High Quality Content by WIKIPEDIA articles! The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by Congress to foster and control the peace time development of atomic science and technology. President Harry S. Truman signed the McMahon/Atomic Energy Act on August 1, 1946, transferring the control of atomic energy from military to civilian hands, effective from January 1, 1947. The agency was abolished by the Energy Reorganization Act of 1974, which assigned its functions to two new agencies: the Energy Research and Development Administration and the Nuclear Regulatory Commission.