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:
ug from repeated water inflow and outflow. Push-in versions subject to several potential errors. Twin-tube hydraulic piezometer Inaccessible components have no moving parts. Reliable. Long, successful performance record. When installed in fill, integrity can be checked after installation. Piezometer cavity can be flushed. Can be used to measure permeability. Application generally limited to long-term monitoring of pore water pressure in embankment dams. Elaborate terminal arrangements needed. Tubing must not be significantly above minimum piezometric elevation. Periodic flushing may be required. Attention to many details is necessary. Pneumatic piezometer Short time lag. Calibrated part of system accessible. Minimum interference to construction: level of tubes and readout independent of level of tip. No freezing problems. Attention must be paid to many details when making selection. Push-in versions subject to several potential errors. Vibrating wire piezometer Easy to read. Short time lag. Minimum interference to construction: level of lead wires and readout independent of level of tip. Lead wire effects minimal. Can be used to read negative pore water pressures. No freezing problems. Special manufacturing techniques required to minimize zero drift. Need for lightning protection should be evaluated. Push-in version subject to several potential errors. a. Diaphragm piezometer readings indicate the head above the piezometer, and the elevation of the piezometer must be measured or estimated if piezometric elevation is required. All diaphragm piezometers, except those provided with a vent to the atmosphere, are sensitive to barometric pressure changes. DG-1392, Appendix G, Page G-2 APPENDIX G, Cont’d. INSTRUMENT TYPE ADVANTAGES LIMITATIONSa Electrical resistance piezometer Easy to read. Short time lag. Minimum interference to construction: level of lead wires and readout independent of level of tip. Suitable for dynamic measurements. Can be used to read negative pore