KITTERY — The nuclear-powered attack submarine USS Annapolis has arrived at the Portsmouth Naval Shipyard for maintenance and upgrades.

The shipyard says the sub and a crew of 16 officers and 122 enlisted personal arrived Saturday.

Officials say it’s the fourth ship to be named for Annapolis, Maryland, site of the U.S. Naval Academy and the 10th “improved” Los Angeles-class nuclear-powered submarine.

The Annapolis was commissioned in 1992 and its homeport is Groton, Connecticut.