Tuesday, November 18, 2003
Copyright © Las Vegas Review-Journal
Chemists' new findings raise concerns about Yucca
Estimates of how fast buried fuel rods would disintegrate could be off
THE ASSOCIATED PRESS
SAN FRANCISCO -- By 2010, if the U.S. Energy Department gets its way, an underground burial site for the nation's spent nuclear reactor fuel will open for business thousands of feet beneath the Nevada desert.
But chemists' new findings raise questions about the repository at Yucca Mountain, the San Francisco Chronicle reported Monday. The findings come at a crucial time, only 13 months before the agency plans to ask for federal nuclear regulators' approval to build the site.
During the past year, two DOE-funded scientific teams discovered that the buried fuel rods could experience unexpected chemical changes. Those changes could alter present estimates of how fast the buried fuel rods would disintegrate, leaking poisonous plutonium, neptunium, iodine and other radionuclides into the surrounding terrain and groundwater.
On the one hand, the chemists' findings might be good news for advocates of the Yucca Mountain burial site.
Their research suggests that as the super-hot fuel rods radioactively decay and are exposed to dripping groundwater, the resulting chemical interactions would breed odd forms of uranium minerals. Like miniature cages, these minerals would tend to lock bits of plutonium and neptunium in the minerals' crystalline atomic lattices. Hence, the disintegrating nuclear fuel probably wouldn't escape very far into the groundwater.
What troubles the chemists is that they've made their discoveries so late in the game. DOE has been funding research into the chemical behavior of buried fuel rods for decades, yet the chemists made their discoveries only during the past year.
"What I find amazing in this story is that the Yucca Mountain story had gone this far without (anyone previously) finding out that these (chemical events occur)," said one co-writer of the article, Peter Burns, a geology professor at the University of Notre Dame. "I wouldn't have thought you'd want big surprises before (you seek) your licensing application."
The main discovery came in two main steps. Last year, Edgar Buck and Bruce McNamara at Pacific Northwest National Laboratory, a DOE lab in Richland, Wash., discovered in lab tests that a type of uranium mineral called studtite forms from decaying reactor fuel in a pool of water.
In Friday's issue of Science, scientists at the University of California, Davis and Notre Dame report that the interaction of radioactivity and groundwater would form a type of studtite called uranyl peroxide. The crystalline atomic structures of uranyl peroxides would tend to trap long-lived, dangerous radioactivity decay products such as plutonium and neptunium.
Their findings don't surprise Bob Loux, director of Nevada's Agency for Nuclear Projects, which has fought for years against the Yucca Mountain repository. On Jan. 14, the state plans to argue against the repository on legal and environmental grounds in the U.S. Court of Appeals in Washington, D.C.
"The uncertainties that are involved in the Yucca Mountain assessment are so large that literally neither DOE nor anyone else knows what's going to occur underground if waste is stored there," Loux said.
Despite DOE's plan to cover the spent fuel with titanium to keep out groundwater, "our experts think no metal will last underground more than 400 or 500 years. Titanium goes away in 50 to 60 years because of fluoride in the water."
