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:
ecific acceptance criteria for radiological events are provided in 10 CFR 50.67, "Accident Source Term," and guidance being developed in Regulatory Position 4.5 of Draft Regulatory Guide DG-1113 (Ref. 5). The specific acceptance criterion for chemical events is given in Regulatory Position 3.1 of Regulatory Guide 1.78 (Ref. 1). Smoke may be a CRH concern if there is significant inleakage from outside the envelope. In this situation, smoke from external sources could challenge the ability of the operator to shut down the reactor from within the control room or remotely. No regulatory limit exists on the amount of smoke allowed in the control room. Therefore, the plant's ability to manage smoke infiltration is assessed qualitatively. Section 6.3 and Appendix E of NEI 99-03 (Ref. 2) provides guidance for this assessment. The staff believes the guidance in NE 99-03 concerning smoke is prudent and should be adopted until further guidance becomes available. 2.7 Maintaining and Monitoring CRHSs CRH is maintained and monitored during the operating life of the plant by a CRHS program. A CRHS program includes periodic evaluations, maintenance, configuration control, and training. This Regulatory Position covers CRHS programs and it provides methods to mitigate degraded and nonconforming conditions when the plant does not meet the specific acceptance criteria given in Regulatory Position 2.6 or is outside its licensing basis. The following methods of maintaining and monitoring CRHSs should be used. 2.7.1 Periodic Evaluations and Maintenance Periodic evaluations demonstrate that the CRHSs meet their functional criteria. These include evaluations of system material condition, testing, and toxic gas evaluations. CRHS programs should evaluate the system and material conditions as described in Section 9.3.1, "System Material Condition," of NEI 99-03 (Ref. 2). Licensees should perform testing to ensure they maintain CRH. Routine performance measurements are described in Regulatory