Officials say workers have sealed off the first of two storage bunkers affected by a radiation leak at the federal government's underground nuclear waste repository in southern New Mexico.

The U.S. Department of Energy says about 85 percent of the containers packed with waste similar to the one that caused the leak have been isolated with the closure of the area known as Panel 6.

Workers used salt mined from another area of the repository, chain link and brattice cloth to build barriers on each end of the storage bunker. Air monitors have been installed.

Work to seal off a second bunker, where the radiation breach occurred, is ongoing. Officials say that should be complete in June.

The Waste Isolation Pilot Plant has been closed since the February 2014 leak.