Leo Seren (1918-2002) was an American physicist.
Seren (in photo, first row standing, far right) was born on May 9, 1918. He grew up in the Chicago suburb of Melrose Park. He joined the Manhattan Project at the Chicago Met Lab in 1942, soon after receiving a Ph.D. from the University of Chicago. He was present at Stagg Field on December 2, 1942 when Chicago Pile-1 went critical.
Seren continued working in the nuclear energy field after World War II, but grew increasingly concerned about nuclear weapons and radioactive waste. He eventually became a vocal opponent of both nuclear weapons and nuclear energy. Speaking to anti-nuclear protesters in 1982, Seren declared that if he were charged with crimes against humanity for his work on the Manhattan Project, "I'd plead guilty. And I'd say for mitigating circumstances that at least I decided that I'd never work on nuclear weapons again."
Seren died on January 3, 2002 in Evanston, Illinois at the age of 83.
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