After a 1975 fire at the Browns Ferry nuclear plant in Alabama threatened the unit¿s ability to shut down safely, the Nuclear Regulatory Comm. (NRC) issued prescriptive fire safety rules for commercial nuclear units. However, nuclear units with different designs and different ages have had difficulty meeting these rules and have sought exemptions to them. In 2004, NRC began to encourage the nation¿s 104 nuclear units to transition to a less prescriptive, risk-informed approach that will analyze the fire risks of individual nuclear units. This report examines: (1) the number and causes of fire incidents at nuclear units since 1995; (2) compliance with NRC fire safety regulations; and (3) the transition to the new approach. Includes recommendations. Illustrations.