ML18247A261
| ML18247A261 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/18/2018 |
| From: | Dominion Energy Nuclear Connecticut |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML18199A125 | List:
|
| References | |
| 18-225 | |
| Download: ML18247A261 (192) | |
Text
Millstone Power Station Unit 3 Safety Analysis Report Chapter 2: Site Characteristics
MPS-3 FSAR 06/28/18 2-i Rev. 31 CHAPTER 2SITE CHARACTERISTICS Table of Contents Section Title Page 2.1 GEOGRAPHY AND DEMOGRAPHY..................................................... 2.1-1 2.1.1 Site Location and Description..................................................................... 2.1-1 2.1.1.1 Specification of Location............................................................................ 2.1-1 2.1.1.2 Site Area..................................................................................................... 2.1-1 2.1.1.3 Boundaries for Establishing Effluent Release Limits................................. 2.1-1 2.1.2 Exclusion Area Authority and Control....................................................... 2.1-2 2.1.2.1 Authority..................................................................................................... 2.1-2 2.1.2.2 Control of Activities Unrelated to Plant Operation.................................... 2.1-3 2.1.2.3 Arrangements for Traffic Control............................................................... 2.1-3 2.1.2.4 Abandonment or Relocation of Roads........................................................ 2.1-3 2.1.2.5 Independent Spent Fuel Storage Installation (ISFSI)................................. 2.1-4 2.1.3 Population Distribution............................................................................... 2.1-4 2.1.3.1 Population Distribution within 10 miles..................................................... 2.1-4 2.1.3.2 Population Distribution within 50 Miles.................................................... 2.1-5 2.1.3.3 Transient Population................................................................................... 2.1-6 2.1.3.4 Low Population Zone.................................................................................. 2.1-6 2.1.3.5 Population Center....................................................................................... 2.1-6 2.1.3.6 Population Density...................................................................................... 2.1-7 2.1.4 References For Section 2.1......................................................................... 2.1-7 2.2 NEARBY INDUSTRIAL, TRANSPORTATION, AND MILITARY FACILITIES........................................................................... 2.2-1 2.2.1 Locations and Routes.................................................................................. 2.2-1 2.2.2 Descriptions................................................................................................ 2.2-1 2.2.2.1 Description of Facilities.............................................................................. 2.2-1 2.2.2.2 Description of Products and Materials........................................................ 2.2-3 2.2.2.3 Pipelines...................................................................................................... 2.2-5 2.2.2.4 Waterways.................................................................................................. 2.2-5 2.2.2.5 Airports....................................................................................................... 2.2-5 2.2.2.6 Highways.................................................................................................... 2.2-6
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-ii Rev. 31 2.2.2.7 Railroads..................................................................................................... 2.2-7 2.2.2.8 Projections of Industrial Growth................................................................. 2.2-7 2.2.3 Evaluation of Potential Accidents............................................................... 2.2-8 2.2.3.1 Determination of Design Basis Events.................................................... 2.2-12 2.2.3.1.1 Missiles Generated by Events near the Millstone Site............................. 2.2-12 2.2.3.1.2 Unconfined Vapor Cloud Explosion Hazard............................................ 2.2-19 2.2.3.1.3
.................................................................................................................. 2.2-19 2.2.3.1.4 Hydrogen Storage at the Site.................................................................... 2.2-22 2.2.3.1.5 Toxic Chemicals....................................................................................... 2.2-22 2.2.3.2 Effects of Design Basis Events................................................................. 2.2-24 2.2.4 References for Section 2.2........................................................................ 2.2-25 2.3 METEOROLOGY...................................................................................... 2.3-1 2.3.1 Regional Climatology................................................................................. 2.3-1 2.3.1.1 General Climate.......................................................................................... 2.3-1 2.3.1.1.1 Air Masses and Synoptic Features.............................................................. 2.3-1 2.3.1.1.2 Temperature, Humidity, and Precipitation................................................. 2.3-2 2.3.1.1.3 Prevailing Winds......................................................................................... 2.3-2 2.3.1.1.4 Relationships of Synoptic to Local Conditions.......................................... 2.3-3 2.3.1.2 Regional Meteorological Conditions for Design and Operating Bases...... 2.3-3 2.3.1.2.1 Strong Winds.............................................................................................. 2.3-3 2.3.1.2.2 Thunderstorms and Lightning..................................................................... 2.3-4 2.3.1.2.3 Hurricanes................................................................................................... 2.3-4 2.3.1.2.4 Tornadoes and Waterspouts........................................................................ 2.3-4 2.3.1.2.5 Extremes of Precipitation............................................................................ 2.3-5 2.3.1.2.6 Extremes of Snowfall.................................................................................. 2.3-5 2.3.1.2.7 Hailstorms................................................................................................... 2.3-5 2.3.1.2.8 Freezing Rain, Glaze, and Rime................................................................. 2.3-6 2.3.1.2.9 Fog And Ice Fog......................................................................................... 2.3-6 2.3.1.2.10 High Air Pollution Potential....................................................................... 2.3-6 2.3.1.2.11 Meteorological Effects on Ultimate Heat Sink........................................... 2.3-6
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-iii Rev. 31 2.3.2 Local Meteorology...................................................................................... 2.3-7 2.3.2.1 Normal and Extreme Values of Meteorological Parameters...................... 2.3-7 2.3.2.1.1 Wind Conditions......................................................................................... 2.3-7 2.3.2.1.2 Air Temperature and Water Vapor............................................................. 2.3-7 2.3.2.1.3 Precipitation................................................................................................ 2.3-8 2.3.2.1.4 Fog and Smog............................................................................................. 2.3-8 2.3.2.1.5 Atmospheric Stability................................................................................. 2.3-8 2.3.2.1.6 Seasonal and Annual Mixing Heights........................................................ 2.3-9 2.3.2.2 Potential Influence of the Plant and Its Facilities on Local Meteorology.. 2.3-9 2.3.2.3 Local Meteorological Conditions for Design and Operating Bases........... 2.3-9 2.3.2.3.1 Design Basis Tornado................................................................................. 2.3-9 2.3.2.3.2 Design Basis Hurricane............................................................................ 2.3-10 2.3.2.3.3 Snow Load................................................................................................ 2.3-10 2.3.2.3.4 Rainfall...................................................................................................... 2.3-10 2.3.2.3.5 Adverse Diffusion Conditions.................................................................. 2.3-10 2.3.2.4 Topography............................................................................................... 2.3-10 2.3.3 On-Site Meteorological Measurements Program..................................... 2.3-11 2.3.3.1 Measurement Locations and Elevations................................................... 2.3-11 2.3.3.2 Meteorological Instrumentation................................................................ 2.3-11 2.3.3.3 Data Recording Systems and Data Processing......................................... 2.3-12 2.3.3.4 Quality Assurance for Meteorological System and Data.......................... 2.3-12 2.3.3.5 Data Analysis............................................................................................ 2.3-13 2.3.4 Short-Term (Accident) Diffusion Estimates............................................. 2.3-13 2.3.4.1 Objective................................................................................................... 2.3-13 2.3.4.2 Calculation................................................................................................ 2.3-13 2.3.4.3 Results....................................................................................................... 2.3-13 2.3.5 Long Term (Routine) Diffusion Estimates............................................... 2.3-14 2.3.5.1 Calculation Objective............................................................................... 2.3-14 2.3.5.2 Calculations.............................................................................................. 2.3-14 2.3.5.2.1 Release Points and Receptor Locations.................................................... 2.3-14 2.3.5.2.2 Database.................................................................................................... 2.3-14
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-iv Rev. 31 2.3.5.2.3 Models...................................................................................................... 2.3-14 2.3.6 References for Section 2.3........................................................................ 2.3-14 2.4 HYDROLOGIC ENGINEERING............................................................. 2.4-1 2.4.1 Hydrologic Description............................................................................... 2.4-1 2.4.1.1 Site and Facilities........................................................................................ 2.4-1 2.4.1.2 Hydrosphere................................................................................................ 2.4-1 2.4.2 Floods.......................................................................................................... 2.4-2 2.4.2.1 Flood History.............................................................................................. 2.4-2 2.4.2.2 Flood Design Considerations...................................................................... 2.4-3 2.4.2.3 Effect of Local Intense Precipitation.......................................................... 2.4-4 2.4.3 Probable Maximum Flood on Streams and Rivers..................................... 2.4-7 2.4.4 Potential Dam Failures, Seismically Induced............................................. 2.4-7 2.4.5 Probable Maximum Surge and Seiche Flooding........................................ 2.4-7 2.4.5.1 Probable Maximum Winds and Associated Meteorological Parameters.... 2.4-7 2.4.5.2 Surge and Seiche Water Levels.................................................................. 2.4-8 2.4.5.3 Wave Action............................................................................................. 2.4-10 2.4.5.3.1 Deep Water Waves................................................................................... 2.4-10 2.4.5.3.2 Shallow Water Waves............................................................................... 2.4-12 2.4.5.3.3 Wave Shoaling.......................................................................................... 2.4-13 2.4.5.3.4 Wave Refraction....................................................................................... 2.4-13 2.4.5.3.5 Wave Runup............................................................................................. 2.4-14 2.4.5.3.6 Clapotis on Intake Structure..................................................................... 2.4-14 2.4.5.4 Resonance................................................................................................. 2.4-14 2.4.5.5 Protective Structures................................................................................. 2.4-15 2.4.6 Probable Maximum Tsunami Flooding.................................................... 2.4-15 2.4.7 Ice Effects................................................................................................. 2.4-16 2.4.8 Cooling Water Canals and Reservoirs...................................................... 2.4-16 2.4.9 Channel Diversions................................................................................... 2.4-16 2.4.10 Flooding Protection Requirements........................................................... 2.4-16 2.4.11 Low Water Considerations....................................................................... 2.4-16
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-v Rev. 31 2.4.11.1 Low Flow in Rivers and Streams.............................................................. 2.4-16 2.4.11.2 Low Water Resulting from Surges, Seiches, or Tsunamis....................... 2.4-17 2.4.11.3 Historical Low Water................................................................................ 2.4-18 2.4.11.4 Future Control........................................................................................... 2.4-18 2.4.11.5 Plant Requirements................................................................................... 2.4-18 2.4.11.6 Heat Sink Dependability Requirements.................................................... 2.4-18 2.4.11.7 Dispersion, Dilution, and Travel Times of Accidental Releases of Liquid Effluents in Surface Waters...................................................................... 2.4-19 2.4.12 Groundwater............................................................................................. 2.4-23 2.4.12.1 Description and Onsite Use...................................................................... 2.4-23 2.4.12.2 Sources...................................................................................................... 2.4-23 2.4.12.3 Accident Effects........................................................................................ 2.4-24 2.4.12.4 Monitoring or Safeguard Requirements................................................... 2.4-28 2.4.12.5 Design Bases for Subsurface Hydrostatic Loading.................................. 2.4-28 2.4.13 Technical Specification and Emergency Operation Requirements.......... 2.4-28 2.4.14 References for Section 2.4........................................................................ 2.4-29 2.5 GEOLOGY, SEISMOLOGY, AND GEOTECHNICAL ENGINEERING......................................................................................... 2.5-1 2.5.1 BASIC GEOLOGICAL AND SEISMIC INFORMATION................... 2.5.1-1 2.5.1.1 Regional Geology.................................................................................... 2.5.1-1 2.5.1.1.1 Regional Physiography and Geomorphology.......................................... 2.5.1-2 2.5.1.1.2 Regional Structure................................................................................... 2.5.1-3 2.5.1.1.3 Regional Stratigraphy.............................................................................. 2.5.1-6 2.5.1.1.4 Regional Tectonics.................................................................................. 2.5.1-6 2.5.1.1.4.1 Domes and Basins.................................................................................... 2.5.1-6 2.5.1.1.4.2 Faulting.................................................................................................... 2.5.1-7 2.5.1.1.4.3 Tectonic Summary................................................................................. 2.5.1-10 2.5.1.1.4.4 Remote Sensing..................................................................................... 2.5.1-10 2.5.1.1.4.5 Structural Significance of Geophysical Studies..................................... 2.5.1-11 2.5.1.1.5 Regional Geologic History.................................................................... 2.5.1-12
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-vi Rev. 31 2.5.1.2 Site Geology.......................................................................................... 2.5.1-16 2.5.1.2.1 Site Physiography.................................................................................. 2.5.1-16 2.5.1.2.2 Local Stratigraphy.................................................................................. 2.5.1-17 2.5.1.2.3 Site Stratigraphy.................................................................................... 2.5.1-17 2.5.1.2.4 Local Structural Geology....................................................................... 2.5.1-18 2.5.1.2.4.1 Site Structural Geology.......................................................................... 2.5.1-20 2.5.1.2.5 Site Geological History.......................................................................... 2.5.1-21 2.5.1.2.6 Site Engineering Geology...................................................................... 2.5.1-24 2.5.1.3 References for Section 2.5.1.................................................................. 2.5.1-25 2.5.2 VIBRATORY GROUND MOTION....................................................... 2.5.2-1 2.5.2.1 Seismicity................................................................................................. 2.5.2-1 2.5.2.1.1 Completeness and Reliability of Earthquake Cataloging........................ 2.5.2-1 2.5.2.1.2 Earthquake History.................................................................................. 2.5.2-2 2.5.2.1.3 Seismicity within 50 Miles of the Site..................................................... 2.5.2-4 2.5.2.1.4 Earthquakes Felt at the Site..................................................................... 2.5.2-5 2.5.2.2 Geologic Structures and Tectonic Activity.............................................. 2.5.2-9 2.5.2.3 Correlation of Earthquake Activity with Geologic Structures or Tectonic Prov inces....................................................................................................... 2.5.2-14 2.5.2.3.1 Correlation with Geologic Structures.................................................... 2.5.2-14 2.5.2.3.2 Correlation with Tectonic Provinces..................................................... 2.5.2-15 2.5.2.4 Maximum Earthquake Potential............................................................ 2.5.2-16 2.5.2.4.1 Maximum Historical Site Intensity........................................................ 2.5.2-16 2.5.2.4.2 Maximum Earthquake Potential from Tectonic Province Approach..... 2.5.2-17 2.5.2.5 Seismic Wave Transmission Characteristics of the Site........................ 2.5.2-17 2.5.2.6 Safe Shutdown Earthquake.................................................................... 2.5.2-18 2.5.2.7 Operating Basis Earthquake................................................................... 2.5.2-18 2.5.2.8 References for Section 2.5.2.................................................................. 2.5.2-18 2.5.3 SURFACE FAULTING.......................................................................... 2.5.3-1 2.5.3.1 Geologic Conditions of the Site............................................................... 2.5.3-1
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-vii Rev. 31 2.5.3.2 Evidence of Fault Offset.......................................................................... 2.5.3-1 2.5.3.2.1 Petrographic Analysis.............................................................................. 2.5.3-3 2.5.3.2.2 Clay Mineralogy, Fluid Inclusion Analysis, and Radiometric Dating.... 2.5.3-4 2.5.3.2.3 Conclusions.............................................................................................. 2.5.3-7 2.5.3.3 Earthquakes Associated with Capable Faults.......................................... 2.5.3-8 2.5.3.4 Investigation of Capable Faults............................................................... 2.5.3-8 2.5.3.5 Correlation of Epicenters with Capable Faults........................................ 2.5.3-8 2.5.3.6 Description of Capable Faults.................................................................. 2.5.3-8 2.5.3.7 Zone Requiring Detailed Faulting Investigation..................................... 2.5.3-8 2.5.3.8 Results of Faulting Investigation............................................................. 2.5.3-8 2.5.3.9 References for Section 2.5.3.................................................................... 2.5.3-8 2.5.4 STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS..................................................................................... 2.5.4-1 2.5.4.1 Geologic Features.................................................................................... 2.5.4-1 2.5.4.2 Properties of Subsurface Materials.......................................................... 2.5.4-2 2.5.4.2.1 Artificial Fill............................................................................................ 2.5.4-3 2.5.4.2.2 Beach Deposits........................................................................................ 2.5.4-3 2.5.4.2.3 Unclassified Stream Deposits.................................................................. 2.5.4-3 2.5.4.2.4 Ablation Till............................................................................................. 2.5.4-4 2.5.4.2.5 Basal Till.................................................................................................. 2.5.4-4 2.5.4.2.6 Monson Gneiss........................................................................................ 2.5.4-5 2.5.4.3 Exploration............................................................................................... 2.5.4-6 2.5.4.4 Geophysical Surveys................................................................................ 2.5.4-6 2.5.4.4.1 Onshore Seismic Refraction Survey........................................................ 2.5.4-7 2.5.4.4.2 Offshore Seismic and Bathymetric Survey.............................................. 2.5.4-7 2.5.4.4.3 Seismic Velocity Measurements.............................................................. 2.5.4-7 2.5.4.5 Excavations and Backfill......................................................................... 2.5.4-9 2.5.4.5.1 Excavation............................................................................................... 2.5.4-9 2.5.4.5.2 Backfill................................................................................................... 2.5.4-11 2.5.4.5.3 Extent of Dredging................................................................................. 2.5.4-14
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-viii Rev. 31 2.5.4.6 Groundwater Conditions........................................................................ 2.5.4-14 2.5.4.6.1 Design Basis for Groundwater............................................................... 2.5.4-14 2.5.4.6.2 Groundwater Conditions During Construction...................................... 2.5.4-16 2.5.4.7 Response of Soil and Rock to Dynamic Loading.................................. 2.5.4-17 2.5.4.7.1 Subsurface Material Properties Used in SSI Analysis........................... 2.5.4-18 2.5.4.8 Liquefaction Potential............................................................................ 2.5.4-19 2.5.4.8.1 Structural Backfill.................................................................................. 2.5.4-19 2.5.4.8.2 Basal Tills.............................................................................................. 2.5.4-19 2.5.4.8.3 Beach and Glacial Outwash Sands........................................................ 2.5.4-20 2.5.4.8.3.1 Dynamic Response Analysis of Beach and Glacial Outwash Sands...................................................................................................... 2.5.4-20 2.5.4.8.3.2 Liquefaction Analysis of Beach and Glacial Outwash Sands................ 2.5.4-22 2.5.4.8.3.3 Liquefaction Analyses of Beach Area Sands using 2-Dimensional Dynamic Response Analysis......................................... 2.5.4-24 2.5.4.8.4 Ablation Till........................................................................................... 2.5.4-26 2.5.4.8.4.1 Dynamic Response Analysis of Ablation Till....................................... 2.5.4-26 2.5.4.8.4.2 Liquefaction Analysis of Ablation Till.................................................. 2.5.4-27 2.5.4.9 Earthquake Design Basis....................................................................... 2.5.4-28 2.5.4.10 Static Stability........................................................................................ 2.5.4-28 2.5.4.10.1 Bearing Capacity.................................................................................... 2.5.4-28 2.5.4.10.2 Settlement of Structures......................................................................... 2.5.4-29 2.5.4.10.3 Lateral Earth Pressures.......................................................................... 2.5.4-30 2.5.4.11 Design Criteria....................................................................................... 2.5.4-30 2.5.4.12 Techniques to Improve Subsurface Conditions..................................... 2.5.4-31 2.5.4.13 Structure Settlement............................................................................... 2.5.4-32 2.5.4.14 Construction Notes................................................................................ 2.5.4-32 2.5.4.15 References for Section 2.5.4.................................................................. 2.5.4-33 2.5.5 STABILITY OF SLOPES....................................................................... 2.5.5-1 2.5.5.1 Slope Characteristics................................................................................ 2.5.5-1 2.5.5.1.1 Shoreline Slope........................................................................................ 2.5.5-1
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS Table of Contents (Continued)
Section Title Page 06/28/18 2-ix Rev. 31 2.5.5.1.2 Containment Rock Cut............................................................................. 2.5.5-3 2.5.5.2 Design Criteria and Analysis................................................................... 2.5.5-3 2.5.5.2.1 Shoreline Slope........................................................................................ 2.5.5-3 2.5.5.2.2 Containment Rock Cut............................................................................. 2.5.5-6 2.5.5.3 Logs of Borings....................................................................................... 2.5.5-7 2.5.5.4 Compacted Fill......................................................................................... 2.5.5-7 2.5.5.5 References for Section 2.5.5.................................................................... 2.5.5-7 2.5.6 EMBANKMENTS AND DAMS............................................................ 2.5.6-1 APPENDIX 2.5A-AGE OF TILL AT MILLSTONE POINT.................................... 2.5A-1 APPENDIX 2.5B-PETROGRAPHIC REPORTS, FINAL GRADE..........................2.5B-1 APPENDIX 2.5C-MINERALOGICAL ANALYSIS OF MILLSTONE FAULT GOUGE SAMPLES......................................................................................2.5C-1 APPENDIX 2.5D-POTASSIUM - ARGON AGE DETERMINATION................... 2.5D-1 APPENDIX 2.5E-SEPARATION OF < 2 FRACTION AND CLAY ANALYSIS OF SAMPLES B, C, D (ESF BUILDING) AND P-1 AND P-2 (PUMPHOUSE).............................................................................2.5E-1 APPENDIX 2.5F-DYNAMIC SOIL TESTING ON BEACH SANDS......................2.5F-1 APPENDIX 2.5G-CONSOLIDATED UNDRAINED TESTS ON BEACH SANDS2.5G-1 APPENDIX 2.5H-SEISMIC VELOCITY MEASUREMENTS................................ 2.5H-1 APPENDIX 2.5I-DIRECT SHEAR TESTS ON NATURAL ROCK JOINTS..........2.5I-1 APPENDIX 2.5J-BORING LOGS..............................................................................2.5J-1 APPENDIX 2.5K-SEISMIC SURVEY...................................................................... 2.5K-1 APPENDIX 2.5L-SEISMIC AND BATHYMETRIC SURVEY...............................2.5L-1 APPENDIX 2.5M-LABORATORY TEST PROGRAM FOR PROPOSED ADDITIONAL STRUCTURAL BACKFILL SOURCES.....................................2.5M-1
MPS-3 FSAR 06/28/18 2-x Rev. 31 CHAPTER 2SITE CHARACTERISTICS List of Tables Number Title 2.1-1 1990 Population and Population Densities Cities and Towns Within 10 Miles of Millstone 2.1-2 Population Growth 1960-1990 2.1-3 Population Distribution 1985 (0-20 km) 2.1-4 Population Distribution Within 10 Miles of Millstone - 1990 Census 2.1-5 Population Distribution Within 10 Miles of Millstone - 2000 Projected 2.1-6 Population Distribution Within 10 Miles of Millstone - 2010 Projected 2.1-7 Population Distribution Within 10 Miles of Millstone - 2020 Projected 2.1-8 Population Distribution Within 10 Miles of Millstone - 2030 Projected 2.1-9 Population Distribution 1985 (0-80 km) 2.1-10 Population Distribution Within 50 Miles of Millstone - 1990 Census 2.1-11 Population Distribution Within 50 Miles of Millstone - 2000 Projected 2.1-12 Population Distribution Within 50 Miles of Millstone - 2010 Projected 2.1-13 Population Distribution Within 50 Miles of Millstone - 2020 Projected 2.1-14 Population Distribution Within 50 Miles of Millstone - 2030 Projected 2.1-15 Transient Population Within 10 Miles of Millstone - 1991-1992 School Enrollment 2.1-16 Transient Population Within 10 Miles of Millstone (Employment) 2.1-17 Transient Population Within 10 Miles of Millstone State Parks and Forests (With Documented Attendance) 2.1-18 Low Population Zone Permanent Population Distributions 2.1-19 Low Population Zone School Enrollment and Employment 2.1-20 Metropolitan Areas Within 50 Miles of Millstone 1990 Census Population 2.1-21 Population Centers Within 50 Miles of Millstone 2.1-22 Population Density* 1985 (0-20 km) 2.1-23 Population Density 1985 (0-80 km) 2.1-24 Population Density Within 10 Miles of Millstone 1990 (People per Square Mile) 2.1-25 Population Density Within 10 Miles of Millstone 2030 (People per Square Mile)
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS List of Tables (Continued)
Number Title 06/28/18 2-xi Rev. 31 2.1-26 Population Density Within 50 Miles of Millstone 1990 (People per Square Mile) 2.1-27 Population Density Within 50 Miles of Millstone 2030 (People per Square Mile) 2.1-28 Cumulative Population Density 1985 2.1-29 Cumulative Population Density Within 50 Miles of Millstone 1990 (People per Square Mile) 2.1-30 Cumulative population Density Within 50 Miles of Millstone 2030 (People per Square Mile) 2.2-1 Description of Facilities 2.2-2 List of Hazardous Materials Potentially Capable of Producing Significant Missiles 2.2-3 Summary of Exposure Distance Calculation 2.2-4 Aggregate Probability of Explosion or Violent Rupture Capable of Missile Generation 2.2-5 Types of Tank Car Missiles 2.2-6 Tank Car Fragment Range (Feet) at 10-Degree Launch Angle 2.2-7 Estimated Ignition Probabilities 2.2-8 Probability of an Unconfined Vapor Cloud Explosion 2.3-1 Monthly, Seasonal, and Annual averages and Extremes of Temperature at Bridgeport, Conn. (1901-1981) 2.3-2 Mean Number of Days with Selected Temperature Conditions at Bridgeport, Conn.
