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:
1302 or, for less-significant release points, at the frequencies specified by the licensee. (See Regulatory Position 1.4.) The use of continuously indicating radiation monitoring system results may be combined with sample analyses to more fully characterize and quantify a discharge. This technique may have particular applicability when (1) a short-term, rapid upscale indication of a process radiation monitor occurs during a discharge or (2) when there is a desire to verify whether a preliminary grab sample is representative. In these instances the radiation monitor responses (i.e., the radiation monitor efficiencies) for various radionuclides should be well characterized. 1.8 Principal Radionuclides for Effluent Monitoring During analysis of samples, licensees should apply the appropriate analytical sensitivities to ensure adequate surveys are conducted. NUREG-1301/1302 provides a list of “principal gamma emitters” for which an LLD control applies. Historically, this list together with the guidance from Revision 1 of RG 1.21 provided the appropriate sensitivity levels for an analysis. Licensees may continue to use this guidance, which essentially classifies all radionuclides as principal radionuclides, and apply the analytical sensitivity levels (e.g., LLDs) directly from NUREG-1301 and NUREG-1302 and Revision 1 of RG 1.21. This method is simple to implement, but in certain cases, it may entail inappropriately long count times or it may involve alternate (or unnecessary) methods of analysis for low-activity radionuclides with no - or extremely low - dose significance. Although the LLD list from NUREG-1301 and NUREG-1302 may be used for determination of principal radionuclides, in reality, the principal radionuclides at a site will be dependent on site-specific factors such as (1) the amount of failed fuel, (2) the extent of system leakage, (3) the sophistication of radioactive waste processing equipment, and (4) the level of expertise in operating radioactive