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:
y 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 calibration, as well as adjustment to such recommendations that are made by licensees, are acceptable provided they follow sound engineering practices and are compatible with the proposed application. Human detection, i.e., smell, may be appropriate when no detection instruments are available in the control room for given chemical types. 1.78-11 Quick-response detectors should be located in the fresh air inlets (both normal and emergency air intakes). It may also be appropriate, depending on the design, to have separate channels of detectors for fresh air inlets and to have detectors in the control room envelope ventilation system recirculation lines. The system response time, which incorporates the detection response time, the valve closure time, and associated instrument delays, should be less than or equal to the isolation time. Remote detectors may be located at storage and unloading locations. These detectors may be placed and the detector trip points adjusted to ensure detection of either a leak or a container rupture. A detector trip signal should isolate the control room before the toxic chemical arrives at the isolation dampers. The detector trip signal should also set off an alarm and provide a readout in the control room. An alternative to the installation of remote detectors would be to provide an isolation system that uses local detectors with a very short isolation time. 4.2 Isolation System The capability to close the air ducts of the control room with dampers and thus isolate the control room should be considered in the evaluation of control room habitability. For onsite storage, the capability to manually isolate the control room should be provided. Upon detection of a toxic chemical, a detector should initiate complete closure of isolation dampers to