DOE says stored nuclear chemical unstable

A Department of Energy team of researchers has discovered that the chemical form of plutonium that is stored in the U.S. nuclear weapons complex may not be as stable as scientists once believed.

The new research published by a DOE Los Alamos National Laboratory team from New Mexico in Friday's journal Science has scientific leaders calling for new evaluations of how plutonium is handled.

What the scientists found could explain how plutonium traveled almost a mile from the crater of an underground nuclear weapons blast at the Nevada Test Site, 75 miles northwest of Las Vegas. That discovery, by a DOE team from Lawrence Livermore National Laboratory in Northern California in 1997, was the first evidence that plutonium did not stay put in the environment.

The finding also may cause scientists to rethink plans for storing plutonium at Yucca Mountain outside Las Vegas, if the repository is approved to hold the nation's high level nuclear waste.

Plutonium is a radioactive metal made in nuclear reactors and used in atomic bombs.

At the time the scientists reported that the plutonium apparently rode microscopic particles known as colloids from the site of a 1968 nuclear experiment.

The new finding indicates that plutonium in the environment could move dissolved in water and be washed into surface or ground water, former Los Alamos scientist John Haschke and his colleagues discovered, according to the article.

In the presence of water, the Los Alamos scientific team discovered, a chemical change occurs in the plutonium and oxygen molecules over time that makes the radioactive element dissolve in water more easily.

Before the discovery, scientists believed that plutonium dioxide, plutonium's version of ordinary rust, was the most stable form for long-term storage.

Scientists working with the material for decades missed the change in molecules because it is so subtle, Haschke said.

That could explain the surprise the DOE scientists expressed when they found the plutonium a mile away from the Test Site's crater, he said.

Some plutonium is destined to go to the proposed Yucca Mountain high-level nuclear waste repository, 90 miles northwest of Las Vegas, if the site passes scientific muster to become the nation's dump for commercial reactor wastes and weapons development wastes.

Plutonium is stored at five Department of Energy sites, including Los Alamos, the Pantex Plant near Amarillo, Texas, the Savannah River site in South Carolina, Hanford in eastern Washington and the Rocky Flats plant outside Denver.

Plutonium-laced wastes from DOE nuclear weapons development are being shipped to the Waste Isolation Pilot Project near Carlsbad, N.M., for burial.

A group of DOE scientists plan to meet in Albuquerque, N.M., later this month to discuss some of the implications of the latest find about plutonium and the future of storing it.

The DOE has already incorporated the preliminary results in department regulations for creating plutonium oxide for storage, the article said.

The new standard requires plutonium be heated to 1,700 degrees Fahrenheit to cook out the water that is implied by the DOE's discovery.

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