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Backgrounder on License for Depleted Uranium at U.S. Army Sites

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The Nuclear Regulatory Commission has amended the U.S. Army’s license to possess and manage depleted uranium (DU) at sites across the country. The March 2016 amendment adds 15 installations to a license the NRC issued in October 2013 for two sites in Hawaii. The Army will apply the same programs for environmental monitoring, radiation safety and physical security to all sites covered by the license.

The physical security and radiation safety programs are similar to those in the original license. But the environmental monitoring program will change. The Army showed, and the NRC agreed, that less environmental monitoring is needed because the exposures would be well below the NRC limits even during ground disturbing activities. The program now has criteria for developing separate environmental monitoring plans for each of the installations. These plans would generally require limited monitoring of potential routes for transport of contamination out of the impact areas. They would also include criteria for periodic review to address any changes that may affect risk, tailored to the conditions at each installation. The license requires the Army to develop these site-specific plans within six months and submit them for NRC review. If they are approved, the Army must implement the plans within six months. They would then be subject to NRC inspection and enforcement.

The license is needed for DU from spotting rounds that were part of the 1960s-era Davy Crockett weapons system. Used for targeting accuracy, the spotting rounds emitted white smoke on impact but did not explode. Remnants of the tail assemblies remain at sites where the Army trained on the weapons system. This system was previously classified and records of its use were closely guarded.


Natural uranium is made up of three isotopes: U-234, U-235 and U-238. “Depleted” uranium has a lower percentage of U-234 and U-235 than natural uranium. DU is about twice as dense as lead, making it useful in commercial and military applications. Uranium in a form that dissolves easily can be toxic to the kidneys if ingested in large amounts, such as by inhaling dust or drinking contaminated water. The DU at the Army sites is not believed to be in this soluble form.

A number of Army sites have DU fragments from spotting rounds left from training with the Davy Crockett system from 1960-1968. The Atomic Energy Commission, the NRC’s predecessor, gave the Army a license to make, test and distribute the spotting rounds. Under that license, the Army distributed the rounds for training. Each round contained about six ounces of DU. At the Army’s request, the license expired in 1978, after the Army had stopped producing and distributing the spotting rounds.

In 2005, the Army found tail assemblies from the spotting rounds at the Schofield Barracks on Oahu. This discovery prompted a review of all sites that trained with the system. The Army found DU at other sites, including the Pohakuloa Training Area on the island of Hawaii. Under NRC regulations, the Army must have a license to possess this material. The Army applied for a possession-only license in November 2008. It was not until 2011 that the Army identified all the sites where it used the Davy Crockett system. At that time, the NRC and the Army decided to continue with licensing the two Hawaiian sites and to address the remaining installations through an amendment.

An Army information booklet states that the DU is mostly in large fragments. It is on operational ranges not accessible to the public. Data the Army collected and analyzed, and the NRC reviewed, show there is no immediate health risk to people who work at the ranges or live or travel nearby. The high density and large fragment size mean the DU cannot easily become airborne or move off-site.

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The NRC's role

M101 Spotting Round (Source: U.S. Army)[2].
M101 Spotting Round (Source: U.S. Army).

Part of the NRC’s role is to oversee licensed “source material,” which includes DU. The NRC license allows the Army to possess up to 12,567 pounds of DU at the sites. It limits the amount of DU the Army can possess at each location. It requires the Army to comply with NRC regulations and standards for protecting the public and the environment from radiation and is subject to NRC inspections and periodic reviews.

The license requires the Army to have environmental monitoring as well as radiation safety and physical security plans. These requirements are meant to ensure the DU will not pose a future health risk. The license does not authorize the Army to use the DU or decommission the sites. Any cleanup would require additional review and approval by the NRC to ensure that public health and safety will continue to be protected.

The amended license will ensure the Army has done careful studies and developed site-specific plans for environmental monitoring. The license continues to cover the Schofield Barracks and Pohakuloa Training Area (Hawaii). It now also applies to Forts Benning and Gordon (Georgia); Forts Campbell and Knox (Kentucky); Fort Carson (Colorado); Fort Hood (Texas); Joint Base Lewis-McChord/Yakima Training Center (Washington); Fort Bragg (North Carolina); Fort Polk (Louisiana); Fort Sill (Oklahoma); Fort Jackson (South Carolina); Fort Hunter Liggett (California); Fort Wainwright (Alaska); Joint Base McGuire-Dix-Lakehurst (New Jersey); and Fort Riley (Kansas).

For additional information, see the Army's website on depleted uranium in Hawaii.

March 2016

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Page Last Reviewed/Updated Tuesday, July 07, 2020