Nuclear power offered a way to make a great deal of electricity without the smoke of coal. The argument of this page is that fear held that buildout back, that the delay put off a cleaner climate, and that people worked against their own interest out of fear. Alexander Wissner-Gross, on Moonshots recorded October 2, 2026, said that for decades people were scared of their shadow, and that nuclear lost 50-plus years after The China Syndrome. That is his statement. It is not a measured delay.
The record is narrower. The World Nuclear Association, updated September 29, 2026, says there were no new US construction starts from 1977 until 2013, about 36 years. After the 1979 Three Mile Island accident, many orders were cancelled or suspended, and new-build went quiet for two decades. The same account says 47 reactors, all approved before 1977, still came online in the late 1970s and 1980s, and that by 1990 more than 100 commercial power reactors had been commissioned. It also says gas often looked cheaper. That is the Association’s account, not a single official cause.
Operating
HTR-PM, Shidaowan, Shandong, China. A high-temperature gas-cooled small reactor. Commercial operation was reported in December 2023. Tsinghua, December 7, 2023. Xinhua, December 6, 2023.
Akademik Lomonosov, Pevek, Russia. A floating plant with two small reactors, 35 megawatts electric each. Commercial operation since May 2020. Nuclear Engineering International, November 5, 2024.
Under construction
Kairos Power Hermes, Oak Ridge, Tennessee. A test reactor, not a power plant. The Nuclear Regulatory Commission issued a construction permit on December 14, 2023. In May 2026 it extended the latest completion date to April 30, 2029. First nuclear concrete was poured in May 2025. Federal Register, May 18, 2026.
GE Vernova Hitachi BWRX-300, Darlington, Ontario. Canada’s nuclear regulator licensed Ontario Power Generation on April 4, 2025 to construct one 300-megawatt reactor. On March 30, 2026 it cleared the foundation work. An operating licence is still a later decision. The company’s target to connect the unit by the end of 2030 is a plan, not an operating date. Canadian Nuclear Safety Commission.
Permit issued, not yet operating
TerraPower Natrium, Kemmerer, Wyoming. On March 9, 2026 the Nuclear Regulatory Commission issued a construction permit for a 345-megawatt sodium-cooled reactor that can raise output to 500 megawatts from storage. An operating licence is still required. Non-nuclear construction began in April 2026. First safety-related concrete is planned for 2027. US Department of Energy, March 9, 2026.
Design approval only
NuScale. The Commission certified an earlier small-reactor design in January 2023, and in May 2025 it approved a later design, the US460, for use in a future application. Neither step is a permit to build a plant. Federal Register, January 19, 2023, and June 4, 2025.
Not yet a licence to build
X-energy and Dow, Seadrift, Texas. An application is in for four small high-temperature reactors to supply electricity and steam to a Dow plant. In May 2026 the Commission finished an environmental review and found no significant impact. No construction permit has been issued. A decision is expected in the first half of 2027. Dow, May 18, 2026.
Oklo Aurora. In January 2022 the Commission denied Oklo’s application for a compact reactor at Idaho National Laboratory because of missing information, and it made no safety finding. As of September 2026 the project is still in pre-application. A Department of Energy pilot step is not a Commission licence. Nuclear Regulatory Commission, January 6, 2022.
Rolls-Royce, Wylfa, Wales. In November 2025 the UK government picked Wylfa for its first small modular reactors. In April 2026 a contract covered design and planning for three 470-megawatt units, ahead of a final investment decision expected in 2029. Not licensed to operate. GOV.UK, November 13, 2025.
Cancelled
NuScale and the Utah Associated Municipal Power Systems ended the Carbon Free Power Project in Idaho on November 8, 2023. They said it was unlikely to have enough customers. It ended before a combined-licence application. NuScale, November 8, 2023.