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:
ns 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 cavities. Provided extreme care is exercised in establishing gravitational references, reasonably accurate results can be obtained. Requires specialized personnel. Anything having mass can influence data (buildings, automobiles, etc.). Data reduction and interpretation are complex. Topography and strata density influence data. Magnetic Variations of earth’s magnetic field Determines presence and location of magnetic or ferrous materials in the subsurface. Locates ore bodies. Minute quantities of magnetic materials are detectable. Only useful for locating magnetic materials. Interpretation highly specialized. Calibration on site extremely critical. Presence of any ferrous objects near the magnetometer influences data. Uphole/downhole (seismic) Vertical travel time of compressional and/or shear waves Determines velocity of vertical P- and/or S-waves. Identifies low-velocity zones. Rapid technique useful to define low- velocity strata. Interpretation straightforward. Care must be exercised to prevent undesirable influence of grouting or casing. Crosshole (seismic) Horizontal travel time of compressional and/or shear waves Determines velocity of horizontal P- and/or S-waves. Elastic characteristics of subsurface strata can be calculated. Generally accepted as producing reliable results. Detects low-velocity zones provided borehole spacing is not excessive. Careful planning with regard to borehole spacing based upon geologic and other seismic data is an absolute necessity. Snell’s law of refraction must be applied to establish zoning. A borehole deviation survey must be run. Requires highly experienced personnel. Repeatable source required. DG-1392, Appendix E, Page E-3 APPENDIX E, Cont’d. GEOPHYSICAL METHOD BASIC MEASUREMENT APPLICATION ADVANTAGES LIMITATIONS