As the past year drew to a close, the US House of Representatives passed legislation that would ban the purchase of enriched Russian uranium for use in American nuclear reactors — a measure meant to hobble Rosatom, Russia’s state nuclear corporation, which is actively participating in Moscow’s invasion of Ukraine.

The Prohibiting Russian Uranium Imports Act, which was approved by voice vote, would bar Russian uranium imports 90 days after enactment while allowing a temporary waiver until January 2028. The bill needs to be passed by the Senate and then signed by President Joe Biden to become law, though the timeline for this remains unclear.

The US has imposed deep sanctions on Russian-produced oil and gas over the war, but Russian-enriched uranium used to fuel America’s 92 commercial nuclear reactors has thus far escaped legislative action.

That a US uranium ban has not been pursued earlier puts in Washington in shaky moral territory, especially as Rosatom helped orchestrate the takeover of the Zaporizhzhia nuclear power plant — both Ukraine and Europe’s largest such facility — a state of affairs that has made the station hostage to an active war zone.

Experts from the UN’s International Atomic Energy Agency have repeatedly raised alarm over the plant’s vulnerability, and agency monitors stationed onsite report constant military fighting nearby. IAEA director General Rafael Grossi has pleaded for both sides to establish a demilitarized zone around the station, without result. Meahwhile, what agency monitors at the plant can view and report on is subject to the whims of the Russian military occupiers.

Yet, like many of its European counterparts that support Ukraine’s resistance, the United States remains heavily dependent on enriched uranium from Russia. Last year — as in decades before — Russia was the United States’ number one supplier of enriched uranium supplies, sending almost a quarter of the nuclear fuel used in the America’s commercial reactor fleet, Department of Energy date show.

Most of the rest is imported from Europe. A final third or so is produced by a British-Dutch-German consortium operating in the United States called Urenco. Nearly a dozen countries around the world depend on Russia for more than half their enriched uranium — many of them likewise Ukraine-allied members of Nato.

Russia is also the only commercially available source of special highly enriched reactor fuel known as Haleu, which is needed for a new breed of advanced nuclear reactors that are under development, numerous nuclear analysts have noted.

The US reliance on Russian-enriched fuel also leaves the country’s current and future nuclear plants vulnerable to a Russian shutdown of enriched uranium sales, which analysts say is a conceivable strategy for President Vladimir Putin, who often wields energy as a geopolitical tool.

”We cannot be held hostage by nations that don’t have our values, but that’s what has happened,” Senator Joe Manchin III, the West Virginia Democrat who leads the Senate’s energy committee, told The New York Times. Manchin is sponsoring a bill that would help rebuilt US enrichment capacity with the help of federal subsidies.

“The United States must ban the sale of Russian uranium in America,” Wyominc Senator John Barrasso, the author of the Senate’s version of the uranium ban, said in a statement following the House vote last month, according to Bloomberg. “Vladimir Putin has used Russia’s nuclear industry to fund his brutal invasion of Ukraine.”

The US spends an estimated $1 billion per year on nuclear fuel from Russia, Barrasso told Bloomberg. While this would pale in comparison to losses Moscow faces in oil and gas sanctions, it nonetheless represents an important source of foreign revenue for Rosatom, whose foreign receipts last year totaled around $8 billion.

So, what has prevented Washington, Ukraine’s primary financial supporter in the West and the de facto head of Nato, from taking steps to phase out its use of Russian-produced uranium?

For one, it is maddeningly difficult to refuse that Russian supply. Throughout the 1990s, the Unites States turned away from its own enrichment capabilities in favor of using down-blended stocks of Soviet-era weapons grade uranium.

That program — dubbed Megatons to Megawatts — was part of a raft of nonproliferation efforts undertaken cooperatively in the 1990s by Moscow and Washington to sequester and dilute post-Soviet stocks of nuclear weapons and materials. Many of these weapons were located in former Soviet republics that, when the union dissolved in 1991, overnight became their own states. Such was the case with Ukraine, which in 1993, relinquished Soviet-era nuclear weapons held on its territory to Moscow.

Megatons to Megawatts provided the US with cheap fuel and Moscow with needed cash during the recurring economic crises of the 90s, and was seen as critical effort to winnow down weapons grade materials. So prevalent were the down blended HEU stocks that every single US nuclear power plant at some point fueled their reactors with them.

But it also destroyed the profitability of America’s inefficient enrichment facilities, which were eventually shuttered.  Then, instead of investing in upgraded centrifuges in the United States when the Megatons to Megawatts program concluded in 2013, successive presidential administrations kept buying enriched uranium from Russia. So prevalent are the Russia uranium stocks that one of every 20 US homes is powered by fuel that Rosatom has enriched.

This now leaves the US on the backfoot should it strive to extricate itself from Russian supply chains. As it stands now, there only one wholly US-owned company that enriches uranium.

As part of the new uranium-ban bill, the Biden administration would earmark $2.2 billion toward the expansion of uranium enrichment facilities in the US. But, under the proposed 2028 implementation of the ban, that only leaves another five years for US nuclear power plants to find alternative suppliers.

That’s a tight deadline. The single facility enriching uranium and providing Haleu is the American Centrifuge Company, owned by Centrus Energy, in Ohio. The plant has been on a 22-year hiatus, but in October, it began enriching again, largely as a response to possible shortages from Russia. But it will be difficult for the company to fully replace that supply in the near term.

As such, the US would likely have to pursue other foreign enriched uranium suppliers, most likely France. But France likewise has deep ties to the Rosatom from which it, like the US, has yet to disentangle.

Meanwhile, the most promising alternative for the US is likely a Urenco plant in New Mexico, which last summer announced plans to expand it production by 2025 to answer demand for non-Russian fuel.

All told, a cold-turkey break with Russian nuclear fuel supplies would be nearly impossible for the US and its allies in the Ukrainian struggle to undertake. But Washington and its European counterparts nonetheless must develop an exit strategy, both for the near term, as the war continues to rage, and for the more distant future as well, when relations with Russia are impossible to predict.

We at Bellona will continue to report on and analyze these strategies, and will over the next several months continue to publish our insights on how a nuclear market free of Rosatom could function.