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:
ould 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 using local detectors but having an isolation time of effectively zero. This can be accomplished by ensuring that the time required for chlorine to travel from the chlorine detector to the isolation damper, within the inlet ducting, is equal to or greater than the time required to detect the chlorine and close the isolation damper. f. Type VI control rooms should include the protective features in paragraph e except that the control room isolated air exchange rate should be reduced to 0.015 air change per hour or less. For isolated exchange rates between 0.0 15 hr- ' and 0.06 hr-' , linear interpolation of the weights given for control room Types V and VI in Table 1 can be made. Verification testing is required within this range of exchange rates (see Regulatory Position 5). 4. The following should be applied to all control room types (I through VI): a. Immediately after control room isolation, the emergency recirculating charcoal filter or equivalent equipment designed to remove or otherwise limit the accumulation of chlorine within the control room should be started up and operated. b. Steps should be taken to ensure that the isolated exchange rate is not inadvertently increased by design or operating error. For instance, the following should be considered: (1) An administrative procedure should require that all doors leading to the control room be kept closed when not in use. (2) Ventilation equipment for the control room and for the adjacent zones should be reviewed to en- sure that enhanced air exchange between the isolated control room and the outside will not occur (e.g., if there is a chlorine release, exhaust fans should be stopped and/or isolated from the control room ven- tilation zone by low-leakage dampers or valves). (3) A control room exit leading directly to the outside of the building