The U.S. Nuclear Regulatory Commission (NRC), created by Congress, began operating in 1975. Its mission is to regulate commercial and institutional uses of nuclear materials, including nuclear power plants. The nuclear industry is strictly regulated because radioactive materials are potentially hazardous. The NRC protects the public by setting limits on radiation exposure from the radioactive materials it licenses and requires those with licenses who use such materials to take steps to keep exposures well below the limits. This book examines the history of nuclear regulation from 1946-2009 and the NRC as an independent regulator of nuclear safety.