WASHINGTON — The contractors in charge of guarding the national stockpile of bomb-grade uranium in Tennessee knew well before an 82-year-old nun and two other pacifists broke through three barriers this summer that a lot of the security equipment was broken, and government managers knew it too, according to an internal audit of Energy Department operations at the weapons facility. The inspector general’s investigation found “troubling displays of ineptitude.”

The intruders used ordinary bolt cutters to penetrate as far as the uranium storage building before dawn on July 28, and then went undiscovered until they approached an officer in his vehicle and surrendered, according to the audit. The officer failed to draw his gun or even secure his gun from seizure, “and permitted the trespassers to roam about and retrieve various items from backpacks they had apparently brought into the area,” the report said.

The three antiwar protesters — Sister Megan Gillespie Rice, of Las Vegas; Michael R. Walli, 63, of Washington; and Gregory I. Boertje-Obed, 57, of Duluth, Minn. — have been charged with felonies in connection with damage to the building. They said they had brought bread and candles for a Christian ritual.

The guard told The Knoxville News that he was being used as a scapegoat, and that it was obvious that the trio posed no threat.