DOE’s ground water prognosis in question

Wednesday, June 27, 2001 | 10:57 a.m.

New research shows that the Energy Department's calculations on the direction and the speed of ground water at a proposed high-level nuclear waste repository could be wrong, a state scientist says.

If the state study -- still in progress -- is correct, radiation from 77,000 tons of high-level nuclear waste buried in a proposed repository at Yucca Mountain, 90 miles northwest of Las Vegas, could escape and expose people sooner than 10,000 years, the life span set for the repository by federal law, hydrologist Linda Lehman, who conducted the research, said.

That could make Yucca Mountain unable to meet new Environmental Protection Agency guidelines for the amount of radiation that can escape the repository through ground water, said Lehman, a former Nuclear Regulatory Commission scientist who works for the state.

Lehman told an international independent review panel last week that the state used U.S. Geological Survey information on ground water temperatures over the past 15 years in its effort to verify DOE computer models on flow. The DOE did not include that information in its projections.

The DOE, which has spent $7 billion and 20 years studying the dump site, plans to include the state's ground water model in its final calculations as it prepares to recommend whether Yucca Mountain is suitable for a repository, said Robert Loux, executive director of the Nevada Agency for Nuclear Projects and Lehman's boss.

It was unclear how the state's new conclusions might affect the DOE's recommendation, Loux said.

Yucca Mountain is the only site under study as a U.S. nuclear waste repository. Nevada opposes the repository, estimated to cost $58 billion to complete. It would accept waste in 2010 at the earliest, if the site is found scientifically suitable.

Preliminary results of hundreds of computer models run by the state indicate the ground water flows southwest toward California along fractures and earthquake faults, Lehman told the scientists meeting in Las Vegas.

The ground water would contain more radiation and escape the repository sooner than DOE's estimates if it runs along the faults and fractures, she said.

Lehman said she plans to publish her results in time for an international high-level nuclear waste conference in February.

DOE and USGS scientists have predicted that the ground water from Yucca Mountain flows east toward the Nevada Test Site, where more than 1,000 above- and below-ground nuclear weapons exploded from 1951 to 1992, then south toward the farming community of Amargosa Valley.

The state expanded its ground water study to include Amargosa Valley and the Death Valley region during the past two years, Lehman said.

Hydrologist Ghislain de Marsily of Paris, a member of the international panel, questioned DOE officials after Lehman's presentation.

Why, de Marsily said, did the United States choose only one site -- Yucca Mountain -- to study as the world's first high-level nuclear waste repository?

In 1987 Congress chose Yucca Mountain as the only site to study, DOE policy adviser Abraham Van Luik said.

Two other sites, one in Hanford, Wash., the other in Deaf Smith County, Texas, were withdrawn at the time, Van Luik said.

The USGS at first suggested burying the highly radioactive wastes from spent commercial reactors and weapons activities deeper than 1,000 feet below the water table at Yucca Mountain, but then moved the repository site at least 600 feet above the water table, he said.

In addition to burying the wastes in relatively dry layers of volcanic ash, Van Luik said, the DOE plans to slow water from reaching the buried wastes by installing $7 billion worth of titanium drip shields and encasing the radioactive materials in containers that can last for up to 1 million years.