Document: NRC Regulatory Guide
Document ID: dff52070-b179-4367-bf66-5d1107c54315
Document Type: regulatory_guide
Title: Design, Inspection, and Testing Criteria for Air Filtration and Adsorption Units of Normal Atmosphere Cleanup Systems in Light-Water-Cooled Nuclear Power Plants + HISTORY – HISTORY 06/2012 – DG-1280 , Proposed Revision 3 10/2000 – DG-1103 , Proposed Revision 2 (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1127/ML11273A057.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.140
CFR Part: 
CFR Title: 

Content:
NS-R-1, “Safety of Nuclear Power Plants: Design” (Ref. 5), addresses controlling the release of radioactive gases into the environment. The NRC has an interest in facilitating the harmonization of standards used domestically and internationally. This regulatory guide is consistent with the recommendations and guidance in the IAEA Safety Guides NS-G-1.10, NG-G-2.7 and NS-R-1. B. DISCUSSION The design of the normal atmosphere cleanup systems of light-water-cooled nuclear power plants includes particulate filtration and radioiodine adsorption units to reduce the quantities of radioactive materials in gaseous effluents released from primary containment or auxiliary building atmospheres during normal operations, including anticipated operational occurrences. These systems operate to meet the “as low as reasonably achievable” requirements of 10 CFR 50.34a and 10 CFR 50.36a. Auxiliary DG-1280, Page 3 buildings can include those referred to as the secondary containment building, turbine building, radwaste building, and fuel handling building. Normal atmospheric cleanup systems are generally designed to operate continuously under normal environmental conditions, such as inlet radioiodine activity levels up to 37 millibecquerels per cubic centimeter (16.4 picocuries per cubic inch), relative humidity up to 100 percent, temperatures up to 52 degrees Celsius (125 degrees Fahrenheit), and normal atmospheric pressure. System design, inspection, and testing anticipates the buildup of radioactive particulates and radioiodine and minimizes consequential degradation of system performance. The ambient environment both within and surrounding the facility may affect the performance of the normal atmosphere cleanup systems. Industrial contaminants and pollutants, as well as temperature and relative humidity, contribute to the aging and weathering of filters and adsorbers and reduce their reliability. Components of the normal atmosphere cleanup systems need to be designed for