Dr. Hans Bethe of Cornell University, who was one of the leading U.S. A-bomb makers at Los Alamos, N.M., sits with other top U.S. physicists at Columbia University in New York, Feb. 4, 1950. (AP Photo/Harry Harris)

Dr. J. Robert Oppenheimer, the new director of the Institute for Advanced Study at Princeton, N.J., is shown in front of a blackboard full of mathematical formulas, Dec. 17, 1947. (AP Photo)

Dr. Norris E. Bradbury is shown in his Los Alamos, N.M. office in this 1955 file photo. (AP Photo)

German physicist Dr. Klaus Fuchs is seen in this undated photo. He was a member of the nuclear research team at Los Alamos Laboratory from 1942 - 1949. (AP Photo/Keystone)

This aerial photo provided by Los Alamos National Laboratory, taken in May 2009, shows Technical Area 21, a Cold War-era site now being cleaned up by the lab. (AP Photo/Los Alamos National Laboratory)

This undated photo provided by the Atomic Heritage Foundation shows the "high bay" building at Los Alamos National Laboratory in Los Alamos, N.M. (AP photo/Los Alamos National Laboratory via Atomic Heritage Museum)

This Nov. 1998 photo from Los Alamos National Laboratory shows a now-abandoned administration building in a Cold War-era site now being cleaned up by the lab. (AP Photo/Los Alamos National Laboratory)