Photos of the Day: The Most Secretive Vessel of the U.S.
In this Nov. 6, 2013 file photo, Michael Riegel, a former commander of the U.S. Navy submarine base in Groton, Conn., looks at a model of the research submarine NR-1, in his Preston, Conn. home. (AP Photo/Rodrique Ngowi)
In this Feb. 2007 handout file photo provided by the US Navy, the research submarine NR-1 is towed away from U.S. Naval submarine base, in New London, Conn. (AP Photo/US Navy, John Fields)
The nuclear-powered NR-1, launched in Groton in 1969, was one of the most secretive vessels in the U.S. undersea force. It was taken out of service in 2008 and disassembled, its reactor disposed of. Now the Navy has collected pieces of it for an exhibit at a submarine museum in Groton, where it was based for the duration of its service life. (AP Photo/US Navy, John Fields)