A ceremony in Wyoming yesterday marked the official start of construction of TerraPower’s planned Natrium reactor demonstration project.

While currently awaiting final review from the U.S. Nuclear Regulatory Commission, TerraPower is moving forward with nonnuclear construction work at a retired coal plant near Kemmerer, Wyo. The groundbreaking brought together TerraPower leaders, government officials, Natrium project partners, industry advocates, and community supporters.

The U.S. Nuclear Regulatory Commission has formally accepted TerraPower’s small modular reactor construction permit application and is scheduling it for review.

The company’s Natrium reactor demonstration project—the nation’s first commercial advanced reactor of its kind—would be built on land in Wyoming near one of the state’s retiring coal plants. Kemmerer Power Station Unit 1 would operate as a 345-MW sodium-cooled reactor in conjunction with molten salt–based energy storage.

TerraPower officials said last week to expect “dirt moving” at its Wyoming site come June—and for operations to begin there as early as 2030—as it advances plans to build new nuclear in the United States. But 40-plus pages of initial commentary from the Nuclear Regulatory Commission, in the form of a preapplication readiness assessment report, may slow TerraPower’s plans.

TerraPower, the advanced nuclear company backed by Bill Gates, announced last week that the start date for its Natrium reactor has been pushed back. As Russia is currently the only commercial source of the high-assay low- enriched uranium (HALEU) the plant requires, the company faces a lack of fuel availability. TerraPower originally planned to use Russian fuel to get its demonstration reactor up and running by 2028, but Russia’s invasion of Ukraine has dashed those plans.