Report details potential rupture of casks

Suzanne Struglinski

Wednesday, Nov. 26, 2003 | 11:15 a.m.

WASHINGTON -- Nuclear waste storage containers inside Yucca Mountain could corrode and break, based on conditions inside the mountain, the Nuclear Waste Technical Review Board told the Energy Department again Tuesday.

The board Tuesday sent a detailed report to Margaret Chu, the department's top Yucca official, that expands on a letter it sent Oct. 21 drawing the same conclusions.

The 33-page report, signed by 10 board members, says previous department experiments on the internal conditions of the site are not adequate since the board believes corrosion and weakening of engineered barriers -- such as shields to cover the casks -- inside the mountain can take place with conditions the department says will exist.

The board based its analysis on presentations it received from Energy Department on the high-temperature -- or "hot" -- repository design. The report concentrates on the first 1,000 years after the repository is closed, when temperatures inside the mountain would be above the boiling point of water.

The Energy Department wants to use the hot repository design, which places waste casks closer than the alternative design known as the cold repository design. The final design won't be known until the department submits its license application to the NRC. The department says it will file the license by December 2004.

The board believes the hot repository design will create conditions for widespread corrosion of the casks that could lead them to break.

"Once started, such corrosion is likely to propagate rapidly even after conditions necessary for initiation are no longer present," the board told Chu. "The result would be perforation caused by localized corrosion of the waste package, with possible release of radionuclides."

According to a letter sent to Chu with the report, the board only focused on corrosion of the Alloy 22 waste packages set to store the 77,000 tons of nuclear waste, about 90 miles northwest of Las Vegas.

Members wrote that the board believes the potential for corrosion of the casks needs to be addressed by the Energy Department.

Chu sent a response back to the board on the Oct. 21 saying she appreciated its findings since it "relates to the thermal operating conditions of the repository and not to the ability to dispose of waste safely at Yucca Mountain."

She also assured the board that the department "will not dismiss the Board's corrosion concerns" as part of the total performance assessment required by the Environmental Protection Agency and the Nuclear Regulatory Commission.

Energy Department spokesman Joe Davis said today the department will complete a detailed review of the board's report but that it does not agree with its conclusions that there will be widespread corrosions.

"Our bottom line is this: Under the current repository design, we meet the EPA standard for radiation," Davis said.

He also noted that the board is no longer debating whether waste should be stored at Yucca but how far apart the canisters should be.