Study sought on Yucca Mountain itself

Friday, April 27, 2001 | 10:47 a.m.

Independent scientists overseeing a study on Yucca Mountain are not convinced the mountain itself is a sufficient barricade in regard to reducing radiation levels emitted from nuclear waste.

Scientists have requested that the Department of Energy study explain to what degree the mountain would reduce radiation levels, as compared to man-made barriers such as nuclear waste containers and titanium drip shields.

Yucca Mountain, 90 miles northwest of Las Vegas, is being considered as the world's first high-level nuclear waste repository.

The Nuclear Waste Technical Review Board has asked the DOE for a computer analysis that depicts a worst-case scenario in which spent nuclear fuel has been dumped on the earth's surface and includes no shielding to block the radiation from entering the atmosphere or ground water.

By calculating radiation exposure resulting from such an unlikely event DOE officials could better inform the public in regard to how much protection volcanic ash layers at Yucca Mountain would provide, board Executive Director Bill Barnard said.

The DOE considers Yucca Mountain as the primary barricade from radiation that could ultimately find its way into the air or water sources, in which case people could be exposed. Engineered waste barriers, such as the waste containers and underground shields, are designed to act as secondary lines of protection.

A March 30 letter from board Chairman Jared Cohon to the DOE's Lake Barrett, acting director of the Office of Civilian Radioactive Waste Management, said there was "some confusion" in relation to DOE studies of the barriers.

"Under such an approach the analysis would start off by estimating the dose, assuming that the radioactive waste is lying exposed at the earth's surface," Cohon said.

The board's approach would give scientists an idea of how effective man-made barriers are in reducing radiation, compared to only mountain, the letter noted.

DOE Yucca Mountain Project Manager Russ Dyer said in ongoing studies scientists have considered the effectiveness of radiation protection provided by the engineered barriers. Dyer said he had not seen a copy of the board's March 30 letter.

Steve Frishman, technical coordinator for the state, said the DOE has changed direction as it relates to relying solely on the mountain's bulk to protect the public. Instead, engineered barriers provide the major shield against radiation exposure, according to the DOE.

In a 1980 report DOE officials said Yucca Mountain would completely contain all radioactivity from commercial reactor and defense waste for at least 300 years without the installation of man-made barriers.