An environmental group said Friday some of the containers that will carry plutonium from Colorado to South Carolina are unsafe.

Citing federal documents it reviewed, Tri-Valley CARES Inc. of Livermore, Calif., said some Department of Energy containers could be crushed during a highway accident. Shipments to South Carolina are expected in the next month.

DOE spokesman Joe Davis said all plutonium coming from Rocky Flats, Colo., to the Savannah River Site will be safely packaged and protected.

But Tri-Valley CARES director Marylia Kelley said DOE records show one type of container is vulnerable in a car or train collision with the DOE's plutonium trucks. The group says federal documents it reviewed show that the containers cannot pass mandatory government crush tests.

"That could disperse deadly plutonium particles across the highway and into the atmosphere," Kelley said Friday afternoon.

Tri-Valley CARES is a watchdog group that follows the Lawrence Livermore National Laboratories nuclear site in California. During her review of the records, Kelley said she learned that suspect containers were going not only to the Livermore site, but also to the Savannah River Site.

She said at least 85 questionable containers would come to South Carolina, based on her review of the federal records.

Davis said the DOE has "stringent" guidelines for material to be shipped to SRS. The containers in dispute are commonly referred to as "DT-22s."

"We have multiple layers of protection with respect to these shipments," Davis said. That includes safeguards on the inner packaging and the trucks to be used, he said.

The Department of Energy intends to begin shipping plutonium from Rocky Flats to SRS as early as May 15. Gov. Jim Hodges has fought to block the shipments, saying the material could be left in South Carolina forever.

Negotiations to resolve the federal-state dispute continued Friday with no resolution. Davis said both sides had made "significant" progress.

Plutonium is a potentially deadly toxin linked to lung cancer. It is used to make nuclear weapons.

Hodges' spokeswoman Cortney Owings said the governor's office had not heard about the container questions. Kevin Bishop, a spokesman for U.S. Rep. Lindsey Graham, R-S.C., said the congressman is comfortable that the shipments will be secure.

Like Hodges, Graham opposes shipping the material to South Carolina without a firm agreement that it will be moved out at a future date. But the shipments are not a worry, Bishop said.