(1966-1981) 2.3-3 Monthly, Seasonal, and Annual Averages and Extremes of Relative Humidity at Bridgeport, Conn. (1949-1981) 2.3-4 Monthly, Seasonal, and Annual Frequency Distributions of Wind Direction at Bridgeport, Conn. (1949-1980) 2.3-5 Occurrence of Bridgeport Wind Persistence Episodes within the same 22.5-Degree Sector (1949-1965) 2.3-6 Monthly, Seasonal, and Annual Frequency Distributions of Wind Direction at Bridgeport, Conn. (1949-1980) 2.3-7 Monthly, Seasonal, and Annual Wind Speed Extremes at Bridgeport, Conn. (1961-1990)
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS List of Tables (Continued)
Number Title 06/28/18 2-xii Rev. 31 2.3-8 Mean Number of Days of Thunderstorm Occurrence at Bridgeport, Conn. (1951-1981) 2.3-9 Monthly, Seasonal, and Annual Averages and Extremes of Precipitation at Bridgeport, Conn. (1901-June 1982) 2.3-10 Estimated Precipitation Extremes for Periods up to 24 Hours and Recurrence Intervals Up to 100 Years 2.3-11 Monthly, Seasonal, and Annual Averages and Extremes of Snowfall at Bridgeport, Conn. (1893-June 1990) 2.3-12 Monthly, Seasonal, and Annual Averages of Freezing Rain and Drizzle at Bridgeport, Conn. (1949-1980) 2.3-13 Average Monthly, Seasonal, and Annual Hours and Frequencies (percent) of Various Fog Conditions (1949-1980) at Bridgeport, Connecticut 2.3-14 Monthly and Annual Wind Direction and Speed Distributions for Surface Winds, at Bridgeport, Conn. (1949-1980) 2.3-15 Monthly and Annual Wind Direction and Speed Distributions for 33-Foot Winds at Millstone (1974-1981) 2.3-16 Comparison of Wind Direction Frequency Distribution by Quadrant at Bridgeport, Conn. and Millstone 2.3-17 Comparison of Average Wind Speed by Quadrant at Bridgeport, Conn. and Millstone 2.3-18 Occurrence of Wind Persistence Episodes Within the Same 22.5-Degree Sector at Millstone (1974-1981) 2.3-19 Millstone Climatological Summary (1974-2000) 2.3-20 Comparison of Monthly and Annual Average Dry-Bulb and Dewpoint Temperature Averages at Bridgeport, Conn. and Millstone 2.3-21 Comparison of Monthly and Annual Average Relative Humidity Averages at Bridgeport and Millstone 2.3-22 Mean Number of Days with Heavy Fog at Bridgeport, Conn. and Block Island, Rhode Island (1951-1981) 2.3-23 Wind Direction/Stability Class/Visibility Joint Frequency Distribution at Millstone 2.3-24 Persistence of Poor Visibility ( 1 Mile) Conditions at Millstone (Hours) (1974-1981)
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS List of Tables (Continued)
Number Title 06/28/18 2-xiii Rev. 31 2.3-25 Bridgeport Pasquill Stability Class Distribution (1949-1980) 2.3-26 Millstone Stability Class Distribution Using Delta-T for Stability Determination 2.3-27 Millstone Stability Class Distribution Using Sigma Theta for Stability Determination 2.3-28 Comparison of Pasquill Stability Class Distribution at Bridgeport, Conn. and Millstone 2.3-29 Persistence of Stable Conditions (E, F, and G Stabilities) at Millstone (1974-1981) 2.3-30 Seasonal and Annual Atmospheric Mixing Depths at Millstone 2.3-31 On-site Meteorological Tower Measurements 2.3-32 Millstone Meteorological Tower Instrumentation 2.3-33 Monthly Summary of Data Recovery Rates/Meteorological System 2.3-34 Distances from Release Points to Receptors 2.4-1 Connecticut Public Water Supplies within 20 Miles of Millstone 3 2.4-2 Maximum Wave Heights Generated by Slow, Medium, and High Speed Storms (Deep-Water Fetch) 2.4-3 Maximum Shallow Water Waves (after Refraction) Slow Speed Probable Maximum Hurricane 2.4-4 Maximum Shallow Water Waves (after Refraction) Medium Speed Probable Maximum Hurricane 2.4-5 Maximum Shallow Water Waves (after Refraction) High Speed Probable Maximum Hurricane 2.4-6 Lowest Tides at New London, Connecticut 1938-1974 2.4-7 Circulating Water System and Service Water System Heat Loads 2.4-8 Dilution Factors and Travel Time
- 2.4-9 Category I Structures - Roof Survey 2.4-10 Input Data to Program HEC-2 Water Surface Computations 2.4-11 Computed Water Surface Elevations at Safety-Related Structures 2.4-12 Roof Area and Ponding Level Due to PMP (1)Category I Structures 2.4-13 Overflow Length of the Parapet Wall on the Roof Used in PMP Analysis - Category I Structures
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS List of Tables (Continued)
Number Title 06/28/18 2-xiv Rev. 31 2.5.1-1 Rock Formations of the Coastal Plain off Southern New England 2.5.1-2 Rock Formations of Western Connecticut 2.5.1-3 Rock Formations of Eastern Connecticut and Western Rhode Island 2.5.1-4 Rock Formations of Central Rhode Island (and not Included in Previous Descriptions) 2.5.1-5 Rock Formations in Northern and Eastern Rhode Island and Southern Massachusetts 2.5.1-6 Rock Formations of Central Massachusetts 2.5.1-7 East of Clinton-Newbury Fault System, Eastern Massachusetts, and New Hampshire 2.5.1-8 Descriptions of Lineaments from LANDSAT Photographs (Shown on Figure2.5.1-10) 2.5.2-1 Modified Mercalli (MM) Intensity Scale of 1931 2.5.2-2 List of Operating Seismic Stations 2.5.2-3 Chronological Catalog of Earthquake Activity within 200 Miles of the Site 2.5.2-4 List of Earthquakes within the 50-Mile Radius 2.5.3-1 List of Faults 2.5.3-2 List of Samples 2.5.3-3 List of K/Ar Age Determinations of Fault Gouge 2.5.4-1 List of Joints - Final Grade Floors of Structures 2.5.4-2 List of Foliations - Final Grade Floors of Structures 2.5.4-3 List of Slickensides - Final Grade Floors of Structures 2.5.4-4 List of Joints - Final Grade Containment and Engineered Safety Features Building Walls 2.5.4-5 List of Foliations - Final Grade Containment and Engineered Safety Features Building Walls 2.5.4-6 List of Slickensides - Final Grade Containment and Engineered Safety Features Building Walls 2.5.4-7 List of Joints - Final Grade Walls of Structures 2.5.4-8 List of Foliations - Final Grade Walls of Structures
MPS-3 FSAR CHAPTER 2SITE CHARACTERISTICS List of Tables (Continued)
Number Title 06/28/18 2-xv Rev. 31 2.5.4-9 List of Slickensides - Final Grade Walls of Structures 2.5.4-10 Rock Compression Test Results 2.5.4-11 Direct Shear Test Results From Joint and Foliating Surfaces 2.5.4-12 Summary of Static Soil Properties for Beach Sands
- 2.5.4-13 Natural Water Contents of Split Spoon Samples 2.5.4-14 Foundation Data for Major Structures 2.5.4-15 List of Approximate Boring Locations, Ground Elevations, and Groundwater Elevations
- 2.5.4-16 Summary of Water Pressure Test Data 2.5.4-17 Groundwater Observations 2.5.4-18 Factors of Safety Against Liquefaction of Beach Sands 2.5.4-19 In-Place Density Test Results on Category I Structural Backfill Beneath the Service Water Intake Pipe Encasement 2.5.4-20 In-Place Density Test Results at Control and Emergency Generator Enclosure Buildings 2.5.4-23 Emergency Generator Enclosure - Soil Properties with Structure Effects from SHAKE Analysis 2.5.4-24 Bearing Capacity of Major Structures 2.5.4-25 Results of Two-Dimensional Liquefaction Analysis of Beach Area Sands
06/28/18 2-xvi Rev. 31 MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures Number Title 2.1-1 General Site Location 2.1-2 General Vicinity 2.1-3 Site Layout 2.1-4 Site Plan 2.1-5 Towns Within 10 Miles 2.1-6 1985 Population Distribution 0-20 km 2.1-7 Population Sectors for 0-10 Miles 2.1-8 Counties within 50 Miles 2.1-9 1985 Population Distribution 0-80 km 2.1-10 Population Sectors for 0-50 miles 2.1-11 Roads and Facilities in the LPZ 2.1-12 LPZ Population Sectors Distribution 2.2-1 Major Industrial, Transportation and Military Facilities 2.2-2 Instrument Landing Patterns at Trumbull Airport 2.2-3 Air Lanes Adjacent to Millstone Point 2.2-4 New London County-State Highways and Town Roads 2.2-5 Propane Concentration Outside and Inside the Control Room 2.3-1 Topography in the Vicinity of Millstone Point 2.3-2 Topographical Profiles within 5 Miles of Site 2.3-3 Topographical Profiles within 5 Miles of Site 2.3-4 Topographical Profiles within 50 Miles of Site (Sheet 1) 2.3-5 Topographical Profiles within 50 Miles of Site (Sheet 1) 2.3-6 General Topography - 50 Miles (Sheet 1) 2.3-7 Meteorological Instrument and Data Quality Assurance Flow Diagram 2.4-1 Facilities Located on the Site 2.4-2 Public Water Supplies within 20 Miles of Site 2.4-3 Locations of Hydrographic Field Survey Stations, June to October 1965
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xvii Rev. 31 2.4-4 Tidal Currents Measured by Essex Marine Laboratory 2.4-5 Bottom Profiles Established by Essex Marine Laboratory 2.4-6 Frequency of Tidal Flooding at New London, Connecticut 2.4-7 Site Grade and Drainage Basins for PMP Runoff Analysis 2.4-8 Bottom Profile Along Path of Maximum Surface Winds 2.4-9 Coincident Wave and Surge Slow-Speed Probable Maximum Hurricane 2.4-10 Coincident Wave and Surge Medium-Speed Probable Maximum Hurricane 2.4-11 Coincident Wave and Surge High-Speed Probable Maximum Hurricane 2.4-12 Locus of Hurricane Eye, Hurricane Type: Large Radius, Slow Speed of Translation 2.4-13 Locus of Hurricane Eye, Hurricane Type: Large Radius, Medium Speed of Translation 2.4-14 Locus of Hurricane Eye, Hurricane Type: Large Radius, High Speed of Translation 2.4-15 Wave Transects on Long Island Sound 2.4-16 Areas Under Effect of Wave Shoaling and Wave Refraction 2.4-17 Wave Refraction Diagram, Block Island Sound Grid 2.4-18 Wave Refraction Diagram, Millstone Grid, Angle of Approach South 30 Degrees East 2.4-19 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 85 Degrees South 2.4-20 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 45 Degrees South 2.4-21 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 17 Degrees South 2.4-22 Topography and Runup Transects, Millstone Location 2.4-23 Intake Transect A 2.4-24 Runup Transect B (West) 2.4-25 Runup Transect C (East) 2.4-26 Wave Clapotis at Intake 2.4-27 Inputs to One Dimensional Setdown Model
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xviii Rev. 31 2.4-28 Large Radius, Probable Maximum Hurricane Isovel Field 2.4-29 Large Radius, Slow Speed of Translation Time Variant Wind Field - Millstone 2.4-30 Setdown Versus Wind Speed 2.4-31 Boundary of the Modeled Area 2.4-32 Onsite Well Locations 2.4-33 Probable Seepage Path From Boron Recovery Tank and Waste Disposal Building to Long Island Sound 2.4-34 Scupper Details - Control, Hydrogen Recombiner, and Containment Enclosure Buildings 2.4-35 Roof Plug Sealing Detail - Hydrogen Recombiner Building 2.4-36 Hatch Cover Details - Circulating Water Pumphouse Service Water Pump Cubicle 2.4-37 Hatch Cover Details - Control Building Mechanical Room 2.5.1-1 Regional Physiographic Map 2.5.1-2 Regional Pre-Pleistocene Sediments of the Continental Margin 2.5.1-3 Site Surficial Geology 2.5.1-4 Regional Geologic Map 2.5.1-5 Regional Geologic Section 2.5.1-6 Regional Tectonic Map 2.5.1-7 Stratigraphic Correlation Chart for the Site and Surrounding Region) 2.5.1-8 Regional Stratigraphic Correlation Chart (Sheet 1) 2.5.1-9 LANDSAT Photographs of Connecticut, Rhode Island, Southern Massachusetts, and Eastern New York 2.5.1-10 Lineament Map from LANDSAT Photographs 2.5.1-11 Regional Aeromagnetic Map 2.5.1-12 Regional Bouguer Gravity Map 2.5.1-13 Site Bedrock Geology 2.5.1-14 Tectonic Map of Eastern Connecticut 2.5.1-15 Contour Diagram of Poles to Foliation Planes - Final Grade 2.5.1-16 Contour Diagram of Poles to Joint Planes - Final Grade
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xix Rev. 31 2.5.1-17 Contour Plot of Bearing and Plunge of Slickensides - Final Grade 2.5.1-18 Generalized Location of Faults 2.5.2-1 Location of Seismic Stations 2.5.2-2 Epicenters of Earthquakes within 200-Mile Radius 2.5.2-3 Location of Earthquakes within the 50-Mile Radius 2.5.2-4 Isoseismal Map, Earthquake of November 9, 1727 2.5.2-5 Isoseismal Map, Earthquake of November 18, 1755 2.5.2-6 Isoseismal Map, Earthquake of May 16, 1791 2.5.2-7 Isoseismal Map, Earthquake of August 10, 1884 2.5.2-8 Isoseismal Map, Earthquake of March 1, 1925 (February 28, 1925 EST) 2.5.2-9 Isoseismal Map, Earthquakes of December 20 and 24, 1940 2.5.2-10 Tectonic Provinces 2.5.3-1 T-2 Fault Zone, Final Excavation Grade - Northern Section 2.5.3-2 T-2 Fault Zone, Final Excavation Grade - Southern Section 2.5.3-3 T-3 Fault Zone, Final Excavation Grade 2.5.4-1 Geologic Map of Final Grade, Service Water Line Walls - East 2.5.4-2 Geologic Map of Final Grade, Service Water Line Walls - West 2.5.4-3 Geologic Map of Final Grade, South Wall of Discharge Tunnel 2.5.4-4 Geologic Map of Final Grade, North Wall of Discharge Tunnel 2.5.4-5 Geologic Map of Final Grade, East Wall of Discharge Tunnel 2.5.4-6 Geologic Map of Final Grade, Floors of Structures 2.5.4-7 Geologic Map of Final Grade, Service Water Line Floor - West 2.5.4-8 Geologic Map of Final Grade, Pumphouse Floor 2.5.4-9 Geologic Map of Final Grade, Service Water Line Floor - East 2.5.4-10 Geologic Map of Final Grade, Southeast Quadrant of Containment Walls 2.5.4-11 Geologic Map of Final Grade, Southwest Quadrant of Containment Walls 2.5.4-12 Geologic Map of Final Grade, Northwest Quadrant of Containment Walls 2.5.4-13 Geologic Map of Final Grade, Northeast Quadrant of Containment Walls
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xx Rev. 31 2.5.4-14 Geologic Map of Final Grade, Engineered Safety Features, Building Sump Walls 2.5.4-15 Geologic Map of Final Grade, Auxiliary Building Pipe Tunnel Pit Walls 2.5.4-16 Geologic Map of Final Grade, North Wall of Excavation 2.5.4-17 Geologic Map of Final Grade, Northeast and Southeast Pumphouse Walls 2.5.4-18 Geologic Map of Final Grade Engineered Safety Features Building Wall 2.5.4-19 Geologic Map of Final Grade Discharge Tunnel Floor 2.5.4-20 Geological Map of Final Grade Discharge Tunnel Floor 2.5.4-21 Geological Map of Final Grade North Wall of Discharge Tunnel 2.5.4-22 Geological Map of Final Grade South Wall of Discharge Tunnel 2.5.4-23 Geologic Map of Final Grade Discharge Tunnel Floor 2.5.4-24 Geologic Map of Final Grade Discharge Tunnel Floor 2.5.4-25 Geologic Map of Final Grade West Wall of Discharge Tunnel 2.5.4-26 Geologic Map of Final Grade East Wall of Discharge Tunnel 2.5.4-27 Geologic Map of Final Grade Discharge Weir Rock Face 2.5.4-28 Corrected Blow Count Plot, Pumphouse Area Sands, Onshore Boring Composite 2.5.4-29 Corrected Blow Count Plot, Pumphouse Area Sands, Borings P1 to P8 Composite 2.5.4-30 Grain Size Distribution Curves (Sheet 1) 2.5.4-31 Boring Location Plan 2.5.4-32 Plot Plan Showing Locations of the Borings and the Geologic Sections 2.5.4-33 Geologic Profile, Sections A-A', B-B' 2.5.4-34 Geologic Profile, Sections C-C', D-D', E-E' 2.5.4-35 Geologic Profile, Sections F-F" and G-G' 2.5.4-36 Top of Basal Till Contour Map 2.5.4-37 Groundwater Contour Map 2.5.4-38 Groundwater Observations in Boreholes 2.5.4-39 Bedrock Surface Contour Map 2.5.4-40 General Excavation Plan 2.5.4-41 Shorefront and Dredging Plan
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xxi Rev. 31 2.5.4-42 Modulus vs Effective Confining Pressure, Structural Fill 2.5.4-43 Lateral Pressure Distribution 2.5.4-44 Gradation Curves for Category I Structural Fill 2.5.4-45 K2 vs Shear Strain for Beach Sands 2.5.4-46 Earthquake Induced Shear Stresses in Beach Sands 2.5.4-47 Cyclic Stress Ratio vs Confining Pressure for Beach Sands 2.5.4-48 Cyclic Stress Ratio vs Penetration Resistance of Sand 2.5.4-49 Factor of Safety Against Liquefaction of Beach Sands 2.5.4-50 Idealized Soil Profile Liquefaction Analysis of Ablation Till Under Discharge Tunnel 2.5.4-51 Geologic Profile, Section H-H
2.5.4-52 Geologic Profile, Section I-I
2.5.4-53 Location of Field Density Tests - Service Water Intake Line 2.5.4-54 Location of Field Density Test - Emergency Generator Enclosure and Control Building 2.5.4-55 Geologic Profile, Section J-J' 2.5.4-56 Geologic Profile, Section K-K' 2.5.4-57 Grain Size Distribution Curves - Pumphouse Area Outwash Sands (Sheet 1) 2.5.4-58 Equivalent Numbers of Uniform Stress Cycles Based on Strongest Components of Ground Motion 2.5.4-59 Plan of Settlement Monitoring Benchmark Locations 2.5.4-60 Control Building Settlement (Sheet 1) 2.5.4-61 Emergency Generator Enclosure Settlement 2.5.4-62
.Solid Waste Building Settlement 2.5.4-63 Liquid Waste Building Settlement 2.5.4-64 Fuel Building Settlement 2.5.4-65 Geologic Profile Section L-L' 2.5.4-66 Geologic Profile Section M-M' 2.5.4-67 Geologic Profile Section N-N'
MPS-3 FSAR NOTE: REFER TO THE CONTROLLED PLANT DRAWING FOR THE LATEST REVISION.
CHAPTER 2SITE CHARACTERISTICS List of Figures (Continued)
Number Title 06/28/18 2-xxii Rev. 31 2.5.4-68 Geologic Profile Section O-O' 2.5.4-69 Geologic Profile Section P-P' 2.5.4-70 Geologic Profile Section Q-Q' 2.5.4-71 Geologic Profile Section R-R' 2.5.4-72 Soil-Structure Interaction Emergency Generator Enclosure 2.5.4-73 Shear Modulus Curve Type 2 Soil (Structural Backfill and Basal Till) 2.5.4-74 Damping Curve Type 2 Soil (Structural Backfill and Basal Till) 2.5.4-75 Shorefront Profile Used in Liquefaction Analyses 2.5.5-1 Section through Shorefront 2.5.5-2 Typical Wedge Geometry 2.5.5-3 Design Loads for Ring Beam 2.5.5-4 Shorefront Slope Stability Section - Sloping Rock Profile 2.5.5-5 Summary of CIU Test Results - Beach Area Outwash Sands 2.5.5-6 Potential Failure Wedges West Side of Containment Excavation 2.5.5-7 Rock Surface Near North Edge of Main Steam Valve Building
MPS-3 FSAR 06/28/18 2.4-32 Rev. 31 TABLE 2.4-1 CONNECTICUT PUBLIC WATER SUPPLIES WITHIN 20 MILES OF MILLSTONE 3 CLICK HERE TO SEE TABLE 2.4-1
MPS-3 FSAR 06/28/18 2.4-33 Rev. 31 TABLE 2.4-2 MAXIMUM WAVE HEIGHTS GENERATED BY SLOW, MEDIUM, AND HIGH SPEED STORMS (DEEP-WATER FETCH)
CLICK HERE TO SEE TABLE 2.4-2
MPS-3 FSAR 06/28/18 2.4-34 Rev. 31 TABLE 2.4-3 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION)
SLOW SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-3
MPS-3 FSAR 06/28/18 2.4-35 Rev. 31 TABLE 2.4-4 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION)
MEDIUM SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-4
MPS-3 FSAR 06/28/18 2.4-36 Rev. 31 TABLE 2.4-5 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION) HIGH SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-5
MPS-3 FSAR 06/28/18 2.4-37 Rev. 31 TABLE 2.4-6 LOWEST TIDES AT NEW LONDON, CONNECTICUT 1938-1974 CLICK HERE TO SEE TABLE 2.4-6
06/28/18 2.4-38 Rev. 31 MPS-3 FSAR NOTES:
(1)
These are maximum heat loads.
(2)
See Table9.2-2.
(3)
An approximate value for operation with 1 to 5 inches of backpressure on the turbine.
TABLE 2.4-7 CIRCULATING WATER SYSTEM AND SERVICE WATER SYSTEM HEAT LOADS Normal Operating Condition (1)
(106 Btu/hr)
Normal Unit Cooldown Condition (106 Btu/hr)
LOCA Coincident with LOP Loss of Power (LOP)
Minimum Engineered Safety Features (106 Btu/hr)
Normal Engineered Safety Features (106 Btu/hr)
Hot Shutdown (106 Btu/yr)
Cold Shutdown (106 Btu/yr)
Service Water System 178.97 (2)
(2)
(2)
(2)
(2)
Circulating Water System 8,200 (3) 0 (after RHR cooling commences) 0 0
0 0
TOTAL 8378.97 (2)
(2)
(2)
(2)
(2)
MPS-3 FSAR 06/28/18 2.4-39 Rev. 31 NOTES:
- For discharge from Millstone 2 and 3
- For Millstone 2 and 3 operation within 500 to 1,000 ft from the discharge point (quarry cut)
TABLE 2.4-8 DILUTION FACTORS AND TRAVEL TIME
- Usage Location Dilution Factor Travel Decay Time (hr)
Pleasure Beach 12.6 0.0 Harkness Memorial 36.0 0.0 Waterford State Park 36.0 0.0 Ocean Beach Park 21.0 0.0 Crescent Beach 40.0 0.0 Rocky Neck State Park 30.0 0.0 McCook Point 43.0 0.0 Edge of Initial Mixing Zone**
3.0 0.0 Far Field 36.0 0.0 (7,000 ft south of discharge)
MPS-3 FSAR 06/28/18 2.4-40 Rev. 31 NOTES:
A = Difference between drain low point and top of parapet.
B = Difference between drain low point and top of lowest roof curb.
C = Difference between drain low point and bottom of overflow scupper.
D = Maximum load (lb/ft2) applied by maximum ponding (assume that roof drains are clogged);
H2O @ 4°C (62.4 pcf).
TABLE 2.4-9 CATEGORY I STRUCTURES - ROOF SURVEY Structure A* (ft)
B* (ft) C* (ft) D* (lb/ft2)
Number and Size of Scruppers Control Building 1.58 0.63 99 2 at 128 in2 = 256 in2 Auxiliary Building North 0.50 34 South 0.50 42 Fuel Building El 106'-0" 1.65 108 El 101'-9" 1.67 109 El 93'-10" 1.88 122 El 61'-5" 1.15 88 Main Steam Valve Building El 85'-11 1/4" 0.25 35 El 71'-2" 0.25 73 Engineering Safety Features Building El 56'-9" 0.75 47 Containment Enclosure Building 2.06 0.83 118 8 at 128 in2 = 1024 in2 Circulating and Service Water Pumphouse (CSWP)
El 39'-0" 1.98 1.31 87 El 26'-0" 1.31 87 Hydrogen Recombiner Building 0.92 57 2 at 90 in2 = 180 in2
MPS-3 FSAR 06/28/18 2.4-41 Rev. 31 TABLE 2.4-9 CATEGORY I STRUCTURES - ROOF SURVEY A
A B
WHERE APPLICABLE C
CSWP ROOF ONLY OTHER SAFETY RELATED STRUCTURE ROOFS
MPS-3 FSAR 06/28/18 2.4-42 Rev. 31 NOTES:
- 1. Drainage areas A and B are graded such that their flows do not contribute to the areas of safety related structures.
- 2. Drainage areasC and C1 are conservatively combined to provide worst case water flows.
TABLE 2.4-10 INPUT DATA TO PROGRAM HEC-2 WATER SURFACE COMPUTATIONS Drainage Basin Surface Area (acre)
Concentration Time (minutes)
Computed Flow (cfs) at Down stream End of Drainage Basin C & C1 (2) 9.58 14.8 267 D
6.43 12.6 351
MPS-3 FSAR 06/28/18 2.4-43 Rev. 31 TABLE 2.4-11 COMPUTED WATER SURFACE ELEVATIONS AT SAFETY-RELATED STRUCTURES Drainage Basin Structure Maximum W. S.
Elevation at Doors to Structure (ft msl)
C Auxiliary Building 24.85 C
Control Building 24.27 C
Emergency Generator Enclosure 24.27 D
Main Steam Valve Building 24.85 D
Hydrogen Recombiner Building 24.85 D
Auxiliary Building 24.85 D
Engineered Safety Features Building 24.85 D
Fuel Building 24.85 D
RWST/SIL Valve Enclosure 24.85 D
Demineralized Water Storage Tank Block House 24.85
06/28/18 2.4-44 Rev. 31 MPS-3 FSAR TABLE 2.4-12 ROOF AREA AND PONDING LEVEL DUE TO PMP (1)CATEGORY I STRUCTURES Structures Plan Area of Roof (2) (ft2)
Other Roof/Area Draining to this Structure's Roof (3)
(Structure/Ft2)
Total Area Considered in Flow off Roof (ft2)
Peak Flow Q=CIA(4)
(cfs)
Top Elevation of Parapet (ft, msl)
Peak Elevation of Water Surface (5)
(ft, msl)
Elevation of Bottom Scupper (ft, msl)
Control Bldg.
5,916 Turbine Bldg. / 2,587 8,503 13.74 92'-4" 92'-5" 91'-5 1/2" Auxiliary Bldg.
North End 7,956 7,956 12.86 94'-0" (6) 94'-1 1/2" (7)
South End 7,912 Containment Encl.
Structure /4,247 Fuel Bldg. / 286 12,445 20.11 93'-6" (6) 93'-10" (7)
Fuel Bldg.
El 106'-0" 2,912 Cont. Enc. Strct. / 956 3,868 6.25 107'-4" 107'-5" El 101'-9" 1,950 Fuel Bldg. / 443 2,393 3.87 103'-0" 103'-1" El 93'-10" 4,352 Liq. Wst. Bldg. / 72 5,514 8.91 94'-8" 94'-9" El 61'-5" 3,264 Fuel Bldg. / 3,942 7,846 12.68 56'-8 1/2" 56'-10 1/2" Main Steam Valve Bldg.
El 85'-11 1/4" 2,900 Aux. Bldg. / 12,445 Cont. Encl. Strt. / 2,283 17,628 28.5 86'-2" 86'-8" El 71'-2" 928 Main. Stm. Valve / 17,628 18,556 30.0 71'-7 5/8" 72'-2" Eng. Safety Feat.
Bldg.
6,931 Cont. Strt. Enc. / 5,628 12,559 20.3 57'-3" 57'-4" Cont. Strt. Encl.
18,252 18,252 29.5 187'-0" 186'-10" 185-9"
06/28/18 2.4-45 Rev. 31 MPS-3 FSAR
- 1. Based on HMR 51/52.
- 2. From SWEC Drawing No. 12179-EA-20A-1.
- 3. Effective area.
- 4. C = 1.0; i = 70.4 in./hr (peak 5 min. period); A = total runoff area flowing over parapet.
- 5. Assume entire length of parapet as weir.
- 6. Elevation of curb at low point.
- 7. Over curb at low point; all other flow on roof is sheet flow.
Hyd. Rec. Bldg.
