WASHINGTON — Inside a highly classified facility in Oak Ridge, Tennessee — the same facility that enriched uranium for the first atomic bomb in the era of the Manhattan Project — workers are turning old, unexploded warheads into fuel that will power cities.

The recipe to create advanced reactor fuel involves melting weapons-grade uranium with low-enriched uranium in a crucible — a massive, metal cauldron heated to around 2,500 degrees Fahrenheit to turn its contents into molten soup.

Emerging from its furnace, a glowing orange cast filled with the hot liquid uranium is slowly lowered into a cooling chamber. The hardened finished product, which looks like black charcoal, can be safely held in-hand.

This fuel is set to power the next generation of America’s nuclear reactors — small, modular power stations that are easier and cheaper to build. They require far less upkeep and physical space than the aging fleet of large nuclear power plants.

One downside? They also require a more-enriched and energy-dense uranium.

Until last year, the United States got the vast majority of its enriched uranium from Russia. A bipartisan law passed after Russia’s invasion of Ukraine put a stop to that. Now, scientists and companies are racing to produce it at home.

After the Cold War, Russia possessed loads of highly enriched uranium — the kind used for weapons. In negotiations after the war, the US and other countries encouraged Russia to dilute that uranium below the weapon-making threshold, and sell it to the world as nuclear fuel. It was a beneficial deal for all parties. The US had a supply of fuel, and Russia — which was struggling economically after the Cold War — had a willing market to sell to.

Downblending old weapons from the nuclear arsenal is not the only way to make this fuel, known as high assay low-enriched uranium — or HALEU for short. A couple of facilities around the country are also making it, and they are expected to produce most of the fuel in the long run. The federal government is expected to award over $2 billion in the coming months to uranium enrichment companies to help kickstart the supply chain.

In the meantime, the feds are doing a “couch cushion exercise,” scouring high and low for suitable nuclear fuel that might have slipped through the cracks, said Michael Goff, principal deputy assistant secretary for the Energy Department’s Office of Nuclear Energy. In addition to the US nuclear stockpile, the Idaho National Laboratory is also downblending part of its collection of fuel from research reactors.

That the US is looking to its own arsenal for nuclear fuel speaks to how much of a scramble there is to get new-age reactors off the ground — like TerraPower, the Bill Gates-backed project in Wyoming that recently broke ground.

Projects like TerraPower are awaiting the fuel shipments, anxious they may run out of time. The company was set to get its first fuel shipments from Russia – the world’s only commercial HALEU supplier.

That changed after the war in Ukraine.

“We are getting to the point where we need to see more urgency from the government,” said Jeff Navin, TerraPower’s director of external affairs. “There’s a huge national interest to move quickly. We don’t fully understand why that same sense of urgency hasn’t gotten to the Department of Energy in getting this material out.”

Bottom line, the amount of HALEU the US can get from its nuclear weapon stockpile is relatively small. It’s going to need a bigger production line.

“The long-term solution is we have to have enrichment,” said Jeff Chamberlin, the acting principal assistant deputy administrator for defense nuclear nonproliferation. “Even if we down-blended all that material tomorrow, we couldn’t supply the demonstration needs of all the advanced reactor companies the US has stated right now.”

The United States currently gets about 20% of its power from nuclear. Inside the US Energy Department, there’s high interest to increase that percentage in the coming years because nuclear energy is reliable and doesn’t produce climate pollution.

“We need some firm, clean baseload electricity — nuclear provides that,” said Goff. “In order to meet our energy security needs and our climate goals, we do need significantly more nuclear energy deployed.”

The nuclear power industry is increasingly looking to smaller reactors, which run on HALEU. These reactors can last longer than conventional ones and fit into smaller spaces — making them more versatile and easier to set up.

The uranium for conventional reactors is enriched up to 5% and HALEU is uranium enriched between 5-20%. Highly enriched uranium is anything more than 20% and is used in weapons or naval submarines.

In other words, if conventional reactor uranium is Miller Lite, and highly enriched uranium is Everclear grain alcohol, HALEU is the nice cool glass of Belgian beer that strikes the balance between two extremes, said Dan Leistikow, vice president of corporate communications at US-based uranium enrichment company Centrus Energy.

“You can get more energy in smaller spaces,” said Josh Jarrell, director of the Idaho National Laboratories fuel cycle science and technology division. “You can be more energy dense, you can make more effective fuel, theoretically, we could generate electricity more economically.”

Centrus is one of two enrichment companies in the US working to break America of its dependence on Russia, which supplies the vast amount of the world’s enriched uranium. Congress recently passed an import ban on Russian uranium, leading to a supply squeeze both for HALEU and fuel for conventional reactors.

After a “lack of investment over decades,” Centrus is aiming to “restore a domestic enrichment capability with US technology” to meet the demand for the country’s electricity and for its national security, Leistikow told CNN.

It will take years to get there.

The Energy Department estimates the advanced nuclear industry will need 40 tons of HALEU by 2030. When it is running at full capacity, Centrus will enrich a little less than 1 ton per year.

What will the country’s leftover nuclear arsenal contribute? Six tons by 2027.

TerraPower’s Navin said six tons is a “great start,” but far from enough for his company’s first core load, let alone other advanced nuclear projects in the US.

Exactly how much highly enriched uranium the US has is a classified secret, and there are a lot of interests competing for it, from national security to research nuclear reactors.

But Congress recently directed the NNSA and Energy Department to prioritize converting America’s old nuclear arsenal for advanced reactor fuel.

“Within their possession, they have more than enough (highly enriched uranium) to make many, many, many tons of HALEU,” Navin said. — CNN