Debate to focus on ‘reasonable expectations’

Monday, Feb. 18, 2002 | 9:34 a.m.

The key words in last week's choice of Yucca Mountain as a high-level nuclear waste repository -- uttered by both Energy Secretary Spencer Abraham and President Bush -- were that the selection was "based on sound scientific principles."

Scientific principles are the basis for an argument that will continue in Congress and the courts for years over what is probably the most complex public works project ever attempted, supporters and critics agree.

Behind those principles is a concept that has become a focus of debate over Yucca Mountain: reasonable expectations.

The Energy Department, in its 20 years of research, has concluded a repository at Yucca Mountain will work within "reasonable expectations" using multiple barriers -- the mountain's volcanic rock, steel alloy containers and titanium shields -- to keep nuclear waste from contaminating the environment.

It bases those expectations on computer models that use information gleaned from an exploratory tunnel at Yucca Mountain and from decades of underground nuclear bomb tests at the Nevada Test Site. Scientists use the models to forecast various possible events, from how the mountain might react as the radioactive waste heats up the rock to the effect of groundwater on waste containers.

DOE scientists say their exhaustive work leaves no reason not to believe that the nuclear waste will be safely contained for 10,000 years -- the federal government's benchmark for the repository. Energy Department scientists believe that's how long it will take for the radioactive waste to become non-poisonous.

But even the Energy Department admits it cannot assure absolute performance from a repository, Peter Swift, manager of the department's performance assessment strategy, said. "I hope people are not asking the exact future of the mountain, because that is unachievable."

That uncertainty is why some critics are calling for a delay in or the end of the Yucca Mountain project. Nevada officials, who oppose the repository, said the DOE should disqualify the site as a dump because it cannot prove its theories.

Part of the problem is no one can predict what will happen in 10,000 years -- all of recorded history covers less than that time period.

TRW Environmental Safety Systems Inc., the former contractor for Yucca Mountain, said in a 2001 report that studies provided "reasonable assurance" that a repository would work, but "uncertainties regarding repository performance over the next 10,000 years certainly do exist and may never be completely eliminated."

Gov. Kenny Guinn, in a Jan. 24 letter to Abraham, noted that, "our slot machines have better odds than that."

Another part of the problem is that the information the DOE used in its computer models consisted of estimates, not actual measurements, said John Bartlett, DOE director of the nuclear waste program from 1991 to 1993 and now a state consultant.

That means the DOE is basing its future estimates on current estimates, which Bartlett said is not enough scientific evidence to make the case that a repository would meet reasonable expectations.

The DOE doesn't expect its scientists to have all of the answers now. Officials say research will continue throughout the respository's construction and over the decades that will be required to fill it with nuclear waste. They argue that advances in science will be put to use to ensure the repository remains safe.

In fact, the department has asked for a flexible design plan so that the size and shape of the repository can change as more is discovered.

It also wants the nuclear tomb to remain open for up to 100 years so that future generations can retrieve the waste if it becomes a valuable resource for generating power in new reactors.

"Not all of the questions are answered," Bill Boyle, senior policy adviser to the DOE's Yucca Mountain Project, said. "But the Department of Energy expects to meet reasonable expectations of performance."

Whether those expectations are reasonable ultimately will be up to the Nuclear Regulatory Commission, which is charged with licensing a repository before it can be built.

The NRC already has expressed doubts about the DOE's scientific work and the assumptions it uses.

It points out that 293 of 300 scientific and technical questions initially posed have yet to be answered.

For example, the DOE does not know how fast water from the surface of the mountain would reach wastes buried 1,000 feet below -- a key question in terms of potential groundwater pollution.

The Nuclear Regulatory Commission also has expressed concern about the possibility of a volcano erupting through the vaults where waste containers would be buried.

The General Accounting Office, the investigative arm of Congress, and the Nuclear Waste Technical Review Board, an independent panel set up by Congress in 1987, have expressed similar doubts about the quality of the science. But none has called for the end of the project.

The NRC is waiting to weigh all of the evidence to determine what is reasonable, William Reamer, deputy director of the NRC's Division of Waste Management, said.