Document: NUREG-0800
Document ID: e1169529-d2cb-4947-9efe-b23d927f4aa9
Document Type: srp
Title: NUREG40800
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350520.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8
CFR Part: 
CFR Title: 

Content:
GROUND The guidance of Regulatory Guide 1.47 needs further detailing as to methods of providing an acceptable design for the bypass and inoperable status indicators for engineered safety feature (ESF) systems. The purpose of this Branch Technical Position is to provide sup lemental guidance for implementation of the guidance of Regulatory Guide 1.49. B. BRANCH TECHNICAL POSITION The design criteria for bypass and inoperable status indication systems for ESF should reflect the importance of providing accurate information for the operator and reducing the possibility for the indicating equipment to affect adversely the monitored safety systems. In developing the design criteria, the following should be considered: 1. The bypass indicators should be arranged to enable the operator to deter- mine the status of each safety system and determine whether continued reactor operation is permissible. 2. When a protective function of a shared system can be bypassed, indication of that bypass condition should be provided in the control room of each affected unit. 3. Means by which the operator can cancel erroneous bypass indications, if provided, should be Justified by demonstrating that the postulated cases of erroneous indications cannot be eliminated by another practical design. 4. Unless the indication system is designed in conformance with criteria established for safety systems, it should not be used to perform func- tions that are essential to safety. Administrative procedures should not require immediate operator action based solely on the bypass indications. 5. The indication system should be designed and installed in a manner which precludes the possibility of adverse effects on plant safety systems. Failure or bypass of a protective function should not be a credible consequence of failures occurring in the indication equipment, and the bypass indication should not reduce the required independence between redundant safety systems. 6. The indication system should