Small Modular Reactors – the technology that could change the game in Britain’s nuclear energy industry

Boris Johnson’s supposed “Green Industrial Revolution” is starting to get underway. Chancellor Rishi Sunak earmarked £525 million for the development of large-scale and advanced nuclear technology yesterday, as he laid out how last week’s Ten Point Plan for fighting climate change would be financed. At least some of this money will be heading to the nuclear industry’s latest great hope, a tantalising promise for a more sustainable future – small modular reactors (SMRs).

The only hitch is that they don’t exist yet…

In the past decade there has been a major push by UK governments, spurred by calls for action on climate change, to revive nuclear power. In 2010, the government approved no less than eight new sites for the construction of new plants, the first new ones to be built in Britain since 1987.

However, making these ambitious plans a reality has proved to be extremely difficult. Only two plants, Hinkley Point C and Sizewell C, are anywhere close to being complete and both have been beset by delays and rising costs. Now, the government and industry is hoping that SMRs might solve at least some of these problems.

So what are they and how do they work?

Like it says on the tin, SMRs main features are that they are smaller than conventional reactors, and they are modular – i.e. they are are made up of numerous smaller parts that can be put together like Lego and replaced independently as opposed to being manufactured as a single whole. To understand why this is potentially so revolutionary one has to dig into the economics of nuclear energy.

“What we have” according to Tom Greatrex, CEO of the Nuclear Industry Association and ex-Labour Shadow Energy Minister, “is an attempt to move from economies of volume to economies of scale.”

Building a nuclear power plant was always expensive. On top of the need for advanced engineering and the safety features, whose numbers only multiplied post-Chernobyl, was the fact that each project was, more or less, bespoke, requiring expensive special orders of rarely produced machinery.

The only way to economise, ironically, was to spend more on each project. One mega-plant ultimately cost less than two smaller ones thanks to economies of scale. The UK’s Sizewell nuclear facility is a perfect example of this. Sizewell A which started generating power in 1966 had an output of 490 MWe, Sizewell B, which started operating 1995, churning out 1250 MWe, and Sizewell C, which (after many delays) is due to start operating 2031, and will churn out a staggering 3260 MWe.

Scale has brought with it new challenges. Now estimated to cost over £20 billion, Sizewell C will provide about 7% of the UK’s electricity – enough for 6 million homes. This is a lot of bang for your buck, but also a lot of buck. The sheer challenge of raising the initial capital for a project that would not show returns for years due to long construction periods further slowed the process.

The hope is that SMRs will drive down costs. A modular reactor would mean one assembled out of mass-produced interchangeable parts, as opposed to more expensive one-off commissions. Being able to transport in and assemble components on site would also speed up build time, somewhat like the concept behind pre-fab houses. It is thought that these savings will offset the costs of having to build more plants in total. Other advantages include potential improvements to safety, and the fact that smaller plants would also expand the number of suitable sites.

Still, economies of volume require the government to commit to building a large number of these new reactors. The savings from modularity would only become effective once a large number of reactors had already been built allowing mass production of parts to be properly up and running and delivering its savings. As such, one key question about SMR viability is whether the government will be willing to make large commitments to this yet-to-be deployed technology.

The newness also raises questions of how frictionless the move from drawing board to reality will be for this new technology. Small reactors do exist. Rolls-Royce for example has designed some that power the UK’s submarines though details, including their potential modularity, are for obvious reasons not publicly available. SMRs for generating civilian power are another story and while some 50 designs have been proposed, with China and Russia showing particular interest, none have been built.

The company NuScale, the company that has come closest to actually building an SMR, only received safety approval from the US Nuclear Regulatory Commission for its designs in August this year. The process took more than three years and required the company to submit more than two million pages of documents. More road-bumps have appeared as well, with a number of backers dropping the project this month after it was announced the project would be delayed three years until 2030 and that estimated costs had risen from $4.2 billion to $6.1 billion.

Still, Professor Tim Scott, an expert in nuclear technology at the University of Bristol, is optimistic after seeing the SMR design proposed by a Rolls-Royce lead consortium as particularly promising.

Rolls-Royce has claimed it could have the first reactors running by 2030. According to Professor Scott this could well be possible. “The technology itself isn’t very new. It’s a light-water reactor, like almost every other reactor in use, built on a smaller scale. The main challenges for getting one running by 2030 are not technical, nothing new needs to be developed, they are regulatory and financial. For the former hopefully the government can give their proposals special attention. The latter may be tricky as money will likely be tight post-Covid and you will need a sweetener to attract private investment.”

Proponents of SMRs are keen to tout other benefits as well. Getting ahead of the curve technologically could leave the UK in possession of valuable patents, and could even establish a high-tech export industry selling SMR components to decarbonising nations across the world. Here, according to Professor Scott, the key innovations would likely be less to do with the reactor design itself than innovations in manufacturing techniques and integration of digital aspects e.g. continuous reactor monitoring into the design.

Still, for all the promise of a revival in nuclear power in the next decade 2030 is in many ways too late. Nearly half of the UK’s current nuclear capacity – which provides about 10% of the UK’s electricity – will be retired by 2025. Delays to planned new reactors, Hinkley Point C and Sizewell C, means they won’t be online before then.

Meanwhile, our electricity consumption will continue to climb and the shortfall will likely be made up by fossil fuels. As a result, it is expected that the UK’s carbon emissions will likely go up a little despite the vast efforts to lower emissions in other areas. As Professor Scott put it “Really, we should have acted a decade ago, but at least we’re doing something now.”