The Chancellor, Jeremy Hunt, announced in Wednesday’s Budget that the Government is launching a competition for scientists to design a new, advanced form of nuclear reactor.
The “Small Modular Reactor” (or SMR for short) would use the same kind of nuclear fission that we know can produce enormous amounts of clean energy in nuclear power stations – but on a far smaller scale.
Nuclear plants take a notoriously long time and a large amount of money – often much longer and larger than originally planned – to get up and running. That’s no reason not to build them, of course (there’s an embarrassing-in-hindsight video of Nick Clegg in 2010 arguing that building nuclear plants isn’t a good option because if they were built that year they wouldn’t come online until the distant future of… “2021 or 2022”). But in the meantime, technology that allows us to harness nuclear power in smaller, quicker, cheaper forms could still help speed us along to our clean-energy goals.
And small nuclear reactors are certainly possible: after all, this is how nuclear submarines are powered. It’s just that worldwide advances in their design for commercial purposes has largely stalled since President Bill Clinton and the US Senate – in a myopic attempt to save money – cut all funding for advanced reactor design in 1994.
The “modular” part refers to the fact that these smaller reactors can be made in pieces that can adapt to different situations. Say a few modules were put together to power a small town, but the town expanded and energy demand increased. The solution is easy: just build some more modules at the factory, and plug them in to the existing set. Another big part of the appeal is that these modules can be set up in places – perhaps rural areas, or areas with difficult terrain – where a full-sized nuclear plant simply couldn’t fit or be safely constructed.
That’s the idea, anyway. The problem is that feasible technology for reactors that are small and modular and cost-efficient isn’t yet ready. That’s why Hunt sounded a note of caution in his speech: “if demonstrated as viable”, he said, the government “will co-fund this exciting new technology”.
There’s no shortage of candidates. A study in 2020 noted that there were more than 100 potential designs for SMRs, all with different features and different pros and cons. There are different coolants for the reactor, including water, molten salt, liquid lead, and gas. There are different settings: some are on land, and some are in water or on floating barges. The reaction itself happens in different ways, too (there are fast and slow neutron reactors), but they’re all smaller versions of pre-existing nuclear reactors.
The real dream would be to design so called “burner” reactors, which can take spent nuclear fuel from other power plants and use it up to generate even more power; or “breeder” reactors, which turn (for example) uranium fuel into a type of plutonium, which can itself be used in power generation. Developing systems like this is particularly important given that some have argued that SMRs will, megawatt-for-megawatt, produce more radioactive waste than larger nuclear plants.
Nuclear energy is among the very safest forms of electricity production – but because of some highly-publicised accidents in the past (think of Chernobyl, Three Mile Island, and Fukushima), it has a bad reputation. Can we be sure that these new kinds of nuclear reactors which, being new, have zero track record to look back on – are safe too? Some scientists worry, for example, that the multiple, modular reactors all being at one site could boost the chances of a serious incident, as happened at Fukushima, where nuclear safety teams had to be dispersed to multiple melting-down cores, and thus had fewer hands to slow the radiation being released.
There’s another catch. Having lots of SMRs around a country would mean that nuclear material was present in many more places than it is currently, where it only exists in a very small number of large, well-secured nuclear plants. That’s a risk: many nuclear researchers worry about SMRs, especially in states with weaker security infrastructure, where the fuel could be an attractive target for terrorist or other groups who might wish to get their hands on the necessary materials for a nuclear weapon.
So the designers of SMRs, in addition to trying to make the reactor itself work well and safely, have to consider these kinds of security concerns, too. To address this, some of the reactors are designed to be built underground, or to have completely sealed reactor cores that never need refueling. The kinds of reactors mentioned above that burn spent fuel are ideal in that any end product wouldn’t be useful for the creation of weapons.
The UK government’s new SMR competition will have to take all these safety and security concerns into account, while at the same time rigorously judging the cost-efficiency of the SMRs and the extent to which they can get us towards our net-zero targets. To what extent could they make up the slack when our current ageing group of nuclear plants are decommissioned? We should also do our best to learn from the experience of other countries, such as South Korea, which has strongly pushed SMRs under its most recent President.
A 2020 review study in the scientific journal Energy argued that the biggest barrier to the development of SMRs was financing: investment from government and other sources has been far below that required to make proper technological progress. With Hunt’s new pledge, could the small modular reactor finally reach its outsized potential?