A Look at the U.S. Military’s Microreactor

Feb. 25—On Feb. 15 three huge U.S. Airforce C-17 transport aircraft airlifted a 5 MW microreactor and seven related modules from March Air Reserve Base in California to Hill Air Force Base in Utah, in what was dubbed Operation Windlord. While the media and Under Secretary of War for Acquisition and Sustainment Michael Duffey and Energy Secretary Chris Wright trumpeted the event as an historic first and as part of revival of U.S. nuclear energy capability, little was said about the reactor itself, such as who built it.

The reactor is a Ward 250 IV generation High Temperature Gas-Cooled Reactor (HTGR). There are only three such reactors operating in the world today, two in China and one in Japan. It is not of the Pebble Bed design but a prismatic-type helium-cooled, graphite-moderated type with a core built from stationary hexagonal graphite blocks holding TRISO fuel compacts, assuring maximum safety.

The reactor was not fully operational. It was transported without the fuel and brought to the Utah San Rafael Energy Lab (USREL) for further validation, with the plan of having it go critical in time for the Fourth of July celebrations of the 250th anniversary of the founding of the United States. Located in the state’s historic coal district, USREL is owned and managed by the State of Utah.

This is not your normal SMR private start-up initiative, where the new company spends its first 10 years raising funds, trying to get its design past all the regulatory hurdles, and writing dozens of press releases. The constructor of this reactor is the El Segundo, California-based Valar Atomics, which was formed in 2023, and was unable to raise its first $19 million until February 2025 but was able to build a reactor ready for validation in 12 months.

Valar Atomics was founded by Isaiah Taylor, an entrepreneur with more enthusiasm and drive than knowledge of nuclear power; nonetheless, he is committed to reviving the ethos of the crash program of the era of the Manhattan Project and the breakthroughs made in nuclear energy in the 1950s. He has pulled together a very able team of 20 engineers and constructors that has enabled him to rapidly build this reactor. The company’s chief nuclear officer is Mark Mitchell, and its head of mechanical engineering is Willem van Rooyen. Both men are South African and worked on the famous South African pebble bed HTGR reactor that was eventually built in China. Both men, as well as several of the other engineers, have years of experience in the nuclear power field.

Their success also is related to the fact that they are partnering with the U.S. Department of War and Department of Energy, which is probably helping them to get past the regulatory hurdles for at least the 5 MW project for the U.S. military. Nonetheless, Valar’s goal is to build a 25 MW reactor of the same design as the Ward 250. Taylor has said he wants to mass produce “thousands” of these reactors to electrify the world. Indeed, a 25 MW reactor of this design would be ideal for locations in Africa, the Arctic, and perhaps even the Moon.

Valar’s reactor would complement the HTMR 100, an HIGR reactor with a capacity of 35 MW now being developed by Stratek Global of South Africa, which is headed by Kelvin Kemm, a South African nuclear engineer.