Jury still out on science issues

Tuesday, June 2, 1998 | 9:49 a.m.

The U.S. Department of Energy must prove Yucca Mountain can safely store high-level nuclear waste before the site is granted a license as the world's first such repository.

The repository would store an estimated 77,000 tons of spent nuclear fuel and waste from nuclear power plants and U.S. weapons facilities. Because the life span of the repository is 10,000 years, scientists must predict how future changes in the mountain rock and climate would affect the buried waste.

"Science must speak for itself. It must stand up to scrutiny and rigor," Allen Benson, a DOE spokesman for the Yucca Mountain project, said.

But opponents of the proposed repository say political pressure is tainting the scientific process. They believe the DOE is tipping the scientific scales in favor of the site rather than objectively evaluating its suitability. They find it highly unlikely that, after years of studies and after spending millions of dollars, the DOE would not recommend Yucca Mountain -- even if it proves to be unsuitable.

Yet Benson says that if the site is found unsuitable, the DOE will walk away.

"Ninety feds and 1,500 contractors here have put their names and reputations on the line. We wouldn't say, 'Yes, it's suitable,' just because we've spent (millions of dollars)," Benson said.

"We're taking the time to check it out. We do not summarily dismiss anything."

The main areas of scientific study -- and scientific disagreement -- are:

* Water and climate -- The DOE believes Yucca Mountain is a dry site for the repository because the water table is 1,000 feet beneath the block of rock in which the waste containers will be buried.

Former DOE geologist Jerry Szymanski and others disagree. Szymanski, who has become one of the most outspoken critics of the repository, says evidence found in crystals throughout the mountain shows deep water invades the site periodically, a situation that would threaten canisters containing nuclear waste. Others believe a climate shift will increase rainfall in the area and raise the water table, which also would threaten the waste containers.

* Earthquakes -- The DOE says careful engineering design, combined with natural rock barriers, will protect the waste canisters from earthquakes for at least 10,000 years.

Nevada state officials say an earthquake measuring 5.7 on the Richter scale damaged surface facilities and raised questions about how the earth's movement would affect the buried waste.

* Volcanos -- The DOE says there is a one in 70 million chance of volcanic eruption at Yucca Mountain, which has been dormant for at least 3 million years.

Szymanski said volcanic eruptions or earthquakes could periodically force water hundreds of feet upward inside the mountain. He based his theory on deposits found in cracks and fissures in the rock.

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The DOE has created an Exploratory Studies Facility, an underground laboratory within Yucca Mountain, that allows scientists and engineers to study the mountain's interior.

One of the key issues being studied is water, according to Russ Dyer, acting project manager for Yucca Mountain.

DOE scientists are studying how fast the water flows beneath the repository, the rate of seepage into the repository level and the chemical changes that water can cause in the rock where the repository lies.

DOE scientists believe that with the water table 1,000 feet below the repository, there will be limited water contact with the waste packages buried there. According to DOE reports, "heat produced by the emplaced waste will reduce relative humidity at the waste package surface." Low relative humidity means less chance of corrosion, they say.

Other scientists disagree. They say that if the climate changes and becomes wetter, the ground water will rise and could flood tunnels and corrode containers, allowing radioactive materials to escape.

DOE scientists once thought Yucca Mountain was dry. But the Nevada Agency for Nuclear Projects, which oversees the project for the state, found that tiny cracks in the mountain's tuff (the rock that forms the mountain) were filled with water, according to agency director Bob Loux.

Yet DOE scientists have never seen water dripping within the mountain. "You probably never will, unless Southern Nevada is deluged with 40 inches of rain a year instead of the 6-inch annual average," Dyer said.

But that could happen during the 10,000-year life span of the repository, James Taranik argues. He is director of the Desert Research Institute, an independent research branch of the University of Nevada system.

Despite the world's attention to global warming, Taranik and other scientists believe the Earth is nearing the end of an interglacial period, signaling a drastic climate shift and more rain and snow for Yucca Mountain.

