The next-generation nuclear reactor project backed by Bill Gates and the U.S. Department of Energy has stalled because the only source of the uranium it needs is Russia, Business Insider wrote.

TerraPower, the company behind the project, has delayed the launch of its flagship reactor for at least two years because of the effects of Western sanctions against Moscow.

CEO Chris Levesque said the war has hit the supply of high-grade low-enriched uranium, or HALEU. That means the Natrium nuclear power plant, which TerraPower is building in Wyoming, will not start up in 2028 as planned.

In February 2022, Russia's invasion of Ukraine resulted in HALEU's only commercial fuel source no longer being a viable part of the supply chain for TerraPower as well as others in our industry, Levesque said.

Efforts to bring U.S. manufacturers into commercial production and find alternative suppliers have not been successful, he said.

Gates helped found TerraPower in 2006 and has been its chairman ever since. The company said its goal is to provide the world with a more affordable, safer and cleaner form of nuclear energy.

Its Natrium project is expected to cost $4 billion, with about half of that funding coming from the U.S. Department of Energy.

TerraPower plans to use sodium as HALEU fuel, which has a higher enrichment level than the 5 percent enriched uranium-235 used in U.S. nuclear reactors already in operation.

According to Levesque, the company assumed it would use Russian supplies for the first core load because the U.S. does not currently have the capacity to enrich uranium-235.

But the war cut off the fuel source after the U.S., the EU and other Western allies imposed sanctions against Moscow.

According to Levesque, TerraPower and the Department of Energy are now seeking alternative sources of HALEU and want lawmakers to approve a $2.1 billion funding package to support low-enriched uranium production in the United States.