Document: NRC Regulatory Guide
Document ID: 8291b9eb-e4a7-4806-8b5b-1deca2ff1fe2
Document Type: regulatory_guide
Title: Control Room Habitability at Light-Water Nuclear Power Reactors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0207/ML020790125.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.196
CFR Part: 
CFR Title: 

Content:
itive pressure, with respect to potentially contaminated adjacent areas, is periodically tested to verify proper functioning of the CREFS. During the emergency mode of operation, the CREFS is designed to pressurize the control room  [0.125] inches water gauge positive pressure with respect to adjacent areas in order to prevent SURVEILLANCE REQUIREMENTS (continued) CREFS 3.7.10 A-12 unfiltered inleakage. The CREFS is designed to maintain this positive pressure with one train at a makeup flow rate of [3000] cfm. The Frequency of [18] months on a STAGGERED TEST BASIS is consistent with the guidance provided in NUREG-0800 (Ref. 4). It addresses both radiological and hazardous chemical challenges. This test is performed using the protocol of [ASTM E741-95]. The test is performed in the configuration which will result in the operating condition which results in the largest inleakage. Based on actual industry-integrated and plant-specific experience from the initial and first 24 months follow-on testing, the NRC staff will work with industry to develop an appropriate performance based frequency. As envelope integrity is demonstrated through satisfactory test results, the testing frequency can be extended. Similarly, if test results indicate that envelope integrity criteria is not met, testing would become more frequent. REFERENCES 1. FSAR, Section [6.4]. 2. FSAR, Chapter [15]. 3. Regulatory Guide 1.52, Rev. [2]. 4. NUREG-0800, Section 6.4, Rev. 2, July 1981. B-1 APPENDIX B ACRONYMS ASHRAE American Society for Heating, Refrigeration and Air-Conditioning Engineers ASME American Society of Mechanical Engineers B&W Babcock and Wilcox BWR Boiling Water Reactor CE Combustion Engineering ASTM American Society for Testing and Materials ESF Engineered Safety Feature FSAR Final Safety Analysis Report GE General Electric GDC General Design Criteria LOCA Loss-of-Coolant Accident LOOP Loss of Offsite Power NEI Nuclear Energy Institute NRC Nuclear Regulatory Commission OL Operating