Bacteria feast on nuclear waste; Ground water might be at risk

By Ed Susman UNITED PRESS INTERNATIONAL, September 1, 1996

ORLANDO, Fla. It seemed like a science-fiction scenario: Nuclear scientists
announced here that bacteria in salt mines, the storage place of choice for
nuclear waste, thrive on radioactive materials.

And these contaminated bacteria are small enough to slip into ground water.

Betty Strietelmeier, a researcher from the Los Alamos National Laboratory
in New Mexico, said the short-term risk to the population is small.

"However, it's very hard to predict what will happen in 10,000 years, the
projected lifetime of the storage facilities. We did our experiments for a
month," said Miss Strietelmeier, who presented her work last week at the
fall meeting of the American Chemical Society in Orlando.

Scientists at Los Alamos are combining microbiology and radiochemistry to
investigate what could happen to bacteria that come in contact with
radioactive waste in a nuclear waste repository.

Miss Streitelmeier found that exposure to radioactive plutonium, neptunium,
uranium, thorium and americium did not kill the halophilessalt-loving
bacteria that abound in salt environments.

"If anything," Miss Streitelmeier said, "the bacteria growth was enhanced."
The bacteria adsorb the radioactive materialpull the radioactive substances
out of the waste material.

Work of colleagues at Los Alamos, Sandia National Laboratories in
Albuquerque and at Brookhaven National Laboratory in Upton, N.Y., found
that most bacteria would be filtered out of ground water, but smaller
bacteriaparticularly the halophilescould be carried off by ground water.

Miss Streitelmeier's work was done in a laboratory setting. In a waste
storage facility, she said there could be differences in levels of toxicity
or in levels of bacteria. "We don't know how long the bacteria would live
carrying the radioactive material," she noted.

She said that bacteria would most likely stick to rock, barrels or the
waste itself and would not slip into ground water; and if radioactive
bacteria did get into ground water, she said the organism would soon die
and the radioactive particles would break into smaller and smaller pieces.

But Miss Streitelmeier acknowledged that radioactivity is a potent
generator of mutagens that could cause the bacteria to become more
efficient transporters of nuclear contamination.

"It could be a scary scenario," she said.

The studies are part of the extensive scientific evidence required to
demonstrate that the U.S. Department of Energy's Waste Isolation Pilot
Plant (WIPP) is safe before the Environmental Protection Agency allows the
site near Carlsbad, N.M., to accept waste from the nations nuclear weapons
laboratories.