The few who are privy to the material won't discuss it, other than to say it can turn highly contaminated plutonium into a less dangerous form.
"It's classified, so we can't tell you what it's made of," said department spokesman Jim Giusti of Savannah River Site.
There is no mention of "stardust" in the vast sea of public documents associated with SRS and the National Nuclear Security Administration, which manages U.S. nuclear weapons programs.
However, it was came up briefly during a meeting in Aiken this week, described as a means to allow tons of problematic plutonium to be moved out of the state.
Allen Gunter, a senior DOE technical adviser, told members of an SRS Citizens Advisory Board committee that the site has 12.8 metric tons of plutonium, of which five tons is unsuitable for processing at the mixed-oxide fuel facility under construction there.
Though officials hope to dispose of that material at a government site in New Mexico, some of the SRS waste is up to 70 percent plutonium oxide and would not meet the facility's waste acceptance criteria.
"You have to blend it with other materials to get it down to less than 10 percent," Gunter said.
A committee member asked him how such a feat would be accomplished.
"Stardust," he replied, adding that he could not divulge the particulars.
The secret compound could be mixed with plutonium oxide so it would be more difficult to reprocess the resulting material to recover the plutonium, which must be carefully guarded because of its possible use by terrorists.
Don Hancock, the director of the Nuclear Waste Safety Program at Southwest Research and Information Center in Albuquerque, N.M., said he has tried unsuccessfully to get more details on "stardust."
"Is it a process? Is it a material? What does it do?" he asked. "If we've come up with a way to make weapons-grade plutonium into where it's not weapons-grade plutonium, that should be a good thing."
More details might be revealed as part of a draft Environmental Impact Statement under preparation as part of the plan to dispose of the plutonium at SRS, he said.
"A lot of people who should know about it don't, including a lot of people with top security classifications," he said. "Whatever 'stardust' is, and I don't know what it is, they need to fess up and tell us about it."