Document: NRC Regulatory Guide
Document ID: a094549d-8685-4dad-b90f-c28c7d279a53
Document Type: regulatory_guide
Title: Geologic and Geotechnical Site Characterization Investigations for Nuclear Power Plants + HISTORY – HISTORY 08/2021 – DG-1392 , Proposed Revision 3 07/2014 – Periodic Review of Revision 2 – Reviewed with no issues identified 02/2001 – DG-1101 , Proposed Revision 2 (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2119/ML21194A176.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.132
CFR Part: 
CFR Title: 

Content:
uld be noted on boring logs, and the artesian heads should be measured and logged. 6. Construction Mapping It is necessary to confirm that in situ conditions revealed in excavations for safety-related structures were accurately captured and interpreted during the preconstruction site characterization stage to ensure that information related to actual in situ conditions is properly incorporated into plant design analyses. Detailed geologic mapping should be performed for all construction excavations for safety-related structures and other excavations important for verification of subsurface conditions (e.g., cut slopes, tunnels, chambers, and water inlets and outlets). Particular attention should be given to geologic features and characteristics that might be important in assessment of the behavior of foundation materials, including tectonic and nontectonic features and lithologic variations, which might be undetected and different from what was assumed based on the results of site investigations prior to excavations. The detailed geologic mapping should be performed after the completion of excavations and before placement of backfill. The importance of the geologic mapping is reinforced by the geologic mapping license condition normally imposed in a combined or construction license. This license condition requires a licensee to commit to performing the following associated activities: (1) conduct detailed geologic mapping of excavations for safety-related structures, (2) examine and evaluate geologic features discovered in those excavations, and (3) notify the NRC once the excavations are open for inspection by NRC staff. Changes in foundation design that result from information acquired by the detailed geologic mapping should be noted on appropriate plans and included in maps, cross sections, and the database. All pertinent newly discovered geologic features should be evaluated for their potential impact on foundation materials. This evaluation might require