2,104 Cont. Strt. Enc. / 1,327 ESF Bldg. / 598 4,029 6.5 51'-10" 51'-11" Circ. and SW Pumphouse El 39'-0" 10,126 10,126 16.4 40'-3 1/2" 40'-7" El 26'-0" 612 C&SW Pumphse / 840 1,452 2.4 27'-3 1/2" 27'-7" TABLE 2.4-12 ROOF AREA AND PONDING LEVEL DUE TO PMP (1)CATEGORY I STRUCTURES (CONTINUED)
Structures Plan Area of Roof (2) (ft2)
Other Roof/Area Draining to this Structure's Roof (3)
(Structure/Ft2)
Total Area Considered in Flow off Roof (ft2)
Peak Flow Q=CIA(4)
(cfs)
Top Elevation of Parapet (ft, msl)
Peak Elevation of Water Surface (5)
(ft, msl)
Elevation of Bottom Scupper (ft, msl)
MPS-3 FSAR 06/28/18 2.4-46 Rev. 31 TABLE 2.4-13 OVERFLOW LENGTH OF THE PARAPET WALL ON THE ROOF USED IN PMP ANALYSIS - CATEGORY I STRUCTURES CLICK HERE TO SEE TABLE 2.4-13
MPS-3 FSAR 06/28/18 2.4-47 Rev. 31 SECURITY-RELATED-INFORMATIONWithheld under 10 CFR 2.390 (d) (1)
FIGURE 2.4-1 FACILITIES LOCATED ON THE SITE
06/28/18 2.4-48 Rev. 31 MPS-3 FSAR FIGURE 2.4-2 PUBLIC WATER SUPPLIES WITHIN 20 MILES OF SITE
06/28/18 2.4-49 Rev. 31 MPS-3 FSAR FIGURE 2.4-3 LOCATIONS OF HYDROGRAPHIC FIELD SURVEY STATIONS, JUNE TO OCTOBER 1965
MPS-3 FSAR 06/28/18 2.4-50 Rev. 31 FIGURE 2.4-4 TIDAL CURRENTS MEASURED BY ESSEX MARINE LABORATORY
MPS-3 FSAR 06/28/18 2.4-51 Rev. 31 FIGURE 2.4-5 BOTTOM PROFILES ESTABLISHED BY ESSEX MARINE LABORATORY
06/28/18 2.4-52 Rev. 31 MPS-3 FSAR FIGURE 2.4-6 FREQUENCY OF TIDAL FLOODING AT NEW LONDON, CONNECTICUT
MPS-3 FSAR 06/28/18 2.4-53 Rev. 31 SECURITY-RELATED-INFORMATIONWithheld under 10 CFR 2.390 (d) (1)
FIGURE 2.4-7 SITE GRADE AND DRAINAGE BASINS FOR PMP RUNOFF ANALYSIS
06/28/18 2.4-54 Rev. 31 MPS-3 FSAR FIGURE 2.4-8 BOTTOM PROFILE ALONG PATH OF MAXIMUM SURFACE WINDS
06/28/18 2.4-55 Rev. 31 MPS-3 FSAR FIGURE 2.4-9 COINCIDENT WAVE AND SURGE SLOW-SPEED PROBABLE MAXIMUM HURRICANE
06/28/18 2.4-56 Rev. 31 MPS-3 FSAR FIGURE 2.4-10 COINCIDENT WAVE AND SURGE MEDIUM-SPEED PROBABLE MAXIMUM HURRICANE
06/28/18 2.4-57 Rev. 31 MPS-3 FSAR FIGURE 2.4-11 COINCIDENT WAVE AND SURGE HIGH-SPEED PROBABLE MAXIMUM HURRICANE
MPS-3 FSAR 06/28/18 2.4-58 Rev. 31 FIGURE 2.4-12 LOCUS OF HURRICANE EYE, HURRICANE TYPE: LARGE RADIUS, SLOW SPEED OF TRANSLATION
MPS-3 FSAR 06/28/18 2.4-59 Rev. 31 FIGURE 2.4-13 LOCUS OF HURRICANE EYE, HURRICANE TYPE: LARGE RADIUS, MEDIUM SPEED OF TRANSLATION
MPS-3 FSAR 06/28/18 2.4-60 Rev. 31 FIGURE 2.4-14 LOCUS OF HURRICANE EYE, HURRICANE TYPE: LARGE RADIUS, HIGH SPEED OF TRANSLATION
06/28/18 2.4-61 Rev. 31 MPS-3 FSAR FIGURE 2.4-15 WAVE TRANSECTS ON LONG ISLAND SOUND
06/28/18 2.4-62 Rev. 31 MPS-3 FSAR FIGURE 2.4-16 AREAS UNDER EFFECT OF WAVE SHOALING AND WAVE REFRACTION
06/28/18 2.4-63 Rev. 31 MPS-3 FSAR FIGURE 2.4-17 WAVE REFRACTION DIAGRAM, BLOCK ISLAND SOUND GRID
06/28/18 2.4-64 Rev. 31 MPS-3 FSAR FIGURE 2.4-18 WAVE REFRACTION DIAGRAM, MILLSTONE GRID, ANGLE OF APPROACH SOUTH 30 DEGREES EAST
06/28/18 2.4-65 Rev. 31 MPS-3 FSAR FIGURE 2.4-19 WAVE REFRACTION DIAGRAM, MILLSTONE GRID, ANGLE OF APPROACH WEST 85 DEGREES SOUTH
06/28/18 2.4-66 Rev. 31 MPS-3 FSAR FIGURE 2.4-20 WAVE REFRACTION DIAGRAM, MILLSTONE GRID, ANGLE OF APPROACH WEST 45 DEGREES SOUTH
06/28/18 2.4-67 Rev. 31 MPS-3 FSAR FIGURE 2.4-21 WAVE REFRACTION DIAGRAM, MILLSTONE GRID, ANGLE OF APPROACH WEST 17 DEGREES SOUTH
06/28/18 2.4-68 Rev. 31 MPS-3 FSAR FIGURE 2.4-22 TOPOGRAPHY AND RUNUP TRANSECTS, MILLSTONE LOCATION
MPS-3 FSAR 06/28/18 2.4-69 Rev. 31 FIGURE 2.4-23 INTAKE TRANSECT A
MPS-3 FSAR 06/28/18 2.4-70 Rev. 31 FIGURE 2.4-24 RUNUP TRANSECT B (WEST)
MPS-3 FSAR 06/28/18 2.4-71 Rev. 31 FIGURE 2.4-25 RUNUP TRANSECT C (EAST)
MPS-3 FSAR 06/28/18 2.4-72 Rev. 31 FIGURE 2.4-26 WAVE CLAPOTIS AT INTAKE
06/28/18 2.4-73 Rev. 31 MPS-3 FSAR FIGURE 2.4-27 INPUTS TO ONE DIMENSIONAL SETDOWN MODEL
MPS-3 FSAR 06/28/18 2.4-74 Rev. 31 FIGURE 2.4-28 LARGE RADIUS, PROBABLE MAXIMUM HURRICANE ISOVEL FIELD
MPS-3 FSAR 06/28/18 2.4-75 Rev. 31 FIGURE 2.4-29 LARGE RADIUS, SLOW SPEED OF TRANSLATION TIME VARIANT WIND FIELD - MILLSTONE
06/28/18 2.4-76 Rev. 31 MPS-3 FSAR FIGURE 2.4-30 SETDOWN VERSUS WIND SPEED
MPS-3 FSAR 06/28/18 2.4-77 Rev. 31 FIGURE 2.4-31 BOUNDARY OF THE MODELED AREA
MPS-3 FSAR 06/28/18 2.4-78 Rev. 31 FIGURE 2.4-32 ONSITE WELL LOCATIONS
MPS-3 FSAR 06/28/18 2.4-79 Rev. 31 SECURITY-RELATED-INFORMATIONWithheld under 10 CFR 2.390 (d) (1)
FIGURE 2.4-33 PROBABLE SEEPAGE PATH FROM BORON RECOVERY TANK AND WASTE DISPOSAL BUILDING TO LONG ISLAND SOUND
06/28/18 2.4-80 Rev. 31 MPS-3 FSAR FIGURE 2.4-34 SCUPPER DETAILS - CONTROL, HYDROGEN RECOMBINER, AND CONTAINMENT ENCLOSURE BUILDINGS
MPS-3 FSAR 06/28/18 2.4-81 Rev. 31 FIGURE 2.4-35 ROOF PLUG SEALING DETAIL - HYDROGEN RECOMBINER BUILDING
06/28/18 2.4-82 Rev. 31 MPS-3 FSAR FIGURE 2.4-36 HATCH COVER DETAILS - CIRCULATING WATER PUMPHOUSE SERVICE WATER PUMP CUBICLE
MPS-3 FSAR 06/28/18 2.4-83 Rev. 31 FIGURE 2.4-37 HATCH COVER DETAILS - CONTROL BUILDING MECHANICAL ROOM
MPS-3 FSAR 06/28/18 2.5-1 Rev. 31 2.5 GEOLOGY, SEISMOLOGY, AND GEOTECHNICAL ENGINEERING This section provides information regarding seismic, geologic, and geotechnical characteristics of the site and the surrounding region.
The following companies and personnel performed tests on materials from the site:
1.
American Drilling and Boring Company, Providence, Rhode Island, under the direction of Stone & Webster Engineering Corporation (S&W), drilled test borings, performed standard penetration tests, sampled soil, cored rock, performed pressure tests on selected holes, and installed piezometers.
2.
Weston Geophysical Engineers, Incorporated, Westboro, Massachusetts, conducted cross-hole and down-hole surveys and refraction and reflection surveys to determine in situ seismic wave velocities and the varying depths to founding strata. S&W performed additional cross-hole surveys using an impact source.
3.
Geotechnical Engineers, Inc., Winchester, Massachusetts, performed cyclic triaxial and resonant column tests on beach sands in the vicinity of the circulating and service water pumphouse.
4.
Geochron Laboratories, Cambridge, Massachusetts, performed potassium-argon (K-Ar) dating to determine the age of rock and fault gouge samples.
5.
Dr. R. T. Martin, Massachusetts Institute of Technology, Cambridge, Massachusetts, and Dr. R. C. Reynolds of Dartmouth College, Hanover, New Hampshire performed x-ray diffraction tests to determine the clay mineral composition of the fault gouge samples.
6.
Dr. R. A. Wobus, Williams College, Williamstown, Massachusetts, performed petrographic analysis of thin sections from fault zones.
7.
Dr. E. Ingerson, University of Texas, Austin, Texas, analyzed quartz crystals found in the fault zone to determine the conditions of formation.
8.
Dr. D. W. Caldwell, Groton, Massachusetts, performed consulting services to determine the age of till at the Millstone site.
9.
Dr. K. Tsutsumi, Tufts University, Medford, Massachusetts, performed unconfined compression strength tests on rock specimens taken from borings.
10.
Dr. Robert F. Black, University of Connecticut, Storrs, Connecticut, performed consulting services regarding the age and origin of features found in site glacial deposits.
The information contained in this section was obtained from the following:
MPS-3 FSAR 06/28/18 2.5-2 Rev. 31 1.
Review of published geologic literature and maps.
2.
Detailed mapping of rock after the removal of overburden and the excavation of structures.
3.
Interviews with authorities on regional geology.
4.
Rock and soil borings.
5.
Laboratory tests of representative soil and rock samples.
6.
Interpretation of aerial photographs, Earth Resources Technology Satellite (ERTS) imagery, gravity, and aeromagnetic maps.
7.
Geophysical surveys on the site.
8.
Piezometer installations and groundwater monitoring.
9.
Bedrock pressure testing (holding test and pressure flow test).
10.
Age dating of rock samples.
11.
Fluid inclusion studies.
12.
Petrographic studies.
13.
Blast monitoring.
The site is located on a low peninsula on the north shore of Long Island Sound and the east shore of the Niantic River. Bedrock is highest on the eastern portion of the site and dips to the west towards Long Island Sound. The reactor containment and most other Category I structures on the eastern side of the site are founded on bedrock, whereas the control, emergency generator, waste disposal enclosure, turbine building, are founded on dense basal till which overlies the rock. The circulating and service water pumphouse is also founded on bedrock. The bedrock surface falls off sharply from the main site area to approximately el -32 feet in the area of the pumphouse.
Section 2.5.1 presents the regional and site area geology and geologic history. A discussion of regional faulting and tectonics and their relationship to rock types at the site is discussed in detail.
Section 2.5.2 presents the regional seismicity and describes the selection of the site safe shutdown earthquake (SSE) of 0.17 g and the operating basis earthquake (OBE) of 0.09 g.
Section 2.5.3 describes the faulting encountered at the site during construction. A description of the origin and nature of the faults mapped at final excavation grades is included in this section.
MPS-3 FSAR 06/28/18 2.5-3 Rev. 31 Section 2.5.4 presents the results of geotechnical investigations and studies related to the stability of subsurface materials and plant structures. Field and laboratory investigations are described in detail, and stability and liquefaction analyses based on these studies are also included in this section, as well as maps and tables from the geological mapping program.
Section 2.5.5 presents the results of stability analyses on two safety related slopes at the site: the containment excavation and the shoreline slope.
Embankments or dams (Section 2.5.6) are not included in the plant design.
MPS-3 FSAR 06/28/18 2.5.1-1 Rev. 31 2.5.1 BASIC GEOLOGICAL AND SEISMIC INFORMATION As shown on Figure 2.5.1-1 the site lies in the Seaboard Lowland section of the New England physiographic province. The site is located in a geologically complex region characterized by metamorphosed and folded rocks of Ordovician-Silurian age. This area has been affected by four orogenies: the Avalonian (575 million years ago m.y.a.), the Taconian (465-445 m.y.a.), the Acadian (400-370 m.y.a.), and the Alleghenian (230-260 m.y.a.). The surrounding region has also been affected by rifting ranging in age from Triassic to Jurassic. Since then the region has been stable, with the exception of epeirogenic uplift during Cretaceous and Tertiary times, and isostatic rebound, resulting from the removal of the weight of ice covering the region during Pleistocene time.
The site lies in an area of low seismic activity. Only 13 earthquakes of Intensity V, Modified Mercalli (MM) or greater, have been recorded within a distance of 50 miles of the site in more than 300 years. The nearest significant earthquake was at East Haddam, Connecticut, in 1791. Its epicenter was approximately 25 miles north of the site. Even though this earthquake is recorded in the Earthquake History of the United States (USCGS 1965) as having an intensity of VIII MM, detailed studies by Rev. Linehan, Director, Weston Geophysical Observatory, based on newspaper accounts and other records of the time, indicate that the intensity was no higher than VI to VII MM. Maximum intensity of ground motion experienced at the site in approximately 300 years of recorded history has not exceeded Intensity V MM, which would correspond to an acceleration of 0.02 to 0.03g.
Faults believed to be related to Triassic tectonics have been found in the excavation for Millstone
- 3. Potassium-argon methods of dating clay gouge found within the faults indicate that the last activity along these faults occurred approximately 142 m.y.a.; therefore, these faults are not capable features (NNECO. 1975, 1976, 1977, 1982). There is no capable fault at or near the site.
A thick layer of very dense basal till blankets the site. The bedrock surface is irregular and was glacially smoothed. Most major plant safety related structures are founded on hard, crystalline bedrock. The control building is founded on structural backfill overlying till and bedrock.
There has been no commercial mining in the area other than the now inactive granite quarry, located approximately 1,200 feet to the southeast of the Millstone 3 plant area. The soils and rock underlying the site are strong, stable materials that are not susceptible to loss of strength, subsidence, or other instabilities during earthquake motion. The gradation and the density of the till are such that liquefaction is precluded. The soils and rock underlying the site are of very low permeability. The groundwater table is highest in the northern part of the site and slopes gradually towards the shoreline. There are some isolated wells in the area; however, there is no industrial, domestic, or municipal use of groundwater from these wells.
2.5.1.1 REGIONAL GEOLOGY New England is characterized by a series of intensely folded anticlinoria and synclinoria trending to the northeast. The geology of these folds has been made more complex by igneous activity, metamorphism, and faulting. Extensive glaciation has modified landforms and deposited or
MPS-3 FSAR 06/28/18 2.5.1-2 Rev. 31 reworked most unconsolidated surficial deposits. The physiography, geological setting, stratigraphy, tectonics, and geologic history of the New England region are discussed in the sections that follow.
2.5.1.1.1 Regional Physiography and Geomorphology The Millstone site is located in the Seaboard Lowland section of the New England physiographic province (Figure 2.5.1-1). The New England province is divided into five sections by Fenneman (1938): the Taconic, the Green Mountain, the White Mountain, the New England Upland, and the Seaboard Lowland. The Connecticut Valley Lowland is discussed by Fenneman (1938), but not considered as a separate province. Just southwest of Millstone Point along the coast of Connecticut lies the Coastal Plain province. These sections are not necessarily characterized by uniform geological terrain, but are defined primarily by similar topographic expression.
Section 2.5.1.2 discusses the local physiography and its significance to the site.
The Seaboard Lowland section is a smooth, low-lying belt extending from Connecticut north to New Brunswick. In Connecticut, the Lowland varies in width from 6 to 16 miles, and as it swings northward in Rhode Island and Massachusetts, it widens to approximately 50 miles in southeastern Massachusetts. The relatively low altitude of the seaboard section is not primarily due to a difference in rock resistance, though the parts underlain by the Carboniferous sediments are lower and flatter than the rest (Fenneman 1938). Along Long Island Sound, it is probable that a narrow zone was covered by Cretaceous formations of the coastal plain (Fenneman 1938). This zone has a steeper seaward slope than the upland and is considered by Fenneman (1938) to be part of the pre-Schooley peneplain. In the Millstone site area, this zone is characterized by glacial outwash and moraines with some swamp deposits.
The Taconic section, the westernmost subdivision of the New England province, extends from approximately 12 miles southeast of Poughkeepsie, New York, northward to approximately Rutland, Vermont. The zone is fairly narrow with a maximum width of about 25 miles, and the area is mostly mountainous. The mountains consist mainly of strongly metamorphosed sediments, now predominantly schists and slates.
The Green Mountain section borders the Taconic section to the northeast. This highland section extends from western Massachusetts into Canada. The Green Mountains are underlain by resistant crystalline rocks of Precambrian age.
The White Mountain section consists of a series of mountain ranges from the White Mountains of New Hampshire northeastward to the Katahdin group in Maine. This section is underlain mainly by metamorphosed sedimentary and volcanic rocks of Paleozoic age and igneous rocks of the White Mountain Plutonic-Volcanic series (Billings 1956).
The New England Upland section, the largest section of the New England physiographic province, extends from Canada to the Highlands area of southeastern New York and northern New Jersey. This section typically reflects underlying fold belts and has the appearance of a plateau dissected by narrow valleys and containing scattered monadnocks (Fenneman 1938). It was first believed that a single peneplain existed at one time and extended from Long Island
MPS-3 FSAR 06/28/18 2.5.1-3 Rev. 31 Sound to the Green Mountains. This peneplain ranged from sea level at the Sound to approximately 2,000 feet in the Green Mountain area (Fenneman 1938).
The exact origin of the peneplain is still questioned. Two hypotheses have been brought forth for the origin of the plateau: marine terracing and terracing by normal erosion (Fenneman 1938).
Neither explanation is widely accepted, although a combination of the two seems more plausible.
The Connecticut Valley Lowland trends northerly through the New England Upland section from the Connecticut shore to just north of Greenfield, Massachusetts. The Lowland is underlain by sandstone, conglomerate, and shale, which is less resistant to weathering, and diabase which is more resistant. There is an abrupt change to crystalline rocks on both sides of the depression.
South of the New England Lowland section is the Atlantic Coastal Plain physiographic province.
This section (Figure 2.5.1-1) encompasses Cape Cod, Long Island, southern New Jersey, and the offshore islands and shoals. In the site area, the Coastal Plain sediments are submerged by the Atlantic Ocean. These sediments are of late Cretaceous and Tertiary ages and thicken seaward.
Figure 2.5.1-2 shows a distribution of pre-Pleistocene sediments off the New England coast. The basement is believed to be a continuation of that found underlying southern New England.
Glaciation has greatly changed much of New England. The rock outcrops have been rounded and smoothed and the valleys filled with glacial deposits. The rivers in many cases had to develop new channels after being dammed by glacial deposits.
Pleistocene glacial deposits are widespread throughout New England. End moraines occur along the southern margins and are prominent along Long Island, Block Island, Martha's Vineyard, Cape Cod, and in southern Rhode Island and Connecticut (Schafer and Hartshorne 1965). End moraines have been mapped in the site area by Flint (1975) and Goldsmith (1964) and are shown on the Site Surficial Map (Figure 2.5.1-3).
2.5.1.1.2 Regional Structure The Millstone site area lies in the northern portion of the Appalachian Mountain system. The Appalachians extend from Alabama to Newfoundland as a series of ranges formed by a number of successive deformations during the Paleozoic era.
The northern Appalachians can be separated into a number of distinct geologic sections. The westernmost area, the foreland, is relatively undeformed. This area includes the Catskill Plateau, the Hudson-Champlain and the St. Lawrence Lowlands, and consists mainly of gently dipping, sedimentary rocks of Early Paleozoic age.
A narrow belt of deformed and metamorphosed lower Paleozoic carbonate rocks, east of the foreland, forms the northern extension of the Valley and Ridge province. These rocks are similar to those of the Catskill Plateau: however, they have undergone at least two deformations and have been broken by thrust faults and high-angle gravity faults.
MPS-3 FSAR 06/28/18 2.5.1-4 Rev. 31 Further eastward lie the Taconic Mountains which consist of allochthonous rocks of Cambrian and Ordovician ages. The Taconics are mainly sedimentary and metasedimentary rocks that have slid westward into place above middle Ordovician shales (Figures 2.5.1-4 and 2.5.1-5).
The New England section is a series of north-south anticlinoria and synclinoria that parallel the general trend of the Appalachian Mountain belt. They are, from west to east: the Green Mountain anticlinorium, the Connecticut-Gaspe synclinorium, the Bronson Hill anticlinorium, the Merrimack synclinorium, and the Rockingham anticlinorium, the Merrimack synclinorium, and the Rockingham anticlinorium. The Merrimack synclinorium in southeastern New England ends abruptly on the east along the Clinton-Newbury and Lake Char fault zones. East of the fault zone lies a belt of Precambrian and Lower and Middle Paleozoic igneous and metamorphic rocks of various lithologies. Figure 2.5.1-4 shows the major stratigraphic units associated with these structural belts and Figure 2.5.1-5 shows the structural units.
The Green Mountain anticlinorium is made up of a series of massifs that are intensely sheared and metamorphosed Paleozoic rocks with a Precambrian core. They are, from north to south: the Green Mountain, the Berkshire, and the Housatonic massifs.
The Hudson Highlands group of rocks including schists, gneisses, granites, and minor marbles of Precambrian age are exposed along much of the anticlinorium. This structural high is believed to separate the miogeosynclinal sequence on the west from the eugeosynclinal sequence on the east.
The eugeosynclinal sequence is generally considered as a homoclinal sequence, of intensely folded and sheared rocks of early Paleozoic age. In the trough of the Connecticut-Gaspe synclinorium is a series of domes surrounded by the entire synclinorial sequence. The synclinorium is a major tectonic unit that extends from Long Island Sound along the Connecticut River to the Gaspe Peninsula and into Newfoundland. The east limb is masked by the younger clastic sediments and basalt flows of the Connecticut Valley Triassic Basin.
The crest of the Bronson Hill anticlinorium coincides with an echelon series of Ordovician gneiss domes (Naylor 1968, Thompson et al., 1968). The metamorphosed sediments and volcanic rocks of Ordovician and Devonian ages are stratigraphically continuous with those of the Connecticut-Gaspe synclinorium. The gneiss domes are believed to have been the loci of volcanic islands within the eugeosynclinal trough during Early Paleozoic time (Naylor 1968, Thompson et al.,
1968).
The Merrimack synclinorium shares its west limb with the Bronson Hill anticlinorium, which includes metamorphosed lower and middle Paleozoic clastic sediments. Metamorphism and plutonism have greatly confused the geology of the area. Metamorphic grade increases from north to south within the synclinorium. The synclinorium has been intruded by rocks belonging to the Devonian New Hampshire Plutonic series (Billings 1956, Page 1968, Foland et al., 1971). The southern extent of the Merrimack synclinorium is obscured by the Honey Hill fault and the local doming and refolding of the Ordovician rocks south of the Honey Hill fault.
MPS-3 FSAR 06/28/18 2.5.1-5 Rev. 31 In New Hampshire and Maine, the east limb of the Merrimack synclinorium is shared with the Rockingham anticlinorium (Billings 1956). This anticlinorium consists of lower and middle Paleozoic metamorphic units of primarily sedimentary origin.
The Merrimack synclinorium and the Rockingham anticlinorium end abruptly along the Clinton-Newbury fault zone. East of this fault and the Lake Char fault lies a belt of Precambrian and lower and middle Paleozoic igneous and metasedimentary rocks. Granites, granite gneisses, schists, and volcanic deposits are characteristic of this area. The Precambrian basement of southeastern New England is younger than that of the Green Mountains to the west (Naylor 1975). The geologic terrain in this southeastern New England belt is comparable to that of the Avalon Peninsula in Newfoundland (Rodgers 1972). A number of Late Paleozoic basins have been superimposed on these rocks: Boston, Norfolk, Woonsocket, North Scituate, and Narragansett Basins. The Narragansett Basin is slightly to moderately metamorphosed with a maximum staurolite grade in the southwest corner (Weston Observatory 1976). The Boston Basin is only slightly metamorphosed (Rodgers 1970).
Along the southern New England coast is an east-west belt of rocks extending eastward from the eastern edge of the Connecticut Valley Triassic Basin (Figure 2.5.1-4). In Connecticut, the strip is made up of complexly folded metasediments and a number of gneiss domes. The domes range in age from late Precambrian to early Paleozoic (Naylor 1968, Rodgers 1970). The Millstone site is located in this region adjacent to the Lyme Dome (Section 2.5.1.2). In Rhode Island, the strip consists of massive, relatively undeformed Late Pennsylvanian or Early Permian granites (Narragansett Pier and Westerly Granite) which intrude the Narragansett Basin deposits, and Precambrian gneisses.
Cretaceous and post-Cretaceous sediments have masked the seaward extension of the Appalachian structures to the south and east. Figure 2.5.1-2 shows the inferred distribution of the coastal plain material. Figure 2.5.1-5 shows what is considered to be the seaward thickening wedge of Cretaceous, Tertiary, and Quaternary sediments dipping to the southeast. These sediments unconformably overlie the pre-Cretaceous rock surface that dips seaward at a low angle. Recent work by Sheridan (1974) indicates that there are some very deep, possibly fault-bounded basins beneath the outer shelf and beyond, containing carbonates and evaporates of Jurassic-Triassic and Permo-Carboniferous age (Figure 2.5.1-6). A number of somewhat shallower Triassic and Permo-Carboniferous basins have been hypothesized in papers by Ballard and Uchupi (1972, 1975) (Figure 2.5.1-6). Table 2.5.1-1 gives the lithologies, ages, and thickness of the coastal plain sediments off the southern New England coast. Figure 2.5.1-2 shows the extent of the Cretaceous sediments and the unconformably overlying Tertiary sediments. A thin veneer of reworked glacial outwash and clastic material covers most of the shelf area (Hoskins 1967). Relief on the surface of the continental shelf of the Long Island, Block Island, and Rhode Island Sounds and in the Buzzards Bay area has been observed by seismic profiling. Tagg and Uchupi (1967) believe these irregularities to be caused by fluvial erosion and modified by glacial erosion and deposition.
Geophysical studies in the Gulf of Maine indicate that its tectonic history is similar to that of the New England coast. Late Paleozoic and Early Mesozoic basins are also believed to exist in this area (Ballard and Uchupi 1972, 1975). These structures are covered by differing amounts of post-
MPS-3 FSAR 06/28/18 2.5.1-6 Rev. 31 Jurassic deposits (Figure 2.5.1-2). Well defined unconformities beneath Georges Bank are inferred to separate the upper Cretaceous sediments from the Tertiary and lower Pleistocene sediments and the Tertiary-lower Pleistocene strata from the Pleistocene glacial deposits (Ballard and Oldale 1973). Moraine deposits cover much of the Gulf of Maine and Georges Bank area (Ballard and Oldale 1973). The topographic expression is believed by Ballard and Oldale (1973) to be due to the result of stream erosion during Tertiary and early Pleistocene time.
2.5.1.1.3 Regional Stratigraphy The generalized regional geologic map (Figure 2.5.1-4) shows the distribution of significant rock types in the region surrounding the Millstone site. The regional geologic section (Figure 2.5.1-5) was taken trending east-west from the Appalachian Plateau in New York to the eastern edge of the Triassic sediments and then southeastward through the Millstone site to the Coastal Plain sediments.
The regional stratigraphic correlation chart (Figure 2.5.1-7) gives a number of stratigraphic columns with correlations between regions of similar latitude as well as correlations between regions of similar longitude. Therefore, correlations are given parallel to and across the regional trend. Figure 2.5.1-8 gives more detailed stratigraphic information for areas within the site region. A detailed description of the rock units shown on this chart is included as Tables 2.5.1-1 through 2.5.1-7.
2.5.1.1.4 Regional Tectonics The Northern Appalachians have been affected by four major orogenies: the Avalonian, Taconian, Acadian, and possibly the Alleghenian. The Avalonian and the Alleghenian orogenies mainly affected the southeastern portions of New England. The first three of these orogenies have produced a complex series of anticlinoria and synclinoria that constitute the New England land mass. The prominent structural belts are the Green Mountain anticlinorium, the Connecticut Valley-Gaspe synclinorium, the Bronson Hill anticlinorium, the Merrimack synclinorium, and the Rockingham anticlinorium, all discussed in Section 2.5.1.1.2 and shown on Figure 2.5.1-6. These anticlinoria and synclinoria trend parallel to the Appalachian Mountain belt. Section 2.5.1.1.5 discusses the geologic history.
A detailed description of regional tectonics is included in this section, which forms the basis for the subdivision of New England into tectonic provinces (Section 2.5.2.2).
2.5.1.1.4.1 Domes and Basins As mentioned in Section 2.5.1.1.2, gneiss domes are present in the Connecticut Valley synclinorium and the Bronson Hill anticlinorium.
