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In 2017, nuclear power generated 21% of UK electricity. Seven of the UK’s nuclear power stations are due to close by around 2030, and six new large stations are planned to help meet future demand. The first of these, Hinkley Point C, is under construction and due to start producing electricity in 2025. Rising costs and construction delays in Europe and the US have raised concerns about new nuclear power continuing to be a source of cost-effective clean energy.

SMRs are made using standardised factory-manufactured parts delivered ready for assembly. SMRs have generated government and industry interest internationally because designers have suggested SMRs may offer lower investment risk, reduced cost and greater compatibility with a flexible electricity network. So far, no commercial SMR has been built worldwide and there is considerable uncertainty around their costs, timescales and challenges. SMR designs based on smaller versions of existing technology are expected to be commercially available for construction within 10 years.

National Grid and government modelling suggest that nuclear power capacity may increase further in the future, and SMRs may comprise some of this new capacity. UK industry is developing different designs, including some supported by the Government’s Advanced Modular Reactors programme and the 2018 Nuclear Sector Deal.

Key points in the POSTnote include:

  • Small modular reactors (SMRs) consist primarily of units built in factories and will generate less electricity than conventional nuclear reactors.
  • Proponents suggest SMRs could reduce the financing challenges faced by conventional nuclear power by reducing cost and construction time. Future cost competitiveness is currently uncertain due to the diversity in SMR designs and few constructed prototypes.
  • There are many diverse SMR designs. No commercial SMR has been built; the first is expected within ten years. Future cost competitiveness is currently uncertain.
  • Potential uses of SMRs in the UK and abroad could be limited by access to new sites, and regulatory and planning matters.
  • SMRs are viewed as a commercial opportunity for the UK nuclear industry. It is unclear whether the UK market alone would provide sufficient demand to justify investment in a new manufacturing supply chain.
  • Many countries, yet to develop nuclear infrastructure, have shown particular interest in SMRs. Complex safety management considerations, infrastructure requirements and compliance with non-nuclear proliferation agreements may create large barriers to accessing nuclear technology.


POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:

  • Alasdair Harper, BEIS
  • Craig Lester, BEIS
  • Richard Deakin, BEIS
  • Joshua Scott, BEIS
  • Daniel Mathers, BEIS*
  • Paul Skelton, Radioactive Waste Management*
  • Deborah Ward, Nuclear Decommissioning Agency*
  • Paula Calle Vives, ONR*
  • Sarah Brown, ONR*
  • Ana Gomez Cobo, ONR*
  • Alan McGoff, Environment Agency*
  • Derek Allen, Innovate UK
  • Jon Halladay, DIT*
  • Bob Bish, DIT*
  • Paul McCaffrey, DIT*
  • Stewart Magruder, IAEA*
  • Camille Scotto de Cesar, IAEA*
  • H. Subki, IAEA*
  • Brian Boyer, IAEA*
  • Andrew Storer, NARMC
  • Johnny Stephenson, NAMRC*
  • Russel Fowler, National Grid*
  • Martin Goodfellow, Rolls-Royce*
  • Alan Wood, Rolls-Royce
  • Peter Haslam, Nuclear Industry Association*
  • Shayne Halfpenny-Ray, Nuclear Industry Association
  • Stephen Haighton, Moltex Energy*
  • Prof Richard Taylor, University of Manchester*
  • Prof Francis Livens, University of Manchester*
  • Prof Juan Matthews, University of Manchester*
  • Dr Neil Irvine, University of Manchester*
  • Dr Laura Leay, University of Manchester
  • Dr Giorgio Locatelli, University of Leeds*
  • Paul Murphy, Gowling WLG*
  • Prof Andrew Worrall, Oak Ridge National Laboratory*
  • Helen Peters, Pinsent Masons LLP
  • Janet Wilson, Touchstone Nuclear
  • Mike Middleton, Energy Technologies Institute*
  • Dr Fiona Rayment, National Nuclear Laboratory*
  • Dr Doug Parr, Greenpeace*
  • Kirsty Gogan, Energy for Humanity
  • POST Board Members*

*denotes people who acted as external reviews of the briefing.

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