President Donald Trump has made rebuilding the United States’s nuclear industrial base a central part of his energy agenda. Last week, a nuclear startup operating in Emery County, Utah, took an important step toward making that revival real. Valar Atomics became the first Department of Energy-authorized reactor built outside a national laboratory to reach “criticality.”

Valar successfully completed a zero-power-fueled criticality demonstration, which means its reactor sustained a controlled nuclear chain reaction at very low power. The milestone does not mean the reactor is yet producing commercial electricity, but it is still a major step. It is the nuclear equivalent of starting an engine for the first time: The car is not yet on the highway, but the machine has come alive. Valar says it aims to produce power by July 4.