Researchers Support Earthquake Claim 

Colorado Scientists Say Yucca Mountain Could Be
Threatened By Tremor

A new study by two Colorado scientists supports a previous claim that an earthquake near the proposed Yucca Mountain nuclear waste dump could cause ground water to surge into the repository site. Geophysicists Charles Archambeau and John Davies -- research associates at the University of Colorado, Boulder -- said computer simulations based on geological data and measurements from 20 test wells show that a magnitude 5 or 6 earthquake could raise the water table up to 750 feet at the repository site.

"The danger is that an earthquake of sufficient magnitude could cause the open fractures underneath the Yucca Mountain site to squeeze shut, forcing water upward into the storage facility," they said in a statement from the Boulder college.

Yucca Mountain, 100 miles northwest of Las Vegas, is the only site the Department of Energy is studying to store the nation's high-level nuclear waste, primarily containers of spent nuclear fuel pellets from commercial power reactors.

The so-called "seismic pumping" phenomenon was observed after a magnitude 7 quake at Idaho's Borah Mountain in 1983 and after a magnitude 7.3 earthquake at Hebgen Lake, Mont., in 1959, according to Archambeau and Davies. If an earthquake that registers a magnitude 6 or more strikes, they said a wall of water locked in geologic features north of Yucca Mountain "could shift southward and cause ground water to rise 750 feet above present levels at the repository site."

Their conclusion backs a theory by former Department of Energy geologist Jerry Szymanski, who claimed evidence of mineral deposits found in a trench dug near the mountain confirms the water table has risen historically and could rise again, corroding waste containers and carrying potentially deadly radioactive contaminants into the environment.

Szymanski, who could not be reached Tuesday, worked for the government's Yucca Mountain Project from 1984 until 1992. He resigned after three out of five members of a peer review panel discredited his theory that, if built, the repository would be threatened by a sudden, upward movement of ground water. In a telephone interview, Archambeau described his work as a "quantitative computer simulation of some of the things that Jerry (Szymanski) said could happen." "We've assigned values to all of that. We put meat on the bones, if you like to put it that way," Archambeau said. He said a presidential panel, the Nuclear Waste Technical Review Board, which meets today in Las Vegas at the Crowne Plaza, has requested to review the new study.

Funded by the Nevada Nuclear Projects Agency, the study will be published in next month's issue of Environmental Geology. Yucca Mountain Project hydrologist Russ Patterson and geologist Mark Tynan said they doubt an earthquake could cause as much water to surge upward as Archambeau and Davies predict.

"They're using some examples that don't really jell with reality," Patterson said. Archambeau said, "Something like this will happen. It could be a lot worse or it could be less drastic because we don't know all the details" of conditions in the Earth. Patterson said that during the 1992 magnitude 5.6 earthquake at Little Skull Mountain -- within 12 miles of Yucca Mountain -- water rose only 1.3 feet in one well.

During the 7.4-magnitude Landers, Calif., earthquake, 190 miles south of Yucca Mountain, which preceded the Little Skull Mountain quake by 22 hours, water rose 3.6 feet in a well two miles from Yucca Mountain, Patterson said.

Readers Note: See related technical paper by Linda Lehman "The Value of State Oversight In the Department of Energy Nuclear Waste Disposal Operations at Yucca Mountain"

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