Friday, July 30, 2004
Copyright © Las Vegas Review-Journal

NUCLEAR WASTE STORAGE: Scientists shift view on Yucca

Potential corrosion of canisters now of less concern to review board

WASHINGTON -- Prominent scientists have shifted their stance on a key element of the Yucca Mountain repository, saying they no longer fear that corrosive brines could penetrate nuclear waste canisters and cause radioactive particles to leak within relatively short periods.

Members of the Nuclear Waste Technical Review Board said new science presented by the Department of Energy caused them to rethink the problem.

A new position by the panel could boost DOE as it maps out blueprints for the proposed Yucca facility.

Conversely, it could downgrade an issue that repository opponents have seized upon.

Staff members for the technical review board cautioned that while some specific concerns have been allayed, much more still needs to be known before scientists fully can be confident that a Yucca repository would work as the Energy Department has advertised.

"This does not mean the board does not have concerns about corrosion of the packages; it means that this specific (corrosion) issue is not a concern," board spokeswoman Karyn Severson said.

The board outlined its position in a letter Wednesday to Margaret Chu, director of DOE's Office of Civilian Radioactive Waste Management. She did not plan to comment, a spokesman said.

The Energy Department considers the review board's shift a "huge deal" that will encourage DOE to pursue its preferred designs, said one Yucca manager who asked not to be identified.

Explaining the change, board director William Barnard said science is evolving as more is learned about the first-of-its-kind repository.

"This is part of a long-term learning process," Barnard said. "It's a learning process for DOE, and a learning process for the board."

The Nuclear Waste Technical Review Board caused a major stir among scientists and policy-makers in October when it issued a report raising questions about the Energy Department's preferred repository design.

Current DOE plans call for canisters of waste to be spaced tightly within tunnels.

The review board said in October that, based on DOE's own research, the metal containers would be vulnerable to localized corrosion within 1,000 years. Such a scenario would make it difficult for the repository to win a safety operating license.

The review board, which was created by Congress to evaluate Yucca science, in May convened a two-day seminar at which the Energy Department and other organizations put forward updated analyses.

Based on those presentations, the board told Chu in its letter that the corrosion scenario it envisioned last year now "appears unlikely."

New research concluded that calcium chloride, a mineral compound, would not be present in dust flakes that will settle on the canisters, according to officials.

The technical review panel had believed that calcium chloride would boil with seepage water or humidity vapors to form a corrosive brine that would eat into canister welds at a fast rate.

The board said in its letter that DOE still needs to draw a clear picture of environmental conditions within the repository and other factors that might encourage package corrosion.

The state of Nevada was among the groups making presentations in May. Steve Frishman, a full-time state consultant on Yucca Mountain, said it appeared clear that DOE had solved the problem.

But, Frishman said, the Energy Department has yet to address questions about the presence of other minerals that could create problems when the decaying nuclear waste causes temperatures to rise inside the repository.

"It is still implicit in all this that (DOE) really doesn't understand what is going on above boiling," Frishman said.

The Energy Department "will try to claim victory, but it is not," Frishman said. "Their usual way of responding to a problem is they will take a specific problem and beat it to death without looking at associated problems."