Getting closer to a small modular reactor reality

Julianne Antrobus | 27 Feb 2017 | Comments

We’ve talked about small modular reactors (SMR) before, looking at what they are and what the benefits and potential drawbacks of the technology are. Since then, industry around the world has been working hard to push forward the development of SMRs ready to bring to market.

The development of SMRs gives UK plc the opportunity to develop home grown intellectual property, create skilled jobs and to be an exporter of technology which can be sold around the world. Whilst it remains largely theory at the moment, two different categories of SMRs are now leading the way in development and we took the opportunity to discuss the pros and cons of each at the recent Nuclear Industry Association (NIA) SMR conference. Atkins is taking a leading role in working with government and industry to push forward the SMR development agenda, and our engineering experience across the energy sector puts us in a great position to assist developers find an engineering solution that will work to bring SMRs to reality.

The more developed designs coming forward are integral pressurised water reactors (IPWR), often referred to as third generation (GEN III). Made of the same four major components that make up a standard large scale light water reactor (LWR) or pressurised water reactor (PWR): the reactor, stream generators, pumps and the pressuriser. Integral is the key word: in the integral SMR, there is one vessel and all of these four components are either inside or directly part of the SMR vessel, removing all of the complicated pipe work that connect the components within a large nuclear reactor. So effectively it’s similar to what we have now, just scaled down with a new configuration.

The problem with these reactors is that they share complexity with the larger PWRs and it now appears unlikely that light water SMRs will be able to significantly reduce the cost of generation compared with larger reactors using the same technology due in part to the inability to reduce the complexity of the required safety control systems and diseconomies of scale in site operations.

However, IPWRs are based on proven technology in a new configuration, they are well advanced in design and some in regulatory approval, and they offer a least risk pathway to early deployment (by 2030). They are generally compatible with UK nuclear infrastructure but offer less opportunity for UK technical development.

The other group of reactors in development is are the “advanced” reactors or non-IPWR’s, commonly referred to as GEN IV. This category groups together some different technological approaches and includes a number of less well developed technologies that may offer significant cost and other advantages but with commensurately higher technical risks.

Non-IPWRs include high-temperature gas-cooled reactors, sodium-cooled reactors and molten salt reactors, amongst others. Some believe that this technology is too far away – it is possible that none could be deployed before 2030 and some significantly later than that date – as there are more uncertainties in both the technical and cost aspects of advanced reactors. Some GEN IV vendors are claiming they could be available only just behind the GEN III designs but these claims have yet to be substantiated.

However, there is the potential for a true price breakthrough because of the simplicity of the design of some of the GEN IV options. For example, they could have intrinsic safety which would reduce risk and control and operation requirements, but this is not yet proven. If you can get this, you remove a lot of the complexity therefore making it simpler, smaller and cheaper. These advanced technologies also offer the potential for greater UK technical development.

The dilemma facing the SMR initiative is: Can GEN III deliver at a globally competitive power price that would create a true mass market? Or is it worth taking the risk on GEN IV which may be able to offer a true safety and price breakthrough a few years after GEN III?1The development of SMRs is moving at different paces in different parts of the world and it remains to be seen who will get there first, and which technology will be able to provide cost competitive and commercial scale power. SMRs could play a major role in a broad energy mix and in theory SMRs could help reduce cost, secure domestic supply of electricity and reduce greenhouse gases, whilst at the same time – with the right competition, the right support and the right approach – the SMR opportunity for the UK could be a major wealth creator.