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:
t layer thickness and/or depth to reflection horizons must be considered approximate unless true velocities are known; some bottom conditions (e.g., organic sediments) prevent penetration; water depth should be at least 5 to 6 m (15 to 20 ft) for proper system operation. DG-1392, Appendix E, Page E-2 APPENDIX E, Cont’d. GEOPHYSICAL METHOD BASIC MEASUREMENT APPLICATION ADVANTAGES LIMITATIONS Surface (Continued) Electrical resistivity Electrical resistance of a volume of material between probes Complementary to refraction (seismic). Quarry rock, ground water, and sand and gravel prospecting. River bottom studies and cavity detection. Economical nondestructive technique. Can detect large bodies of “soft” materials. Lateral changes in calculated resistance often interpreted incorrectly as depth related; hence, for this and other reasons, depth determinations can be grossly in error. Should be used in conjunction with other methods, i.e., seismic. Acoustic (resonance) Amplitude of acoustically coupled sound waves originating in an air-filled cavity Traces (on ground surface) lateral extent of cavities. Rapid and reliable method. Interpretation relatively straightforward. Equipment readily available. Must have access to some cavity opening. Still in experimental stage; limits not fully established. Ground-penetrating radar Travel time and amplitude of a reflected electromagnetic wave Rapidly profiles layering conditions. Stratification, dip, water table, and presence of many types of anomalies can be determined. Very rapid method for shallow site investigations. Online digital data processing can yield “on site” look. Variable density display highly effective. Transmitted signal rapidly attenuated by water. Severely limits depth of penetration. Multiple reflections can complicate data interpretation. Generally performs poorly in clay-rich sediments. Gravity Variations in gravitational field Detects anticlinal structures, buried ridges, salt domes, faults, and