US to fire up small reactors in 2026 as part of ‘nuclear renaissance’

Despite the fact that it provides almost a fifth of American electricity productionNuclear energy in the country has been stagnant for decades. Regulatory hurdles, public skepticism and cheaper energy sources have led to plant closuremoratoriums and lack of funding for new nuclear technologies. But the sharp increase in demand for electricity – mainly thanks to data centers — is spurring a renaissance in nuclear power, and the Energy Department appears to be making up for lost time. His Reactor pilot program is accelerating testing of advanced reactor designs, with the first major milestone targeted for mid-2026.

The program is part Department of Energy Strategy with the goal of quadrupling production in this sector by 2050. Eleven companies developing advanced nuclear reactor technologies have been selected to participate, and the goal is for at least three to achieve criticality – a state in which the nuclear fission reaction becomes stable and self-sustaining – by July 4, 2026.

“This is a deliberately very ambitious deadline,” says Leslie DewanNuclear engineer specializing in advanced reactor technologies. “One of the goals of this pilot project is to flesh out what concepts can be implemented under real-world constraints.”

Reactor designs under development range from molten salt reactors and high-temperature gas reactors to fast reactors, sodium-cooled designs, and pressurized water systems. One company believed to be furthest along is California-based Valar Atomics, which is developing high temperature gas reactor (HTGR) called Ward 250.

HTGRs operate on tiny particles of uranium coated with layers of carbon and ceramics. The coatings transform each particle into a self-contained fuel unit that does not melt even at extremely high temperatures, providing a built-in shield to prevent radioactive leakage.

Fuel particles are loaded into graphite blocks that form the reactor core and have channels for the passage of helium gas. The fission reaction of the fuel heats the helium, and this heat heats the water, creating steam that runs a generator to produce electricity. The helium is then returned to the reactor to be reheated.

Valar broke the ground at Ward 250 in September, making it the second company to begin construction (the first was from Texas). Halo Atomicswhich broke the ground in August). Valar was the first to reach cold criticalityself-sustaining fission reaction without releasing heat. This was done at a government test site under strictly controlled conditions, and while it validates the core physics and provides useful data, Dewan says, “it's not the same as building your own integrated test reactor and running it at power.”

Molten Salt Reactors, Texas Nature Resourcesthe chosen design work completely differently, but are also considered to be inherently safe. The uranium is mixed with molten salt, which is heated by a fission reaction. Pumps move the liquid salt through a heat exchanger, where it transfers heat to another circuit that produces steam or drives a turbine. If the salt overheats, it expands and melts the emergency “freeze plug,” which drains the fuel into a safe tank where it cannot sustain a chain reaction.

“Molten salt reactors operate at atmospheric pressure, so any accident can only happen on site,” says Dewan. “Even if it lost all power, even if there were no operators on site, it would be able to shut down safely.”

Although Natura has not yet achieved success, it provided construction Nuclear Regulatory Commission approval to build a 1-megawatt research reactor, and recently acquired Shepherd Poweralso based in Texas, whose supply chain and regulatory expertise will help move Natura's technology toward adoption. The company has a “very positive cooperative relationship with the NRC,” Dewan says, but “molten salt is corrosive and at high temperatures it is radioactive, so material issues should not be underestimated.”

With the criticality deadline only about six months away, Valar, Natura and the other nine companies participating in the pilot program will have to work at an unprecedented pace to meet it. However, this is just one of many obstacles that companies will have to overcome.

“The real evidence will be things like: can you bring the reactor up to power and shut it down again in a controlled manner; can you operate at the design temperature for thousands of hours; can you demonstrate that materials and fuels behave as expected; and can you do all of this reliably enough that the NRC and future customers will trust the design?” says Devan. “I view this date in 2026 as the start of an interesting period of data collection, but by no means the finish line.”