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:
s. These samples should be obtained by means of suitable fixed-piston, thin-wall tube samplers (see Appendix F to EM 1110-1-1804 for detailed procedures) or by methods that yield samples of equivalent quality. Borings used for undisturbed sampling of soils should be at least 7.6 centimeters (3 inches) in diameter. 4.5.4 Obtaining Undisturbed Samples In a strict sense, it is physically impossible to obtain “undisturbed” samples in borings because of the adverse effects resulting from the sampling process (e.g., unloading caused by removal from confinement) and from shipping or handling. Undisturbed samples are normally obtained using one of two general methods: push samplers or rotary samplers. These methods permit obtaining satisfactory samples for shear strength, consolidation, permeability, and density tests, provided careful measurements are made to document volume changes that occur during each step in the sampling process. Undisturbed samples can be sliced to permit detailed study of subsoil stratification, joints, fissures, failure planes, and other details. Guidance on commonly used undisturbed sampling methods can be found in relevant America Society for Testing and Materials (ASTM) standards. Undisturbed samples of clays and silts can be obtained, as well as nearly undisturbed samples of some sands. Care is necessary in transporting any undisturbed sample, and sands and silts are particularly vulnerable to vibration disturbance. One method to prevent handling disturbance is to obtain 7.6-centimeter (3-inch) Shelby tube samples, drain them, and freeze them before transportation. The commonly used general procedure for recovering cohesionless soil is to stabilize the soil, extract the sample, and later remove (reverse) the stabilizing agent after transportation, then trim and confine the specimen in a testing device. Reversible stabilization methods include the biopolymers agar and agarose, Elmer’s glue, and freezing. These stabilization methods must be