A driver ran a checkpoint at a nuclear weapons plant in Tennessee early Monday and crashed into a barrier, then fled on foot, authorities said. Guards at the Y-12 nuclear weapons plant, a primary storehouse for bomb-grade uranium, said the man "appeared to be impaired in some way" when they stopped him at a security checkpoint near a rear entrance, spokesman Bill Wilburn said. They asked him for identification, but the man hit the gas and drove through the checkpoint, then crashed into security barriers a short distance away, Wilburn said. Wilburn added no weapons were in the car. "They checked the car very thoroughly before they moved it. They found nothing," he said.