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:
ctures. Useful in examining casing interior. Graphic display of images. Fluid clarity immaterial. Highly experienced operator required. Slow log to obtain. Probe awkward and delicate. Continuous sonic (three-dimensional) velocity Time of arrival of P- and S-waves in high-velocity materials Determines velocity of P- and S-waves in near vicinity of borehole. Potentially useful for cavity and fracture detection. Modulus determinations. Sometimes S-wave velocities are inferred from P-wave velocity. Widely used method. Rapid and relatively economical. Variable density display generally impressive. Discontinuities in strata detectable. Shear wave velocity definition questionable in unconsolidated materials and soft sedimentary rocks. Only P-wave velocities greater than 1,500 meters per second (m/s) (5,000 ft/s) can be determined. Natural gamma radiation Natural radioactivity Lithology, correlation of strata, may be used to infer permeability. Locates clay strata and radioactive minerals. Widely used, technically simple to operate and interpret. Borehole effects, slow logging speed, cannot directly identify fluid, rock type, or porosity. Assumes clay minerals contain potassium-40 isotope. Gamma-gamma density Electron density Determines rock density of subsurface strata. Widely used. Can be applied to quantitative analyses of engineering properties. Can provide porosity. Borehole effects, calibration, source intensity, and chemical variation in strata affect measurement precision. Radioactive source hazard. DG-1392, Appendix E, Page E-4 APPENDIX E, Cont’d. GEOPHYSICAL METHOD BASIC MEASUREMENT APPLICATION ADVANTAGES LIMITATIONS Borehole (Continued) Neutron porosity Hydrogen content Moisture content (above water table), total porosity (below water table). Continuous measurement of porosity. Useful in hydrology and engineering property determinations. Widely used. Borehole effects, calibration, source intensity, and bound water all affect measurement precision. Radioactive