These domes differ geologically because the gneiss cores of those in the synclinorium may consist partly of Precambrian basement from beneath the Paleozoic sequence, whereas, the core gneisses on the anticlinorium seem to be intrusions into the pre-Silurian part of the rock sequence (Rodgers 1970). The Lyme and Willimantic domes (Figure 2.5.1-5) lie east of the Bronson Hill
MPS-3 FSAR 06/28/18 2.5.1-7 Rev. 31 anticlinorium. These domes are important to the geology of the Millstone site. Millstone is located just east of the Lyme dome. Both domes are overlain by an early Paleozoic sequence (Hebron Gneiss, Brimfield Schist, Tatnic Hill Formation, and Quinebaug Formation) and have a Precambrian-Cambrian core (Ivoryton Group, Plainfield Formation, and Sterling Plutonic Group)
(Lundgren and Ebblin 1972).
The most prominent basins in the region are the Triassic basins of the Connecticut Valley and New York-New Jersey and Pennsylvania areas, and the Carboniferous basins of southeastern New England (Figure 2.5.1-6). Offshore basins have been located by geophysical methods south of New England and in the Gulf of Maine (Section 2.5.1.1.2).
2.5.1.1.4.2 Faulting The effects of the different stages of mountain building are widespread throughout New England.
The varying types of faults present in different sections have allowed a reconstruction of the geologic history and an increased understanding of the tectonic forces related to each orogeny.
Characteristic crustal structures have been left by the Taconian and Acadian orogenies and later by the rifting during the Triassic-Jurassic period.
The area most affected by the Taconian orogeny is along the Hudson River from approximately Sudbury, Vermont, to the vicinity of Poughkeepsie, New York, and eastward into western Massachusetts. The region exhibits a number of gravity slices that slid off an uplifted block to the east during middle to late Ordovician time (Bird 1969).
A number of thrust faults are noticeable in New England. The Ammonoosuc fault in western New Hampshire (Figure 2.5.1-6) trends N25E (Rodgers 1970) and dips at approximately 38 degrees to the northwest. Silicified zones have been noted along the fault and the displacement has been estimated to be 7,000 feet (Billings 1956). The fault offsets the metamorphic isograds associated with the Acadian orogeny: however, it is intruded by granitic rocks associated with the White Mountain magma series (Billings 1956). Potassium-argon studies on biotite from the Conway Granite yield a radiometric age of 172 3 m.y.a. (Foland et al., 1971) indicating no movement along this fault since the granitic intrusion. Rodgers (1970) suggests that the Ammonoosuc may be a normal fault; however, Billings (1956) considers it a thrust fault.
Another major thrust fault system, the Lake Char-Honey Hill, lies in southern and eastern Connecticut. The Honey Hill, the east-west segment, extends from Chester near the Connecticut River eastward to south of Preston. The Lake Char section runs north-south from Lake Char in Massachusetts to Preston, Connecticut. The fault system is characterized by zones of cataclastic rocks up to 2,500 feet thick (Dixon and Lundgren 1968). The plane of the fault is an irregular, warped surface. The dip of the Honey Hill section is generally at low angles to the north with a maximum at 55 degrees in the Preston area; the Lake Char section dips westward at approximately 10 degrees (Dixon and Lundgren 1968). The Honey Hill part of the system is approximately 14 miles from the Millstone site.
The thrust fault activity along the Lake Char-Honey Hill system is thought to have begun in the middle to late Devonian and continued into the Permian period (170-225 m.y.a.). Movement on
MPS-3 FSAR 06/28/18 2.5.1-8 Rev. 31 the Honey Hill fault may have begun during metamorphism as part of the eastward displacement of the recumbent Chester syncline, which is not cut by the fault (Lundgren 1963). The major movement on the fault plane was toward the southeast (Dixon and Lundgren 1968). Dixon and Lundgren (1968) believe that movement associated with the Lake Char-Honey Hill system comprised the last pre-Triassic activity in the area.
Recently, Lundgren and Ebblin (1972) have hypothesized that the thick zones of cataclastic rock are related to relative upward movement of basement at different places and at different times from late Devonian to Permian. This intense folding developed major cataclastic units in zones of high shear between mantling rock and basement complexes. Three different episodes of uplift brought about the present alignment of structure in southern Connecticut.
Rodgers (1970) indicates that late movements occurred sometime after Carboniferous, but before the late Triassic. The Honey Hill fault is cut by faulting believed to be related to Triassic rifting (Rodgers 1970, Goldsmith 1967c).
Further to the northeast in Massachusetts is another large thrust fault system, the Clinton-Newbury, paralleling the Bloody Bluff system. Skehan (1969, 1973), Castle et al. (1976), and Dixon (1976) have suggested that the Clinton-Newbury - Bloody Bluff system is a continuation of the Lake Char-Honey Hill system of Connecticut. The Clinton-Newbury -Bloody Bluff zones run northeasterly from south of Worcester to Newburyport and into the Gulf of Maine (Skehan 1969).
Detailed mapping linking the Lake Char to the Bloody Bluff has yet to be done. Exposures in the Wachusett-Marlboro tunnel indicate that these faults dip to the northwest and are reverse in nature (Skehan 1968). The average direction of tectonic transport is to the east, similar to that of the Lake Char-Honey Hill fault. The dominant faulting is later than the metamorphism and is probably late Paleozoic to mid-Mesozoic (Skehan 1968). A prominent number of northerly trending, younger, high-angle faults have been observed throughout the New England area, some cutting the thrust faults associated with the Clinton-Newbury system.
The northern border of the Triassic Newark Basin is bounded by a series of closely spaced subparallel faults that commonly trend N30E to N50E and dip to the southeast. This Ramapo fault system has a complex history of movements dating back to late Precambrian (Ratcliffe 1971).
Late Triassic rejuvenation of the old fracture system produced the Newark depositional basin.
Normal faulting associated with the regional rifting and the deposition of the coarse conglomerates in the basin continued into the Jurassic (Ratcliffe 1971). Page et al. (1968) have reported recent seismic activity in the vicinity of the Ramapo, but there has been no movement detected at the surface.
The Triassic Connecticut Valley Basin extends from the Connecticut shore northward to the Massachusetts-Vermont border. The basin averages about 20 miles in width and exposes clastic sedimentary deposits interlayered with basalt flows and sills generally dipping to the east. At the eastern edge, the deposits are abruptly ended by a west dipping normal fault zone. It has been generally accepted that the Connecticut portion of the basin was formed by faulting that was contemporaneous with the deposition of the clastic sediments, and the fault zone of the east side brings into contact the Triassic sediments with the Paleozoic crystalline rocks to the east (Wheeler 1939, Sanders 1960). The northern part of the Triassic Basin may have had a slightly different
MPS-3 FSAR 06/28/18 2.5.1-9 Rev. 31 origin. Bain (1932) indicates that sections of the eastern contact between the Triassic and the Paleozoic sediments are depositional contacts with no evidence of faulting. Faulting along the northern portion of the basin has been established in the Mineral Hill area of Montague, Massachusetts (NUSCO. 1974). This fault has been interpreted as a thrust fault, which was later reactivated with minor normal displacement. Potassium-argon radiometric dating of fault gouges found along this fault and other small faults in the region yielded dates between 140 and 180 m.y.a. (NUSCO. 1974). These dates reflect the movement related to the extension tectonics of the Jurassic-Triassic period.
A number of smaller faults are associated with the Carboniferous basins of eastern Massachusetts and eastern Rhode Island. Some of these faults bound the basin. Many of the faults associated with the Boston Basin are thrust faults. These are smaller splays off the large Bloody Bluff fault system previously mentioned (Nelson 1976). These faults were originally formed during the compressional forces associated with the Acadian orogeny. Movement along the faults is believed to be associated with the climax of the regional metamorphic event (Nelson 1976). Nelson (1976) indicates that another near-surface fault system is post-Pennsylvanian in age, and that this system may be related to the faulting of the Pennsylvanian rocks of Rhode Island.
The eastern margin of the Woonsocket and North Scituate Basins is bounded by high angle faults (Quinn and Oliver 1962). Although a short portion of the western boundary of the Narragansett Basin is a normal fault (Quinn 1971), silicification along this fault may indicate some association with Triassic activities (Rodgers 1970). Other small faults on the northeast edge of the Narragansett Basin bring Pennsylvanian sedimentary rocks in contact with older plutonic rocks.
Geophysical studies by Ballard and Uchupi (1975) indicate a number of basins in the Gulf of Maine and the Georges Bank. These basins were postulated to be bounded by faults associated with the Triassic-Jurassic period. As shown on Figure 2.5.1-6, these authors suggest a Carboniferous basin extending offshore northeast of the Boston Basin. However, rock samples recovered from these areas by Ballard and Uchupi (1975) fail to support the existence of these geophysically-inferred basins.
Offshore geophysical studies by McMaster (1971) indicate a fault occurring southwest of Block Island. Recent work performed by Weston Geophysical Engineers, Inc., for New England Power Company (1976) and by the USGS (Needell and Lewis 1982) has indicated that this fault, named the New Shoreham fault, lies slightly east and extends further northward then originally indicated by McMaster (1971). It is a normal fault, striking approximately N30-50W and dipping at approximately 75 degrees to the northeast. The fault displaces sediments identified as Cretaceous; however, Pleistocene deposits are undisturbed. The nearest approach of the New Shoreham fault is approximately 21 miles southeast of Millstone Point (Figure 2.5.1-6).
Many faults have recently been investigated throughout New England. These investigations indicate that the last episode of movement was associated with Jurassic-Triassic tectonics. Lyons and Snellenburg (1971) have investigated three normal faults in New Hampshire. The study included the radiometric dating of the clay gouge generated during faulting. Radiometric testing performed on the illite portion of the clay gouge yielded ages between 157 and 164 m.y.a.
MPS-3 FSAR 06/28/18 2.5.1-10 Rev. 31 The Triassic Border fault was studied in detail in the Montague, Massachusetts area, and radiometric age determinations on clay gouge yielded dates between 140 and 180 m.y.a (NUSCO.
1974).
North-south trending high-angle faults have been analyzed in the Charlestown, Rhode Island area.
Potassium-argon test results on the illite clay gouge indicated dates ranging from 169 to 226 m.y.a. (NEPCo. 1976).
High-angle, north-south trending normal faults uncovered in the excavation of Millstone 3 have also been investigated (NNECO 1975, 1976, 1977) and are discussed in greater detail in Section 2.5.3.2. Radiometric age determinations on clay gouge indicate dates ranging from 109 to 200 m.y.a.
High-angle normal faults are quite common in southern New England. Two of these faults, the Lantern Hill (Rodgers 1970) and the unnamed fault in the Uncasville quadrangle, (Goldsmith 1967c), cut the Honey Hill fault. The unnamed fault in Uncasville (Goldsmith 1967c) dies out approximately 10.5 miles northeast of Millstone Point. These faults are believed to be related to the rifting associated with the Trassic-Jurassic period because radiometric age dating indicates that the last activity along some of these faults occurred in that period. Rodgers (1975), Skehan (1975), and Goldsmith (1973) believe that the hydrothermal activity, typically silicification, along faults of this type represents the youngest known tectonically related event in southern New England.
2.5.1.1.4.3 Tectonic Summary The structural pattern of New England (Figure 2.5.1-6) is characterized by strong north-northeast trends. The major anticlinoria and synclinoria, the alignment of domes and basins, the trend of the faulting, and the alignment of most of the granitic intrusions indicate a constant and pervasive tectonic force acting in the same orientation for a prolonged period of time.
Many of the features are the result of compressional forces acting throughout the region during much of the Paleozoic era. The area has undergone folding, igneous intrusion, refolding, and subsequently, thrust faulting.
The Mesozoic era was characterized by faulting and igneous activity differing from that of the Paleozoic era. Normal faulting associated with extensional forces is well developed in the southern New England area. The intrusion of diabase dikes and sills is also associated can be observed, physiographic and tonal. Tonal linear features may be due to a change in vegetation, whereas physiographic lineaments generally are due to topographic expression accentuated by erosion. These features are probably related to structural discontinuities, chiefly faults, shear zones, and joints (O'Leary et al., 1976).
2.5.1.1.4.4 Remote Sensing Land Satellite (LANDSAT) photographs of Connecticut, Rhode Island, southern Massachusetts, and eastern New York were studied to identify linear features or lineaments. A lineament is
MPS-3 FSAR 06/28/18 2.5.1-11 Rev. 31 defined as a mappable linear feature of a surface, with parts aligned in a rectilinear or slightly curvilinear relationship and which differs distinctly from the patterns of adjacent features and presumably reflects a subsurface phenomenon (O'Leary et al., 1976). Two types of lineaments can be observed, physiographic and tonal. Tonal linear features may be due to a change in vegetation, whereas physiographic lineaments generally are due to topographic expression accentuated by erosion. These features are probably related to structural discontinuities, chiefly faults, shear zones, and joints (O'Leary et al., 1976).
Figure 2.5.1-9 shows the LANDSAT photographs used for the study, and Figure 2.5.1-10 shows the lineaments greater than 10 miles long identified on the photographs. The explanation for the lineations shown on Figure 2.5.1-10 are given in Table 2.5.1-8. The linear features shown on Figure 2.5.1-10 are grouped into three categories:
1.
Those coinciding with mapped faults 2.
Those coinciding with mapped geologic contacts 3.
Those which are not identifiable with either of the above, but associated with topographic expression The lineaments shown on Figure 2.5.1-10 are, for the most part, due to differences in topography.
These differences may be due entirely to the resistance to erosion of the varying rock units. The majority of the lineaments coincide with geologic contacts which have been accentuated by the erosion of rivers and streams. As can be seen on Figure 2.5.1-10 and listed in Table 2.5.1-8, planes of weakness within rock masses have also accounted for a number of the lineaments.
Regional joint patterns and mapped faults are easily identifiable on the LANDSAT photographs.
These often correspond to topographic lows due to the erosion of the broken and more easily weathered material.
2.5.1.1.4.5 Structural Significance of Geophysical Studies Geophysical studies have aided in the interpretation of the geology of New England. The aeromagnetic and Bouguer gravity maps relating to regional geologic features are presented on Figures 2.5.1-11 and 2.5.1-12, respectively.
The aeromagnetic information shown on Figure 2.5.1-11 generally conforms to the regional geologic trends observed in New England.
A number of areas exhibit strong alignment or high intensity of magnetic character. The Lake Char-Honey Hill system in Connecticut and the Clinton-Newbury fault zone in Massachusetts are the most prominent lineations on the aeromagnetic map. The Cape Ann area, north of Boston, is characterized by its high magnetic intensity. This is caused by the combination of the high intensities related to the basic rock of the Salem Gabbrodiorite and the existence of a highly faulted and brecciated zone. The northwestern and southern boundaries of the Cape Ann area closely coincide with the Clinton-Newbury, the Bloody Bluff, and the Boston border faults
MPS-3 FSAR 06/28/18 2.5.1-12 Rev. 31 (Barosh and Pease 1974). The other obvious magnetic anomalies correspond to the plutons of the White Mountain series of New Hampshire and Maine.
Smaller, less striking anomalies occur in the site area, in the Cape Cod area, and in central Massachusetts just east of the Connecticut River Valley Triassic Basin. The anomaly in the Millstone area follows the folded pattern of the interlayed metasedimentary and metavolcanic rocks. The rock with very high susceptibilities apparently wraps around the structural features adjacent to the site (Lyme dome, Figures 2.5.1-13 and 2.5.1-14) and extends out into Long Island Sound (Barosh and Pease 1974). The anomalies on Cape Cod are probably due to large basic intrusive bodies (Barosh et al., 1974). The north-south trending anomaly east of the Triassic Basin in central Massachusetts is related to the presence of metavolcanic rocks of high magnetic susceptibility. Barosh and Pease (1974) indicate that the metavolcanic rocks to the south are less magnetically susceptible due to the effects of retrograde metamorphism and they are not noted on the aeromagnetic map.
Small isolated anomalies can be observed on the east side of the axis of the Green Mountain anticlinorium. A series of ultramafic bodies extending from Canada southward to Massachusetts (Skehan 1961) may be the cause of these anomalies.
Figure 2.5.1-12 shows the regional gravity in relation to the geologic structures of New England and the trend of the gravity anomalies corresponding to the differing structural alignment. The most prominent anomaly is along the axis of the Green Mountain anticlinorium. This gravity high appears to be caused by the relative uplift of a dense lower crust (Kane et al., 1972). In the eastern portion of New England, it is still apparent that the gravity anomalies follow the structural trend.
This trend is sharply broken by the large negative anomaly encompassing the White Mountains of New Hampshire. Other locally pronounced anomalies are found throughout New England and are, for the most part, associated with igneous masses. The large anomaly on Cape Ann is probably due to mafic rock underlying the Cape Ann series.
2.5.1.1.5 Regional Geologic History The Regional Geologic Map (Figure 2.5.1-4) shows the distribution and generalized age relationships of rocks in the New England area.
The geologic history of New England is complex because the region has been subject to several orogenies during the Precambrian and Paleozoic eras. The early and middle Paleozoic rocks represent geosynclinal sequences which have been deformed and recrystalized to varying degrees during the disturbances discussed below.
Younger, relatively unchanged rocks are found in the Carboniferous basins in southeastern New England and in the Triassic-Jurassic basins in south-central New England and New Jersey-Pennsylvania.
The youngest igneous activity in New England took place in the Mesozoic Era. The passive emplacement of the White Mountain series during the Jurassic and Cretaceous periods, and the
MPS-3 FSAR 06/28/18 2.5.1-13 Rev. 31 slightly younger activity of the Monteregian Hills during the Cretaceous period, appear to be the last tectonic activity.
Precambrian Differences have been recognized between the Precambrian rocks in the western part of New England and those of eastern New England. Basement rocks of western New England belong to the Grenville province. The older Precambrian rocks in this province include those in the core of the Adirondack Mountains and those of the Green Mountain, Berkshire, Housatonic, and Hudson Highlands massifs (Figure 2.5.1-6). Isachsen (1964) considers the Manhattan Prong to be Precambrian and is considered by Naylor (1975) to be part of the western basement. These rocks are characterized by high temperature, high pressure (granulite facies) metamorphism at 1,100 to 1,200 m.y.a. and may include units that formed significantly earlier (Naylor 1976). Rodgers (1968a) suggests that the eastern edge of the North American continent during the Cambrian and Early Ordovician periods coincided with the eastern edge of these massifs.
Precambrian rocks of eastern New England are believed to be associated with the Avalonian orogeny (Rodgers 1972). At Hoppin Hill, Massachusetts, the Dedham Granodiorite is unconformably overlain by lower Cambrian slate that is lithologically similar to sequences in Newfoundland (Skehan 1968). The eastern basement is considered to be a thick sequence of predominantly mafic volcanic rocks with intercalated metasedimentary rocks and granitic to gabbroic plutons lying underneath fossiliferous lower and middle Cambrian strata (Naylor 1976).
Rubidium-strontium (Rb-Sr) whole-rock ages for the Hoppin Hill Granite, Northbridge and Milford Granite, and the Dedham Granodiorite date from 514 to 591 m.y.a. (Fairbairn et al.,
1967). The eastern basement is nowhere characterized by granulite facies metamorphism and has not yielded zircon or rubidium-strontium whole-rock ages greater than 650 m.y.a. This basement represents a period of widespread volcanism and plutonism with peak activity between 600 and 650 m.y.a. (Naylor 1975). The eastern basement lies, for the most part, east of the Lake Char-Clinton Newbury fault system. Naylor (1976) considers the gneisses along the southeastern coast of Connecticut to be part of the eastern basement and not an eastward extension of the Bronson Hill sequence. The Millstone site lies in this sequence and it is discussed in greater detail in Section 2.5.1.2. Late Precambrian through early Devonian stratified sequences occupy most of the area between the eastern and western basements (Naylor 1975).
Early Paleozoic Two bands of Cambrian rocks are observed in New England; one along the Hudson and Champlain Valleys extending northward to Quebec, and the other in scattered outcrops along the present-day coast (Theokritoff 1968). The western band was a sand-carbonate shelf sloping steeply eastward and grading into a basin of mud deposition. The eastern band consists mainly of mud deposits around nonvolcanic islands. During early and middle Cambrian, Pacific province faunas occupied sites on the shelf and adjacent parts of the basin, whereas Acado-Baltic faunas occupied sites around the island chains (Theokritoff 1968).
Sedimentation continued into the Ordovician period. In early middle Ordovician, much of both the platform carbonates and terrain to the east were folded and became emergent (Berry 1968).
MPS-3 FSAR 06/28/18 2.5.1-14 Rev. 31 Breaks in deposition are noted by unconformities throughout New England. The uplifts caused instabilities including the submarine gravity slides of the Taconics, the folding and emergence of land masses to the east, and the deposition of deltaic sediments westward from these lands (Berry 1968). The uplifts were the surface effects of the orogenic deformation at depth accompanied by low-grade metamorphism (Rodgers 1970). Also associated with these events, referred to as the Taconian orogeny, was the intrusion of plutons related to the Highlandcroft magma series (Berry 1968). During much of middle Ordovician time, a series of volcanoes and islands existed along the present day Bronson Hill anticlinorium. Much of eastern Connecticut is underlain by metasedimentary, metavolcanic, and plutonic rocks related to this volcanic-island chain.
Activity related to the Taconian orogeny occurred as a discontinuous series of disturbances between 450 to 500 m.y.a. with the area of maximum deformation located in western New England (Rodgers 1970).
Middle Paleozoic During the Silurian period, those areas uplifted by the Taconian orogeny were gradually encroached upon and eventually covered (Boucot 1968). Volcanic rocks continued to be deposited along the Bronson Hill anticlinorium and volcanic activity became apparent along the Avalonian belt from southern New Brunswick through southeastern Maine to eastern Massachusetts (Rodgers 1970). A belt coinciding with the present-day Merrimack synclinorium was the locus of the thickest sequence of Silurian sediment in the New England region (Boucot 1968).
Graywackes and thick argillaceous sandstones characterize this sequence.
Carbonate sequences reached a maximum in the earliest part of the Devonian period in western New England (Rodgers 1970, Boucot 1968). Clastic material was deposited upon this calcareous sequence as the land mass to the east expanded westward (Boucot 1968).
By middle Devonian, deposition had ceased throughout the region and the area then underwent its most severe deformation, metamorphism, and granitic intrusions (Rodgers 1970). The Acadian Orogeny is responsible for most of the folding in the rocks presently exposed through the region.
The belt of maximum intensity of this activity extends southward from central Newfoundland to eastern Connecticut (Rodgers 1970). Faulting related to the Acadian Orogeny is widespread throughout the region. Disturbance of the regional metamorphic isograds indicates that folding and faulting continued after the peak of metamorphism (Thompson et al., 1968).
Late Paleozoic The deposition of material from this period is concentrated in the southeastern part of the region.
The Boston Basin of eastern Massachusetts and the Narragansett, Norfolk, Woonsocket, and Scituate Basins of Rhode Island and southeastern Massachusetts are the only remnants of sedimentation. Rocks in these basins consist generally of coarse clastic sediments of continental origin. The basins are controlled by faulting; the Boston Basin by high-angle reverse faulting (Nelson 1976) and the Narragansett by high-angle normal faulting (Weston Observatory 1976).
Metamorphism has only slightly affected the Boston Basin, whereas the Narragansett Basin has,
MPS-3 FSAR 06/28/18 2.5.1-15 Rev. 31 in the southwest portion, been metamorphosed to staurolite grade, with the grade of metamorphism decreasing to essentially none at the northern extent of the basin.
Deformation during the late Paleozoic is not widespread throughout New England. The Alleghenian orogeny has affected some areas of southern New England. The major manifestation of this orogeny is the granitic intrusion in southern Rhode Island and Connecticut. The gentle folding and the metamorphism of the Narragansett Basin sediments may also be attributed to the Alleghenian orogeny. Activity along the region's extensive system of thrust faults may have continued into the Permian period. A thermal disturbance yielding K-Ar dates of 230 to 260 m.y.a. has been observed in an area 60 to 80 miles wide extending northward from the southern Connecticut coast to southwestern Maine, the cause of which is still unknown (Zartman et al.,
1970). The igneous activity in Rhode Island and Connecticut may account for the southern extent; however, Permian granitic intrusions are not observed further north. Granitic and pegmatitic intrusions related to the Westerly Granite intrude the Monson Gneiss at the Millstone site.
Potassium-argon dating (NNECO. 1975) also indicates that the Monson Gneiss at the site has been affected by the thermal disturbance described by Zartman et al. (1970) (Section 2.5.1.2).
Mesozoic and Cenozoic Toward the end of the Triassic period, a series of linear, generally fault-bounded troughs formed in which continental clastic sediments and volcanics accumulated. Two of these basins are apparent in this region: the Connecticut Valley Triassic Basin and the Newark-Delaware Basin (Figure 2.5.1-9). Similar basins beneath and beyond the continental shelf off the eastern and southern coasts of New England have been inferred by geophysical studies (Sheridan 1974, Ballard and Uchupi 1972 and 1975, Mayhew 1974). Dikes of Triassic-Jurassic age are common throughout the region. High-angle faulting related to the rifting is also widespread throughout southern New England (Section 2.5.1.1.4.2).
Igneous activity in the region continued with the intrusion of the White Mountain plutonic-volcanic series. These rocks are found from northern to southeastern New Hampshire, southern Maine, and east central Vermont. Age determinations indicate that activity associated with the White Mountain series began in the Triassic and continued into the early Cretaceous period, 216 to 112 m.y.a. (Foland et al., 1971, Armstrong and Stump 1971). This plutonism-volcanism represents the last known localized tectonic activity that has occurred in the region of the site. Further north, igneous activity continued with the intrusion of the Monteregian Hills plutonic rocks. The latest activity associated with the Monteregian Hills is approximately 100 m.y.a. (NUSCO. 1974).
The Appalachian Mountains have apparently undergone continuous erosion since late Paleozoic except in the areas of down-dropped Triassic fault blocks (Rodgers 1967). After Jurassic peneplanation of the Piedmont Plateau and what presently underlies the Coastal Plain, a broad area parallel to the coast was submerged. Material eroded from the exposed Piedmont was deposited in the coastal area in the form of a seaward thickening wedge. This wedge is dominantly Cretaceous in age (Figures 2.5.1-2 and 2.5.1-5), but includes some thin deposits of Tertiary age.
MPS-3 FSAR 06/28/18 2.5.1-16 Rev. 31 During the Pleistocene epoch, all of New England was covered with ice. Before glaciation began, the principal valleys, ridges, and hills had already been shaped by long-continued erosion and, except in detail, were similar to those of today (Flint 1975). The ice scoured the land leaving scattered deposits throughout the area and advancing to and beyond the southern New England coast. Glacial deposits are the sole rock type exposed on eastern Long Island, Cape Cod, and Nantucket. The ice began to retreat from the Connecticut coast approximately 15,000 years ago (Flint 1975). Temporary advances and retreats of the front of the glacier caused deposits of end moraines prominent throughout southern Connecticut and Rhode Island (Flint 1975). Pleistocene deposition on the submerged Coastal Plain is dominated by a complex series of sedimentary sequences separated by unconformities. These relationships are the result of fluvial and marine processes active during regressions and transgressions of the sea (Knott and Hoskins 1968).
2.5.1.2 SITE GEOLOGY The Millstone site is located at the southern tip of Millstone Point in Waterford, Connecticut. The site is a low lying peninsula within the Seaboard Lowland section of the New England physiographic province. Its physiography is discussed in Section 2.5.1.2.1.
The Millstone area, like the rest of New England, was covered with glacial ice until approximately 15,000 years ago. The glaciers deposited a thick layer of glacial till and, as they receded, left end moraine and outwash deposits. The surficial geology of the area surrounding the Millstone site is shown on Figure 2.5.1-3.
The bedrock geology is characterized by extensive deformation, metamorphism, and intrusion by igneous bodies. The bedrock geology of the 5-mile radius is shown on Figure 2.5.1-13.
The geology of the eastern portion of Connecticut is made difficult to decipher by the complex folding and faulting of the Late Paleozoic era. The tectonic features of the eastern section of Connecticut are shown on Figure 2.5.1-14. As shown on this figure, the Millstone site lies approximately 30 miles east of the Triassic Border fault, and approximately 15 miles south of the Honey Hill fault. The area south of the Honey Hill fault is complexly folded. The site lies on the east limb of the recumbent Hunts Brook syncline which mantles the Lyme dome. The site location with relation to these structures is shown on Figure 2.5.1-14.
