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:
essary): a. sample and analyze ground water from existing monitoring wells, and b. conduct additional hydrogeologic testing using existing wells (or new wells) if required. 3. Test the site conceptual model and radionuclide transport predictions using groundwater sample results and data collected during hydrogeologic testing. 4. Modify site conceptual model and radionuclide transport parameters as necessary to predict discharges and assess doses to members of the public. 5. Return to step 1. The ground water monitoring results should be used in the development and testing of a site conceptual model to predict radionuclide transport in ground water. A more thorough discussion is contained in the references listed in section C.3.6. The site conceptual model is generally considered adequate when it predicts the results of monitoring (sometimes called a calibrated model). Ground water monitoring results are used to evaluate the validity of the site conceptual model. Following a leak or spill of contaminated material, the site conceptual model may be used in conjunction with radionuclide transport modeling and ground water monitoring to comprise a basis for predicting future effluents from the site. Account should be taken of dispersion and dilution that occurs over time and in three dimensions. The site conceptual model together with a strategic and carefully planned monitoring program can ensure that necessary and reasonable surveys are performed (i.e., limited scoping surveys or more extensive surveys). Limited scoping surveys should be performed to determine if significant residual radioactivity exists and to determine if there is adequate protection of public health and safety. If the limited scoping surveys identify significant residual radioactivity, then the extent of the contamination Rev. 2 of RG 1.21, Page 23 should be further evaluated by more extensive surveys (e.g., monitoring wells or other evaluations as appropriate). These survey activities may be direct