CARLSBAD, N.M. (AP) — Crews investigating a radiation leak from the federal government's underground nuclear waste dump in southeastern New Mexico plan to make a second trip into the half-mile-deep repository today.

Officials say workers who went into the Waste Isolation Pilot Plant on Wednesday to install air monitors and communications equipment found no airborne radiation. But they say workers are prepared to encounter contamination as they make their way further into the mine.

If all goes well, officials say that should set the stage for a third entry, when crews will try to figure out what caused the release.

The dump near Carlsbad has been closed since mid-February, when the mysterious leak sent low levels of radiation into the air and contaminated 21 workers.

The leak happened nine days after a truck hauling salt in the mine and repository caught fire on February 5.

The dump is the federal government's only permanent repository for waste from decades of nuclear-bomb building.

(Story by: The Associated Press with minor editing by WIBX)