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:
EE Std 7-4.3.2-2003 provides requirements for equipment qualification of digital computers used in safety systems. REGULATORY POSITION Conformance with the requirements of IEEE Std 603-1991 provides a method that the NRC staff considers acceptable for satisfying the agency’s regulatory requirements with respect to bypassed and inoperable status indication, subject to the following: 1. Administrative procedures should be supplemented by an indication system that automatically indicates for each affected safety system or subsystem the bypass or deliberately induced inoperability of a safety function and the systems actuated or controlled by the safety function. Provisions should also be made to allow operations staff to confirm that a bypassed safety function has been properly returned to service. 2. The indicating system of Position 1 above should also be activated automatically by the bypassing or deliberately induced inoperability of any auxiliary or supporting system that effectively bypasses or renders inoperable a safety function and the systems actuated or controlled by the safety function. 3. Annunciating functions for system failure and automatic actions based on self-test or self- diagnostic capabilities of digital computer-based I&C safety systems should be consistent with Positions 1 and 2 above. 4. The bypass and inoperable status indication system should include a capability for assuring its operable status during normal plant operation to the extent that the indicating and annunciating functions can be verified. 5. Bypass and inoperable status indicators should be arranged such that the operator can determine whether continued reactor operation is permissible. The control room of all affected units should receive indication of the bypass of shared system safety functions. 6. Bypass and inoperable status indicators should be designed and installed in a manner that precludes the possibility of adverse effects on plant safety systems. The indicator