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The Science of Yucca Mountain
Debate Lingers over Safety of Nation's Proposed Nuclear Vault
 Listen to David Kestenbaum's report.
July 10, 2002 -- On Tuesday, the U.S. Senate joined the House and President Bush in choosing Yucca Mountain, Nevada as the final resting place for the nation's most potent radioactive waste -- deadly leftovers from nuclear reactors and decades of building and testing bombs. The Senate vote overturns a veto by the state of Nevada.
Approval from one more government authority is necessary before construction can begin: The U.S. Nuclear Regulatory Commission. The NRC must decide whether Yucca Mountain's containment design is good enough to guarantee safety. Radioactivity will eventually leak out of Yucca Mountain. As NPR's David Kestenbaum reports, the question is only when the vault will leak -- and how much.
The biggest safety concern is water. The site's safety depends on whether, over the next 10,000 years, rain will get deep into the ground, corrode the waste storage containers, and seep out to nearby wells.
Abe Van Luik and other Department of Energy scientists have spent billions of dollars studying the mountain, and have created a computer model to follow the flow of water to get an estimate of how much radiation might be encountered by a local farmer 10,000 years from now. To officially start construction of the containment site, the DOE must show that the hypothetical future farmer's well water won't expose him to more radiation than a dental X-ray each year.
An independent report for the government this year concluded the science underlying the DOE's colossal computer model was "weak to moderate." But Van Luik tells Kestenbaum he thinks the computer model is good enough, in part because it will take a "sizeable rain or snowfall event" to push water deep into the mountain.
Skeptical geologists point out that it's hard to predict how much rain will fall in Nevada 10,000 years from now. But even if more rain does fall, Van Luik says, it will take thousands of years to get deep inside the mountain where the waste will be stored.
But eventually the water will win. The computer model predicts the canisters will start to crumble, and water will carry some radioactive material another 1,000 feet down to the water table where it can escape. The hope is it will happen slowly. After 10,000 years, 99.99 percent of the radioactivity will have decayed away.
Still, the NRC will have to be convinced. At last count, the NRC had listed over 200 outstanding technical and scientific issues.
In Depth
 NPR's David Welna reports on the July 9, 2002 Senate vote to override Nevada's veto on use of Yucca Mountain.
NPR's David Kestenbaum visits Nevada on the day the U.S. House votes in favor of Yucca Mountain.
Kestenbaum reports on President Bush's Feb. 15, 2002 endorsement of the Yucca Mountain site.
NPR's John Biewen reports in 1997 that the DOE wants Yucca Mountain to be a "temporary" waste repository.
Other Resources
• YuccaMountain.org, a Web site created and maintained by the Eureka County (Nev.) Yucca Mountain Information Office.
• Analysis of radiation exposure levels by the Environmental Protection Agency
• The official Yucca Mountain Project home page created and maintained by the Department of Energy's Office of Civilian Radioactive Waste Management.
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