Document: NRC Regulatory Guide
Document ID: ceaeb6d7-d85a-46d3-a1b6-70059a498965
Document Type: regulatory_guide
Title: 12/2001 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0131/ML013100014.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.78
CFR Part: 
CFR Title: 

Content:
ntrol room envelope inleakage determination for control room habitability testing is being developed and will be published as a regulatory guide. If credit is taken in the evaluation of the removal of hazardous chemicals by filtration, adsorption, or other means, a technical basis for the dynamic removal capability of the removal system considered should be provided. 4. PROTECTION MEASURES For adequate protection of the control room operators against the types of accidental releases discussed above, features should be included in the plant design to (1) provide capability to detect such releases, (2) isolate the control room if there is a release, (3) make the control room sufficiently leak tight, and (4) provide equipment and procedures for ensuring the use of breathing apparatus by the control room operators. Provisions that are adequate for the large instantaneous release will also provide protection against the low-leakage-rate release. The guidance for Item 3 is provided in Section 3.4. The guidance for other design features is provided below. Licensees may select and implement specific protection measures as long as these measures ensure adequate protection. Implementation of protection measures for a particular chemical species may be excluded if the detailed evaluation of control room habitability shows that the highest concentration predicted in the control room is below the toxicity limit. 4.1 Detection System The detection system should be able to detect and signal a concentration level that is significantly lower than the IDLH level, for example, a concentration level of 5 ppm for chlorine. The detection system should be qualified for all expected environments, including severe environments. The system should also be designated as Seismic Category I and be qualified as such. The installation of the detectors should ensure that they are protected from adverse temperature effects. The manufacturer's recommendations for maintenance, testing, and