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:
operators, as demonstrated by the control room accident dose analyses for the most limiting design basis loss of coolant accident, fission product release presented in the FSAR, Chapter [15] (Ref. 2). The analysis of toxic gas releases demonstrates that the toxicity limits are not exceeded in the control room following a toxic chemical release, as presented in Reference 1. The worst case single active failure of a component of the CREFS, assuming a loss of offsite power, does not impair the ability of the system to perform its design function. The CREFS satisfies Criterion 3 of 10 CFR 50.36(c)(2)(ii). LCO Two independent and redundant CREFS trains are required to be OPERABLE to ensure that at least one is available assuming a single failure disables the other train. Total system failure could result in exceeding a dose of 5 rem to the control room operator in the event of a large radioactive release. LCO (continued) CREFS 3.7.10 A-8 The CREFS is considered OPERABLE when the individual components necessary to limit operator exposure are OPERABLE in both trains. A CREFS train is OPERABLE when the associated: a. Fan is OPERABLE, b. HEPA filters and charcoal adsorbers are not excessively restricting flow, and are capable of performing their filtration functions, and c. Heater, demister, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained. In addition, the control room boundary must be maintained, including the integrity of the walls, floors, ceilings, ductwork, and access doors, and the unfiltered inleakage must be maintained within the assumptions of the design analysis. The LCO is modified by a Note allowing the control room boundary to be opened intermittently under administrative controls. For entry and exit through doors, the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls consist of stationing a dedicated individual at the opening who is in continuous