Document: NRC Regulatory Guide
Document ID: 4b34bbdf-f837-4227-9a0d-3f0ad3778b30
Document Type: regulatory_guide
Title: Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chlorine Release (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A134.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.95
CFR Part: 
CFR Title: 

Content:
uality that ensures high reliability and availability. One method to meet these goals is to provide a system that meets the requirements of IEEE-279, "Criteria for Protection Systems for Nuclear Power Generating Stations." In all cases, the isolation system, recirculating filter system, and air condition- ing system should meet IEEE-279 since they are re- quired to maintain a habitable environment in the control room during design basis radiological events. Specific acceptance criteria for the chlorine detec- tion system and allied actuating electronics are as fol- lows: (1) Chlorine Concentration Level. Detectors should be able to detect and signal a chlorine con- centration of 5 ppm. (2) System Response Time. The system response time, which incorporates the detector response time, the valve closure time, and associated instrument delays, should be less than or equal to the required isolation time. (3) Single Failure Criteria. The chlorine detection system should be redundant and physically separate to accomplish decoupling of the effects of unsafe en- vironmental factors, electric transients, physical acci- dents, and component failure. Local detectors should consist of two physically separate channels for each fresh air inlet. Each chan- nel should consist of a separate power supply, detec- tor, actuating electronics, and interconnecting ca- bling. Remote detectors should also consist of two separate channels having detectors located at the chlorine unloading facility. (4) Seismic Qualification. The chlorine detection system should be designated as Seismic Category I and be qualified as such. (5) Environmental Qualification. The detection system should be qualified for all expected environ- ments and for severe environments that could clearly lead to or be a result of a chlorine release. The instal- lation of the detectors should ensure that they are protected from adverse temperature effects. (6) Maintenance, Testing, and Calibration. The manufacturer's