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:
tems outside the CRE may impact CRE integrity. Testing may also be needed to understand the influence of these systems on CRH. Licensees should establish the performance characteristics of ventilation systems and fix any deficiencies before testing for CRE integrity. This is because CRE inleakage may be altered by a change in ventilation system performance. Licensees should know how these ventilation systems perform under varying conditions. The response to a particular challenge, e.g., radiological, may vary depending on the accident. Licensees may need to conduct a variety of performance assessments for the same type of challenge. 2.3.2 Identification of the Limiting Condition The limiting condition for CRH is the configuration that results in the maximum consequences. Sometimes the limiting condition will arise from the configuration that produces the greatest inleakage and sometimes it will not. The latter situation can occur because the configuration that results in the largest inleakage may have mitigative features that result in smaller consequences to the control room operators. As an example, CRE inleakage may be greatest for a radiological accident that does not have a LOOP. However, the absence of a LOOP could provide mitigative features that reduce the overall consequences to the control room operators. In the determination of the limiting condition for potential radiological accidents, it should not be presumed that the LOCA is the limiting accident because it has the largest initial source of activity. Other accidents, e.g., fuel handling accidents, may produce larger control room operator doses because the manner in which the CRHSs respond may provide less protection to the operators. Therefore, licensees should perform an analysis of the consequences of each potential radiological accident to ensure that they have identified the limiting accident. Unless a facility relies on a common control room isolation process for all types of radiological