Radioactive munitions won’t be buried in Utah’s West Desert anytime soon after a decision issued Thursday by state regulators, who rejected EnergySolutions’ emergency request to accept several thousand tons of armor-piercing projectile points made of heavier-than-lead depleted uranium.

The radioactive-waste processor had petitioned the Department of Environmental Quality for an exemption to Utah’s provisional prohibition on burying depleted uranium, or DU. But agency staff and outside consultants concluded metallic DU is more hazardous and unstable than EnergySolutions had characterized it in its presentations.

The company has failed to demonstrate that the “exemption will not result in undue hazard to public health and safety or result in undue hazard to the environment,” Stephen Marschke, nuclear engineer with SC&A Consulting, told the Waste Management and Radiation Control Board.

The panel voted unanimously Thursday to reject the military ordnance, which grows more radioactive over time.

Board members said they were uncomfortable authorizing such waste before DEQ completes its long-running “performance assessment” of the Clive facility, 80 miles west of Salt Lake City, where EnergySolutions hopes to bury far more DU oxide, a granular waste product from the uranium-enrichment process.

“It’s not prudent,” board member Danielle Endres said. “I have not been persuaded there is a need for urgency on this.”

The vote means EnergySolutions will likely lose a potential contract with the Defense Department to take millions of 30 mm bullet tips, called penetrators, currently stored at Utah’s Tooele Army Depot and Indiana’s Crane Army Ammunition Activity. The military plans to dismantle 7 million old rounds a year for four years and has issued a request for proposals from the few facilities qualified to take depleted uranium.

The deadline for submitting proposals closes before Utah will issue a decision, expected next year, on EnergySolutions' larger DU request.

“While disappointed by the Utah regulators' recommendation today,” said the firm’s marketing vice president, Mark Walker, “EnergySolutions will continue to cooperate with the ongoing regulatory review of the performance assessment that was initially submitted to the Utah Department of Environmental Quality in 2011 and concurs with the [waste] board’s request to expeditiously complete their review.”

The environmental group HEAL Utah leads a campaign against the firm’s DU proposals, arguing this waste, while not highly radioactive now, poses a dire threat to future inhabitants of Skull Valley because the material becomes dangerous, and eventually deadly, over thousands of years.

“We feel good in that the board realized it’s premature to allow EnergySolutions to bring in depleted uranium before the assessment is done,” HEAL’s executive director, Scott Williams, said. “Allowing this exemption would have created a dangerous precedent that business interests can sidestep Utah’s public health policies."

DEQ’s assessment is investigating whether the 8.7 million-cubic-yard cell at Clive can contain the waste for tens of thousands of years. The munitions would take less than 1 percent of that capacity, according to EnergySolutions.

The site lies in a desert that was once 1,000 feet under the waters of Lake Bonneville during the ice age.

Williams cautioned that Thursday’s vote is no harbinger of how the board will vote in the spring, when it considers the larger proposal to import 800,000 tons of depleted uranium stored in casks at various Department of Energy sites. This is the waste created from enriching uranium for nuclear fuel and weapons.

On Thursday, some board members emphasized they are confident the Clive facility can safely handle the waste.

The rejected munitions are metal slugs that aren’t explosive. The material, however, can change quickly, especially in the presence of water, DEQ staffers warned the waste board. In recommending against the exemption, they cited unresolved questions and “significant data gaps in the information” EnergySolutions provided.

The Department of Energy, for example, has concluded that metallic DU breaks down when exposed to the elements, produces heat, swells and forms oxides. DOE won’t accept this material at its disposal sites.

According to the staff report, metallic DU is geochemically unstable and particularly reactive in a moist, carbonate-rich environment, such as what is found at Clive.

“In such an environment, DU metal can form relatively soluble carbonate compounds,” which can easily migrate, division staff said. “DU metal can react to form pyrophoric or explosive substances.”