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:
explained by glaciation? How do the water table and deeper aquifers inform understanding about cavern formation? Is surface topography rough and irregular without apparent cause? Anhydrites or gypsum layers Anhydrites in foundations beneath major structures may hydrate and cause expansion, upward thrust, and buckling. Determine possible existence from available geologic information and delineate possible outcrop locations. Look for surface evidence of uplift; seek local information on existing structures. Are uplifts caused by possible anhydrite expansion or “explosion?” Gypsum may cause settlement, subsidence, collapse, or piping. Solution during life of structure may be damaging. Check area carefully for caves or other evidence of solution features. DG-1392, Appendix A, Page A-3 APPENDIX A, Cont’d. GEOLOGIC FEATURE OR CONDITION INFLUENCE ON PROJECT OFFICE STUDIES FIELD OBSERVATIONS QUESTIONS TO ANSWER Caves Extent may affect project feasibility or cost. Can provide evidence about faulting that may relate to seismic design. Can result from unrecorded mining activity in the area. See studies suggested for karst. Observe cave walls carefully for evidence of faults and recent faulting. Estimate age of any broken stalactites or stalagmites from column rings. Are any stalactites or stalagmites broken from apparent ground displacement or shaking? Erosion resistance Determines need for total or partial channel slope protection. Locate contacts of potentially erosive strata along drainage channels. Note stability of channels and degree of erosion and stability of banks. Are channels stable or have they shifted frequently? Are banks stable or easily eroded? Is there extensive bank sliding? Internal erosion Affects stability of foundations and dam abutments. Gravelly sands or sands with deficiency of intermediate particle sizes may be unstable and develop piping when subject to seepage flow. Locate possible outcrop areas of sorted alluvial materials or terrace