Revision Standard – Superseded.The application of the single-failure criterion to the electrical power, instrumentaion, and control portions of nuclear power generating station safety systems is covered. Conformance with the requirements of IEEE Std 603-1991 and the single-failure criterion as stated in that document is established. Interpretation and guidance in the application of the single-failure criterion, a discussion of the failures, and an acceptable method of single-failure analysis are presented.