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:
deliberately rendered inoperative, then this fact should be automatically indicated in the control room. With regards to surveillance testing, if the protective action of some part of a protection or safety system is bypassed or deliberately rendered inoperative for testing, that fact should be continuously indicated in the control room. Operations staff should also be able to confirm that a bypassed safety system has been properly returned to service. In a given plant design, it may be best to group the bypass indicators according to the safety systems’ dependence on a common electric power supply; for example, the bypass indicators for all engineered safety feature systems that are assigned to one standby power source could be located near the bypass indicator for that source. Other groupings could be acceptable. The arrangement of bypass indicators should enable the operator to determine the status of each safety system and whether continued reactor operation is permissible. When a protective function of a shared system can be bypassed, the control room of each affected unit should receive an indication of that bypass condition. In any design, it may be necessary to include an audible, as well as visual, alarm to attract the operator’s attention when the status of the safety system changes. Clause 5.8.3.3 of IEEE Std 603-1991 requires that, for indication of bypasses, “the capability shall exist in the control room to manually activate this display indication.” The effectiveness of an automatic indicating system is enhanced by including a manual capability to activate the indicators. Manual capability is useful in displaying those inoperable or bypassed conditions, whether deliberately induced or not, that are not automatically indicated. Bypass indication should aid the operator in recognizing the effects on plant safety of seemingly unrelated or insignificant events. Therefore, the indication of bypass conditions should be at the safety group level,