Document: NRC Regulatory Guide
Document ID: 30181e34-3bc1-46b8-8de9-ef073c34bc13
Document Type: regulatory_guide
Title: Bypassed and Inoperable Status Indication for Nuclear Power Plant Safety Systems + HISTORY - HISTORY 10/2008 – DG-1205 , Proposed Revision 1 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0821/ML082140114.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.47
CFR Part: 
CFR Title: 

Content:
ion. These signals include those that actuate a reactor trip and that, in the event of a serious reactor accident, actuate engineered safety features, such as containment isolation, core spray, safety injection, pressure reduction, and air cleaning. This standard defines “protective function” as “the sensing of one or more variables associated with a particular generating station condition, signal processing, and the initiation and completion of the protective action at values of the variables established in the design bases.” Clause 4.13 of IEEE Std 279-1971 requires in part that, if the protective action of some part of the protection system has been bypassed or deliberately rendered inoperable for any purpose, this fact shall be DG-1205, Page 3 continuously indicated in the control room. Clause 5.8.3 of IEEE Std 603-1991 requires that, if the protective actions of some part of a safety system have been bypassed or deliberately rendered inoperative for any purpose other than an operating bypass, continued indication of this fact for each affected safety group shall be provided in the control room. Clause 5.8.3 also provides guidance that (1) the bypass display instrumentation need not be part of the safety systems, (2) this indication shall be automatically actuated if the bypass or inoperative condition is (a) expected to occur more frequently than once a year and (b) expected to occur when the affected system is required to be operable, and (3) the capability shall exist in the control room to manually activate this display indication. The NRC issues regulatory guides to describe to the public methods that the staff considers acceptable for use in implementing specific parts of the agency’s regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory guides are not substitutes for regulations and compliance with them is not required. This regulatory