Valar Atomics Powers Nvidia Blackwell Chip With Ward 250 Reactor

Valar Atomics, a California-based nuclear startup, staged a live demonstration in Emery County, Utah, on July 1, 2026, connecting its Ward 250 test reactor to an Nvidia RTX Spark desktop PC built on Nvidia's Blackwell architecture, and used the reactor's electricity to briefly run a temporary website. Bloomberg and Tom's Hardware report the reactor's thermal output was converted to electric current via a thermal-electric generator. Separately, Valar and Nvidia announced a joint feasibility study to explore designs for a 30-megawatt computing facility that would use a closed-loop, water-free cooling system instead of drawing on local municipal water supplies, according to Tom's Hardware and InterestingEngineering.

1. June 18, 2026

   Valar Atomics' Ward 250 test reactor reached criticality in Utah, according to the American Nuclear Society and the U.S. Department of Energy.

2. July 1, 2026

   Valar staged the live Nvidia demonstration in Utah and announced the joint 30-megawatt feasibility study.

Ward 250 is a High-Temperature Gas-Cooled Reactor using TRISO-coated fuel particles and helium coolant, per InterestingEngineering and heise. Despite the name, "250" refers to a program or model designation rather than a capacity rating: the unit is built for an initial test-power target of around 100 kilowatts thermal, with a design intended to scale toward roughly 5 megawatts electric, per the American Nuclear Society's reporting. At the July 1 demo, Valar CEO Isaiah Taylor said the core was producing about 100 kilowatts of thermal energy, per Tom's Hardware; outlets differ slightly on how that figure relates to the reactor's full-scale rating, so treat exact percentage-of-capacity claims as approximate.

The demonstration combines three distinct subsystems relevant to data-center planning: an HTGR heat source, a thermal-to-electric conversion chain, and Nvidia's closed-loop liquid cooling for GPUs. Each has different maturity and monitoring needs, and integrating them raises systems-engineering and site-operations questions rather than purely algorithmic ones. For teams modeling long-term power and water constraints on AI infrastructure, this is an early but concrete data point that on-site advanced-reactor generation paired with water-free cooling is technically feasible at small scale, not that it is commercially available.

Whether follow-up tests scale steady electrical output beyond the demo's kilowatt-level output, any finalized designs or site selection for the 30-megawatt facility, regulatory filings or licensing milestones with the Nuclear Regulatory Commission, and further technical disclosure on the heat-to-electric conversion chain.