Concern over leaks at radwaste site.

Concern over leaks at radwaste site

An evaluating committee last week recommended major changes in the design and operation of the nation's first underground nuclear waste repository, located near Carlsbad, N.M. The recommendations follow recent reports that water is leaking into the facility, which is scheduled to begin accepting waste in October of this year. But engineers working for the Department of Energy (DOE), which operates the repository, contend that the water will not create significant problems.

The repository, called the Waste Isolation Pilot Program (WIPP), is located in salt deposits 2,150 feet below ground. It will house Defense Department waste that is contaminated with plutonium, an element that remains radioactive for thousands of years. DOE originally selected this site because scientists believed the salt deposits would keep the waste dry. However, tests in the last three years have indicated that the salt contains more moisture than had originally been assumed, and that the moisture is leaking into the repository.

"It is possible that because of the problem, the WIPP site may not meet EPA [Environmental Protection Agency] standards," says Lokesh Chaturvedi, a member of the Environmental Evaluation Group, a committee of scientists that oversees the WIPP project on behalf of the state of New Mexico. The group presented information on the water problem to a state task force last week.

"The problem should be resolved before they put a large quantity of waste in," Chaturvedi told SCIENCE NEWS. "We are not saying that the site should be abandoned. We are saying that some engineering changes can take care of the problem."

But scientists from the federal government's Sandia National Laboratory in Albuquerque, who have studied the hydrology of the WIPP site for the DOE, told the task force that the amount of water entering the repository was insignificant. "We think there's no problem at all. It doesn't require us to change our plans as far as when we proceed or how we proceed," says Wendell Weart, chief of Sandia's waste management technology department.

The repository is designed so that the walls of salt will slowly collapse, enveloping the canisters of waste and sealing them in a watertight salt capsule. But an independent group of University of New Mexico scientists testified last month before a congressional subcommittee that the brine leaking into the repository would corrode the waste canisters and turn the solid waste into a liquid slurry before the rooms have collapsed.

Future generations searching for oil, gas or mineral deposits may unwittingly drill into the repository. And if they hit a slurry, pressurized by the collapsing room, this radioactive waste would gush to the surface.

The current EPA standards require DOE to consider such a possibility. If the waste becomes liquefied, it is likely the repository will violate the standards, says Chaturvedi.

The repository will contain 56 rooms, each measuring 100 meters long, 10 m wide and 4 m high. At the task force meeting, Sandia's Weart presented estimates, based on computer models, that the amount of water entering each room in the next 100 years would be less than 43 cubic meters. According to Weart, these estimates represent the most complete and accurate data on the inflow rate.

"We believe that we could accommodate something like five times as much water as the maximum that we predict and the waste would still be solid," says Weart. "We don't think there's any real concern or potential for a slurry to exist in those rooms."

Chaturvedi and the University of New Mexico scientists question the accuracy of Sandia's numbers. Both groups have calculated that water is leaking into the repository at rates much higher than 43 cubic meters per 100 years. They also believe that calculations of risk should consider time well beyond the 100-year mark.

Legislation now before Congress would allow the DOE to fill 15 percent of the WIPP repository before the department demonstrates that the facility will meet EPA safety standards. DOE is scheduled to complete by 1992 a performance assessment study that will indicate whether the repository can comply with the standards.

Chaturvedi's Environmental Evaluation Group recommends that DOE alter its plans because of the water leakage. If inflow rates are high enough, DOE may have to reprocess the waste before placing it in the repository. Therefore, he says, "they should only put that amount of waste in that is necessary for genuine experiments."

But Konrad Krauskopf of Stanford University, who heads a National Academy of Sciences committee that periodically reviews the WIPP site, contends that the water inflow is "nothing new."

"Personally, as an individual," he says, "I think it would be sensible at this point to start putting in waste according to schedule and see what happens. Everybody expects that the waste will be retrievable for the first few years. That has been part of the plan for years and years.

"The expense of putting it in and taking it out isn't prohibitive. I think we'd learn a good deal if we started putting it in. Chances are very good that it will just stay there."