2.5.1.2.1 Site Physiography The Seaboard Lowland section of the New England physiographic province narrows along the Connecticut coast, as shown by Figure 2.5.1-1. In the Millstone Point area, this section narrows to approximately 15 miles, bordered on the north by the New England Upland section and just south of the site by the Coastal Plain physiographic province.
The most striking topographic expression in the area is the north-south trending ridges and valleys. The area is drained by a number of brooks and also the Thames, Niantic, and the Connecticut Rivers, the latter approximately 8 miles west of the site.
MPS-3 FSAR 06/28/18 2.5.1-17 Rev. 31 Glacial deposits dominate the Seaboard Lowland province in the Millstone area. Till covers much of the bedrock surface on both hills and smaller valleys, showing that the bedrock had been sculptured, by weathering and rainwater runoff, essentially to its surface existing before glaciation occurred (Flint 1975). End moraine and glacial stream deposits are also prevalent throughout the region (Figure 2.5.1-3).
The Millstone site is located on a small peninsula near the mouth of the Niantic River. Wave action has eroded the blanket of till from the promontories of Millstone Point, exposing rock. The reworked material was deposited as beach sand in the protected areas. Eolian deposits are found in some locations, and tidal marshes and swampy areas are common.
Much of the plant area has been graded and backfilled during the construction of the three units of the power generating facilities now at Millstone Point.
There is no physiographic evidence indicative of actual or potential localized subsidence, mass wasting, or landslides in the vicinity of the site.
2.5.1.2.2 Local Stratigraphy The site surficial and site bedrock maps are shown as Figures 2.5.1-3 and 2.5.1-13, respectively.
These maps cover approximately the area within the 5-mile radius of the site. The age relationships and descriptions of the differing bedrock units found within this region are shown on Figure 2.5.1-13.
The site is underlain by the Monson gneiss of pre-Silurian age and the Westerly Granite of Pennsylvanian or younger age. The bedrock units shown on Figure 2.5.1-13 are dominated by metasedimentary and metavolcanic rocks of Cambrian or possibly Precambrian or Ordovician age. The metasedimentary and metavolcanic units have been intruded by several granitic masses, of which the Sterling Plutonic Group is the oldest. The granitic gneisses seem to have been emplaced at fairly deep levels in the crust, for they are associated with migmatites and are intimately intermingled with, and grade into, some associated metasedimentary and metavolcanic gneisses (Goldsmith and Dixon 1968). The Sterling gneiss units have not been noted stratigraphically above the Monson gneiss in the site area. The younger granitic intrusions are the nodular granites located in the Lyme dome and the Westerly Granite located along the coastline.
These granites are believed to be Permian in age (Goldsmith 1967b).
The distribution of Quaternary surficial material is shown on Figure 2.5.1-3. This material includes such glacial deposits as glacial till, end moraine deposits, and stream deposits. Younger swamp, littoral, alluvial, and eolian deposits also occur.
2.5.1.2.3 Site Stratigraphy The excavation for Millstone 3 has been extensively mapped. These maps are shown and described in Section 2.5.4.1. In the site area, the bedrock surface is very irregular and completely covered with glacial till. Construction activities from Millstone 1 and 2 disturbed the naturally deposited material in the site area which, for the most part, was replaced with artificial fill.
MPS-3 FSAR 06/28/18 2.5.1-18 Rev. 31 The Monson gneiss is the main rock found at the site, as shown on Figure 2.5.1-13. This rock is a biotite-quartz-andesine gneiss. Petrographic analyses indicate that the main constituents are:
plagioclase (45 percent), quartz (35 percent), and biotite (15 percent). Sericite, garnet, apatite, epidote-clinozoisite, and zircon are also present (NNECo. 1975). The Monson gneiss is medium-grained, light gray with strong biotite foliation. A number of biotite segregation bands were observed throughout the excavation (Section 2.5.4).
The Monson gneiss is intruded by pegmatite and granite sills related to the Westerly Granite which was quarried on Millstone Point until 1960. The distinction between a granitic and a pegmatitic intrusion is a subtle one. Both intrusions are related to the same source and variable grain sizes are inherent in each. The Westerly Granite is considered to be a dike rock consisting of gray to pink, fine-to-medium-grained, equigranular granite composed of oligoclase, microcline, and quartz. The pegmatitic intrusions are similar in composition to the Westerly Granite intrusions except for their coarser grain size. Biotite, muscovite, and accessory minerals are also present in smaller percentages (Goldsmith 1967b, Lundgren 1967).
The entire bedrock surface at Millstone is covered by a layer of glacial till consisting of both basal and ablation tills. The basal till is a dense, unsorted soil material plastered and compacted into place by the weight and dynamic pressure of an actively moving glacier. The ablation till was deposited as the ice retreated. It is generally an unsorted material and, because it was subjected to a lighter load than the basal till, it is less dense.
The basal till consists of a mixture of cobble and boulder size rock fragments, gravel size material, sand, and some silt binder. The ablation till is irregularly stratified with lenses of sand and gravel and mixtures of cobbles, gravel, sand, and silts.
Glacial stream deposits are also present on Millstone Point (Figure 2.5.1-3), for the most part consisting of stratified sands with some silts and gravel.
Younger beach, swamp, and marsh deposits are also observed in the site area (Figure 2.5.1-3).
The beach deposits are chiefly well sorted sand and pebbly gravel deposited by current and wave action.
2.5.1.2.4 Local Structural Geology The Millstone site lies on the southeastern coast of Connecticut. The regional tectonic map (Figure 2.5.1-6) shows the location of the site with respect to the major structural features of New England. Figure 2.5.1-14 illustrates the generalized tectonic elements of eastern Connecticut and Figure 2.5.1-13 shows the structure within the 5-mile radius.
The tectonic map of eastern Connecticut (Figure 2.5.1-14) shows the major folds and faults that have affected the region. Three orogenies (Taconian, Acadian, Alleghenian) have structurally left their imprint on a series of complexly deformed rocks. As shown by the site bedrock geology map (Figure 2.5.1-13), the Lyme dome, Hunts Brook syncline, and two smaller anticlines lie within the site area. The larger structural features, such as the Bronson Hill anticlinorium, the Merrimack synclinorium, and the Lake Char-Honey Hill fault system, have been discussed in
MPS-3 FSAR 06/28/18 2.5.1-19 Rev. 31 Sections 2.5.1.1.2 and 2.5.1.1.4.2 and are shown on Figure 2.5.1-6.
The structural trend south of Honey Hill is generally east-west, whereas, in the remaining portions of the state, the structural trends are north-south, paralleling the regional trend.
The north-south and east-west structures tend to meet in the Killingworth dome. This is not a simple dome and must have reached its present form and acquired its complicated internal structure in several stages (Lundgren and Thurrell 1973). Recumbent isoclinal folds are common throughout and the dome itself may consist of a series of antiforms and synforms.
The Lyme dome, east of the Killingworth dome (Figure 2.5.1-14), also appears to be a simple anticlinal structure; however, the dome is mantled by the folded isoclinal Hunts Brooks syncline.
The extent of the dome is marked by the contact between the Mamacoke Formation, Monson gneiss, or the Brimfield schist with the Plainfield Formation (Figure 2.5.1-13). The broad internal structure of the dome is indicated by the pattern of the middle unit of the Plainfield Formation and the alaskite units (Sterling Plutonic Group) and by the foliation pattern (Lundgren 1967).
Distribution of the stratigraphic units indicates that the dome is a northward plunging anticline.
The Lyme dome lies just west of the Millstone site (Figure 2.5.1-13).
The Selden Neck dome, which parallels the Honey Hill fault, is the last major dome south of the fault. This dome is essentially an overturned, possibly recumbent, anticline having a folded axial surface that dips north or northwest (Lundgren 1966).
The Hunts Brook syncline, which separates the Selden Neck dome from the Lyme dome, is the last prominent fold south of the Honey Hill fault. The isoclinal syncline bends around the Lyme dome and the trace of the axial plane lies within the belt of the Brimfield schist and the Tatnic Hill Formation. The axial plane of the Hunts Brook syncline dips away from the Lyme dome; in the Millstone area, the syncline dips to the east with the site lying on the overturned limb.
The Hunts Brook syncline meets the Chester syncline in the Killingworth dome area. Lundgren (1966) has proposed two theories concerning the relationship between these two synclines. If the Hunts Brook syncline is a folded overturned syncline with a nearly horizontal axis, then this axis probably meets the axis of the Chester syncline at a right angle, implying that the Hunts Brook formed after or during the development of the recumbent Chester syncline. However, if the Hunts Brook syncline plunges steeply to the northwest, then it could merge with the Chester syncline beneath the Selden Neck dome (Lundgren 1966).
The Chester syncline is a recumbent isoclinal syncline trending north from the Killingworth dome region and exhibiting a complexly folded axial plane which parallels the Monson anticline until it reaches a point north of the Honey Hill fault which it parallels for some distance (Figure 2.5.1-14).
Two smaller anticlines are shown on Figure 2.5.1-13. Both are overturned isoclinal anticlines with their axial planes dipping to the northwest. The area is complexly folded and it appears that the two anticlines may actually be one.
MPS-3 FSAR 06/28/18 2.5.1-20 Rev. 31 Faulting is not conspicuous on quadrangle maps within the site area; however, faulting has played an important role in the geological history of southern Connecticut.
The Honey Hill fault (Section 2.5.1.1.4.2) lies approximately 15 miles north of the Millstone site.
The closest mapped fault is approximately 10 miles northeast of the site in the Uncasville quadrangle (Figure 2.5.1-14). This fault trends north-south and is believed by Goldsmith (1973) to be a normal fault related to Triassic tectonics. The amount of displacement is unknown, but it is shown to cut the Honey Hill fault (Goldsmith 1967c). This faulting is thought to be related to the Lantern Hill fault further to the east due to its similar attitude. The Triassic Border fault lies approximately 30 miles west of the site (Figure 2.5.1-14).
A number of faults have been uncovered during the construction of Millstone 3 and are discussed in detail in Section 2.5.3.2.
2.5.1.2.4.1 Site Structural Geology The Millstone site lies on the overturned eastern limb of the Hunts Brook syncline (Figure 2.5.1-13). The axial plane of the syncline in the site area dips to the east as shown on Section A-A of Figure 2.5.1-13. Detailed mapping of the excavation has yielded much information on the geology of Millstone Point (Sections 2.5.3.2 and 2.5.4.1).
The site is founded for the most part on the Monson gneiss which is part of a series of lower Paleozoic metavolcanic and metasedimentary rocks and granitic gneisses that underlie most of eastern Connecticut (Goldsmith and Dixon 1968). The Monson gneiss at the site area is light gray, medium grained, thinly layered with light feldspathic and dark biotite and hornblendic layers (Goldsmith 1976b). It consists of plagioglase (45 percent), quartz (35 percent), and biotite (15 percent) with accessories of garnet, apatite, epidote-clinozoisite, and zircon (NNECo. 1975). The foliation is a well defined alignment of biotite flakes. Figure 2.5.1-15 is a lower hemisphere plot showing the foliation readings taken from final grade mapping. The average foliation attitude for 344 points is N67W, 48NE. Segregation bands of biotite are apparent throughout the site.
The Monson gneiss has been intruded by a series of pegmatite and granite bodies. For the most part, these granitic intrusions are parallel to the foliation and believed to be related to the injection of the Westerly Granite (Goldsmith 1967b), which is a prominent intrusion throughout southeastern Connecticut and Rhode Island (Goldsmith 1967b).
Jointing is well developed at the site with the major joint set striking N03W and dipping 63NE.
Figure 2.5.1-16 gives a contour diagram of poles to joint planes for the joints observed while mapping final grade. Minor joint sets have attitudes of N02W, 78SW; N69E, 74SE; and N48W, 07NE. The joints generally exhibit smooth, planar surfaces with a majority having a coating of chlorite and some showing iron oxide staining. Jointing at the site is discussed further in Section 2.5.3.2.3. Slickensides were found in 241 locations. Figure 2.5.1-17 gives the contour plot of these data. The points are concentrated along the east-west axis, indicating that the major direction of displacement is east-west. The points also indicate the association of the slickensides with high angle planes, thus implying a minor readjustment of dip-slip type.
MPS-3 FSAR 06/28/18 2.5.1-21 Rev. 31 Eleven separate fault zones with numerous minor associated faults have been uncovered at the Millstone site. Section 2.5.3.2 discusses these faults in greater detail. All but one of the faults trend northerly and dip at high angles east or west. The other fault is a minor low angle thrust.
Figure 2.5.1-18 shows the location of these faults. The faults are all incapable features with the last activity occurring approximately 142 m.y.a. Slickenside information and a section through fault 18 in the Millstone 2 and 3 condensate polishing facilities indicate that the faulting is of the normal type, with some oblique dip-slip movement.
2.5.1.2.5 Site Geological History The geological history of southeastern Connecticut is obscured by the complex folding and metamorphism that the area has undergone. The Taconian, Acadian, and Alleghenian orogenies have affected the area to a varying extent (Goldsmith and Dixon 1968).
The ages of the rocks present in the site area are still in doubt. The Monson gneiss, the New London gneiss, the Mamacoke Formation, and the Plainfield Formation are pre-Silurian in age, and most probably the rocks range in age from late Precambrian or Cambrian to Ordovician, (Goldsmith 1976). The Brimfield schist, which lies unconformably beneath the Bolton Group, is similar to and can be traced into the Partridge Formation and the Ammonoosuc volcanics of Middle Ordovician age (Goldsmith and Dixon 1968). Two major plutonic rocks are present in the site area, the Sterling Plutonic Group and the Westerly Granite. The older Sterling Plutonic Group is believed to be Cambrian or older in southern Connecticut and does not occur stratigraphically above the Monson Gneiss around Millstone Point (Goldsmith and Dixon 1968). However, the Sterling Group is younger that the Monson gneiss, so the Sterling may be Ordovician or younger.
The youngest rock type present in the site area is the Westerly Granite, which is regarded as Permian (Lundgren 1967). A granitic intrusion other than the Sterling Plutonic Group or Westerly Granite occurs in the Lyme dome. This nodular granite is believed to be older than the Westerly Granite and younger than the granitic intrusions of the Sterling Plutonic Group (Goldsmith 1967b).
The relationship of the rocks within the site area is shown on the stratigraphic chart for the surrounding area (Figure 2.5.1-7) and described in Tables 2.5.1-1 through 2.5.1-7. Figure 2.5.1-13 shows the distribution of the bedrock units.
The origin of the oldest rocks found in the site area, the Plainfield and the Mamacoke Formations, is obscure. These probably were originally quartz sandstone, limestone and dolostone, and shale (Lundgren 1966). The age of these rocks is still questioned, although it is believed that the rocks are of Cambrian age (Page 1976). The remaining rocks in the site region with the exception of the Nodular and Westerly Granites are probably Ordovician in age.
The Monson and New London gneisses are believed to be metamorphosed andesitic and dacitic volcanics and associated intrusions (Lundgren 1967). As mentioned in Section 2.5.1.1.5, the present day Bronson Hill anticlinorium was the location of a series of volcanoes and islands which served as a source area for much of the middle Ordovician period.
MPS-3 FSAR 06/28/18 2.5.1-22 Rev. 31 The Sterling Plutonic Group is present throughout much of the site area. The youngest unit it intrudes is the Monson gneiss. The age of the Sterling Group is still questioned. Radiometric dates for contiguous granitic gneisses in southern Connecticut suggest a Cambrian or older age (Goldsmith and Dixon 1968). However, the Monson gneiss, outside of the site area, has been dated as 472 m.y.a. +/-15 (Brookins and Hurley 1965) and radiometric work by Zartman et al.
(1965) implies that the Quinebaug Formation, correlated with the Monson, is middle Ordovician.
The Sterling gneisses seem to have been emplaced at fairly deep levels in the crust, for they are associated with migmatites and are intimately intermingled with and grade into some associated metasedimentary and metavolcanic gneisses (Goldsmith and Dixon 1968). The Sterling Plutonic Group is widespread in Rhode Island, underlying most of the central portion of the state and considered to be late Precambrian or Cambrian in age.
Thus, the age relations are problematic and have not been resolved to date.
The Brimfield schist consisted originally of shale imbedded with minor amounts of quartz, sandstone, limestone, andesitic and basaltic pyroclastics, and manganese-bearing chert. The deposition of this pelitic unit represents a major change in the character of sedimentation, as volcanic rocks are of subordinate importance in the section above the base of the Brimfield and Tatnic Hill Formations (Lundgren 1964). The Brimfield and Tatnic Hill Formations may have been deposited as geographically separate facies of a single stratigraphic unit (Lundgren 1964).
The Brimfield schist is the youngest pre-Pennsylvanian rock found within the site area.
Much of the deformation that occurred in the Millstone area has been attributed to the Acadian orogeny, which affected much of central and eastern New England. The initial stages in the formation of the complex structure now observed are the north-south trending recumbent isoclinal folds (Monson anticline and Chester syncline) which were formed in response to an east-west compression during early stages of post-Silurian metamorphism (Figure 2.5.1-14) (Lundgren 1964). Deformations continued with the development of the east-west trending anticlines and synclines, the Selden Neck dome and Hunts Brook syncline, respectively. Most of the major features of the map pattern in the rocks south of the Honey Hill fault are the combined result of the formation of the Lyme dome and the antiform at Chester. This uplift deformed the Hunts Brook syncline, the Selden Neck dome, and the Honey Hill fault, resulting in the present structural configuration.
Metamorphism accompanied the structural development mentioned above. Metamorphism of all the rocks produced assemblages characteristic of the upper amphibolite facies (Lundgren 1966).
Lundgren (1964) believes the metamorphism took place when the rocks were deeply buried, probably at depths of 15 to 20 kilometers where the temperature was 550 to 650°C.
Metamorphism presumably began during the Devonian period but may have continued into the Permian (Lundgren 1963).
The Honey Hill faulting also was initiated during the Acadian orogeny as part of the eastward displacement of the recumbent Chester syncline. Movement along the Honey Hill fault is believed to be southeasterly, continuing beyond the period of peak metamorphism (Dixon and Lundgren 1968).
MPS-3 FSAR 06/28/18 2.5.1-23 Rev. 31 Lundgren and Ebblin (1972) have proposed that the Honey Hill fault zone is related to the shearing between the Putnam Group and the underlying Ivoryton and Sterling Plutonic Groups during the folding and uplifts of the Acadian orogeny. Movement along the Honey Hill fault may have continued into the Permian period.
Following the highly active Acadian orogeny was a milder period of gentle folding, granitic intrusion, and localized thermal activity. The Alleghenian orogeny affected only the southeastern portion of New England, mainly Rhode Island and southeastern Connecticut. The main manifestation of the Alleghenian orogeny was the intrusion of the Narragansett Pier Granite and the Westerly Granite. The Pennsylvanian sediments of the Narragansett Basin of Rhode Island exhibit folding associated with this orogeny. The thermal activity is exhibited by a narrow band extending from southern Connecticut to southwestern Maine. These rocks yield potassium-argon dates of 230 to 260 m.y.a. The actual cause of this disturbance is still questioned although it could be attributed to contact metamorphism related to contemporaneous igneous activity, alteration associated with major faulting, regional metamorphism in late Paleozoic time, or burial followed by uplift and erosion (Zartman et al., 1970).
The Millstone site has been affected by thermal disturbance and granitic intrusion. Granitic intrusions parallel to the foliation of the Monson gneiss, folded and overturned during the Acadian orogeny, are widespread throughout the site area.
Potassium-argon dating of biotite from the gneiss and the granitic intrusions at the site yielded a range of ages from 208 to 273 m.y.a. (NNECo. 1975). At Millstone Point, the thermal disturbance could be attributed to contact metamorphism during emplacement of the Westerly Granite.
The most recently known expression of tectonic activity in the local area is faulting related to Triassic-Jurassic rifting. Small high angle faults and joints associated with the larger Triassic faults of the Triassic Basin (Figure 2.5.1-14) are common in the Clinton quadrangle to the west (Lundgren and Thurrell 1973) and in the Moodus and Colchester quadrangles to the north (Lundgren et al., 1971). Goldsmith (1967a) shows two small high-angle faults in the Uncasville quadrangle northeast of the site, which he believes to be related to the Triassic-Jurassic tectonics (Goldsmith 1973). No faults are shown adjacent to the site on the quadrangle maps. In the process of mapping the excavation at the Millstone site, eleven fault zones were uncovered (Section 2.5.3.2). Potassium-argon dating of clay gouge from some of these fault zones indicates that the last activity along these zones occurred about 142 m.y.a. Also associated with the Triassic-Jurassic periods are the deposits of arkosic clastic sediments in the Connecticut Basin, extrusive igneous activity, and related injection of basic dikes throughout southern New England.
Hydrothermal activity, typically silicification, is commonly found along faults related to the Triassic-Jurassic tectonics. Rodgers (1975), Skehan (1975), and Goldsmith (1973) believe that the hydrothermal activity represents the youngest known tectonically related event in southern New England.
Recent study of dikes in southwestern Rhode Island and eastern Connecticut indicates that a few lamprophyre dikes may be as young as Cretaceous. Their relation to hydrothermal activity is not known.
MPS-3 FSAR 06/28/18 2.5.1-24 Rev. 31 Lundgren (1966) estimates an uplift of 15,000 to 20,000 feet occurred between the Permian and late Triassic periods. A long, continuous period of erosion followed, shaping principal valleys, ridges, and hills, similar to those of today (Flint 1975). Cretaceous and Tertiary sediments are present south of the site (Figure 2.5.1-2). The northernmost previous extent of these deposits is unknown. During Tertiary and Quaternary time, alternating periods of transgression and regression occurred along the coast of southern New England. The two major regressions took place during the Oligocene epoch and during the Pleistocene glaciation (Garrison 1970).
Evidence from outside the site area indicates that during the last million years or more, Connecticut was covered by continental glaciers at least twice, and possibly several times, however, evidence of only one glaciation is found locally (Flint 1975). The ice at its maximum reached its outer limit along a line on, or south of, what is now Long Island and culminated approximately 18,000 years ago (Flint 1975). Pollen studies and radiocarbon dates on samples taken in New London show that glaciation took place more than 13,000 years ago (Goldsmith 1960, 1962a). Caldwell (Appendix 2.5A), after visiting the Millstone site, indicated that the last deposition of till was approximately 18,000 years ago and that ice covered the area until about 14,000 years ago. The cumulative effect of the glaciation was to smooth, round off, and widen some of the valleys and to remove most of the pre-existing regolith (Flint 1975).
The Millstone area is covered with glacial till, end moraine deposits, and outwash sands as shown on Figure 2.5.1-3. The end moraines are common across Rhode Island and southern Connecticut.
They were deposited when the recession of the glacial margin slowed or stopped for some period (Flint 1975).
Excavations along the discharge tunnel uncovered slumped and faulted ablation till and outwash deposits. These features were found to be quite common in the outwash and are believed to be related to penecontemporaneous soft sediment deformations, in some cases associated with melting out of buried ice blocks (NNECO. 1982).
Since the glacial period, the surficial geology has been most drastically changed by the rise in sea level, which reworked the glacial outwash and eroded till and rock promontories, then depositing this material on the beach to be reworked by the wind to form dunes.
2.5.1.2.6 Site Engineering Geology All Category I structures at Millstone 3 are founded on rock, dense basal till, or compacted granular backfill. The properties of the subsurface materials are given in Section 2.5.4.2.
The country rock at the site is the Monson gneiss. This gneiss exhibits a well-developed foliation due to the alignment of biotite flakes. Segregation bands of biotite were also uncovered at the site.
Figure 2.5.1-15 shows that the attitude of the foliation is quite consistent at N67E, 48NE. Jointing at the site is also very well-developed. The contour plot of the Lower Hemisphere projection (Figure 2.5.1-16) indicates one major joint set with three minor sets. The most prominent set has an average attitude of N03W, 63NE. The minor sets have attitudes of N02W, 78SW; N69E, 74SE; and N48W 07NE.
MPS-3 FSAR 06/28/18 2.5.1-25 Rev. 31 The combination of the weakness planes, joints, and foliation indicates that a potential for instability of rock slopes exists. This potential is explained in detail in Section 2.5.4.14.
The geology of the excavation is also described in Section 2.5.4.1. Maps showing the geology of the floors and walls of structure excavations accompany this description. During the mapping of the excavation, eleven fault zones were uncovered. The relationship between these faults is shown on Figure 2.5.1-18 and shown in greater detail on the geology maps associated with Section 2.5.4.1.
An old granite quarry is located in the Westerly Granite about 1,200 feet south-southeast of the plant area. This quarry was in operation as an open pit, unsupported excavation from 1830 to 1960. The rock is sound and self-supporting, and this excavation does not influence the stability of the site in any way. Neither the Westerly Granite nor the Monson gneiss are ore-bearing and there are no mining activities at present and none are anticipated in the future.
Both the basal and overlying ablation tills are relatively impervious. The only water flow through the gneiss noted during construction was along intersecting joints that extended upward to the surface. This flow was handled quite readily by sumps located throughout the excavation.
Permanent sumps have been located around the structures to take care of this groundwater flow during the operation of the plant. The site groundwater conditions are covered in detail in Section 2.4.13 and the structure dewatering system is described in Section 3.8.5.1.
2.5.
1.3 REFERENCES
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Implications of New Radiometric Ages in Eastern Connecticut and Massachusetts.
