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:
ctors 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 waste processing system. Since the principal radionuclides will vary from site to site, licensees who wish to deviate from the historical method of determining principal radionuclides (as described above) may adopt a risk-informed approach to identify principal radionuclides (and the associated sensitivity levels) at a site. This regulatory guide introduces the term “principal radionuclide” in a risk-informed context. A licensee may evaluate the list of principal radionuclides for use at a particular site. The principal radionuclides may be determined based on their relative contribution to (1) the public dose compared to the 10 CFR 50 Appendix design objectives or (2) the amount of activity discharged compared to other site radionuclides. Under this concept, radionuclides that have either a significant activity or a significant dose contribution should be monitored in accordance with a predetermined and appropriate analytical sensitivity level (LLD) outlined in a licensee’s ODCM. This implementation of “primary radionuclides” ensures both (1) radionuclides that are present in relatively large amounts but that contribute very little to dose, and (2) radionuclides that are present in very small amounts but that have a relatively high contribution to dose are appropriately included in the ARERR. Rev. 2 of RG 1.21, Page 15 NOTE: With respect to principal radionuclides, “dose” is the measure of risk whereas “activity” is not. For example, a relatively large amount of tritium released into a large body of water has little dose significance. If adopting a risk-informed perspective, a radionuclide is considered a principal radionuclide if it contributes either (1) greater than 1 percent of the 10 CFR Part 50, Appendix I, design objective dose for all