Depleted uranium shells for Ukraine are dense, armor-piercing ammunition

The shells can literally sharpen themselves, making them effective at striking tanks. But they come with environmental and health concerns.
depleted uranium shells
The Department of Defense says that these depleted uranium shells "had been compromised" and needed to be destroyed. This image is from June, 2022, in Utah. Nicholas Perez / US Air National Guard

On September 6, the Department of Defense announced $175 million in military aid to Ukraine. Included in this drawdown of existing US military equipment is “120mm depleted uranium tank ammunition for Abrams tanks,” making the United States the second country after the United Kingdom to not just supply Ukraine with tanks (due mid-September), but with depleted uranium ammunition for them. The ammunition, derived from nuclear refining processes, has immediate military applications as well as potential health impacts as an environmental pollutant after it’s been expended. 

The drawdown fact sheet includes the Abrams ammunition alongside rockets for HIMARS launchers, anti-tank missiles, artillery rounds, and over 3 million bullets for small arms (rifles and the like). It’s a list that largely matches the state of the war, where demolition munitions are paired with weapons designed to crack open enemy armor, and it reflects Ukraine’s longer goal of retaking territory occupied and held by Russia since the February 2022 invasion.

“We want to make sure that Ukraine has what it needs not only to succeed in the counteroffensive but has what it needs for the long term to make sure that it has a strong deterrent, strong defense capacity so that, in the future, aggressions like this don’t happen again,” said Secretary of State Antony J. Blinken ahead of his meeting in Kyiv with Ukraine’s Foreign Minister Dmytro Kuleba. 

Depleted uranium tank ammunition, built and designed for the Abrams tanks the United States is sending Ukraine, factors into this calculus. Depleted uranium has several properties that make it appealing as an ammunition. It is denser than lead, it sharpens in flight, and it is pyrophoric, meaning it ignites easily under high pressures and at temperatures between 1,100 and 1,300 degrees Fahrenheit, which it reaches when fired as a round. All of this combines to create a dense, potent, incendiary armor-piercing round, useful for tanks fighting other tanks.

Where does depleted uranium come from?

The first time Popular Science covered depleted uranium, it was in 1953, as part of a story on nuclear reactors. Uranium occurs in nature, but to get to the most useful isotopes for weapons or reactors, uranium has to undergo a process of enrichment. As the useful isotopes get sifted out of the mix, the remainder is depleted. Some of this depleted uranium is used in breeder reactors to create plutonium. It can also be combined with plutonium oxide to create another kind of reactor fuel. 

Uranium naturally occurs in three kinds of isotopes: U-234, U-235, and U-238. Uranium for nuclear fuel and nuclear weapons is enriched, increasing its concentration of the U-235 isotope from a natural level of 0.72% by mass to “between 2% and 94% by mass,” according to the International Atomic Energy Agency (IAEA). The unenriched by-product is the depleted uranium, defined as having a U-235 concentration of less than 0.711 percent. “Typically,” states the IAEA, “the percentage concentration by weight of the uranium isotopes in DU used for military purposes is: U-238: 99.8%; U-235: 0.2%; and U-234: 0.001%.”

Finding other uses (besides reprocessing it to create more nuclear fuel) for depleted uranium took a while. In 1969, Popular Science called depleted uranium an “ugly duckling” with limited uses, saying, “Extra-heavy, it makes compact counterweights for aircraft linkage systems, and ballast for the launch-escape tower of the Apollo spacecraft.” It’s in ammunition and armor plating that depleted uranium really found its military use. In 1982, Popular Science included the Phalanx anti-missile system in a feature on smart missiles, emphasizing the weapons’ “radar-guided, computer-driven Gatling gun” that “blasts incoming missiles at a rate of 3,000 rounds a minute. Its ammunition is more potent than most because the core of each round is made of depleted uranium, the heaviest metal available, for maximum impact.” 

Tungsten is a heavier metal, but it’s specifically worse for armor-piercing projectiles because, as Scientific American noted in 2001, “Like its slightly denser cousin, tungsten, uranium can penetrate most heavy armor. But whereas tungsten projectiles become rounded at the tip upon impact, uranium shells burn away at the edges. This ‘self-sharpening’ helps them bore into armor.”

The Environmental Protection Agency records that the Department of Defense started making bullets and mortar shells out of depleted uranium in the 1970s, which was then expanded to making armor for tanks and weights for balancing aircraft. This was all possible, in part, because depleted uranium was an abundant byproduct of nuclear weapons production and nuclear reactors, making depleted uranium “plentiful and inexpensive.”

Cleanup costs and concerns

The EPA has a page on depleted uranium specifically because it can be an environmental hazard that requires cleanup. 

“Like the natural uranium ore, [Depleted Uranium] DU is radioactive. DU mainly emits alpha particle radiation. Alpha particles don’t have enough energy to go through skin. As a result, exposure to the outside of the body is not considered a serious hazard,” reads the fact sheet. “However, if DU is ingested or inhaled, it is a serious health hazard. Alpha particles directly affect living cells and can cause kidney damage.”

The International Atomic Energy Agency emphasizes that while depleted uranium poses some risk from radiation if ingested, the primary harms come from it being a heavy metal absorbed into a human digestive, circulatory, or respiratory system. The main way depleted uranium gets into such a system is through inhalation, when the uranium becomes aerosolized in the process of an explosion. That means the most immediate health effects will be borne by the people on the receiving end of weapons fire, but also on people who immediately go into a tank that’s been hit to try to rescue people inside.

After a battle, farmers returning to a field could possibly encounter depleted uranium in the environment, though the IAEA notes that the “risk will be lower because the re-suspended uranium particles combine with other material and increase in size and, therefore, a smaller fraction of the uranium inhaled will reach the deep part of the lungs. Another possible route of exposure is the inadvertent or deliberate ingestion of soil. For example, farmers working in a field where DU ammunitions were fired could inadvertently ingest small quantities of soil, while children sometimes deliberately eat soil.”

On June 23, 2022, compromised 30mm rounds of depleted uranium ammunition were found at the Tooele Army Depot in Utah. Cleaning up the rounds was the task of an Explosive Ordnance Demolition (EOD) team, who worked to separate the depleted uranium projectile from the explosive part of the round. In photographs of the work, the team can be seen wearing masks and protective gear to avoid ingestion and inhalation of uranium.

“Handling DU rounds is especially dangerous, so we take extra precautions and follow our procedures 100 percent,” said EOD technician Derin Creek at the time. “We have to ensure not only the safety of everyone in the area and my team, but to also protect the environment and eliminate radioactive contamination.” 

Depleted uranium rounds, like the tanks that will fire them, are part of Ukraine’s growing arsenal to repel the Russian forces that have invaded the country since February 2022. The ammunition will need to be handled with care, as the Tooele Depot demonstrates, and cleaning up afterwards will take some special attention, once the battlefields are no longer active. Ukraine has already received cluster munitions, which are a unique cleanup challenge, from the United States. With that hurdle already cast into the future, cleaning the same fields from depleted uranium should just be an incremental hardship on top of the long work of restoration that may come, when the war finally ends.