Posted on 03/11/2004 5:19:16 PM PST by Ernest_at_the_Beach
It could take about 1,000 years for contaminated water to flow from Yucca Mountain to the Amargosa Valley, scientists said Wednesday.
Scientists presented studies this week in Las Vegas to the U.S. Nuclear Waste Technical Board, a panel of scientists and engineers who will advise the Energy Department on the planned Yucca Mountain nuclear waste repository.
The studies all show that the complex terrain and water flow near Yucca Mountain make it more difficult to safely store about 77,000 tons of highly radioactive nuclear waste planned for the site.
How quickly water moves from the mountain could be important. By law, the Energy Department is supposed to design the dump to safely hold waste for at least 10,000 years.
But studies presented Tuesday found that the mountain is damper and colder than previously thought, meaning the metal canisters holding the waste could corrode more quickly.
At least one scientist was left with concerns this week about how well the casks will hold up in the mountain.
"The testing that's being done has not answered the question we'd like answered," said Ronald Latanision, a nuclear engineering expert and member of the Technical Review Board. "What is the likely stability of the materials over the life of the project?"
J. Russell Dyer, the top Yucca Mountain official attending the meetings, said Energy Department scientists plan to address concerns that current project designs could let waste containers corrode and leak radioactivity.
"We've got some data. We're acquiring more," Dyer said, adding that some questions may remain unanswered while the Energy Department applies for a license to operate the Yucca site.
"Some tests are going to go on for a very long time," he said.
Decades ago, scientists thought that the volcanic rock underneath Yucca Mountain would impede water flow, meaning leaks of nuclear waste wouldn't contaminate the ground water.
But scientists said Wednesday it now is clear that fissures in the rock will allow tainted water to flow down the mountain toward Amargosa Valley and Death Valley, scientists said.
Several factors affect how quickly the water will flow, including faults in the area and the temperature of the mountain, scientists said.
Some said it could take as few as 10 years for contaminated water to travel to water supplies. But that would take a worst-case scenario of a number of "unlikely" conditions, said Bill Arnold, a principal member of the technical staff at Sandia National Laboratories.
There is less than a 5 percent chance that any contaminated water would reach the water table in less than 500 years, Arnold said.
Another scientist, Gary L. Patterson of the U.S. Geological Survey, tested water on the eastern and western sides of the mountain to determine where it flows. He said it likely would take thousands of years for water to flow from the mountain to other major washes.
Studies on how water flows have not changed the Energy Department's calculations on how ground water could be contaminated, said Russell Dyer, assistant to the deputy director on Technical and Regulatory Programs of the Energy Department's Office of Repository Development.
He showed a graph from the Energy Department showing the earliest potential contaminated water from the mountain reaching the water supply in a little more than 500 years.
"We don't feel the new information will affect time travel," Dyer said.
Several scientists advocated Wednesday for further study on how water flows through the mountain.
Dr. John Bredehoeft, a hydrodynamics expert who consults for Inyo County in California, said there is a "fragile" water system that runs from Yucca Mountain to the southern Funeral Mountain range and, eventually, toward Death Valley.
There are several unknowns, Bredehoeft said, including several faults in the area that could affect the speed of contaminated water moving through the aquifer.
Also, several cities want to draw more water from the aquifer. That also could affect water flow, he said.
All in all, Inyo County wants to drill more wells in the region to determine how long local water has been in the aquifer and where it came from. Those tests are being held up because the drilling sites are on protected federal land, he said.
The studies presented Wednesday didn't answer questions for Judy Treichel, executive director of the Nevada Nuclear Waste Task Force, who sat through the two-day presentation to the board.
While the Energy Department hopes to resolve scientific questions about Yucca by December so it can file for a license to build it, Treichel told the panel she thinks the answers will come "a little too late."
"The site's been recommended," she said, "and they're in a race to get the license application in."
Never mind.
So the walls might have a pinhole in them after 500,000 years instead of 1,000,000 years? I don't think that's going to matter all that much.
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