Experts question safety of Yucca casks

Stephen Curran

Tuesday, Sept. 21, 2004 | 10:59 a.m.

A metal drip shield that would keep water from penetrating casks holding high-level nuclear waste at a proposed dump at Yucca Mountain may be less effective than originally thought, members of an independent oversight board said Monday.

Robert Andrews, a geologist for Bechtel SAIC, the project's main contractor, said scientists are still developing models to determine if water seeping into the mountain could penetrate the alloy shield roughly 980 feet below the surface.

He was one of several scientists with both the Energy Department and private contractors who addressed the U.S. Nuclear Waste Technical Review Board on Monday.

But even if water does go through cracks in the protective layer, researchers still do not know if it could corrode the cylindrical casks that would store the 77,000 tons of high-level nuclear waste in the mountain, Andrews said.

"The fact that it could crack is well known, but what happens when water comes in contact (with the cask) needs to be assessed," Andrews told the board, which met Monday at the Atrium Suites hotel on Paradise Road.

The scientists' concerns came as scientists continue a study on possible risks stemming from the proposed nuclear waste dump 90 miles northwest of Las Vegas. The study is part of the long-term license application process, which Energy Department officials say could lead to nuclear waste being shipped to Yucca as soon as 2010.

The department has until the end of the year to submit the license application to the Nuclear Regulatory Commission.

A team of geologists is studying whether water flowing on the surface could alter the chemistry of the rocks, which could cause the barrier to degrade. If enough water penetrates the shield, scientists worry that radioactive nucleotides could seep into the water table another 980 feet below the casks, he said.

Six teams with three geologists each are developing a plan to study the risks that could arise from a possible earthquake near the proposed repository, said Jon Ake, a geophysicist from the federal Bureau of Reclamation.

A key part of the plan, he said, is incorporating possible but unlikely scenarios about the potential endangerment of those living near the proposed dump. Little Skull Mountain not far from Yucca suffered a 5.6 magnitude earthquake in 1992 and the area was shaken by a 4.4 magnitude quake in June.

Ake and others are currently evaluating faults near the proposed dump to see how dangerous a similar quake would be for the nuclear waste, he said.

"We need to find a way to incorporate the unknown," Ake said.

The meeting came a day after a high-level Energy Department official said the government will likely miss the Dec. 30 deadline to submit the application.

Bechtel had a financial stake in finishing the application on time, as the DOE has promised to pay the contractor another $15 million if scientists for the company finish the application by Nov. 30. The company could also get another $22 million if the Nuclear Regulatory Commission puts the item on its docket by March.

The project has been on shaky ground since a federal court this summer ruled planners' 10,000-year radiation standard falls short of a stricter standard mandated by the Environmental Protection Agency.

The next step for the Energy Department is to submit the application, which it plans to do by the end of the year.

If approved, a 319-mile railroad would carry the waste through much of rural Lincoln County to the nuclear waste dump.

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