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:
ation in hole size. Use is limited to materials with P-wave velocity greater than that of borehole fluid. DG-1392, Appendix C, Page C-7 APPENDIX C, Cont’d. METHOD PROCEDURE APPLICABILITY LIMITATIONS Electrical resistivity log Apparent electrical resistivity of soil or rock in neighborhood of borehole is measured by in-hole logging tool containing one of a wide variety of electrode configurations. Appropriate combination of resistivity logs can be used to estimate porosity and degree of water saturation in rocks. In soils, may be used as qualitative indication of changes in void ratio or water content for correlation of strata between boreholes and for location of strata boundaries. Can be obtained only in uncased boreholes. Hole must be fluid filled, or electrodes must be pressed against borehole. Apparent resistivity values are strongly affected by changes in hole diameter, strata thickness, resistivity contrast between adjacent strata, resistivity of drilling fluid, etc. Neutron log Neutrons are emitted into rock or soil around borehole by a neutron source in the logging tool. A detector, isolated from the source, responds to either slow neutrons or secondary gamma rays. Response of detector is recorded. Correlation of strata between boreholes and location of strata boundaries. Provides an approximation to water content and can be run in cased or uncased, fluid-filled, or empty boreholes. Because of very strong borehole effects, results are generally not of sufficient accuracy for quantitative engineering uses. Gamma-gamma log (density log) Gamma rays are emitted into rock around the borehole by a source in the logging tool, and a detector isolated from the source responds to back-scattered gamma rays. Response of detector is recorded. Estimation of bulk density in rock, qualitative indication of changes of density in soils. May be run in empty or fluid-filled holes. Effects of borehole size and density of drilling fluid must be accounted for. Presently not