Valar Atomics ran an Nvidia Blackwell chip on electricity from its Ward 250 reactor in Emery County, Utah, on July 1, marking the first time a next-generation American reactor has powered an AI chip.
The demonstration itself was modest. Valar connected an Nvidia RTX Spark desktop machine built on Blackwell architecture to power drawn from Ward 250, its helium-cooled test reactor, and used it to briefly host a live website. No racks of GPUs, no data center, just enough electricity from a fission reaction to prove the circuit works. But the symbolism is what matters here, and Nvidia knows it. The company that sells the chips everyone wants just put its name next to a nuclear startup that reached criticality less than two weeks earlier.
Ward 250 went critical on June 18, according to the Department of Energy, making it the second advanced reactor to reach that milestone under the DOE's Reactor Pilot Program and the first authorized under that program to be built and run outside a national laboratory. The program traces back to Executive Order 14301, signed by President Trump in May 2025, which set a target of at least three advanced reactors achieving criticality by July 4, 2026, the country's 250th birthday. Valar built the Emery County site from an empty lot in under a year.
The reactor is a Generation IV design, cooled by pressurized helium and fueled with TRISO pellets, running graphite moderation instead of the water-cooled systems that dominate the existing US fleet. At the July 1 demo it was producing around 100 kilowatts of thermal energy, converted to electricity through a thermoelectric generator. That is barely enough to run a household appliance, let alone a data center. Valar says it plans to scale the design to 5 megawatts of electric output.
Alongside the demo, Valar and Nvidia announced a feasibility study for a 30-megawatt data center in Utah that would run entirely on Ward 250's power and use almost no water. The pitch pairs Valar's helium cooling loop, which never touches water in the first place, with cooling technology Nvidia has been developing for its own systems. Conventional data centers evaporate millions of gallons a year to keep chips cool, and water rights in Utah's high desert are not exactly abundant. If the pairing works at 30 megawatts, it becomes a template other reactor developers will want to copy.
Here's the thing worth being honest about: a website loading off 100 kilowatts of thermal output is not a commercial data center, and the jump to 30 megawatts is roughly 300 times the scale of what actually happened on July 1. Valar has not said when construction on that facility would begin, or who would pay for it. Proof of concept and bankable infrastructure are different animals, and the gap between them is where most nuclear startups have historically stalled.
Still, the direction is unmistakable. Big tech has spent the past two years signing power purchase agreements for nuclear electricity delivered over the existing grid. Microsoft restarted Three Mile Island Unit 1 in Pennsylvania under a 20-year deal with Constellation. Amazon locked up 960 megawatts at its Susquehanna campus. Google signed a fleet agreement with Kairos Power for 500 megawatts of small modular reactor capacity starting in 2030. Total committed nuclear capacity for data centers now tops 9.8 gigawatts, according to tracking by smrintel.com, more capital committed to nuclear power than in any prior decade of US history. What Valar and Nvidia are testing is different in kind: a reactor sitting next to the chips it powers, off the public grid entirely, rather than a contract for electrons delivered somewhere down the transmission line.
That distinction matters because the grid itself is buckling under AI demand right now, not in 2030. PJM Interconnection, which covers a swath of the mid-Atlantic and Midwest, got emergency federal approval in May to curtail data centers and other large loads during heat waves, and Energy Secretary Chris Wright signed two more curtailment orders on June 30 as the region forecast electricity demand that would break the grid's twenty-year-old record. PJM projects data centers could add 30 gigawatts of new demand by 2030. Google's own sustainability report, released the same week as the Valar demo, showed the company's electricity consumption jumped 37% in 2025, its largest annual increase ever, with Google acknowledging flatly that its AI buildout is outrunning the grid's ability to decarbonize.
Frankly, that is the real context for a 100-kilowatt reactor lighting up a desktop PC in the Utah desert. Nvidia does not need Valar's electrons today. It needs proof that reactors small enough to sit on a data center campus, built in under a year instead of the decade typical of conventional nuclear plants, can actually work. Whether Ward 250's approach scales to 30 megawatts and beyond will decide if this was the start of something or a one-day story with a good photo.
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