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:
teristics Isolation Air Exchange Local Remote Time Rate - Normal Detectors Detectors (sec) (hrI Air Exchange Rate - Isolated (hr 4 ) 0.06 Maximum Weight (1000 Ib) of Chlorine as a Function of Distance from Control Rooma 100 m 200 m 300 m 500 m 2000 m (330 ft) (660 ft) (980 ft) (1640 ft) (6560 ft ) 10 1200 II •D III IV V VI Yes Yes Yes Yes Yes Yes No No No No Yesb Yesb 10 4 10 4 1 0.3 0.3 0.06 0.06 0.015 0.06 0.015 1 2 6 8 70 1 0.5 5 12 40 3400 6 14 36 2700 20 60 230 32000 20 50 120 5000 2 4 10c 10c 1 180 380 1300 60000 aTo determine allowable chlorine inventories for distances between those given in this table, log-log interpolation is acceptable. bsee Regulatory Position 3.e for an alternative to remote detectors. cThe isolation time of 10 seconds refers to detection by local detectors. If detection is by remote detectors, isolation time is effectively zero since detection and isolation will be accomplished before the chlorine reaches the control room isolation dampers. containers are interconnected in such a manner that failure of a single container could cause a chlorine release from several containers. a. Type I control rooms should include the follow- ing protective features: (1) Quick-response chlorine detectors located in the fresh air inlets. Within 10 seconds3 after arrival of the chlorine, detection should initiate complete closure of isolation dampers to the control room. (2) A normal fresh air makeup rate of less than one air change per hour. The fresh air inlet should be at least 15 meters above grade. (3) Low-leakage construction with an equivalent air exchange rate of less than 0.06 hr-I when all penetrations are exposed to a 1/8-inch water gage pressure differential. Construction details should be provided to show that this limit is met. (4) Low-leakage dampers or valves installed on the upstream side of recirculation fans or other loca- tions where negative systems pressure exists and where inleakage from chlorine-contaminated outside air is