Lack of water could delay Yucca

Thursday, Nov. 11, 1999 | 11:24 a.m.

Wanting water

The Department of Energy is asking State Engineer Michael Turnipseed to allow the agency to use 430 acre-feet of water a year for building and operating a high-level nuclear waste repository at Yucca Mountain, 90 miles northwest of Las Vegas.

The DOE says the water will be used for:

If Yucca Mountain is approved as the nation's dump for high-level nuclear waste, construction could be delayed because of a lack of water, Department of Energy officials said Wednesday.

DOE officials say the building and operation of the waste repository at the site 90 miles northwest of Las Vegas may require more water than the agency is requesting. The discrepancy could slow construction and delay the project beyond its 2010 projected opening date.

Yucca Mountain is the only site being considered for the storage of the nation's 77,000 tons of highly radioactive waste. If the mountain passes scientific muster, the earliest it would be ready to accept waste shipments is 2010.

DOE officials on Wednesday admitted during hearings on the agency's request to use 430 acre feet of ground water a year that the project at Yucca Mountain may require far more water than it has requested.

They said that under one scenario, in which the waste is kept cool -- or below boiling point -- activities above and below ground to simultaneously build and operate the repository could demand almost double the amount of water requested.

DOE contract engineer Michael Ruben said that the lower the heat inside the repository, the more water is necessary. A cool repository would demand about 490 acre feet of water a year after construction. Demands for building and operating surface and below-ground facilities could reach 910 acre feet a year.

When asked if the DOE would ask for more water, Ruben said, "They'll have to live within the state's appropriation."

The State Engineer's Office has determined that there is enough ground water to provide the 430 acre feet a year the DOE has requested. An acre foot of water is enough to provide the needs of a family of four for a year.

The alternative is to allow the repository to reach temperatures above the boiling point of water. That would require 402 acre feet of water a year, Ruben said, which is within the 430 acre feet the DOE has requested.

Wendy Dixon, manager of DOE's environmental impact studies, said the department will live within the state's limit by slowing construction if necessary. The repository's design is changing as the DOE learns more about the site, she said.

DOE engineers showed colorful drawings of what a nuclear waste repository might look like as robots place radioactive casks into Yucca's rock.

A big concern for the DOE is the variety of nuclear wastes destined for burial, mining engineer Daniel McKenzie III said.

There would be 70,000 tons of highly radioactive wastes removed from commercial nuclear reactors, and another 7,000 tons of defense wastes from weapons development, including Navy nuclear reactor wastes. The Navy wastes require the biggest containers.

If a repository is tightly packed with containers and runs hot -- above the boiling point of water -- it would cover 741 acres, McKenzie said. A repository designed to stay cool would need 2,500 acres. "The big difference is tunneling," he said.

McKenzie explained that the DOE would build 70 to 100 miles of tunnel for a hot load and up to 200 miles for a cool repository.

Turnipseed asked McKenzie where water that might be trapped in the rock would go if the nuclear wastes heat it over the boiling point.

"That's where the uncertainty comes in," McKenzie replied. Scientists don't know what would happen, he said.

Some DOE researchers speculate that the heat might drive the water through cracks and away from the casks until the rock cools, then allow water to condense and drip back onto the containers. Scientists worry that the containers exposed to water could corrode, allowing radiation to escape.

Under an alternate scenario, a lukewarm repository might threaten tunnel performance by changing the chemistry of the water, so builders would have to support the tunnel walls with steel bands and rock bolts, he said.

And how long would such a scheme last? Turnipseed asked.

"The warranty runs out the day we close the doors," McKenzie said.

DOE scientists expect the tunnels would eventually collapse onto the casks, and in their scenario continue to contain the radioactivity.

Meanwhile, Turnipseed said Wednesday he wants to see written briefs from the DOE and opponents of the repository on their interpretations of state and federal law.

While it appeared on Monday that Turnipseed was inclined to grant DOE's request for water rights, his desire for more information on what constitutes "public interest" gave opponents of the repository hope in their fight to block the DOE. The agency needs the water rights before it can get a license to operate a repository from the Nuclear Regulatory Commission.

On Monday the state engineer said that he has already determined that there is enough ground water to accommodate the request and that it does not infringe on other uses, such as farming, ranching and drinking water for residents. In addition, he decided in June that he would not address the possibility that ground water would be contaminated by escaping radioactivity.

That left only the requirement that the water permit serve the public interest for opponents to argue.

The state, the most vocal critic of the proposed repository, argued Monday and Tuesday that highly radioactive waste stored less than 100 miles away would create devastating socioeconomic impacts on Las Vegas, a city attracting wealthy retirees and tourists.