"The U.S. Nuclear Regulatory Commission (NRC) developed this regulatory guide to describe a method that the NRC staff considers acceptable for use in complying with the agency's regulations with respect to satisfying criteria for accident monitoring instrumentation in nuclear power plants."
REGULATORY GUIDE 1.97
U.S. Nuclear Regulatory Commission. Posted here from Lessons Learned Information Sharing database (LLIS). Documents are for personal use only and copyright laws apply.
Lessons Learned Information Sharing (LLIS)