Dogs trained to search for explosives and other substances were pushed “beyond their physical capacity” while working last year at a federal facility that handles, processes and stores highly enriched uranium, according to a report released this week.

The Energy Department’s inspector general found that canine security teams at the Y-12 National Security Complex in Oak Ridge, Tenn., were overworked, citing an instance in which a handler and a dog conducted 102 vehicle searches over a two-hour period.

Workers for the private contractor providing the dogs told investigators that requests for breaks were ignored by supervisors.

The highly sensitive site is patrolled by human-dog teams that search for explosives, drugs and intruders. The facility was broken into last year by antiwar activists, prompting questions into the security at Energy Department installations.

Investigators were unable to corroborate reports that some dog competence testing had been rigged, but the report did find that “half of the canine teams we observed failed explosive detection tests, many canines failed to respond to at least one of the handler's commands, and that canines did not receive all required training.”