U.S. Senators. Susan Collins of Maine and Jeanne Shaheen of New Hampshire are looking at the damage caused by a fire on a nuclear-powered submarine at the Portsmouth Naval Shipyard.Shipyard Cmdr. Capt. Bryant Fuller is meeting with the senators on Friday morning.The USS Miami’s nuclear propulsion was spared from the intense blaze but officials said some forward compartments including living quarters, command and control, and torpedo room suffered extensive damage. The cause is being investigated.The Navy was unable to complete a formal assessment, but the damage was severe enough to raise questions about whether costly repairs would make sense for the 22-year-old submarine.