10 Breakthrough Technologies 2026See the full list

Next-gen nuclear

New reactors use novel materials and compact designs to make nuclear power safer and cheaper.

Casey Crownhartarchive page

January 12, 2026

WHOBWXT, China National Nuclear Corporation, Kairos Power, Newcleo, TerraPower, X-energy

WHEN3 to 5 years

VICHHIKA TEP/MIT TECHNOLOGY REVIEW | ADOBE STOCK

Nuclear power has been a critical part of the electricity grid for decades, but old reactor designs—which often come in years behind schedule and billions over budget—could soon get a big refresh.

Next-generation nuclear reactors are smaller and simpler to manufacture, and they use different materials to generate a constant stream of electricity. These changes could help nuclear power contribute flexibility and resilience to the grid, which is crucial as global electricity demand rises because of electric vehicles, air-conditioning, and data centers.

Among the new players, no single design dominates. While conventional reactors typically have the capacity to power a city, some companies are now pursuing microreactors, which would generate less than 0.1% as much power as traditional designs. Others are exploring alternative coolants like molten salt or metal, which would eliminate the need to operate under the super-high pressures seen in today’s water-cooled plants.

In 2024, Kairos Power won the first US approval to begin construction on an electricity-producing next-generation nuclear reactor—a molten-salt reactor called Hermes 2. More approvals could soon follow for other companies, including TerraPower and X-energy.

China is emerging as a leader in some new reactor technologies. The country’s national nuclear company reportedly has several sodium-cooled fast reactors in the works (so named because they don’t slow down the high-energy neutrons that split uranium atoms). Russia is building a lead-cooled fast reactor that could come online later this decade.

One key question for new reactor technologies: Can they scale up to meet demand? While the first demonstrations are now in the late planning stages or under construction, making the grid more resilient will require building many more such reactors worldwide, and doing it economically.