Scientists detail Yucca water threat

Wednesday, March 10, 2004 | 11:18 a.m.

Reports issued Tuesday to an independent federal review board could spell troubling news for backers of a nuclear waste dump at Yucca Mountain.

Scientists told the U.S. Nuclear Waste Technical Review Board that the climate at Yucca Mountain, 90 miles northwest of Las Vegas, has been and will again be cooler and wetter than it is today, providing more water to corrode metal canisters holding the highly radioactive waste.

Another scientist told the board's panel on the natural systems at Yucca Mountain that old Energy Department models of the rate that water seeps through the mountain's rock were inadequate, meaning that much more water may penetrate the mountain than once thought.

The issues discussed Tuesday shed light on potentially problematic issues for the Energy Department, which plans to begin storing 77,000 tons of nuclear waste in Yucca Mountain by 2010. The Energy Department plans to submit a license application with the Nuclear Regulatory Commission by December that would allow the agency to move forward with the plan to dump the waste.

The Energy Department is trying to answer hundreds of technical questions raised by the NRC before submitting the license application.

The Nuclear Waste Technical Review Board is charged with analyzing the Energy Department's scientific and technical activities related to the Yucca Mountain program.

The Energy Department's long-standing flow models said water traveled a millimeter or less through the rock. At the review board's panel discussion, Alan L. Flint, a research hydrologist with the U.S. Geological Survey, said the flow could be 5 millimeters to 80 millimeters in some locations.

Flint said the government's early models showed a high degree of lateral movement of the water. That model would indicate that much of the water flowed off Yucca Mountain.

But Flint, referring to numerous studies, said evidence now shows much of the water can move vertically through fractures or fissures in the rock.

Robert Loux, executive director for the Nevada Agency for Nuclear Projects, said the research presented Tuesday backs long-standing concerns among scientists and Nevada policymakers.

"The state has always believed that the infiltration of ground water is the big problem," Loux said. "The Energy Department knows it has a big problem with ground water and how to manage it, and that's the big problem with Yucca Mountain."

Steve Frishman, technical policy coordinator for the Nevada Agency for Nuclear Projects, said the Energy Department "vastly underestimated" the flow through the rock.

"It's a model that we had been telling them for years is wrong," he said. "The fracture flow is very important to the system. ... We're looking at something that was a millimeter or less a year to a minimum of 5 millimeters to as high as 80 millimeters a year.

"If they had known in 1987 that the more correct hydrologic flow included fractured flow, they probably would never have continued with this site," Frishman said.

The Energy Department now has the tough job of finding ways to reduce the movement of water through Yucca Mountain and must also address the possible flow of radioactive particles into the ground water if and when the storage canisters leak, Frishman said. Engineering a solution is difficult because the time frame to deal with is in the tens or hundreds of thousands of years, he said.

"No matter how you tweak the model, you can't make the mountain better than what it is," Frishman said. "As soon as you lose the metal container, the mountain takes over."

Another issue that the federal government has to handle is the weather -- or more precisely, the long-term climate change that some scientists now believe is inevitable.

Saxon Sharpe, a climatologist with the Desert Research Institute in Reno, looked at the climate 500,000 years in the past and in the future, and found broad cycles corresponding to the movement of the solar system.

One implication of those cycles is that the earth generally is moving from an intermediary stage to a colder, wetter glacial stage, which means more water falling on and moving through Yucca Mountain.

"The last 400,000 years encompassed higher, sometimes much higher, effective moisture relative to today," Sharpe said. "Climate is cyclical."

The cooler, wetter period that the earth is entering should last more than 75,000 years, she said.

Sharpe discounted global warming as a counteragent to the long-term trend because fossil fuels, the suspected trigger for global warming, will eventually run out. One model, she said, shows the man-made effects on the climate dissipating after 10,000 years.

"There is a lot of controversy in terms of whom you talk to about long-term climate, but I would argue that the past is the key to the future," Sharpe told the panel.

Irene Navis, planning manager for Clark County's Nuclear Waste Division, said the reports Tuesday reinforced suspicions that earlier studies on the suitability of Yucca Mountain as a waste site were "inadequate."

"We are watching carefully the Nuclear Regulatory Commission's handling of the key technical issues to be sure that the technical matters such as how fast water travels through the repository are properly handled," she said. "One of the things we need to be sure of is if we have addressed all the variables."

Yucca Project spokesman Allen Benson said the department's performance assessment models took into account water on small areas of the waste containers.

"That employs as conservative an approach as possible," he said.

As for Sharpe's studies, Benson said the department has incorporated her studies and even referenced her work in the performance models.

Overall he said thousands of tests have been conducted during the 20 years of research on the program and most of the study had been on hydrology and geology of the site. About 450 bore holes have been drilled into the mountain for the tests.