Document: NUREG-0800
Document ID: 8c2fce42-281a-4a50-9de7-513df024f27c
Document Type: srp
Title: CONTROL ROOM HABITABILITY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340712.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.4
CFR Part: 
CFR Title: 

Content:
fficult to repair manually without opening the ductwork) must be judged to have a very low probability of failure. The component design details will be reviewed and characteristics such as simplicity, ruggedness, and suspectibility to postulated failure mechanisms will be considered in arriving at an engineered judgment of the acceptability of the internal component design with respect to reliability. For example, a butterfly valve welded or keyed onto a pivot shaft would be con- sidered a high reliability internal component. Conversely, multiple- blade dampers, actuated by multi-element linkages or pneumatically- operated components internal to the ducts, would be viewed as being subject to failure. b. External valve components (i.e., components including motors and power supplies that are to be assumed repairable or removable) must be designed to ensure that the failed valve component can be bypassed easily and safely and that the valve can be manipulated into an acceptable position. The electronic components must be isolated from other equipment to assure that the repair operations do not result in further equipment failure. 6.4-17 Rev. 2 - July 1981 2. The location and positioning of the valve or damper must permit easy access from the control room for convenient repair, especially under applicable DBA conditions. 3. Appropriate control room instrumentation should be provided for a clear indication and annunciation of valve or damper malfunction. 4. Periodic manipulation of the valve or damper by control room operators should be required for training purposes and to verify proper manual operability of the valve or damper. 5. The need for manual manipulations of the failed valve or damper should not be recurrent during the course of the accident. Manipulation should not occur more than once during the accident. Adjustment or realignment of other parts of the system should be possible from the control room with the failed valve in a fixed position. 6. The time for