LONDON, Jan. 24 — Alan Nunn May, a British atomic scientist who spied for the Soviet Union, died on Jan. 12 in Cambridge. He was 91. The Times and the Daily Telegraph reported his death but did not give a cause. One of the first Soviet spies uncovered during the cold war, Dr. Nunn May worked on the Manhattan Project and was betrayed by a Soviet defector in Canada. His unmasking in 1946 led the United States to restrict the sharing of atomic secrets with Britain. His discovery ignited a search for other spies inside the Manhattan Project and led...