Lower temperatures could increase rainfall there by three to 10 times the current 6-inch average, Taranik said. So the repository must be built to withstand the climate shift and subsequent higher water table.

Dyer believes some individual waste containers will leak after 1,000 years because of corrosion caused by climate changes that will increase the amount of water in the mountain. But he said the amount of leakage would be too small to harm the public or environment.

While Taranik believes it may not be wise to put nuclear waste underground, he stopped short of saying a repository shouldn't be built at Yucca Mountain.

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The Yucca Mountain repository would be different from other man-made facilities in that the surrounding mountain rock will be subjected to heat from buried waste, the DOE said. Because prolonged heat triggers mechanical, hydrological and chemical changes, scientists must understand what changes will occur so that the waste containers and the repository itself can be designed to withstand them.

To determine how Yucca Mountain's volcanic rock will react to heat generated by the thousands of irradiated fuel rods that would be buried there, DOE scientists have plugged heaters into the rock.

They are heating the site for four years, then will cool it down for another four, in an effort to determine how the heat generated by the buried waste will impact water in the rock and the direction of its flow.

The final results of the heater tests won't be available until 2006, but they are a vital part of a mountain of scientific reports written by more than 1,000 scientists working on the project.

The heater tests are extensive -- and expensive. Based on typical electric rates, the power bill was $26,470 in just three months, Dyer said, pointing to an electronic board lit up like a Las Vegas casino sign that keeps track of power delivery and heat to Yucca Mountain.

Also under study -- and dispute -- is the potential for earthquakes in the area.

Repository opponents say 34 earthquake faults slice through Yucca Mountain. The DOE's Benson says the block of rock in which the repository would be sited is solid.

When the 1992 earthquake that measured 5.7 on the Richter scale struck the area, the epicenter was 12.4 miles from Yucca Mountain. Benson said repairs to damaged surface facilities cost about $40,000. However, he added, there was no damage to tunnels at the mountain.

"The engineering is designed to complement the geology to make it safe," Benson said. "The nuclear waste also will be in specially designed canisters, so it will be protected (in the event of an earthquake)."

Scientists are designing double-layered containers made of metal alloys and ceramics that resist corrosion and are strong enough to resist surrounding ground motion. The specific container materials, however, have not been chosen, nor is there a prototype. Endurance estimates are based on experiments that have been under way at DOE's national laboratories for about 10 years.

Szymanski thinks the containers can be compromised. The former chief geologist for the DOE, who now works for the state of Nevada, has become one of the most outspoken critics of the repository.

Szymanski said a flooded repository could cause the containers to crack open, allowing radiation to escape into the ground water or air and threaten the health and safety of people and the environment.

The National Academy of Sciences convened a 17-member panel to review Szymanski's theory. Although the panel discounted it, the independent Nuclear Waste Technical Review Board continues to review his data.

Other scientists say the earth around Yucca Mountain is stretching, a factor that also could compromise the waste containers.

Using the Global Positioning System, a series of satellites that can track activity on Earth, nine geology experts measured the surface around Yucca Mountain for seven years.

The study's chief geologist, Brian Wernicke of the California Institute of Technology in Pasadena, said that at the rate the Yucca surface is moving, the ground could stretch more than 3 feet over the next 1,000 years.

The geologists never expected to see the surface move and now question what impact that would have on buried waste. They don't know why it's moving and theorize it could be a prelude to an earthquake in the distant future that could crush the waste canisters.

Dyer is puzzled by the findings. "Either something is wrong in the way scientists are interpreting the data or there's been a misunderstanding in geological strain rates.

"If that had been the rate (of movement), we would have seen all kinds of changes in our studies," Dyer said. "It is inconsistent with the geological record."

The DOE has decided to fund further studies at the mountain on the geologists' theory. The U.S. Geological Survey also will conduct its own examination of the site.

"What does it all mean?" Dyer asks. "The jury's still out."

Loux, head of the state's repository oversight program, believes the issues of rising ground water, earthquakes and volcanos would have been reason enough to stop work on any other project. But Loux said those concerns have been minimized in the DOE's rush to get Yucca Mountain approved for a repository.

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