FROM THE EDITOR
success
hidden key to SMR
The
A highly promising area for nuclear development, SMRs are in a global race to commercial deployment. A look at the leader board reveals something about the keys to success.
mid all the hyperbole surrounding small modular reactor technology, the latest version of the International Atomic Energy Agency’s (IAEA) SMR catalogue is revealing. Covering advances in the design developments of land- and marine-based
reactors whether cooled with water, gas, liquid metal or molten salts, close to a hundred designs could have been listed in the 2025 edition. That the IAEA covered only 70 active designs illustrates their strong focus on those demonstrating sustained development and prospects to develop into real commercial products. At the last update the catalogue reports only two SMR designs in operation and four under construction with a further nine in the advanced stages of licensing. Of these 15 though, eight are essentially scaled-down pressurised water reactors (PWRs). The Rolls Royce SMR design, for example, is a 470 MWe three-loop PWR destined for the UK’s first three SMRs at the Wylfa site in North Wales. Many of the PWR designs are integral pressurised water
reactors (iPWRs) which are more complex to construct. Nonetheless, one such design is already in operation aboard Russia’s floating NPP Akademik Lomonosov, which is powered by two 35 MWe KLT40S units and began operation in May 2020. Another leading design broadly based on conventional reactor technology is the GE Hitachi BWRX-300. This
290 MWe boiling water reactor (BWR) is the choice for a number of projects, including the Darlington New Nuclear Project (DNNP) for Ontario Power Generation. The Canadian Nuclear Safety Commission (CNSC) issued a construction licence for the project last year. At face value then, the leading SMR designs are
essentially smaller versions of the large light water units that already make up the vast bulk of the world’s reactor fleet. However, this suggestion is entirely erroneous. While it is fair to suggest that using tried and tested technology does evidently confer some early mover advantage that is far from the whole story of SMR development. One of the SMR designs that is already operating
is China’s HTR-PM comprising two pebble-bed high temperature gas cooled reactor (HTGR) modules generating 200 MWe. This plant began operation in 2023. Other novel designs under construction include Russia’s
300 MWe BREST-OD-300 lead-cooled fast reactor, which is expected to begin operation in 2028 or 2029 and Kairos Power’s 140 MWe Fluoride Salt-Cooled High-Temperature Reactor (KP-FHR). Kairos recently broke ground on its Hermes 2 Demonstration Plant in Oak Ridge, Tennessee under a deal with Google to develop an advanced reactor fleet. This demonstration plant will supply up to 50 MWe to the Tennessee Valley Authority (TVA). Most recently, TerraPower announced the start of
construction of its Natrium plant, Kemmerer unit 1, in Wyoming after the Nuclear Regulatory Commission granted the first ever construction permit for a commercial-scale SMR earlier this year. The TerraPower design features a 345 MWe sodium-cooled fast reactor integrated with a molten salt energy storage system. Completion of the plant is targeted for 2030 and Kairos is already signing customers. In January, the company reached a deal with Meta to build up to eight Natrium reactors in the US with the first two targeted to come online by 2032. It would certainly be precipitous to declare winners
at this early stage, but it is equally clear that the key to SMR success does not rest solely with convention. Nuclear engineering is an industry that truly flourishes when it embraces the spirit of innovation and it is that fundamental value which is the ultimate key to success. The diverse ecosystem of the leading SMR designs are a daily reminder of that salient fact. ■
David Appleyard
www.neimagazine.com | May 2026 | 3
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