LAS VEGAS (AP) — A suspicious item discovered Tuesday at a nuclear test site about 65 miles north of Las Vegas turned out to be harmless, authorities said.The item was discovered shortly before 4 p.m. near the center of the Energy Department’s National Nuclear Security Site. The object was outside a perimeter fence at a device assembly facility, said Stacey Alderson, a spokesman at the facility’s joint information center. The item, which he couldn’t describe, turned out to be nonthreatening.Spokeswoman Kelly Snyder says the site’s own fire and rescue team responded first, and then federal and state law enforcement officers were called in.Nye County Sheriff Tony Ganios told The Associated Press he was notified after 7 p.m. that the incident was not a public safety emergency.“We know enough to know that we can stand down, Ganios said.The 1,450-square-mile National Nuclear Security Site is a vast proving ground where experiments and safety training is conducted related to the nation’s nuclear stockpile. It was formerly known as the Nevada Test Site and hosted more than 1,000 nuclear detonations until 1992, when the U.S. agreed to a moratorium on full-scale nuclear testing.