Does the Trump administration understand how ‘enriched’ uranium is made into weapons?

By Harmeet Kaur, CNN

(CNN) — For the US to reach a deal with Iran or to end its war in the country, President Trump has said he wants Iran to surrender its “enriched” uranium.

“We want no enrichment, but we also want the enriched uranium,” he told CNN’s Kaitlan Collins last week.

The president has at times cited Iran’s “enriched” uranium stores as part of his ever-changing rationale for the war, and in recent days, he’s reportedly considered sending US troops in to seize them. But nuclear arms experts say the way Trump and his lead negotiator have talked about uranium enrichment raises doubts about how well they understand the technicalities.

For one, Trump keeps referring to “nuclear dust,” which is not a known term in the nuclear energy industry. And since the February 26 US-Iran nuclear talks, Steve Witkoff, a former real estate developer who has been leading US negotiations with Iran along with Trump’s son-in-law Jared Kushner, has made claims that experts say betray a similarly weak expertise.

“Enriched,” from the French “enrichir” meaning to make rich, seems to have entered English around the 1380s, when the Oxford English Dictionary notes that it appeared in John Wycliffe’s Middle English translation of the Bible (“The Lord hath enrychide me with a good dower”). Over time, its strictly literal use expanded into the figurative, referring to the enhancement of something by adding or increasing a particular quality or ingredient. A person could be “enriched” with knowledge, the land could be “enriched” by fertilizing the soil and food could be “enriched” to add nutrients.

When scientists split the atom in the 20th century and then set about creating nuclear chain reactions, they applied the word “enriched” to radioactive fuel that had been made more susceptible to fission. The physicist Henry DeWolf Smyth wrote in the official account of the Manhattan Project published in 1945 of “uranium which had already been partially enriched.”

Uranium is abundant in Earth’s crust, but most of it — about 99% — is the relatively fission-resistant isotope uranium-238. A chain reaction calls for the uranium-235 isotope, which has an odd number of neutrons, making its nucleus easier to split. But only 0.7% of naturally occurring uranium is uranium-235, says François Diaz-Maurin, editor for nuclear affairs at the Bulletin of the Atomic Scientists. To be used as fuel for nuclear reactors, or to make an explosive nuclear weapon, uranium is “enriched” to increase the concentration of uranium-235.

The enrichment process is primarily accomplished via gas centrifuges, Diaz-Maurin explains: A gas that contains uranium is fed into a cascade of spinning centrifuges. The slightly heavier uranium-238 moves to the periphery of the centrifuge, allowing the uranium-235 to be collected in the center. The gas “enriched” in uranium-235 is then injected into the next centrifuge to be spun again, and the process is repeated until the desired concentration of uranium-235 is achieved.

The scant starting concentration of uranium-235 in nature leaves a lot of room for enrichment. And different levels of enrichment have very different uses and strategic significance.

Uranium that has been enriched above the natural 0.7% level of uranium-235 and up to a 20% concentration is considered low-enriched uranium, used for civilian purposes. Commercial reactors typically require uranium enriched to less than 5%, while research reactors used for testing or medicine generally require uranium enriched to up to 20%.

Uranium enriched beyond 20% is considered highly enriched uranium, and uranium enriched above 90% is considered weapons-grade.

The higher the enrichment level, the more quickly uranium can be enriched to weapons-grade, Diaz-Maurin says. Once uranium has been enriched to 20%, a vast majority of the work required to enrich it to weapons-grade levels has been completed. It becomes exponentially easier to enrich 20% uranium to 60%; enriching from 60% to 90% is even easier, he says.

The higher the enrichment level, the lower the minimum mass of enriched uranium required to produce a bomb, says Diaz-Maurin. For example, uranium that’s been enriched above 20% can technically be used to produce a crude weapon, but you would need about 400 kilograms of it, making it inefficient and impractical. When the enrichment level goes up to 60%, the critical mass drops down to about 42 kilograms. Uranium enriched to weapons-grade requires about 28 kilograms, which can fit into a missile warhead, he says.

Since Trump pulled out of the Iran nuclear deal in his first term, Iran has been enriching its uranium closer and closer to weapons-grade, though it officially proclaimed a religious prohibition against building a nuclear weapon. Now, given that the US and Israel have attacked the country as negotiations were ongoing, Iran’s hardliners in parliament are calling on the regime to advance to full nuclear armament.

Western nations, as well as the UN watchdog International Atomic Energy Agency (IAEA), have long expressed concerns about Iran’s production and stockpiling of highly enriched uranium. On June 12 last year, the IAEA estimated that Iran’s stockpile included 440 kilograms of uranium enriched up to 60%, Diaz-Maurin wrote in a recent analysis. The next day, Israel attacked Iran, killing prominent nuclear scientists and significantly damaging Iran’s main enrichment site.

Enrichment level is an important indicator of risk, but there are a host of other factors that should be considered in assessing how quickly Iran could produce weapons-grade enriched uranium, says Kelsey Davenport, director for Nonproliferation Policy at the Arms Control Association. Those other considerations include the amount of enriched uranium a country has, its capacity to enrich it and whether the uranium is being held in solid fuel rods or in gas form.

“Witkoff had a poor grasp of the details,” she says.

For example, Davenport says comments that Witkoff made in the aftermath of February 26 negotiations with Iran indicated some confusion between nuclear reactors, which use enriched uranium for power, and the centrifuge facilities where the enrichment process takes place. Witkoff seemed particularly concerned about a research reactor in Tehran that he claimed was being used to stockpile highly enriched uranium. Reports from the UN’s nuclear watchdog estimate that Iran had about 45 kilograms of 20% enriched uranium stored in fuel assemblies at the reactor, which Davenport says “is not even enough for one bomb.”

To be developed into a nuclear weapon, she says the uranium at the reactor would need to be converted back to gas form and then be further enriched to weapons-grade. Before Israel’s strike on Iran’s main conversion facility last June, that might not have been difficult. Now, the situation has changed. “Could Iran convert that material back to gas form? Yes,” she says. “Could they do it quickly and easily at this point? No.”

Davenport says Witkoff was also reportedly surprised by how much enriched uranium was in Iran’s stockpile, even though this information was well documented by international inspectors. “I think he was focused on the wrong details and did not have the nuclear expertise or the expert team available to him to assess how the Iranian proposal would have impacted risk overall,” Davenport says.

Iran also said that it made an offer to dilute its 60% enriched uranium to a lower percentage, which Diaz-Maurin calls “a sound one from a non-proliferation perspective.” But he says it doesn’t appear that US negotiators took the proposal seriously. “I suspect that they did not really understand what the meaning was,” he adds. “And here we are.”

Less than two days after Witkoff and Kushner met with Iran to discuss its nuclear program, the US and Israel attacked the country. Some experts suggest that the decision was informed, at least partially, by a shallow understanding of Iran’s nuclear program and positions.

“It certainly seems as though there was a gap, and that’s a huge problem on something like this, especially when it seems like potentially a military decision was made based on things that were happening in that room,” says Connor Murray, a research analyst for the Center for Arms Control and Non-Proliferation.

A month on, the US is engaged in an intense war that experts argue could potentially have been avoided with another word: Diplomacy. US and Israeli strikes have indeed severely diminished Iran’s capacities to enrich uranium, Diaz-Maurin says. But he says Iran’s know-how and political will to build nuclear weapons probably won’t be destroyed so easily.

“​​You can’t really bomb away an idea, a program and knowledge. So there will always be a suspicion that Iran is doing something,” he says. “And one could argue that now more than ever, they have incentive to accelerate whatever program they have.”

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