By Laura Zuckerman
April 17 (Reuters) - Robots may be needed to probe a radiation leak inside a nuclear waste disposal site beneath the New Mexico desert after a team of inspectors was forced to turn back due to high radiation levels, facility managers said on Thursday.
The Waste Isolation Pilot Plant, where drums of plutonium-tainted refuse from nuclear weapons factories and laboratories are buried in salt caverns 2,100 feet (640 meters) underground, has been shut down since unsafe radiation levels were first detected inside on Feb. 14.
An initial group of inspectors descended into the repository on April 2, once radiation readings had declined. But a team that ventured farther into the mine on Wednesday was forced to retreat after contamination levels rose sharply as the inspectors neared the presumed source of the leak.
"We know now part of the mine is contaminated," Tammy Reynolds, a recovery process manager for the contractor, said on Thursday at a meeting in the nearby town of Carlsbad that was streamed live on the Internet.
Radiation levels will likely require more protective gear for teams if they are dispatched in the future, Reynolds said.
If radiation levels still prevent inspectors reaching the leak, Reynolds said, "we're looking at the use of robots."
The facility is the nation's only permanent repository for the U.S. government's stockpile of nuclear waste, much of it left over from the Cold War era.
The unexplained leak of radiation, a small amount of which escaped to the surface, ranks as the worst accident at the facility, and one of the few blemishes on the plant's safety record since it opened in 1999.
The plant is located in the Chihuahuan Desert about 25 miles (40 km) east of Carlsbad, New Mexico.
Twenty-one workers at the site, operated for the U.S. Energy Department by a private contractor, the Nuclear Waste Partnership LLC, later tested positive for contamination, though managers of the plant said the level of exposure was too low to pose any health risks.
Officials believe the leak may have originated from a structural collapse at one of the storage compartments, a vault called Panel 7. (Reporting by Laura Zuckerman from Salmon, Idaho; Editing by Steve Gorman and Michael Perry)