On Monday, November 17, the U.S. startup Valar Atomics announced that it had reached a historic milestone through collaboration with one of the country’s leading nuclear laboratories. The previous week, the El Segundo, California-based company had revealed that it had raised $130 million in funding, supported by Anduril founder Palmer Luckey and Palantir CTO Shyam Sankar. Valar Atomics now claims to be the first startup in the nuclear sector to achieve criticality in a fission reaction.
Valar is also the first company to announce that it has reached this milestone within a special pilot program run by the U.S. Department of Energy, which aims to bring at least three startups to criticality by July 4 of next year. The initiative, launched following an executive order signed by President Donald Trump in May, has transformed regulations for nuclear startups in the United States, enabling companies to achieve innovative results more quickly.
The term criticality refers to a nuclear reactor’s ability to sustain a chain reaction, representing the first essential step toward energy production. However, there is a distinction between the type of criticality achieved by Valar this week, known as cold criticality or zero-power criticality, and the level required for actual nuclear power generation.
In reactors designed for energy production, the reaction utilizes the heat generated; in cold criticality, however, the reaction is sufficient only to test the reactor’s design and physical properties, without producing enough heat to generate energy. The reactor that recently reached criticality is not a model entirely designed by Valar Atomics, but combines the startup’s fuel and technology with structural components provided by the Los Alamos National Laboratory, one of the main research and development centers of the U.S. Department of Energy.