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MPS-3 FSAR 06/28/18 2.5.1-37 Rev. 31 TABLE 2.5.1-1 ROCK FORMATIONS OF THE COASTAL PLAIN OFF SOUTHERN NEW ENGLAND CLICK HERE TO SEE TABLE 2.5.1-1
MPS-3 FSAR 06/28/18 2.5.1-38 Rev. 31 TABLE 2.5.1-2 ROCK FORMATIONS OF WESTERN CONNECTICUT CLICK HERE TO SEE TABLE 2.5.1-2
MPS-3 FSAR 06/28/18 2.5.1-39 Rev. 31 TABLE 2.5.1-3 ROCK FORMATIONS OF EASTERN CONNECTICUT AND WESTERN RHODE ISLAND CLICK HERE TO SEE TABLE 2.5.1-3
MPS-3 FSAR 06/28/18 2.5.1-40 Rev. 31 TABLE 2.5.1-4 ROCK FORMATIONS OF CENTRAL RHODE ISLAND (AND NOT INCLUDED IN PREVIOUS DESCRIPTIONS)
CLICK HERE TO SEE TABLE 2.5.1-4
MPS-3 FSAR 06/28/18 2.5.1-41 Rev. 31 TABLE 2.5.1-5 ROCK FORMATIONS IN NORTHERN AND EASTERN RHODE ISLAND AND SOUTHERN MASSACHUSETTS CLICK HERE TO SEE TABLE 2.5.1-5
MPS-3 FSAR 06/28/18 2.5.1-42 Rev. 31 TABLE 2.5.1-6 ROCK FORMATIONS OF CENTRAL MASSACHUSETTS CLICK HERE TO SEE TABLE 2.5.1-6
MPS-3 FSAR 06/28/18 2.5.1-43 Rev. 31 TABLE 2.5.1-7 EAST OF CLINTON-NEWBURY FAULT SYSTEM, EASTERN MASSACHUSETTS, AND NEW HAMPSHIRE CLICK HERE TO SEE TABLE 2.5.1-7
MPS-3 FSAR 06/28/18 2.5.1-44 Rev. 31 TABLE 2.5.1-8 DESCRIPTIONS OF LINEAMENTS FROM LANDSAT PHOTOGRAPHS (SHOWN ON FIGURE 2.5.1-10)
CLICK HERE TO SEE TABLE 2.5.1-8
MPS-3 FSAR 06/28/18 2.5.1-45 Rev. 31 FIGURE 2.5.1-1 REGIONAL PHYSIOGRAPHIC MAP
MPS-3 FSAR 06/28/18 2.5.1-46 Rev. 31 FIGURE 2.5.1-2 REGIONAL PRE-PLEISTOCENE SEDIMENTS OF THE CONTINENTAL MARGIN
MPS-3 FSAR 06/28/18 2.5.1-47 Rev. 31 FIGURE 2.5.1-3 SITE SURFICIAL GEOLOGY
MPS-3 FSAR 06/28/18 2.5.1-48 Rev. 31 FIGURE 2.5.1-4 REGIONAL GEOLOGIC MAP
MPS-3 FSAR 06/28/18 2.5.1-49 Rev. 31 FIGURE 2.5.1-5 REGIONAL GEOLOGIC SECTION
MPS-3 FSAR 06/28/18 2.5.1-50 Rev. 31 FIGURE 2.5.1-6 REGIONAL TECTONIC MAP
MPS-3 FSAR 06/28/18 2.5.1-51 Rev. 31 FIGURE 2.5.1-7 STRATIGRAPHIC CORRELATION CHART FOR THE SITE AND SURROUNDING REGION)
MPS-3 FSAR 06/28/18 2.5.1-52 Rev. 31 FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 1)
MPS-3 FSAR 06/28/18 2.5.1-53 Rev. 31 FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 2)
MPS-3 FSAR 06/28/18 2.5.1-54 Rev. 31 FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 3)
MPS-3 FSAR 06/28/18 2.5.1-55 Rev. 31 FIGURE 2.5.1-9 LANDSAT PHOTOGRAPHS OF CONNECTICUT, RHODE ISLAND, SOUTHERN MASSACHUSETTS, AND EASTERN NEW YORK
MPS-3 FSAR 06/28/18 2.5.1-56 Rev. 31 FIGURE 2.5.1-10 LINEAMENT MAP FROM LANDSAT PHOTOGRAPHS
06/28/18 2.5.1-57 Rev. 31 MPS-3 FSAR FIGURE 2.5.1-11 REGIONAL AEROMAGNETIC MAP
MPS-3 FSAR 06/28/18 2.5.1-58 Rev. 31 FIGURE 2.5.1-12 REGIONAL BOUGUER GRAVITY MAP
MPS-3 FSAR 06/28/18 2.5.1-59 Rev. 31 FIGURE 2.5.1-13 SITE BEDROCK GEOLOGY
MPS-3 FSAR 06/28/18 2.5.1-60 Rev. 31 FIGURE 2.5.1-14 TECTONIC MAP OF EASTERN CONNECTICUT
06/28/18 2.5.1-61 Rev. 31 MPS-3 FSAR FIGURE 2.5.1-15 CONTOUR DIAGRAM OF POLES TO FOLIATION PLANES - FINAL GRADE
06/28/18 2.5.1-62 Rev. 31 MPS-3 FSAR FIGURE 2.5.1-16 CONTOUR DIAGRAM OF POLES TO JOINT PLANES - FINAL GRADE
06/28/18 2.5.1-63 Rev. 31 MPS-3 FSAR FIGURE 2.5.1-17 CONTOUR PLOT OF BEARING AND PLUNGE OF SLICKENSIDES - FINAL GRADE
MPS-3 FSAR SECURITY-RELATED-INFORMATIONWithheld under 10 CFR 2.390 (d) (1) 06/28/18 2.5.1-64 Rev. 31 FIGURE 2.5.1-18 GENERALIZED LOCATION OF FAULTS
MPS-3 FSAR 06/28/18 2.5.2-1 Rev. 31 2.5.2 VIBRATORY GROUND MOTION The site region is characterized by earthquakes of low to moderate intensity. During the past 300 years, only 13 earthquakes greater than or equal to Intensity V Modified Mercalli (MM) have been reported within 50 miles of the site. The site lies in the Southeastern New England-Maritime Tectonic Province. The largest earthquake in this province was an Intensity VI (MM) event which occurred in 1904 east of Eastport, Maine. Two moderate size earthquakes have occurred in the Moodus, Connecticut area, located in the adjacent New England Province, in 1568 (Intensity VII (MM)) and 1791 (Intensity VI-VII (MM)). The maximum earthquake potential at the site is assumed to be due to an earthquake of Intensity VII (MM) occurring close to the site. This corresponds to a peak ground acceleration of 0.10 g. The safe shutdown earthquake (SSE) has conservatively been specified as 0.17 g. The operating basis earthquake (OBE) has been specified as 0.09 g, which corresponds to approximately half the SSE.
2.5.2.1 SEISMICITY Most of the information on earthquake activity in the northeastern United States is based on historical reports, old diaries, and newspaper accounts. These earthquakes are classified on the basis of intensity corresponding to the Modified Mercalli scale. This scale, developed in 1931 and described in Table 2.5.2-1, is based on observations of the effects of earthquakes and damage to structures. The instrumental monitoring of earthquakes began in the mid 1920s in the northeastern United States. Magnitude, a measure of earthquake energy, is determined from instrumental data.
The number of seismographic stations has greatly increased in recent times. At present, Weston Observatory of Boston College, Lamont-Doherty Geological Observatory of Columbia University, Massachusetts Institute of Technology, University of Connecticut, Pennsylvania State University, and Delaware Geological Survey operate seismographic stations in the northeast and coordinate the publication of the Northeastern United States Seismic Network (NEUSSN) bulletin. Figure 2.5.2-1 shows the location of stations in this network and Table 2.5.2-2 lists the locations and other pertinent data for these stations. Historical reports of earthquakes and information obtained from instrumental coverage in recent years form the basis of this examination of the seismicity of the site region.
2.5.2.1.1 Completeness and Reliability of Earthquake Cataloging Even though major historical catalogs carry entries dating back almost three centuries, the coverage of this period is not continuous. The completeness and reliability of the data are related to population distribution and, recently, to the seismograph network coverage. Therefore, accuracy of epicentral coordinates and the assigned maximum intensities must be evaluated carefully.
For the earlier historical events, epicenters were located closer to population centers due to the absence of reports from the true epicentral area. The intensity of an earthquake at a given location depends not only on accurate and complete human observations, but also on foundation conditions, design, type, and quality of building construction. Construction practices, particularly of chimneys in the earlier centuries, were certainly not those envisioned in the Modified Mercalli
MPS-3 FSAR 06/28/18 2.5.2-2 Rev. 31 scale. Interpretation of historical damage reports, without consideration of construction practices or subsurface conditions, may result in erroneously high intensities.
Seismological information for the instrumental period (since 1900) must also be evaluated carefully. Seismic instrumentation began in the early 1900s in the United States and Canada with progressively improved quality of earthquake data. Epicentral locations based on felt reports were complemented and somewhat controlled by instrumental data. From the 1900s until the 1960s, only a few seismographs operated in the eastern United States. Most of these stations were part of the regional network operated by the Jesuit Seismological Association. In the early decades, numerous factors, such as the type of instrumental response, lack of accurate time control, awkward configuration, use of graphical methods, and limited knowledge of crustal velocities were potential sources of errors. These produced large uncertainties in the epicentral coordinates which, in many cases, amounted to tens of kilometers.
Since the 1960s, increased interest in understanding local seismicity has resulted in the implementation of dense seismographic networks. Seismic data in the northeastern United States are now gathered by NEUSSN and reported in its bulletin. NEUSSN reports earthquake hypocentral locations and magnitudes determined through the cooperation of several institutions.
Although the coverage of this network is uneven, it is now capable of detecting and locating all earthquakes in New England of magnitude greater than or equal to 2.0 (Chiburis 1979; Sbar and Sykes 1977). Chiburis (1979) has recently examined the seismicity of New England based on recent earthquakes and has reevaluated the location and intensity of several earlier events.
2.5.2.1.2 Earthquake History Studies of the earthquake history of the site region are based on the Chiburis (1979) catalog.
Table 2.5.2-3 lists all earthquakes with intensity greater than or equal to IV (MM) within 200 miles of the site and all instrumentally located earthquakes regardless of magnitude. The table also lists the date, origin time, epicentral coordinates, epicentral intensity, magnitude, seismic moment, and a description of location. Except for the seismic moments, which were determined by Street and Turcotte (1977), all other information is from Chiburis (1979). The earthquakes listed in Table 2.5.2-3 and plotted on Figure 2.5.2-2 show that the site is located in an area of low to moderate seismicity.
The cumulative historical seismicity data (Figure 2.5.2-2) reveal the presence of several distinct areas of concentrated seismic activity. They are: Moodus, Connecticut; Narragansett Bay, Rhode Island; Cape Ann, Massachusetts; the area around Ossipee, New Hampshire; northern New York; southeastern New York; northeastern New Jersey; and the Hudson River Valley. These are discussed in terms of their location, areal extent, level of historical seismicity, and their tectonic framework as inferred from current research.
Activity in Southern New England Areas of central Connecticut, near East Haddam and Moodus, and the region near Narragansett Bay in Rhode Island and southeastern Massachusetts have experienced a low level of activity.
MPS-3 FSAR 06/28/18 2.5.2-3 Rev. 31 The largest events for this region are the Intensity VII (MM) (1568), and the Intensity VI-VII (MM) (1574, 1791) East Haddam earthquakes. More recent activity is restricted to several lesser events ranging in magnitude to approximately 3.5.
Activity in Southeastern New York and Northeastern New Jersey The seismic activity in southeastern New York, eastern Pennsylvania, and New Jersey is characterized by several repeated occurrences of Intensity VII (MM) earthquakes. Three of these events occurred near New York City in 1737, 1884, and 1927. Two others occurred in southwestern New Jersey in 1840 and 1871. Several Intensity VI events are also distributed throughout this area of low level activity.
Recent investigations by Page et al. (1968), Aggarwal and Sykes(1978), and Sbar and Sykes (1977) propose a spatial correlation of instrumentally recorded, small earthquakes with the Ramapo fault system, which extends in a northeasterly direction parallel to the Appalachian trend in this region. Available focal mechanism solutions for this area, by Aggarwal and Sykes (1978),
suggest high angle reverse faulting along planes that parallel mapped or inferred segments of the northeast-trending Ramapo system.
White Mountains Plutons The area of central New Hampshire and northeastern Massachusetts, including the Cape Ann area, once considered to be a segment of a continuous Boston-Ottawa seismic trend by Sbar and Sykes (1973), is presently interpreted as a separate seismic region. Recently, Sbar and Sykes (1977) have recognized the presence of a seismicity gap in Vermont and western New Hampshire.
Extensive regional investigations, geological and geophysical, conducted for the Preliminary Safety Analysis Report (PSAR) of Pilgrim Unit 2 (BECo 1976a), have stressed the individual entity of this seismic zone. The largest events to affect this region are the Intensity VIII (MM)
Cape Ann earthquake of 1755 and three Intensity VII (MM) events, one near Cape Ann in 1727, and two near Ossipee, New Hampshire on December 20 and 24, 1940. Street and Turcotte (1977) suggest a magnitude of 5.4 for the Ossipee events, based on reanalysis of several seismograms.
The larger earthquakes in the Ossipee and Cape Ann areas have been individually correlated to certain plutons of the White Mountains series in combination with anomalous country rock faulting in the Pilgrim Unit 2 PSAR (BECo 1976a), whereas the Nuclear Regulatory Commission has associated these earthquakes with a larger zone of weakness, and the United States Geological Survey, following Hadley and Devine (1974), has correlated the earthquakes with northeast-trending faults.
Recent activity in this region, including central New Hampshire and the Cape Ann area, appears to be low. Two events ranging in magnitude to just over 3.0 have been reported in the last decade.
MPS-3 FSAR 06/28/18 2.5.2-4 Rev. 31 Northern Coastal Zone The seismicity of Maine, characterized by a maximum Intensity VI (MM), is spatially distributed in the central and west-central regions, the New Brunswick border area, and the Quebec border region near northern New Hampshire.
Two Intensity VI (MM) earthquakes, one located in the ocean off Portland in 1957 and the other near the Maine-Quebec border in 1973, are both assigned magnitudes of 4.8. For the 1973 event, Wetmiller (1975) determined an oblique strike-slip focal mechanism with nodal planes oriented NO4E and N37W.
Hudson River Valley Few earthquake epicenters have been located in the Hudson River Valley. The largest of these earthquakes was Intensity VII (MM) near Lake George, New York, on April 20, 1931.
Although a number of large earthquakes (Intensity IX-XI (MM)) have occurred in the St.
Lawrence River Valley, these earthquakes fall outside the 200-mile radius and, therefore, are discussed in Section 2.5.2.4 with relation to maximum earthquake potential at the site.
The cumulative historical seismicity data, carefully interpreted, can yield valuable information on the spatial and temporal distribution of larger and more significant earthquake events and the location of zones of concentrated activity. Four years of operation of the NEUSSN have produced a complete record of accurately located events of magnitude 1.8 to 2.0 and larger in the region.
Sbar and Sykes (1977) and Chiburis (1979) have noted that the spatial distribution of this instrumental seismicity closely tracks the distribution of less accurately located historical events, thus reinforcing confidence that older events are fairly well located and that areas of seismic activity are relatively stationary.
2.5.2.1.3 Seismicity within 50 Miles of the Site Earthquake activity within 50 miles of the site is listed in Table 2.5.2-4 and shown on Figure 2.5.2-3. There have been 50 earthquakes of intensity greater than or equal to Intensity IV (MM). Almost half of this earthquake activity has occurred in the Moodus-East Haddam area, about 25 miles northwest of the site. A temporary microearthquake network (five stations) has been installed in this area by Professor E. Chiburis of Weston Observatory to examine the nature and significance of this activity.
Large earthquakes have occurred in the Moodus area in 1568, with epicentral Intensity VII (MM),
and on May 16, 1791, with Intensity VI-VII (MM) (Chiburis 1979). The earthquake of May 16, 1791, was felt over an area of 35,000 square miles extending from Boston to New York. Several aftershocks were reported for the next few days.
Since 1791, at least 40 earthquakes have been lightly felt in the East Haddam-Moodus area. A moderate earthquake took place in the same epicentral area on November 14, 1925 and, although it reportedly did some minor damage at Hartford and Windham, it was not strong enough to be
MPS-3 FSAR 06/28/18 2.5.2-5 Rev. 31 recorded on seismographs in Cambridge, Massachusetts, or New York City. The last felt earthquake to occur in this general area took place on November 3, 1968 with an instrumentally determined epicenter about 19 miles northwest of the site. The earthquake had a maximum intensity of IV (MM) and was generally felt from Old Lyme, Connecticut, on the south to East Hartford on the north. The most recent earthquake in the Moodus area was of magnitude 2.2 in 1976.
Earthquake activity within 10 miles of the site has been limited to four very slight earthquakes with maximum intensities of Intensity III (MM). Two of these earthquakes occurred in New London on November 23, 1894 and August 9, 1935; one occurred in Groton on August 1, 1852; and the fourth was felt in Mystic, Moodus, and Norwich on September 20, 1938.
2.5.2.1.4 Earthquakes Felt at the Site To determine the earthquake hazard at the site, it is necessary to examine how severely the site has been affected by large earthquakes in the past. This examination for Millstone 3 is based on available historical records. A discussion of these earthquakes follow.
June 11, 1638 (46.5°N, 72.5°W, Intensity IX (MM))
This earthquake, centered in the St. Lawrence River Valley, probably near Three Rivers, Quebec, was felt throughout New England with no damage reported except to chimneys at Plymouth and Salem, Massachusetts. Perley (1891) described the chimneys at Plymouth as follows: The chimneys of the first houses here were built on the outside at the ends of the houses, with the tops rising just above the roof. They were massive piles of rough and uneven stones, generally some six feet square, besides being nearly perpendicular. Imperfectly built, without mortar except for filling, they readily yielded to the terrible shaking they received, and the tops of many of them fell off, striking on the house or on the ground. Felt (1899) reported that the shock was felt in Connecticut, Narragansett, Pascataquack, and surrounding areas. Based on available reports and the intensity attenuation characteristics of other earthquakes occurring in the vicinity of the St.
Lawrence River Valley, the estimated maximum intensity of the earthquake at the site was IV-V (MM).
February 5, 1663 (47.6°N, 70.1°W, Intensity X (MM))
This earthquake was centered in the St. Lawrence River northeast of Quebec City and was felt over a 750,000-square-mile area of eastern North America, accompanied by landslides along the St. Maurice, Batiscan, and St. Lawrence Rivers. Other damage was confined to cracked chimneys and the like. Effects in New England were similar to those of the 1638 earthquake. Brigham (1871) reported that on the shore of Massachusetts Bay, houses were shaken so that pewter fell from the shelves and the tops of several chimneys were broken. Based on available reports and intensity attenuation characteristics of other earthquakes occurring in the vicinity of the St.
Lawrence River Valley, the estimated maximum intensity of this earthquake at the site was IV-V (MM).
MPS-3 FSAR 06/28/18 2.5.2-6 Rev. 31 November 9, 1727 (October 29, 1727 Old Calendar) (42.8 +/-0.5°N, 70.55 +/-0.1°W, Intensity VII (MM))
The epicenter of this earthquake was located off the coast of northeastern Massachusetts.
Maximum damage in the intensity range of VI to VII (MM) occurred near the mouth of the Merrimack River where no buildings were thrown down but parts of walls of several cellars fell in and the tops of many chimneys were shaken off (Crowell, 1868). Slight damage equivalent to Intensity V (MM) consisting of cracked chimneys was noted as far north as Portsmouth, New Hampshire; as far west as Lowell, Massachusetts; and as far south as Boston, Massachusetts. The earthquake was felt over an estimated area of 75,000 square miles from the Kennebunk River in Maine to the Delaware River south of Philadelphia. The intensity distribution of this earthquake is shown on Figure 2.5.2-4. Based on available reports, the estimated maximum intensity of this earthquake at the site was IV (MM).
September 16, 1732 (45.5°N, 73.6°W, Intensity VIII (MM))
This earthquake was centered near Montreal where 300 homes were damaged and 7 people were killed. It was felt in Boston and throughout New England and possibly as far south as Maryland.
Based on available reports and the intensity attenuation characteristics of other earthquakes occurring in the vicinity of the St. Lawrence River Valley, the estimated maximum intensity of this earthquake at the site was IV (MM).
December 18, 1737 (40.8°N, 74.1°W, Intensity VII (MM))
This earthquake appears quite similar to the earthquake of August 10, 1884, in that it was felt from Boston, Massachusetts, to New Castle, Delaware and the epicenter was located in the New York City area where some chimneys were thrown down and bells rang. Although the damage in the epicentral area appears similar, it is possible that the epicentral intensity of the 1737 earthquake may have been one intensity less (or Intensity VI (MM)) due to the difference in the construction quality over the 147-year interval between earthquakes. Based on available reports and a comparison of this earthquake with the 1884 earthquake, the probable intensity in the vicinity of the site was IV (MM) with an estimated maximum intensity of V (MM).
November 18, 1755 (42.7 +/-0.1°N, 70.3 +/-0.1°W, Intensity VIII (MM))
This earthquake had its epicenter off the Massachusetts coast, east of Cape Ann. It was felt over an estimated area of 300,000 square miles from the Chesapeake Bay in Maryland on the south to the Annapolis River in Nova Scotia on the north and from Lake George in New York on the west to approximately 200 miles east of Cape Ann (ship thought to have run aground). Most of the damage (Intensity VI (MM) or greater) from this earthquake occurred along the coast from the New Hampshire-Massachusetts line south to the Boston area. Some slight damage to chimneys (Intensity V (MM)) occurred as far north as Portland and Brunswick, Maine; as far south as Scituate, Massachusetts; and as far west as the Lowell, Massachusetts and Nashua, New Hampshire area. The intensity distribution for this earthquake is shown on Figure 2.5.2-5.
MPS-3 FSAR 06/28/18 2.5.2-7 Rev. 31 The only damage reported from the Connecticut River Valley was at Springfield, Massachusetts, where a vane atop a church was bent to a right angle (Winthrop 1757). Based on available reports, the estimated maximum intensity of this earthquake at the site was V-VI (MM).
May 16, 1791 (41.5°N, 72.5°W, Intensity VI-VII (MM))
The epicenter of this earthquake was located in the vicinity of East Haddam, Connecticut. This earthquake was felt over an area of 35,000 square miles extending from Boston to New York.
Examination of the dates and times mentioned in the technical references suggests that a number of earthquakes occurred; the first and largest on May 16, 1791, at 8:00 pm, with a number of aftershocks during the next few days.
The only reports of damage were from the East Haddam area where stone walls and the tops of chimneys were thrown down and latched doors were thrown open. Linehan (1964) reports that a group of professors from Wesleyan University visited the East Haddam area in 1841 and was able to confirm these reports. However, contrary to the original reports, the professors found that only one large stone had been displaced (it was in a tenuous position to begin with) and that no fissures had opened in the earth.
Forty houses of pre-1791 construction were still occupied in the East Haddam-Middletown area as late as 1938. A study of the houses in the East Haddam area shows that they were not of sturdy construction nor had deep foundations, yet none were structurally damaged in the 1791 earthquake. The fact that some stone walls or chimneys might have been damaged could be attributed to an earthquake of intensity not more than V (MM), as there was little brick used and the stones were glacial cobbles. Clay and fibers made up the morta (Linehan 1964).
Previous reports of this earthquake placed the intensity at VIII (MM). However, Linehan (1964) concludes that the intensity of the seismic event which was felt in East Haddam on May 16, 1791 was no greater than V-VI (MM). If the disturbance was of Intensity VIII (MM), the damage would have been considerable in ordinary substantial buildings, with partial collapse, as defined by the MM scale. There is no record of any damage to buildings, even though most of these were poorly constructed. Therefore, the intensity of these earthquakes could have been no higher than VI-VII (MM).
Newspaper accounts indicate that the earthquake was strongly felt without any reported damage at Hartford or New Haven, Connecticut. The intensity distribution for this earthquake is shown on Figure 2.5.2-6. Based on Linehan's analysis of the earthquake's effects in the East Haddam-Moodus area and other available accounts, the estimated maximum intensity of the earthquake in the vicinity of the site was V (MM).
October 17, 1860 (47.5°N, 70.1°W, Intensity VII to IX (MM))
This earthquake had its epicenter in the St. Lawrence River Valley, northeast of Quebec City, and was felt over an area of 700,000 square miles extending as far south as Newark, New Jersey, and as far west as Auburn, New York and included most of New England. The earthquake was strongly felt in Maine, but no damage was reported there or elsewhere in New England. Based on
MPS-3 FSAR 06/28/18 2.5.2-8 Rev. 31 available reports and the intensity attenuation characteristics of other earthquakes occurring in the vicinity of the St. Lawrence River Valley, the estimated maximum intensity of this earthquake at the site was IV (MM).
October 20, 1870 (47.4°N, 70.5°W, Intensity IX (MM))
This earthquake was centered near Baie-St. Paul, Quebec, and was felt over a 1,000,000 square-mile area of eastern Canada and the northeastern United States. The damage reported in the United States included some bricks thrown from chimneys in Lewiston, Maine and some window glass broken in Portland, Maine. In Springfield, three distinct periods of vibration were noticed with the longest estimated at 7 to 8 seconds; while at Hartford, a single shock lasting a minimum of 20 seconds was felt.
Based on available reports, the estimated maximum intensity of this earthquake at the site was IV (MM).
August 10, 1884 (40.6°N, 70.4°W, Intensity VII (MM))
This earthquake was felt over an estimated 70,000 square-mile area of the northeastern United States and had its epicentral location in the New York City area. The greatest damage occurred in Jamaica and Amityville on western Long Island, New York, where some walls were cracked, accounting for the epicentral intensity of VII (MM). The epicentral location is further evidenced by a moderate aftershock which took place on August 11, 1884, and was felt in a number of towns on western Long Island.
An analysis of this earthquake by Rockwood (1885) resulted in the isoseismal map shown on Figure 2.5.2-7. Rockwood's map was based on more than 215 observations, of which 30, all within Rockwood's Isoseismal IV, reported some damage such as fallen bricks and cracked plaster. As shown on the figure, the site is located within Rockwood's Isoseismal III.
In the southern Connecticut area, damage included some bricks shaken from chimneys and a few cracked walls at New Haven, and dishes thrown from shelves and broken at Bridgeport. The shock was strongly felt at Hartford, but no damage was reported.
In New London, the earthquake was felt by everyone and the water in the harbor was reportedly agitated. Reports also indicate a few instances of cracked and fallen plaster but no damage to chimneys (The Day 1884).
Based on Rockwood's data and other available reports, the estimated maximum intensity in the site area was V (MM).
February 10, 1914 (45N, 76.9°W, Intensity VII (MM), Magnitude 5.5)
This earthquake had its epicenter about 25 miles west of Lanark, Ontario, and was felt over a 200,000 square-mile area including New England, New York State, and Pennsylvania. Some damage was reported in New York State with minor damage noted as far east as Albany. The
MPS-3 FSAR 06/28/18 2.5.2-9 Rev. 31 earthquake was strongly felt throughout New England although no damage was reported.
Intensities of III to IV (MM) were noted as far south as Boston, Hartford, and New Haven. Based on available reports of this earthquake, the estimated maximum intensity at the site was IV (MM).
March 1, 1925 (47.6°N, 70.1°W, Intensity IX (MM), Magnitude 7.0)
This earthquake, which had its epicenter in the St. Lawrence River Valley northeast of Quebec City, was felt over approximately 2,000,000 square miles of North America, extending as far south as Virginia and west to the Mississippi River. Important damage was confined to a narrow belt along the St. Lawrence River Valley. Isoseismals prepared by the Dominion Observatory of Canada and shown on Figure 2.5.2-8 indicate that most of New England experienced intensities of III and IV (MM), the exception being extreme northern Maine, which probably experienced an intensity of V to VI (MM). The shock was generally felt throughout Connecticut with a maximum intensity of IV (MM) in the site area.
November 14, 1925 (41.5°N, 72.5°W, Intensity V to VI (MM))
This earthquake was felt over an 850 square-mile area of central Connecticut. Minor damage was reported at Hartford where some plaster fell and at Windham where dishes fell from shelves.
Newspaper reports indicated that the earthquake was strongly felt from the Haddam-Middletown area to Hartford.
Along the southern Connecticut coast, the earthquake was generally felt but no damage reported.
Available reports indicate intensities of III to IV (MM) in the site area.
December 20, and 24, 1940 (43.8N, 71.3W, Intensity VII (MM), Magnitude 5.8)
The epicenters of these earthquakes were located near Lake Ossipee, New Hampshire. Damage of Intensity VII (MM) occurred at Tamsworth and Wonalancet, New Hampshire, while damage of Intensity VI (MM) was noted in a dozen localities in central New Hampshire and western Maine.
The shocks were felt over a 150,000 square-mile area of the United States including all of New England, New York, and New Jersey. The earthquakes were noticeably felt in the vicinity of the site but no damage was reported.
The isoseismal map prepared by the Northeast Seismological Association, Figure 2.5.2-9, indicates that the intensity of these earthquakes in the vicinity of the site was IV (MM).
2.5.2.2 GEOLOGIC STRUCTURES AND TECTONIC ACTIVITY The site region encompasses a large segment of the northern Appalachian region. This region has undergone at least four orogenies, Mesozoic rifting and igneous activity, epeirogenic uplift, and glaciation. The tectonics and geologic history are discussed in Section 2.5.1. Figure 2.5.2-2 shows the regional geologic structure and the locations of epicenters within the 200 mile radius of the site.
MPS-3 FSAR 06/28/18 2.5.2-10 Rev. 31 Portions of 10 tectonic provinces are located within this 200 mile radius (Figure 2.5.2-10). Three of the 10 -- the Southeastern New England-Maritime Province, the New England Province, and the White Mountains Plutonic Province -- comprise most of the area. The remaining provinces are: the Coastal Plain, the Blue Ridge and Piedmont, the Northern Valley and Ridge, the Appalachian Plateau, the Central Stable Region, the Grenville, and the Monteregian Plutonic Province. The provinces are delineated on the basis of the following criteria:
1.
Style and degree of deformation 2.
The age of orogenic, igneous, or tectonic activity 3.
The age of the basement rocks These provinces are shown on Figure 2.5.2-10.
Southeastern New England-Maritime Province The site is located in the southwestern edge of the Southeastern New England-Maritime Province.
The western boundary follows the Honey Hill Lake Char-fault system northward into Massachusetts. The rock fabric and structural trends are different than those of the New England Province to the west. The province is characterized by Late Precambrian basement rock overlain by mildly metamorphosed rocks of Carboniferous age. Unlike the remainder of New England, the effects of the Alleghenian orogeny are apparent within the province.
The Southeastern New England area is considered by Skehan (1973) to be a piece of the Paleo-African continental plate with the Clinton-Newbury fault zone being the collision boundary.
Rodgers(1970) considers the rocks east of the Clinton-Newbury fault to be similar to those of the Avalon Peninsula of Newfoundland. The reopening of the Atlantic Ocean, which began in the Mesozoic, isolated the pieces of the African continent. Gravity and magnetic data also indicate that the province boundary represents a juncture between two discrete crustal blocks in near isostatic equilibrium.
