly how to proceed and on what basis. For
example, should SMRs replace large nuclear plants in any future programme? In the UK context, ETI’s 2015 report on ‘The role for nuclear
within a low carbon energy system’ said that contrary to the claim SMRs might
be better than large nuclear plants, ‘large reactors are best suited for baseload
electricity production’. However, it notes that, based on using existing (nuclear)
sites for them, there is ‘an upper
capacity limit in England and Wales to 2050 from site availability of around 35
GWe,’ while there could be
room for at least 21GW of SMRs in the UK, given that more sites could be available
for them, including near cities, where the heat option offered a key economic
compensation. So, although SMRs ‘may be
less cost effective for baseload electricity production, SMRs could fulfil an
additional role in a UK low carbon energy system by delivering combined heat
and power (CHP) - a major contribution to the decarbonisation of energy use in
buildings’, assuming the necessary district heating
infrastructure was available, with SMRs delivering heat into cities ‘via hot water pipelines up to 30km in
length’.
In this context it is interesting that, more recently, the Newcastle-based SMR enthusiasts Penultimate Power thinks SMRs will work
best as ‘complementary to, rather than
competing with’ the large-scale nuclear plants: http://www.chroniclelive.co.uk/business/business-news/newcastle-company-forefront-technology-small-10869984
A SMR assessment programme has been launched
by the UK government, and SMR programmes are going ahead in the USA and
elsewhere: http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspxThis is all in a context where, according to the UK National Nuclear
Laboratory, the potential market for SMRs might be up to 85 GWe by 2035:
http://www.world-nuclear-news.org/NN-UK-considers-how-to-use-small-reactor-opportunity-1910161.html That may be optimistic. The OECD says ‘up to 21 GWe of SMRs could be added globally by 2035’. http://www.oecd-nea.org/ndd/pubs/2016/7213-smrs.pdf And there is no
shortage of critical comment on the whole idea:
http://oilprice.com/Alternative-Energy/Nuclear-Power/Why-Small-Modular-Reactors-Are-Not-The-Next-Big-Thing.html
and http://realfeed-intariffs.blogspot.co.uk/2016/04/small-modular-reactors-wishful-thinking.html
It’s not a new idea: in addition to the small
units developed for the US military in 1940’s, (for planes and ships) there
were may attempts to build small civilian nuclear plants in the USA in the
1950s, mostly with poor results: http://spectrum.ieee.org/energy/nuclear/the-forgotten-history-of-small-nuclear-reactors The current flurry of enthusiasm for SMRs seems to be mainly driven by
the failure of conventional nuclear to expand as fast as the industry would
like. It’s stalled or declining in many
parts of the world, due to poor economics and local opposition, and the
existence of better, cheaper renewable alternatives. However, SMRs may not
offer much help in changing this situation. There will no doubt be some
prototype projects around the world in selected sites, and some projects may be
suited to specialised applications, for example in remote sites or for some
industrial processes: http://www.sciencedirect.com/science/article/pii/S0301421512000249
Or even mobile units like this: http://www.independent.co.uk/news/world/asia/china-nuclear-reactor-south-china-sea-spratly-islands-soviet-submarines-a7356246.html
However, in terms of widespread use for public
power and heat production, given the practical problems of finding acceptable
sites and the uncertain economics, plus all the usual problems with nuclear,
including what to do with the radioactive wastes that are produced, it could be
that SMRs may not prove to be that significant. But it’s also possible that
they may boom, if a wider market emerges and/or if there are some major
technological breakthroughs: http://www.powermag.com/market-small-modular-reactors/
All this and much more is covered in Dave
Elliott’s new book for the Institute of Physics: ‘Nuclear Power: Past, present
and Future’, out soon.
