US to fire up small reactors in 2026 as part of 'nuclear renaissance'
Eleven companies are working towards an ambitious goal as part of the US Department of Energy's plan to fast-track the development of advanced nuclear reactor technologies
Valar Atomics’ Ward 250 reactor under construction
Daria Nagovitz/Valar Atomics
Despite providing nearly a fifth of US electricity generation, nuclear power in the country has stagnated for decades. Regulatory hurdles, public scepticism and cheaper energy sources led to plant closures, moratoriums and a lack of funding for novel nuclear technologies. But spiking electricity demand – driven largely by data centres – is spurring a nuclear revival, and the Department of Energy appears to be making up for lost time. Its Reactor Pilot Program is fast-tracking the testing of advanced reactor designs, with the first major milestone set for mid-2026.
The programme is part of a DOE strategy aiming to quadruple the sector’s output by 2050. Eleven companies developing advanced nuclear reactor technologies were selected to participate, and the goal is for at least three of them to reach criticality – a state where a nuclear fission reaction becomes stable and self-sustaining – by 4 July 2026.
“It is deliberately a very ambitious deadline,” says Leslie Dewan, a nuclear engineer specialising in advanced reactor technologies. “One of the purposes of this pilot is to really flesh out which concepts are executable under real-world constraints.”
The reactor designs being developed range from molten salt and high-temperature gas reactors to fast reactors, sodium-cooled designs and pressurised water systems. One of the companies that is thought to be furthest along is California-based Valar Atomics, which is developing a high-temperature gas reactor (HTGR) called the Ward 250.
HTGRs run on tiny particles of uranium coated in layers of carbon and ceramic. The coatings turn each particle into a self-contained fuel unit that won’t melt even at extremely high temperatures, providing a built-in safety shield that prevents radioactive leakage.
Fuel particles are loaded into graphite blocks, which form the reactor’s core and have channels for helium gas to flow through. The fuel’s fission reaction heats the helium, and that heat boils water to create steam, which turns a generator to produce electricity. The helium then flows back to the reactor to be reheated.