Document: NRC Regulatory Guide
Document ID: 96baa826-d3bb-478b-8f38-e74500f6d433
Document Type: regulatory_guide
Title: 06/2009 (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0911/ML091170109.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.21
CFR Part: 
CFR Title: 

Content:
ionuclide (as defined in this document) in gaseous effluents. Rev. 2 of RG 1.21, Page 16 C-14 releases in PWRs occur primarily as a mix of organic carbon and carbon dioxide released from the waste gas system. In BWRs, C-14 releases occur mainly as carbon dioxide in gaseous waste (Ref. 21). Because the dose contribution of C-14 from liquid radioactive waste is much less than that contributed by gaseous radioactive waste, evaluation of C-14 in liquid radioactive waste is not required. Many documents provide information about the magnitude of C-14 in typical effluents from commercial nuclear power plants (e.g., Refs. 21, 22). Those documents suggest nominal annual releases of C-14 in gaseous effluents are approximately 5 to 7.3 curies from PWRs and between 8 to 9.5 curies from BWRs. Licensees should evaluate whether C-14 is a principal radionuclide for gaseous releases from their facility. 10 CFR 50.36a requires that operating procedures be developed for the control of effluents and that quantities of principal radionuclides be reported. The quantity of C-14 discharged can be estimated by sample measurements or by use of a normalized C-14 source term and scaling factors based on power generation (see National Council on Radiation Protection and Measurements Report No. 81, “Carbon-14 in the Environment,” issued January 1985 (Ref. 23)) or estimated by use of the GALE code from NUREG- 0017, “Calculation of Releases of Radioactive Materials in Gaseous and Liquid Effluents from Pressurized Water Reactors PWR-GALE Code,” April 1985 (Ref. 22). Because the production of C-14 is expected to be relatively constant at a particular site, if sampling is performed for C-14 (instead of estimating C-14 discharges based on calculations from a normalized source term), the sampling frequency may be adjusted to that interval that allows adequate measurement and reporting of effluents. If estimating C-14 based on scaling factors and fission rates, a precise and detailed evaluation