Dugway may close last radiological site

Dugway Proving Ground is nearing the end of an era, when the last of its four sites containing radioactive material is officially closed.

Dugway, an Army base of 1,300 square miles whose nearest boundary is 85 miles west of Salt Lake City, has been the site of extensive chemical warfare testing since the 1940s. Presently it is restricted to researching defenses against chemical attack, but in the past it tested offensive weapons.

It also was the site for non-warfare projects involving radiation, and these left waste behind, too.

For about 13 years, Dugway has been identifying contaminated sites and hiring contractors to deal with them. Concern includes locations that were left with residues of nerve and blister agent, unexploded ordnance, laboratory waste, sludge disposal and PCB and dioxin contamination. Old landfills and sewage lagoons are among the cleanup targets.

Experts identified 216 sites that needed further investigation, with potentially dangerous material of various types. Of these, four concerned radiological contamination, said Scott Reed, the base's restoration program manager.

In the 1970s, the Atomic Energy Commission (renamed the Nuclear Regulatory Commission in 1975) declared all four of the radiological sites closed, meaning they were no longer a hazard. That occurred when Dugway returned its atomic materials license to the agency. The effort included getting rid of remaining nuclear material.

But a radioactive legacy remains. According to Reed, the sites were primarily for food preservation tests where scientists irradiated food. "We didn't ever test nuclear warheads or things like that," he said.

However, Dugway did carry out experiments involving radioactive tantalum. It was sprayed onto roofing material to see how well roofs of defensive bunkers could repel radioactive isotopes in case of an attack. The tantalum had "a very, very short half-life," he added. "It's got a half-life of like 160 days."

That means that every 160 days since the material was used in the 1960s, it lost half its remaining radioactivity.

Around 2000, the NRC returned to Dugway to validate the AEC closures. "They (NRC officials) decided none of the previous closures would be grandfathered," he said. Inspectors checked the four sites against new standards, he said.

The NRC found that three of the sites met all of the new standards. With the fourth, "we still needed to meet the new closure requirements. We needed to cap it."