The US Navy is convening a special panel to investigate the fire that damaged the nuclear submarine USS Miami while it was in a dry dock for an overhaul at Portsmouth Naval Shipyard in the river between Maine and New Hampshire. All other investigations will be folded into the committee’s probe, which was ordered by US Fleet Forces Command in Norfolk, Va. Early estimates put the fire damage at $400 million. It started May 23 after burning material was sucked into a vacuum cleaner. Lieutenant Commander Mike Kafka, a Navy spokesman, said the goal is to gain a detailed understanding of what happened to ensure that nothing similar happens in the future. He said the Navy has not yet concluded whether the submarine will be repaired or retired.