Two physicists, Dr. Charles D. Bowman and Dr. Francesco Venneri, of the Los Alamos National Laboratory in Los Alamos, NM, recently released a thesis claiming that geologic disposal of high-level nuclear waste at the proposed Yucca Mountain site could potentially cause a nuclear explosion, dispersing radioactivity into the wind and water. The theory gained national attention after it was reported in a front page article of the New York Times in early March.

Dr. Bowman, the originator of the theory, has stated that he believes there is "a generic problem with putting fissile materials underground." Fissile materials are those that fission, or split apart, during a nuclear reaction.

Bowman believes that serious dangers could arise thousands of years after high-level radioactive waste is emplaced in an underground repository such as the proposed Yucca Mountain site. He theorizes that over time, the steel canisters holding the nuclear waste will disintegrate. He postulates that plutonium 239 could migrate into the surrounding rock, through water movement. If the plume is the right shape and dimension, contains as little as one kilogram of plutonium, and the rock-water ratio is correct, an explosive nuclear chain reaction could take place when the mass becomes critical, causing an explosion in the underground repository.

A press release response from DOE's Yucca Mountain Project Office stated that the Department of Energy will evaluate Dr. Bowman's theory regarding Yucca Mountain, and will seek independent peer review by outside experts if the theory raises issues that are not already addressed.

Sandy Green, with the Eureka County Yucca Mountain Information Office, said she continues to have concerns about the theory. "They had three internal groups review the theory (at the Los Alamos Laboratories). If they couldn't dismiss the theory internally, then there are still some questions and concerns."

Carl Johnson, Administrator os Technical Programs for the Nevada Agency for Nuclear Projects, said the state is taking Bowman's theory seriously. Johnson admonished the DOE for not discussing the theory openly at an earlier time. "This is one scenario they should have been studying and evaluating all this time. Why did one of their laboratory scientists have to bring it up? Why only now do we learn about it? Why do we have to learn about it in the press first?"

Some questions remain about Bowman and Venneri and the release of their theory to the New York Times. The two have worked on accelerator-transmutation of high-level waste into non-radioactive elements, not geologic disposal. Funding for transmutation has decreased, and work on geologic disposal has increased. Some wonder whether the two scientists released their theory to the press in order to raise doubts about geologic disposal and increase funding for their work in transmutation.

Although the thesis was disputed by teams of scientists at Los Alamos, scientists from the Department of Energy at the Savannah River nuclear site near Aiken, SC, supported the theory, calling it a "discovery," and an "original piece of work."

In May, scientists from the Lawrence Livermore National Laboratory in California released a 17-page report refuting the explosion theory. Bowman fired back, charging that the critics did not do a thorough scientific investigation.

The Bowman-Venneri paper has been submitted to a peer-reviewed journal for publication. Those Los Alamos scientists who disagree with the paper will submit a response paper in an attempt to discredit the theory.