The term PART OF AEC refers to two solutions in a crossword puzzle, ATOMIC (6 letters) and ENERGY (6 letters). ATOMIC refers to the smallest unit of matter, while ENERGY is the capacity for doing work. Both terms are part of the ATOMIC ENERGY Commission (AEC), which was established in 1946 by the United States government to promote the development of nuclear ENERGY. The AEC was responsible for the development of nuclear power plants, research into nuclear weapons, and the regulation of nuclear materials.