What Happened to Small Nuclear Reactors (SMRs)?

The concept of Small Nuclear Reactors (SMRs) dates back to the 1940s with naval propulsion, and early civilian small reactors emerged in the 1950s and 1960s. However, these early designs struggled with economic viability compared to larger reactors, leading the industry to focus on bigger plants. Renewed interest in SMRs gained momentum in the late 20th and early 21st centuries, driven by the need for low-carbon energy, enhanced safety features, and more flexible deployment options. SMRs are characterized by their compact size (typically less than 300 MWe), modular design allowing for factory assembly, and scalability.

Key turning points in SMR development include the commercial operation of Russia's KLT-40S floating nuclear power plant in 2020 and China's HTR-PM pebble-bed modular high-temperature gas-cooled reactor connecting to the grid in 2021. These projects, while significant milestones, experienced longer development timelines, higher costs, and lower initial capacity factors than anticipated (Source: Stanford University, 2025). The mid-2020s have seen a mixed but generally accelerating trajectory for SMRs. In a notable setback, NuScale Power's Carbon Free Power Project (CFPP) with Utah Associated Municipal Power Systems (UAMPS) was mutually terminated in November 2023 due to escalating costs and insufficient subscription from UAMPS members. This cancellation led to significant staff layoffs at NuScale and raised concerns about the commercial viability of SMRs (Source: NucNet, 2024). NuScale's stock price has fallen by over 40% in 2026, reflecting market uncertainty despite its design being the only one certified by the U.S. Nuclear Regulatory Commission (NRC).

However, other SMR projects have shown significant progress. TerraPower, chaired by Bill Gates, officially began nuclear construction on its Natrium plant in Kemmerer, Wyoming, in April 2026, following an NRC construction permit issued in March 2026. This marks the first commercial non-light-water US power reactor approved for construction in over 40 years, with completion targeted for 2031. TerraPower has also signed an agreement with Meta to support up to eight Natrium plants by 2035.

In Europe, Rolls-Royce SMR has emerged as a leading player. In 2026, it was selected by Great British Energy – Nuclear as the preferred technology for the UK's SMR program. A contract was signed in April 2026 to begin work on deploying three Rolls-Royce SMR units at Wylfa, North Wales, aiming to supply power by the mid-2030s. Rolls-Royce SMR has also secured agreements for deployment in the Czech Republic (up to 3 GW with ČEZ Group) and Sweden (three units with Videberg Kraft). The company is investing in a manufacturing development center in Derby, UK, slated to open in late 2026, to establish factory-build processes.

As of June 2026, the U.S. leads globally with 28 SMR siting announcements, followed by Canada (9) and the UK (7). The global SMR market was valued at approximately USD 6.7 billion in 2026 and is projected to reach USD 14.1 billion by 2036, growing at a CAGR of 7.7% (Source: Future Market Insights, 2026). The demand is driven by industrial decarbonization, the integration with the hydrogen economy, and the need for stable power for data centers. However, challenges persist, including the high first-of-a-kind capital requirements, fuel qualification (especially for High-Assay Low-Enriched Uranium or HALEU), regulatory capacity, and securing long-term power purchase agreements.