NANTUCKET — At the height of Cold War tensions, just after President John F. Kennedy was sworn into office, Nantucket’s small Navy base suddenly took on a much more important mission: sheltering the president and his family from radioactive fallout in the event of nuclear war. Kennedy was famous for spending his summer weekends at the family’s Hyannisport compound on Cape Cod, and military leaders needed a place for him to safely run the [...]