Many Utahns have been following EnergySolutions' efforts to obtain a waiver in the state’s regulations that would allow the company to store hundreds thousands of pounds of “depleted uranium,” (DU), in its storage site in the desert west of Grantsville.
As a chemist, I oppose granting that waiver because my professional experience has made me aware of exactly what could happen with those rather exotic and unfamiliar chemicals. Even short-term storage can be dangerous, and assuring safe long-term storage is probably impossible.
To begin with, it’s unclear from most of the published information just what “depleted uranium” consists of. There are actually two types of DU. The first type is composed primarily of old armor-piercing shells and armor plating. The second type is mostly the byproducts from the process of enriching uranium for use in reactors. The risks of the two types of depleted uranium are quite different, though neither type is benign.
Solid DU from armor or armor-piercing shells is only slightly radioactive, as most of the more-radioactive materials are removed before making the shells. The EPA has established fairly strict standards for storage of these materials, and the risks seem to be minimal — at least at first. Regardless of the initial radioactivity, over time depleted uranium decays into other materials more highly radioactive than uranium itself. Thus the radioactivity of the stored DU actually increases over time. Peak activity is not reached for approximately 1 million years!
Interestingly, the biggest danger with DU shells and armor plate is not radiation, but toxicity from uranium salts leaching into ground water if the containment vessels are breached. Thus, this form of DU must be stored securely for a very, very long time.
DU from enrichment starts out more radioactive than DU from shells and also increases in radiation for a million years. But there is an even greater initial risk, a risk that endures as long as the material itself. Chemically, enrichment DU is mainly uranium hexafluoride, UF6, which is a solid at room temperature. It can be safely stored for short periods of time in coated steel containers. However, contact of UF6 with water results in the formation of a number of uranium/oxygen/fluorine compounds, and also of hydrofluoric acid, HF.
HF is used in scores of oil refineries around the world to make high-octane gasoline. As a research chemist for a major oil company, I worked for years with HF in the lab and refineries, and hold patents in that area. But HF is one of the strongest acids known to science (it is one of the few things that will etch glass, for example), and can be extremely dangerous. Working with HF in the tightly controlled environment of a laboratory or refinery can be done safely, but even in these settings there have been numerous fatal accidents over the years.
I cringe at the high probability of disastrous accidents in a storage facility where UF6 would have to be kept away from even the slightest contact with water for hundreds of thousands of years! We simply do not have the technology to assure that kind of security for that period of time. Bear in mind that a few 10s of thousands of years ago, EnergySolution’s proposed storage site — proposed in part because of its aridity — was about 1,000 feet under the surface of Lake Bonneville!
I invite you to join me in opposing EnergySolutions’ application to store depleted uranium of any type in our state, particularly in view of the high likelihood that we will be unable to assure that DU can be successfully sequestered for the millions of years that will be required. It would be trading a very grave long-term risk for the people of Utah (and our descendants) for a short-term gain for EnergySolutions.
Alan D. Eastman, Holladay, received his Ph.D. in chemistry from the University of Utah in 1975. He is chief technical officer at GreenFire. A hearing on the EnergySolutions petition is set for 11 a.m. Thursday before the Utah Waste Management and Radiation Control Board.