This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. Discussion concentrates on the radiological and thermal aspects of the environmental effects of nuclear power plants; on the procedures followed by the Atomic Energy Commission (AEC) to minimize the impact of nuclear plants on man and his environment; and on the research conducted by the AEC and others to further expand our knowledge. Numerous photographs and diagrams are utilized and a list of suggested references is included. (Author/PR)