Reverse faulting is prominent in the intensely faulted zone between the Clinton-Newbury and Lake Char faults and the Boston Border fault, although transcurrent or strike-slip components may exist. Northeastward along the Norumbega fault, the movement has been right lateral and may exceed several hundred kilometers. Skehan (1973) considers the area to be an ancient subduction zone, although all the elements have not been demonstrated. Certainly, large scale underthrusting has played a major role in the development of the province.
New England Province Just west of the Southeastern New England-Maritime Province lies the New England Province, extending southward to 4030'N latitude. The New England Province is structurally similar to the Piedmont. The region has been strongly affected by the Taconic and Acadian Orogenies, whereas the Blue Ridge and Piedmont Province and the Valley and Ridge Province to the south were affected by the Alleghenian orogeny. Grenville-age basement is exposed in the cores of the
MPS-3 FSAR 06/28/18 2.5.2-11 Rev. 31 Berkshire-Green Mountain anticlinorium and the Reading prong and shows evidence of involvement in the earlier Paleozoic deformations. As discussed in Section 2.5.1.1, the Precambrian basement disappears beneath the high grade metamorphic rocks of the Merrimack synclinorium to the east. The structural fabric of the province suggests a Paleozoic compressive stress directed from the east or southeast. The presence of the New Hampshire Plutonic series emplaced during the Acadian Orogeny aids in distinguishing the New England Province from the Southeastern New England-Maritime Province.
White Mountains Plutonic Province The emplacement of magmas of the White Mountains Plutonic-Volcanic Series began in the Mesozoic and overprinted the Paleozoic effects. The series was intruded along a north-northwest trend extending offshore of Cape Ann, Massachusetts, into northern New Hampshire, Vermont, and southern Quebec, crossing the older structural grain of the Appalachians. Radiometric dating has shown that the igneous activity began in and continued sporadically throughout the Mesozoic Era (BECo 1976a). All the plutons are related in age, shape, magnetic signature, gross mineralogy, and mode of intrusion. The zone has been spatially correlated with a region of seismic activity in New Hampshire and Massachusetts.
This zone is defined to include all mapped occurrences of White Mountains Plutonic-Volcanic Series rocks and is extended offshore to include a group of magnetic anomalies similar to the onshore structures. It extends northwestward to include Mt. Ascutney in Vermont and northward to encompass Mt. Megantic in southern Quebec. Southeastward, it includes the Agamenticus complex and Cape Nedick pluton.
Monteregian Plutonic Province This province, which represents an overprinting similar to the White Mountains intrusives, is composed mainly of alkaline, basic, and ultrabasic intrusives of Cretaceous age. They intrude early Paleozoic folded metasedimentary and undeformed sedimentary rocks of the New England Province. The trend of the plutonic belt cuts across the Paleozoic structural grain. The Cretaceous age, duration and mode of emplacement, size of plutons, extreme alkalic nature, contact relationships, and evidence of explosive activity distinguish the Monteregian plutons from the White Mountain Series. The zone is defined to include all known occurrences of Monteregian type rocks including several subsurface magnetic anomalies. It extends to the Oka Complex on the northwest and surrounds Mt. Shefford and Mt. Brome on the northeast. The zone includes the Cuttingsville stock near Rutland, Vermont, and all known alkalic dike occurrences in the Champlain Valley. It has also been the site of a moderate amount of seismic activity and includes the September 16, 1732, Intensity VIII (MM) event near Montreal.
Coastal Plain Province The Atlantic Coast section of this province lies seaward of the Piedmont, New England, and Southeastern New England-Maritime Provinces. It is characterized by gently seaward-dipping, unconsolidated Jurassic, Cretaceous, and Tertiary sediments overlying Precambrian or Early
MPS-3 FSAR 06/28/18 2.5.2-12 Rev. 31 Paleozoic bedrock. Somewhere on the continental slope, or a little beyond, the continental basement rocks of the underlying Appalachian system give way to oceanic crust.
Tectonically, the province is characterized as a zone of subsidence, occurring mainly since the Jurassic and persisting through most of the Tertiary. Several arches and embayments exist in the basement rocks and serve to subdivide the Coastal Plain into distinct sedimentary basins, some of which contain between 10 and 12 km (32,800 and 39,400 ft) of sediments of Jurassic age and younger. Most of the deposits were placed in relatively shallow water indicating a progressive downwarping of the edge of the continent toward the oceanic floor.
Grenville Province The Grenville Province borders the New England Province on the northwest and forms a belt 250 miles wide from Lake Huron to the Atlantic in Labrador. The rocks of the province are divided almost evenly between medium grade marbles, quartzites and gneisses, and higher grade gneisses and plutonic rocks of a slightly older series. An appendage of the Grenville Province occurs in New York State as the Adirondack uplift. Distinctive anorthosite bodies of the Adirondacks are included in the Grenville Province because they were deformed during the Grenville orogeny between 1.1 and 1.3 billion years ago. The Grenville Province appears to be an orogenic belt built against the stabilized older part of the shield and is more nearly comparable to the orogenic belts of the Paleozoic.
Lower Paleozoic platform rocks do exist in the Ottawa-Bonnecherre graben west of Logan's Line as a thin veneer on Grenville basement rocks. They represent a portion of the Central Stable Region which has been isolated by the uplift of the intervening Adirondacks. Their tectonic stability is related to the general stability of the underlying Grenville and, therefore, for simplicity, they are included in the Grenville Province.
Piedmont-Blue Ridge Province The Piedmont-Blue Ridge Province is characterized by metamorphosed Precambrian and Early Paleozoic eugeosynclinal rocks which were deformed during the Taconic and Alleghenian orogenies and may have been recrystallized during the Acadian orogeny. It includes the Blue Ridge anticlinorium, a relatively narrow belt of folded and faulted upper Precambrian crystalline schists and gneisses which were thrust westward several kilometers over the rocks of the valley and ridge. Terrains of intrusive igneous rocks are notable in the Piedmont of Virginia and North Carolina. Long, narrow, graben structures filled with continental deposits of late Triassic age are superimposed intermittently on the crystallines from Pennsylvania to South Carolina. The effects that each orogeny had on the rocks in the Piedmont are not yet fully understood due to the lack of outcrop, lack of fossils, and the strong recrystallization.
The southern and eastern boundaries of the Piedmont are drawn at the present westward limit of Cretaceous Coastal Plain deposits. Piedmont geology certainly continues beneath the Coastal Plain for some distance but the line where Coastal Plain mobility becomes the dominant force is presently not well established. The northern boundary of the Piedmont with the New England Province is hidden beneath the Triassic Newark Basin.
MPS-3 FSAR 06/28/18 2.5.2-13 Rev. 31 Appalachian Plateau Province The Appalachian Plateau Province borders the Central Stable Region on the east and on the south at its limit in New York. Geologically, the province is a broad, gentle, elongated basin whose youngest rocks are of probable Early Permian age. The basin forms the western part of the former Appalachian geosyncline with sediments thickening generally southeastward from the Cincinnati-Findlay arch. Grenville basement dips beneath the province in the same direction. The basement gradient steepens through central Ohio demarking the westernmost edge of Appalachian Plateau Province (USNRC 1977). Deformation of the province had its greatest development during the post-Early Permian Allegheny orogeny and resulted in gentle folding and uplift of the sedimentary pile with perhaps some decollement movements along weak units within the section.
Mild epeirogenic movements have been the only tectonic events to affect the province since Late Paleozoic time.
Valley and Ridge Province The Valley and Ridge Province lies east of the Appalachian Plateau except at the north end where the New England Province intervenes. The Valley and Ridge Province contains the major portions of the sediments which were deposited in the Appalachian geosyncline, of which it comprises the southeastern part. The province is characterized by unmetamorphosed Paleozoic sediments that were tightly folded and faulted during the Allegheny orogeny, about 250 million years ago.
Intense pressure exerted from the southeast folded the sediments into large synclines and anticlines, some strongly overturned to the northwest. Thrust faults were commonly developed, particularly south of Central Virginia. The Valley and Ridge Province has been divided into northern and southern sections based on the difference in structural styles. The northern section is dominated by folding, whereas the southern section is characterized by thrust faulting. In addition, the southern section has historically experienced a higher level of seismic activity while the northern section is nearly aseismic (USNRC 1977, USNRC 1978). The boundary between the two provinces is somewhat indistinct but is believed to occur between Roanoke and the James River in Central Virginia, roughly along latitude 37°-45' north. A striking change in the trend of Valley and Ridge structures also occurs at this line; the folds to the north trend about N25 E, whereas the faults to the south trend N70°E. The nature of the structural discontinuity is not known but may be related to basement transcurrent faulting (Cardwell, et al., 1968).
Central Stable Region The Central Stable Region is the westernmost tectonic province of concern to the analysis contained herein. The province is bounded on the east by the Appalachian Plateau Province and the north and northeast by the Grenville Province and the New England Province. The Coastal Plain bounds the province on the south. The Central Stable Region extends westward to the east flank of the Rocky Mountains and includes a wide variety of morphology and structure. The province is made up of a foundation of Precambrian crystalline rock with a veneer of sedimentary cover which varies widely in thickness. It represents the craton or central stable area of the North American crustal plate. Deformation since the Precambrian has been restricted to the development of several broad basins, arches, domes, and similar features. Several of the basins
MPS-3 FSAR 06/28/18 2.5.2-14 Rev. 31 contain in excess of 10,000 feet of strata, while some of the arches expose Precambrian rocks.
Tectonic movements since the Paleozoic have been mostly a series of epeirogenic uplifts and downwarps followed by long periods of erosion. The eastern boundary of the province represents the western limit of effects from the Allegheny orogeny. The boundary follows the steepening of the basement contours as the gradient increases to form the Appalachian Basin.
2.5.2.3 CORRELATION OF EARTHQUAKE ACTIVITY WITH GEOLOGIC STRUCTURES OR TECTONIC PROVINCES The relationship between earthquake locations and geologic structures is important in assessing earthquake hazard for a particular site. The absence of major spatial displacements through historical times that might be associated with tectonic activity in eastern United States makes the association of larger historical earthquakes with specific structures difficult. Only during the past 10 to 15 years have seismologists been able to determine earthquake locations with sufficient precision to relate them to geologic structures.
2.5.2.3.1 Correlation with Geologic Structures White Mountain Plutons The majority of the significant seismic activity in New England has been associated with the White Mountains Plutonic Province. The strong concentration of events in southern New Hampshire and northeastern Massachusetts has been spatially associated with plutons of the White Mountains (Figure 2.5.2-2). A detailed investigation of the White Mountains Plutons has indicated that the Ossipee, New Hampshire, earthquakes and the Cape Ann earthquake are associated with the plutons (BECo 1976a). The largest activity was located off Cape Ann in 1755.
It was assigned Intensity VIII (MM). Also, there have been a number of Intensity VII (MM) events, two in Ossipee, New Hampshire in December 1940, and another located off Cape Ann in 1727.
Ramapo Fault The Ramapo fault system, which bounds the Triassic-Jurassic Newark graben on its northwest side in northeastern New Jersey and southeastern New York, has been known for about 100 years and has been commonly presumed to be an inactive fault. Aggarwal and Sykes (1978) have observed a spatial correlation of some epicenters in southeastern New York with surface traces of faults in the area. A large majority of events lie on or very close (0.5 to 1.2 miles) to the faults.
Furthermore, an examination of focal mechanism solutions shows that for each of the solutions, one of the nodal planes trends north to northeast, which is also the predominant trend of the faults in this area. The spatial correlation of one nodal plane with the trend of the mapped faults suggests that earthquakes in this area occur along pre-existing faults.
Considering both geology and seismicity, the Ramapo fault is not considered capable in accordance with the criteria for capable faults in 10 CFR 100, Appendix A. This was established by the Atomic Safety and Licensing Board (USNRC 1977) in 1977, after extensive hearings on the issue.
MPS-3 FSAR 06/28/18 2.5.2-15 Rev. 31 2.5.2.3.2 Correlation with Tectonic Provinces As most earthquake activity in the site region cannot be correlated with geologic structures, it is assumed (in accordance with 10 CFR 100, Appendix A) that these earthquakes are associated with the tectonic provinces (Figure 2.5.2-10) in which they occur. A discussion of earthquake activity in various tectonic provinces follows.
Much of the seismicity of the Grenville Province is associated with the LaMalbaie seismic zone and the Monteregian Plutonic Zone, considered to be separate source areas and described below.
The remaining activity is confined to a broad belt of epicenters extending from the Adirondack uplift northwestward into southwestern Quebec and eastern Ontario to the vicinity of Kirkland Lake. The largest historical events in this province were the 1944 Cornwall-Massena event of Intensity VIII (MM) and the 1935 Timiskaming, Quebec earthquake of magnitude 6.2 which had an epicentral intensity of VII (MM).
The Monteregian Plutonic Province overprints the older structural features of the Grenville and New England Provinces. Its seismicity includes the easternmost part of the prominent belt of epicenters which trends northwestward across the Grenville Province. The largest historical earthquake within the Monteregian Plutonic Province occurred at Montreal in 1732. Earlier catalogs have listed this event as Intensity IX (MM); however, recent evaluations of original accounts (Chiburis 1979; NYSE&G 1978) conclude that the epicentral intensity did not exceed VIII (MM).
The LaMalbaie Seismic Zone lies outside the 200-mile radius on the boundary between the Grenville Province and the New England Province. It occurs as a distinct concentration of epicenters extending northeast from Quebec City. The LaMalbaie Zone is the most important seismic source in the northeast in terms of energy released. Historically, numerous large earthquakes have occurred in this zone with intensities ranging from VII to X (MM). A conjunction of the Charlevoix meteoritic impact structure with the tectonic boundary between the Grenville Province and the Appalachian structures of the New England Province has been described by Leblanc and Buchbinder (1977) as a likely structural basis for the concentration of strain release in this zone.
The major seismicity of the New England Province is related to the White Mountains Plutonic Province described above. The remainder of the province is characterized by a band of activity which trends along the coast from northern New Jersey to eastern Connecticut. This area has experienced earthquakes up to Intensity VII (MM). These have occurred in 1737 and 1884 at New York City and 1791 at Haddam, Connecticut. Another diffuse pattern of epicenters of maximum Intensity VI (MM) occurs in coastal and central Maine. Minor microearthquake activity is also reported to originate along the Ramapo fault in New Jersey and New York (Aggarwal and Sykes 1978).
Earthquakes in 1568 and 1791 near East Haddam, Connecticut, are also part of the New England Province since these have not been associated with any specific geologic structures or faults. An investigation is currently in progress to study the Moodus noises. However the noises have not been associated with specific faults.
MPS-3 FSAR 06/28/18 2.5.2-16 Rev. 31 The Southeastern New England-Maritime Province is an area of low seismicity. Most of the activity in southeastern Massachusetts, offshore, and in eastern Maine has been lower than Intensity V (MM). The largest earthquake in this province was an Intensity VI (MM) event which occurred in 1904 east of Eastport, Maine.
The Atlantic Coastal Plain Province has experienced a number of minor earthquakes throughout the historic record. Exclusive of the Charleston, South Carolina area, the largest events have been of Intensity VII (MM). These occurred in 1871, 1884, and 1927 near the boundary with the New England and Piedmont Provinces in northern New Jersey and near New York City.
The Piedmont-Blue Ridge Province exhibits a fairly low level of seismicity throughout its length with diffuse areas of higher activity in central Virginia and western South Carolina. The largest historical earthquake in the province was of Intensity VII (MM). It occurred in central Virginia in 1875.
2.5.2.4 MAXIMUM EARTHQUAKE POTENTIAL The maximum earthquake potential for the site is evaluated by utilizing maximum earthquakes associated with all nearby tectonic provinces and geologic structures. This analysis is made for two different sets of conditions. First, actual site intensities resulting from larger historical earthquakes are determined. Second, the maximum potential site intensities resulting from hypothetical events are calculated. These hypothetical events are specified as the largest known earthquakes in each adjoining tectonic province. Each is postulated to occur at the point where its province or structure most closely approaches the site.
2.5.2.4.1 Maximum Historical Site Intensity A detailed analysis of large historical earthquakes in the northeastern United States indicates (Section 2.5.2.1.4) that four earthquakes have been felt with intensities of V (MM) or greater at the site. The 1755 Cape Ann earthquake caused damage corresponding to Intensity V-VI (MM) at towns near the site. The East Haddam-Moodus earthquake of 1791 was reportedly felt strongly but no damage resulted at such localities as Hartford and New London, indicating an intensity of approximately V (MM). A similar intensity value is indicated for the Millstone site. Data collected by Rockwood indicate that the 1884 earthquake, with an epicenter approximately in the New York City area, was felt at the site with a probable intensity of V (MM). Bricks were thrown from chimneys and a few walls were cracked at New Haven, and plaster was cracked and dislodged at New London. The 1737 earthquake with epicentral location also in the New York City area appears similar to the 1884 earthquake and may have been felt with an intensity of V at the site.
It is clear that these four earthquakes in the site region caused Intensity V or V-VI (MM) at the site. The epicentral intensity of these four earthquakes was either VII, VI-VII, or VIII (MM). In the site region, the 1755 Cape Ann earthquake was of highest intensity (VIII (MM)). Earthquakes larger than the 1755 Cape Ann, for example, have all occurred outside the site region in the LaMalbaie area of the St. Lawrence River Valley. Large earthquakes in this zone are estimated to have caused Intensity IV-V (MM) at the site. The 1886 Charleston earthquake of Intensity X
MPS-3 FSAR 06/28/18 2.5.2-17 Rev. 31 (MM) caused Intensities II-III (MM) at the site. Therefore, from historical data, it is concluded that the site experienced maximum intensity of V-VI (MM).
2.5.2.4.2 Maximum Earthquake Potential from Tectonic Province Approach To account for the possibility of large errors in epicentral determination, especially for events occurring prior to 1950 and in the absence of capable faults, the largest known earthquake in each province was attenuated to the site from points of nearest approach of the tectonic province in which the earthquakes occurred, using the conservative attenuation relationship of Howell and Schultz (1975). Justification for this procedure is that individual epicenters are not properly located and, therefore, cannot be associated with specific structures.
The site is located in the Southeastern New England-Maritime Tectonic Province. The largest earthquake in this province was of Intensity VI (MM). The New England Tectonic Province is very near the site and several earthquakes of Intensity VII (MM) have occurred in this province (1568 and 1791 at Moodus and 1737 and 1884 at New York City). Assuming that these earthquakes occur at the nearest approach point of the New England Province to the site (20 km),
intensity at the site would be VII (MM). The Coastal Plain Province is also close to the site (about 10 km). The 1927 earthquake near Asbury Park, New Jersey, was in the Coastal Plain Province and had an epicentral intensity of VII (MM). A similar earthquake in the Coastal Plain Province near the site would cause Intensity VII (MM) at the site. Only one earthquake of Intensity VIII (MM) is associated with any of the provinces or structures in the site region. This earthquake occurred near Cape Ann, Massachusetts, in the White Mountains Plutonic Province. Such an earthquake occurring in that province at a minimum distance from the site (170 km) would cause site intensity of V-VI (MM). In other tectonic provinces in the site region, the maximum intensity of earthquakes was VII (MM). Therefore, the effect of these earthquakes would be less than VII (MM).
In the eastern United States, earthquakes with intensities greater than VIII (MM) have occurred only in LaMalbaie, Quebec; Charleston, S.C.; and New Madrid, Missouri. Earthquake activity at these places is assumed to be associated with specific structures and, based on historical data, would not cause greater effects at the site than Intensity IV-V (MM). Therefore, the maximum earthquake potential at the site due to earthquakes occurring within 10 to 20 km of the site is Intensity VII (MM).
2.5.2.5 SEISMIC WAVE TRANSMISSION CHARACTERISTICS OF THE SITE Properties of subsurface materials at the site are discussed in detail in Section 2.5.4. The compressional and shear wave velocities of in situ materials are tabulated in Section 2.5.4.4.3 and other properties of the in situ materials are described in Section 2.5.4.2. The groundwater conditions at the site are discussed in Section 2.5.4.6.
The safe shutdown earthquake (SSE) value of 0.17 g is applied to the bedrock surface. For structures founded on soils, the effect of the overburden on the earthquake motion has been considered in soil-structure interaction computations, as discussed in Section 3.7B.2.4.
MPS-3 FSAR 06/28/18 2.5.2-18 Rev. 31 2.5.2.6 SAFE SHUTDOWN EARTHQUAKE As discussed in Section 2.5.2.4, the maximum earthquake potential at the site is an Intensity VII event occurring 10 to 20 km from the site. Murphy and O'Brien (1977) have published an analysis of acceleration-intensity correlations using a new worldwide data base and a variety of statistical models. Their correlation equation relating Intensity I (MM) and peak horizontal ground acceleration (Ah) is:
log Ah = 0.25 I + 0.25 where Ah is in cm/sec2. For a Modified Mercalli Intensity VII earthquake, this equation gives an average horizontal component peak acceleration of 0.10 g. In order to be conservative in the Millstone 3 plant design, the SSE is specified as 0.17 g. The duration of strong ground motion associated with an Intensity VII earthquake is estimated at 6 seconds using an assumed threshold acceleration value of 0.05 g according to Bolt (1973).
2.5.2.7 OPERATING BASIS EARTHQUAKE A study of the earthquake history of the site region has shown that the maximum historical intensity at the site has been V-VI (MM), corresponding to a peak horizontal ground acceleration of 0.05 g (Murphy and O'Brien 1977). In accordance with 10 CFR 100, Appendix A, the operating basis earthquake is taken to be at least one half of the SSE, or 0.09 g.
2.5.
2.8 REFERENCES
FOR SECTION 2.5.2 2.5.2.1-1 Aggarwal, Y. P. and Sykes, L. R. 1978. Earthquakes, Faults and Nuclear Power Plants in Southern New York and Northern New Jersey. Science, Vol 200, p 425-429.
2.5.2.1-2 Bolt, B. A. 1973. Duration of Strong Ground Motion. Proceedings of the Fifth World Conference on Earthquake Engineering, Rome, Italy, Vol 1, p 1304-1308.
2.5.2.1-3 Boston Edison Company 1976a. Summary Report - Geologic and Seismologic Investigations. Pilgrim Unit 2, USNRC Docket No. 50-471. Boston, Mass.
2.5.2.1-4 Boston Edison Company 1976b, Historical Siesinicity of New England. Pilgrim Unit 2, USNRC Docket No. 50-471.
2.5.2.1-5 Brigham, W. J. 1871. Volcanic Manifestations in New England. Memories of the Boston Society of Natural History, Vol 2, p 1-28.
2.5.2.1-6 Brooks, J. E., S. J. 1960. A Study in Seismicity and Structural Geology, Part II -
Earthquakes of Northeastern United States and Eastern Canada. Obs. Geophys.
College Jean-de-Brebeuf, Bull. Geophys., No. 7, 12-40.
MPS-3 FSAR 06/28/18 2.5.2-19 Rev. 31 2.5.2.1-7 Cardwell, D. H.; Erwin, R. B.; and Woodward H. P. 1968. Geologic Map of West Virginia, West Virginia Geological and Economic Society. Scale 1:250.000.
2.5.2.1-8 Chiburis, E. C. 1979. Seismicity of New England. (In press).
2.5.2.1-9 Coffman, J. L., and Von Hake, C. A. 1973. Earthquake History of the United States.
Publication 41-1, U.S. Dept. of Commerce, Supt. of Documents, Washington, D.C.
2.5.2.1-10 Crowell, R. D. D. 1868. History of the Town of Essex from 1634-1868. Town Press of Samuel Bowles and Company, Springfield, Mass., p 143-144.
2.5.2.1-11 Felt, J. D. 1899. Annals of Salem, Boston. James Munroe & Company, Boston, Mass.
2.5.2.1-12 Hadley, J. B. and Devine, J. F. 1974. Seismotectonic Map of the United States.
USGS Miscellaneous Field Studies, Map MF-620.
2.5.2.1-13 Howell, B. F. and Schultz, T. R. 1975. Attenuation of Modified Mercalli Intensity with Distance from the Epicenter. Bulletin of the Seismological Society of America, Vol 65, No. 3, p 651-666.
2.5.2.1-14 Leblanc, G. and Buchbinder, G. 1977. Second Microearthquake Survey of the St.
Lawrence Valley near LaMalbaie, Quebec. Canadian Journal of Earth Sciences, Vol 14, No. 12, p 2778-2789.
2.5.2.1-15 Linehan, D. 1964. Report on the Seismicity of the East Haddam-Moodus Area of Connecticut. Prepared for Stone & Webster Engineering Corporation by Weston Geophysical Research, Inc., Westboro, Mass.
2.5.2.1-16 Murphy, J. R. and O'Brien, L. J. 1977. The Correlation of Peak Ground Acceleration Amplitude with Seismic Intensity and Other Physical Parameters. Bulletin of the Seismological Society of America, Vol 67, No. 3, p 877-915.
2.5.2.1-17 New York State Electric and Gas Corporation 1978. Preliminary Safety Analysis Report. Amendment 2, New Haven Units 1 and 2, Docket No. STN50-506 and STN50-507.
2.5.2.1-18 Page, R. A.; Molnar, P. H.; and Oliver, J. 1968. Seismicity in the Vicinity of the Ramapo Fault, New Jersey-New York. Bulletin of the Seismological Society of America, Vol 68, No. 2, p 681-688.
2.5.2.1-19 Perley, S. 1891. Historic Storms of New England. Salem Press Publishing and Printing Company, Salem, Mass.
2.5.2.1-20 Rockwood, C. G., Jr. 1885. Notices of Recent Earthquakes. American Journal of Science and Arts, Third Series, Vol 29, p 425.
MPS-3 FSAR 06/28/18 2.5.2-20 Rev. 31 2.5.2.1-21 Rodgers, J. 1970. The Tectonics of the Appalachians. Wiley Interscience, NY.
2.5.2.1-22 Sbar, M. L. and Sykes, L. R. 1973. Contemporary Compressive Stress and Seismicity in Eastern United States. Bulletin of the Geological Society of America, Vol 84, p 1861-1882.
2.5.2.1-23 Sbar, M. L. and Sykes, L. R. 1977. Seismicity and Lithospheric Stress in New York and Adjacent Areas. Journal of Geophysical Research, Vol 82, p 5771-5786.
2.5.2.1-24 Skehan, J. W. 1973. Subduction Zone between the Paleo-American and Paleo-African Plates in New England. Geofisica International (Mexico), Vol 13, No. 4, p 291-308.
2.5.2.1-25 Smith, W. E. T. 1966. Earthquakes of Eastern Canada and Adjacent Areas, 1928-1959. Dom. Observ. Publ., Vol 32, p 87-121.
2.5.2.1-26 Street, R. L. and Turcotte, F. T. 1977. A Study of Northeastern North American Spectral Moments, Magnitudes and Intensities. Bulletin of the Seismological Society of America, Vol 67, No. 3, p 599-614.
2.5.2.1-27 The Day 1884. New London, Conn., August 11.
2.5.2.1-28 United States Earthquakes 1940. U.S. Dept. of Commerce, U.S. Coast and Geodetic Survey, Washington, D.C.
2.5.2.1-29 U.S. Nuclear Regulatory Commission 1977. Atomic Safety and Licensing Appeal Board. 6NRC547 (1977), Indian Point Units 1, 2, and 3, Docket No. 50-3, 50-247, 50-286.
2.5.2.1-30 U.S. Nuclear Regulatory Commission 1978. Safety Evaluation Report, Erie Power Station, Docket No. 50-580, 50-581.
2.5.2.1-31 Wetmiller, R. J. 1975. The Quebec-Marine Border Earthquake, 15 June 1973.
Canadian Journal of Earth Sciences, Vol 12, p 1917-1928.
2.5.2.1-32 Winthrop, J. 1757. An Account of the Earthquake Felt in New England and the Neighboring Parts of America on the 18th of November 1755. Philosophical Transactions, Vol 50, Part 1, p 1-18.
