Document: NRC Regulatory Guide
Document ID: c0dbb594-6262-4b83-96b1-366758ad9676
Document Type: regulatory_guide
Title: Interim Licensing policy on as low as Practicable for Gaseous Radiodine Releases from Light-Water-Cooled Nuclear Power Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A137.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.42
CFR Part: 
CFR Title: 

Content:
coal Adsorber 10 9. Decontamination Factors (DF) for Demineralizers Note: For two demineralizers in series, the DF for the second demineralizer is given in parentheses. DF (Anion) 0 Mixed Bed (H+ OH-) Reactor Coolant Condensate Clean Waste Dirty Waste (Floor Drains) Cation Bed (H ) Dirty Waste Powdex (any system) Reverse Osmosis 10 10 2(10) 10 2(10) 1(1) 10(10) 1.5 per stage for all radionuclides 10. Decontamination Factors (DF) for Evaporators DF Miscellaneous Radwaste Evaporators Separate Evaporator for Detergent Waste 103 102 0 1.42-A6 11. Flow Through Charcoal Delay Systems The release of radioiodine in gaseous effluent is negligible (<10-4 Ci/yr of iodine-131). 12. Decontamination Factor (DF) for Cryogenic Distillation Use a DF of 1 x 104 for radioiodine. 13. Guidelines for Rounding Off Numerical Values In calculating the estimated annual release of radioactive materials in gaseous waste, round off all numerical values to two significant figures. 1. 42-A7 APPENDIX B PROCEDURE FOR CALCULATION OF ANNUAL AVERAGE RELATIVE CONCENTRATIONS IN AIR Annual average relative concentration (x/Q) may be estimated from onsite meteorological data or suitable offsite data in the form of joint frequency distributions of wind direction and wind speed by atmospheric stability class. Wind direction should be based on 22-1/2 degree sectors repre- senting the 16 compass points, and wind speed classes based on the Beaufort wind scale or other suitable class divisions. Wind directions and speeds should represent conditions at the release point for stack releases and at the 10-meter level for rooftop vent and building releases. Wind speeds may be adjusted downward (but not upward) to represent conditions at appro- priate release heights, using a standard power law extrapolation procedure (Ref. 1) if data from the appropriate levels are not available. Atmos- pheric stability may be divided into seven classes to represent Pasquill stability classes A (extremely unstable) through G