MPS-3 FSAR 06/28/18 2.5.2-21 Rev. 31 TABLE 2.5.2-1 MODIFIED MERCALLI (MM) INTENSITY SCALE OF 1931 CLICK HERE TO SEE TABLE 2.5.2-1
MPS-3 FSAR 06/28/18 2.5.2-22 Rev. 31 TABLE 2.5.2-2 LIST OF OPERATING SEISMIC STATIONS CLICK HERE TO SEE TABLE 2.5.2-2
MPS-3 FSAR 06/28/18 2.5.2-23 Rev. 31 TABLE 2.5.2-3 CHRONOLOGICAL CATALOG OF EARTHQUAKE ACTIVITY WITHIN 200 MILES OF THE SITE CLICK HERE TO SEE TABLE 2.5.2-3
MPS-3 FSAR 06/28/18 2.5.2-24 Rev. 31 TABLE 2.5.2-4 LIST OF EARTHQUAKES WITHIN THE 50-MILE RADIUS CLICK HERE TO SEE TABLE 2.5.2-4
MPS-3 FSAR 06/28/18 2.5.2-25 Rev. 31 FIGURE 2.5.2-1 LOCATION OF SEISMIC STATIONS
MPS-3 FSAR 06/28/18 2.5.2-26 Rev. 31 FIGURE 2.5.2-2 EPICENTERS OF EARTHQUAKES WITHIN 200-MILE RADIUS
MPS-3 FSAR 06/28/18 2.5.2-27 Rev. 31 FIGURE 2.5.2-3 LOCATION OF EARTHQUAKES WITHIN THE 50-MILE RADIUS
MPS-3 FSAR 06/28/18 2.5.2-28 Rev. 31 FIGURE 2.5.2-4 ISOSEISMAL MAP, EARTHQUAKE OF NOVEMBER 9, 1727
MPS-3 FSAR 06/28/18 2.5.2-29 Rev. 31 FIGURE 2.5.2-5 ISOSEISMAL MAP, EARTHQUAKE OF NOVEMBER 18, 1755
MPS-3 FSAR 06/28/18 2.5.2-30 Rev. 31 FIGURE 2.5.2-6 ISOSEISMAL MAP, EARTHQUAKE OF MAY 16, 1791
MPS-3 FSAR 06/28/18 2.5.2-31 Rev. 31 FIGURE 2.5.2-7 ISOSEISMAL MAP, EARTHQUAKE OF AUGUST 10, 1884
MPS-3 FSAR 06/28/18 2.5.2-32 Rev. 31 FIGURE 2.5.2-8 ISOSEISMAL MAP, EARTHQUAKE OF MARCH 1, 1925 (FEBRUARY 28, 1925 EST)
MPS-3 FSAR 06/28/18 2.5.2-33 Rev. 31 FIGURE 2.5.2-9 ISOSEISMAL MAP, EARTHQUAKES OF DECEMBER 20 AND 24, 1940
MPS-3 FSAR 06/28/18 2.5.2-34 Rev. 31 FIGURE 2.5.2-10 TECTONIC PROVINCES
MPS-3 FSAR 06/28/18 2.5.3-1 Rev. 31 2.5.3 SURFACE FAULTING None of the published geology maps show faults in the vicinity of the site. Figure 2.5.1-13 shows a composite bedrock geologic map for the area surrounding the site. The closest mapped fault to the site is in the Uncasville quadrangle, 10.5 miles northeast of the Millstone site (Goldsmith 1967a). Faulting has also been observed in the Clinton quadrangle, approximately 17 miles west of the site, and in the Moodus and Colchester quadrangles, approximately 15 miles north of the site (Lundgren et al., 1971; Lundgren and Thurrell 1973). These faults are all believed to be high-angle faults related to extension tectonics of Late Triassic-Jurassic time (Lundgren et al., 1971; Lundgren and Thurrell 1973; Goldsmith 1973).
Sixty-two faults were found during the mapping of the rock excavation for Millstone 3 between July 1979 and July 1982. Forty of the faults have apparent displacements equal to or less than one foot with the remaining faults exhibiting apparent displacements greater than one foot. The extent of the areas mapped shows eleven separate fault zones with numerous minor associated faults.
Figure 2.5.1-18 shows the general location of these faults. Table 2.5.3-1 lists the faults mapped at the site and provides a reference for those faults discussed in previous reports (NNECo. 1975; 1976; 1977; 1982).
Samples from the gouge zone of faults T-2, T-3, 1541, and 2819 were taken at final excavation grade in the containment structure and discharge tunnel excavations. Petrographic analyses, x-ray diffraction studies, and potassium-argon radiometric dating were performed on these samples.
X-ray diffraction studies were performed on material from faults 1940, 2282, 2339, and 2781 which indicated that the material was not suitable for age dating. The results of these tests are discussed in detail in Section 2.5.3.2. Table 2.5.3-2 describes the samples and shows the tests performed. The analyses and tests show excellent agreement with previous studies performed at the site (NNECo. 1975; 1976; 1977).
2.5.3.1 GEOLOGIC CONDITIONS OF THE SITE Section 2.5.1.2 discusses the stratigraphy, structural geology, and geologic history of the site area in detail. The bedrock geologic map and cross section of the site area and the tectonic setting of eastern Connecticut are shown on Figures 2.5.1-13 and 2.5.1-14, respectively.
2.5.3.2 EVIDENCE OF FAULT OFFSET The published geologic maps which include the site area do not indicate the presence of faulting.
A study of LANDSAT photographs (Figure 2.5.1-9) of southern New England identifies 72 lineaments greater than 10 miles long. None falls within the 5-mile radius of the site.
Figure 2.5.1-10 shows the lineaments and Section 2.5.1.1.4.4 discusses them.
A number of small faults were uncovered at the site during excavation and were mapped in detail.
The larger faults were observed and mapped both at top of rock and at final excavation grade. One fault (508) (NNECo. 1975) was mapped at top of rock and not observed at final grade; others found at final grade were not observed at the rock surface. Figure 2.5.1-18 shows all of the faults uncovered during the mapping at the site. The larger faults exhibiting brecciated and silicified
MPS-3 FSAR 06/28/18 2.5.3-2 Rev. 31 zones are identified by T on this figure and throughout this report. Figure 2.5.1-18 identifies the smaller faults by numbers.
Eleven fault zones (T-1, T-2, T-3, 18, 471-1541, 1599, 1940, 2250, 2282-2295, 2339-2347, and 2380) have been found in the main site area and pumphouse excavations. Figure 2.5.1-18 also shows the remaining ancillary faults. Two of the smaller faults, 508 and 368, terminate within the limits of the main site excavation. Fault 508 is the only fault that was mapped at top of rock that was not noted at final grade. The other faults extend beyond the boundary of the excavation at least in one direction. Fault 1541 in the auxiliary building was mapped as fault 461 in the containment excavation. Displacement along this fault dies out before intersecting the southwestern wall of the containment.
Most of the faults trend to the north and dip at high angles either to the east or to the west.
Table 2.5.3-1 lists their characteristics. Slickenside information (Figure 2.5.1-17) indicates that the sense of movement was in an east-west direction (dip slip). Slickenside information in the T-2, T-3, and 2339 fault zones indicates that the motion along the fault was oblique. Exposures of the faults (T-2, 18, and 1541) in the excavation walls indicate that they are normal (gravity) faults.
Therefore, the oblique motion along the larger faults has a greater dip slip component.
Two of the larger faults, T-2 and T-3, were previously studied in detail immediately after their discovery during the mapping of the bedrock surface (NNECo. 1975). Figures 2.5.3-1 through 2.5.3-3 show the detailed maps of these faults at final excavation grade. Both faults are characterized by a zone of gouge, breccia, microbreccia, and cataclasite derived from the Monson Gneiss and igneous rocks which intrude the Monson Gneiss. Hydrothermal fluids have permeated the gouge zones of these faults. Free-growing crystalline quartz was found in the T-2 zone, and drusy quartz coated the fracture surfaces and vugs in the breccias and cataclasite of the T-3 fault zone. Drusy quartz was also found in open cavities adjacent to T-2.
The brecciated zone of T-2 varies in thickness from 4 to 6 inches. However, in some areas the zone widens to 1.5 feet, and in others narrows to a single, nearly clean fracture. For the most part, the breccia is partially to completely rehealed. The clay gouge varies in thickness along the fault zone although it rarely exceeds 1.0 inch. The T-3 brecciated zone is similar to that of T-2, except in dimensions. The fault zone varies in thickness from 6 inches to 2 feet, and the clay gouge typically forms a thin, 0.5 to 2 inch, continuous seam. It is occasionally found as a thin filling between brecciated blocks. Both zones are moderately to severely weathered with much of the area stained by iron oxide.
Fault T-2 trends N15W, dips at 70 degrees to the east, and is located on the eastern side of the containment excavation. The geologic maps of the walls of the containment and of the discharge tunnel, Figures 2.5.4-11 through 2.5.4-14 and 2.5.4-3 through 2.5.4-5, respectively, show a section across the fault in four locations. The largest fault at the site, T-3, lies on the western edge of the rock exposure in the excavation. T-3 strikes N28W and dips 70 degrees to the east.
Table 2.5.3-1 shows the apparent displacements of the faults in the horizontal plane and lists the calculated displacements, determined from the offset pegmatite veins and from slickenside information. The eastern blocks of T-3, T-2, 1599, and most of the faults in the pumphouse appear
MPS-3 FSAR 06/28/18 2.5.3-3 Rev. 31 to be downthrown relative to the western block, whereas with faults T-1, 18, 461-1541, 368, 2251, and 2426, the western block appears to have been downthrown relative to the eastern block.
A complex irregular pegmatitic intrusion has obscured the contacts in the vicinity of faults 2250 and 2282 making it impossible to determine the sense of development.
Fault 1940 shows low-angle thrust displacement of between 1.0 and 2.0 inches toward the northeast. The southwest dipping fault zone consists of a zone of weathered and fractured rock and clay varying from less than 1.0 inch to about 10 inches thick. The fault ends at joint 198 but is paralleled by a similar zone about 3 feet below it. This parallel zone crosses joint 198 but ends at fault T-2 in a southwesterly direction. Projection of 1940 updip places the intersection of the fault with the rock surface in the vicinity of the demineralized water storage tank. Geologic mapping of this area did not reveal the trace of the fault at the surface. Hydrothermal activity along the fault is evident by the presence of smectite clay in the gouge which is probably related to the same period of hydrothermal activity shown in the high angle faults at the site.
Four separate fault zones were uncovered in the pumphouse excavation (2250, 2282, 2330 plus 2347, and 2380) with smaller faults splaying from these zones, as shown by Figures 2.5.1-18 and 2.5.4-8. These faults are similar in trend, fault zone composition, and amount and type of displacement to those faults uncovered in the main excavation. The shear zones of the faults in the pumphouse were characterized by hydrothermal quartz. Clay gouge was generally restricted to very thin coatings on fracture surfaces.
Four other faults (2781, 2817, 2818, and 2819) were found in the discharge tunnel excavation and are included in Figure 2.5.1-18 and in Figures 2.5.4-19 through 2.5.4-22. A separate report has been submitted detailing the investigation of these faults (NNECo. 1982).
Fault 2781 dips 45 degrees to the west and shows reverse displacement of a biotite seam of 2.5 inches. Clay from the 0- to 4-inch thick fault zone was found unsuitable for age dating. Till and outwash directly overlying the fault was examined and found to be not disturbed. The largest fault uncovered in this portion of the discharge tunnel consists of three related faults, numbers 2817, 2818, and 2819. Offset of pegmatite veins up to 1.5 feet were observed across 2817 and 2818, whereas no continuity could be determined across 2819 in the width of the excavation. Fault gouge material from 2819 produced a K/Ar age date of 142 million 6 million years. The zone was filled with undisturbed drusy quartz and also showed no disruption of overlying stratified and unstratified glacial deposits. Faults 2894 and 2899 (NNECo. 1982) show 4-inch and 0.5-inch displacements, respectively, on very narrow fault zones. Displacements on both faults were observed to end within the excavation.
2.5.3.2.1 Petrographic Analysis Six samples were taken from the T-2 and T-3 fault zones at final excavation grade to determine the geologic history of the faulting. Figures 2.5.3-1 through 2.5.3-3 show the location of these samples. Table 2.5.3-2 lists the samples and gives a general description of each.
Appendix 2.5B includes a report on the petrographic analyses performed by Dr. Reinhard A.
Wobus of Williams College, Williamstown, Massachusetts. The work described herein
MPS-3 FSAR 06/28/18 2.5.3-4 Rev. 31 supplements previous studies performed on these faults (NNECo. 1975) from samples taken at the bedrock surface.
Petrographic analyses of the samples indicate that the fault zones have undergone at least one period of deformation, and possibly more. The cataclasite samples (2F, 5F, 6F, 9F, and 11F) consist mainly of a very fine-grained matrix of subhedral quartz prisms. For the most part, these prisms exhibit no preferred orientation. Chlorite is also common in the matrix, along with some plumose muscovite. The remainder of the cataclasite is made up of quartz, plagioclase, and mica fragments. The fragments indicate that large pieces have undergone some deformation. The quartz crystals are highly strained and the plagioclase twin lamellae have been deformed. All of the larger fragments have been altered and chlorite is present between many of the crystals.
Chlorite has replaced the plagioclase in many places, and, where it has not been replaced, the plagioclase has been altered to a highly-birefringent clay (Appendix 2.5B).
Sample 12F is a sample of the Monson Gneiss taken adjacent to the T-3 fault zone. Hand specimens of the gneiss appear to be sheared. The analysis indicates that quartz present in the thin section is very highly strained and that the plagioclase has been altered to highly birefringent clay.
Wobus (Appendix 2.5B) classifies this as an altered biotite-quartz-andesine gneiss.
The petrographic analysis by Wobus (Appendix 2.5B) indicates that the material from the two different fault zones, T-2 and T-3, is similar. He has classified the material in the zones as hydrothermally altered and silicified cataclasite. Samples taken from the bedrock surface mapping also indicate the same results (NNECo. 1975).
The geologic history inferred from the petrographic study is as follows:
1.
Formation of a breccia and cataclasite from faulting of Monson Gneiss and the pegmatites.
2.
The injection of hydrothermal fluids producing a matrix of subhedral quartz, and altering the original breccia to produce a highly birefringent clay.
3.
Fracturing and granulation of the crystallized quartz matrix.
4.
Continuation of hydrothermal activity resulting in the development of chlorite and plumose muscovite in the cracks and fractures.
5.
Weathering effects, varying with the degree of silicification.
2.5.3.2.2 Clay Mineralogy, Fluid Inclusion Analysis, and Radiometric Dating Samples of the clay gouge in the fault zones were taken at final excavation grade. Table 2.5.3-2 lists these samples, their location, and the tests performed. Six samples were analyzed by x-ray diffraction and radiometrically dated using the potassium-argon (K/Ar) method. Five of the samples (7F, 10F, 13F, 14F, and 15F) were taken from the larger T-2 and T-3 fault zones. Sample 1F was taken from a small fault shown as 1541-461 on Figures 2.5.1-18 and 2.5.4-6. The
MPS-3 FSAR 06/28/18 2.5.3-5 Rev. 31 locations of the samples taken from the T-2 and T-3 fault zones are shown on Figures 2.5.3-1 through 2.5.3-3, respectively.
The samples were analyzed to determine their composition by x-ray diffraction techniques prior to being radiometrically dated. Dr. R. T. Martin of the Massachusetts Institute of Technology, Cambridge, Massachusetts performed these analyses. His report is included as Appendix 2.5C.
Prior studies made by Dr. Martin on clay gouge materials have been reported in detail in Geologic Mapping of the Bedrock Surface (NNECo. 1975) and Report on Small Fault in Warehouse 5 -
Millstone 2 and Condensate Polishing Facility (NNECo. 1976).
The samples were comprised mainly of quartz and clay. Feldspar is noted in three of the samples (7F, 13F, and 14F); however, the amount is small enough to have no effect on the age determined by K/Ar methods. The clay portion of the gouge consists of smectite, chlorite, and illite.
The 1Md, 1M, and 2M polymorphs are the mica polymorphs (illite) of the clay size fraction. The relative amounts of the polymorphs are summarized below from Dr. Martin's report (Appendix 2.5C):
Complete loss of argon is possible as a result of intense cataclastic deformation (Sutter 1971).
Lyons and Snellenburg (1971) have previously performed K/Ar dating of illite gouge and have indicated that the 1Md mica polymorphs are developed at the time of faulting and are authigenic.
The 1Md polymorph is a low temperature mineral. Both the 1Md and the 1M polymorphs appear to be metastable, even at low temperatures (Velde 1965). With increasing temperature, the 1Md, 1M, 2M reaction takes place (Yoder and Eugster 1955). The temperature necessary for the initiation of the reaction from 1Md to 1M at low pressures is no greater than 250°C (Velde 1965).
Quartz crystals found in the brecciated zones of T-2 and T-3 at the bedrock surface were tested to determine their temperature of formation by Dr. Earl Ingerson of the University of Texas at Austin (NNECo. 1975). The temperature range for the hydrothermal formation of these quartz crystals is 118°C to 198°C. This information, together with Dr. Martin's analysis indicating the relative amounts of the mica polymorphs, infers that some of the 1Md polymorphs may have reverted to the 1M polymorph. Apparently, the hydrothermal activity was not intense enough or long enough to complete the reaction.
The 2M polymorph was noted in only one sample, 7F. Because it appears in only one sample, it seems unlikely that the 2M polymorph is caused by the completion of the reaction. The 2M polymorph is common in most igneous and metamorphic rocks (Velde 1965). Since both rock types are involved in the faulting at Millstone, the 2M polymorph in Sample 7F may be a 1F 7F 10F 13F 14F 15F 2M 0
0.12 0
0 0
0 1M 0
0.13 0.42 0.22 0.20 0.42 1M 0.17 0.28 0.09 0.24 0.18 0
MPS-3 FSAR 06/28/18 2.5.3-6 Rev. 31 contaminant from the country rock, and the date obtained may be slightly older than the actual faulting. Sample 7F yielded the oldest date of all samples of fault gouge tested from Millstone.
Geochron Laboratories, Cambridge, Massachusetts, dated the samples analyzed by Dr. Martin.
The results of the potassium-argon testing performed by Geochron Laboratories on samples from final excavation grade are included in Appendix 2.5D and are summarized in Table 2.5.3-3. The samples ranged in age from 109 to 200 m.y.a. Three samples from T-3 (10F, 13F, and 15F) were analyzed and yielded dates of 182+/-7, 155+/-6, and 178+/-7 m.y.a. Dates of 200+/-7 and 165+/-6 m.y.a.
were obtained on samples taken from T-2 (7F and 14F). Sample 1F was taken from a smaller fault, 1541. The age indicated by the K/Ar method for this sample was 109+/-5 m.y.a.
All of the samples tested yield results that are consistent with previous tests performed on samples from Millstone, with the exception of 1F. Table 2.5.3-3 lists the dates of samples previously tested at Millstone. These samples had a range of ages between 168 to 198 m.y.a. Excluding the date from Sample 1F, the average age of faulting from all tests performed on the clay gouge from the Millstone site is 176 m.y.a.
The date on Sample 1F is considerably lower than the other dates. Compared to the other samples taken at final grade, this sample had considerably smaller amounts of the illite fraction (Appendix 2.5C), and a higher ratio of smectite to illite. The smectite may have formed after the gouge material, due to weathering, hydration of the illite, or by hydrothermal alteration. The younger date may reflect the interference of the smectite portion of the sample. As mentioned in Section 2.5.3.2.1, hydrothermal alteration is quite prominent, and the fault zone has been influenced by weathering.
Five samples of gouge were taken from fault 1940 in the engineered safety features building and faults 2282 and 2339 in the Millstone 3 pumphouse. Dr. R. C. Reynolds of Dartmouth College analyzed the clay mineralogy of these samples. His reports are included as Appendix 2.5E.
Large amounts of smectite and little illite were present in the samples (B, C, and D) from fault 1940 which precluded K/Ar dating of the material. Samples P-1 and P-2, taken from faults 2282 and 2339, respectively, were composed mostly of kaolinite with a small percentage of montmorillinite (Appendix 2.5E). A trace of illite was noticed in sample P-2 but neither sample could be dated.
The form and quantity of the smectite present in the samples from fault 1940 does, however, indicate a probable hydrothermal origin for the material. The kaolinite from the faults in the pumphouse (P-1 and P-2) was found to have a crystalline structure, also indicative of a hydrothermal origin. The date of the last hydrothermal event, as indicated by the studies of faults, T-2 and T-3, is between 168 and 198 m.y.a.
Clay gouge samples from faults 2781 and 2819 (NNECo. 1982) in the discharge tunnel were also analyzed by Dr. R. C. Reynolds. His study indicated the material from fault 2781 was not suitable for age dating, as it comprised mostly original micas from the parent rock. The material from 2819 was found to contain sufficient authigenic illite and was suitable for age dating. It produced a K/Ar age date of 142 million +1-6 million years.
MPS-3 FSAR 06/28/18 2.5.3-7 Rev. 31 2.5.3.2.3 Conclusions The K/Ar age dating, petrographic analysis, x-ray diffraction studies, soils mapping, and the detailed mapping of the fault zones indicate that the faults at the Millstone site are incapable features. The petrographic analysis shows that the cataclasite has been silicified and hydrothermally altered, and that the fractures and cracks have been filled with chlorite. Prismatic quartz crystals, drusy quartz, and the silicified cataclasite found in the fault zones would be fractured and/or granulated if any additional movement had occurred.
The radiometric age dates on the fault gouge indicate that the last activity along the faults occurred approximately 142 m.y.a. Silicified breccias, microbreccias, and cataclasites within the T-2 and T-3 zones indicate that earlier episodes of movement and silicification occurred. The presence of the 1M mica polymorph indicates that the unordered 1Md has undergone changes initiated by the heat associated with the introduction of hydrothermal fluids along the fault zones.
The tabulation in Section 2.5.3.2.2 summarizes the relative amounts of polymorphs from the x-ray diffraction analysis reported in Appendix 2.5C. It was found that the clay gouge is comprised mainly of 1M and 1Md polymorphs. Therefore, the dates obtained by radiometric analysis indicate some hydrothermal heating of the clay gouge zone - the last activity along the faults.
The petrographic and radiometric studies are reinforced by the published geologic history of the region (Section 2.5.1.1.5) and of the site area (Section 2.5.1.2.4.1). Detailed mapping of the excavation showed that the most prominent joint set trends northerly and dips at high angles to the east or west, as shown on Figure 2.5.1-16. All of the smaller faults parallel the prominent jointing, indicating that the same tectonic forces were responsible for their formation. Slickenside information (Figure 2.5.1-17) and exposures in the excavation indicate that the major component of movement is down-dip. Regionally, a prominent northerly joint set exists. Many of these surfaces also exhibit slickensides (Lundgren et al., 1971; Lundgren and Thurrell 1973). West of the site, the Triassic-Jurassic Basin is bordered by a northerly trending, high angle fault (Rodgers 1970). The Clinton quadrangle to the west and the Moodus and Colchester quadrangles to the north of the site are cut by numerous high-angle faults related to the major Triassic faults to the west (Lundgren et al., 1971; Lundgren and Thurrell 1973). All available information indicates that the forces necessary to develop most of the jointing and faulting at Millstone Point are related to the extensional regime of the Juro-Triassic period. The compressional forces evident by faults 1940 and 2781 may have resulted from shear couples associated with the tensional forces or may have been the result of pre-Triassic tectonism during the Allegheny Orogeny. Hydrothermal activity along the faults represents the youngest known fault-related event in southern New England (Goldsmith 1973; Skehan 1975; Rodgers 1975).
Millstone Point, like much of New England, is covered by a layer of glacial till. The till has been observed to overlie several faults at the site. No disturbance of the till has been noted (NNECo, 1975, 1982). Caldwell (Appendix 2.5A) estimated the age of the till at the site to be approximately 18,000 years old. Flint (1975) estimates that the margin of the glacier had melted back to the line of the present Connecticut coast about 15,000 years ago.
MPS-3 FSAR 06/28/18 2.5.3-8 Rev. 31 Considering all the geologic data presented, it is concluded that the faults at the Millstone site are not capable. The last activity along them occurred approximately 142 m.y.a. This indicates that the faulting at the site is related to the Triassic-Jurassic rifting as stated in Section 2.5.1.1.4.2 or older events as in the case of fault 1940.
2.5.3.3 EARTHQUAKES ASSOCIATED WITH CAPABLE FAULTS There is no evidence of capable faults within the 5-mile radius of the site. As stated in Section 2.5.2.3.1, the majority of the significant seismic activity has been associated with the White Mountain Plutonic Province. Some activity has been associated with the Ramapo fault system (Aggarwal and Sykes 1978); however, the fault is not considered capable (NRC 1977).
2.5.3.4 INVESTIGATION OF CAPABLE FAULTS There are no capable faults within the site area. The faults uncovered in the excavation are discussed in Section 2.5.3.2.
2.5.3.5 CORRELATION OF EPICENTERS WITH CAPABLE FAULTS As discussed in Section 2.5.2.3.2, there has been no spatial correlation between earthquakes and faults in the site region. Some correlation has been suggested with the Ramapo fault in New York and New Jersey. As discussed in Section 2.5.2.3.1, however, the Ramapo is not considered capable (NRC 1977).
2.5.
3.6 DESCRIPTION
OF CAPABLE FAULTS There are no capable faults within 5 miles of the site.
2.5.3.7 ZONE REQUIRING DETAILED FAULTING INVESTIGATION Eleven incapable fault zones have been uncovered during excavation at the site. These faults have been mapped in detail and are discussed in Section 2.5.3.2. Figure 2.5.4-6 shows the map of the floors of structures. There are no other zones requiring detailed investigation.
2.5.3.8 RESULTS OF FAULTING INVESTIGATION There is no evidence of capable faulting within the 5-mile radius of the site. The faults at the site are related to the rifting associated with the Triassic-Jurassic Period or older, with the last activity occurring approximately 142 m.y.a.
2.5.
3.9 REFERENCES
FOR SECTION 2.5.3 2.5.3.1-1 Aggarwal Y. P. and Sykes, L. R. 1978. Earthquakes, Faults, and Nuclear Power Plants in Southern New York and Northern New Jersey. Science, Vol. 200, No.
4340, p 425-429.
MPS-3 FSAR 06/28/18 2.5.3-9 Rev. 31 2.5.3.1-2 Flint, R. F. 1975. The Surficial Geology of Essex and Old Lyme Quadrangles. State Geological and Natural History Survey of Connecticut, Quadrangle Report No. 31.
2.5.3.1-3 Goldsmith, R. 1967a. Bedrock Geologic Map of New London Quadrangle, Connecticut. U.S. Geological Survey, Quadrangle Map GQ 574, Washington, D.C.
2.5.3.1-4 Goldsmith, R. 1973. Oral Communication with L. Martin and D. Carnes, Stone &
Webster Engineering Corp., Boston, Mass.
2.5.3.1-5 Lundgren, L., Jr.; Ashmead L.; and Snyder, G. L. 1971. The Bedrock Geology of the Moodus and Colchester Quadrangles. State Geological and Natural History Survey, Quadrangle Report No. 27.
2.5.3.1-6 Lundgren, L., Jr. and Thurrell, R. F. 1973. The Bedrock Geology of the Clinton Quadrangle. State Geological and Natural History Survey of Connecticut, Quadrangle Report No. 29.
2.5.3.1-7 Lyons, J. B. and Snellenberg, J. 1971. Dating Faults. Geological Soc. Amer., Bull.
82, p 1749 1752.
2.5.3.1-8 Northeast Nuclear Energy Co. (NNECo.) 1975. Geologic Mapping of Bedrock Surface, Millstone Nuclear Power Station Unit 3. NRC Docket No. 50-423, Hartford, Conn.
2.5.3.1-9 Northeast Nuclear Energy Co. (NNECo.) 1976. Report on Small Fault Uncovered in Warehouse No. 5 Unit 2 and Condensate Polishing Facility, Millstone Nuclear Power Station Unit 3. NRC Docket No. 50-423, Hartford, Conn.
2.5.3.1-10 Northeast Nuclear Energy Co. (NNECo.) 1977. Fault in the Demineralized and Refueling Water Tank Area, Millstone Nuclear Power Station Unit 3. NRC Docket No. 50-423, Hartford, Conn.
2.5.3.1-11 Northeast Nuclear Energy Co. (NNECo.), 1982, Report on Faults and Soil Features Mapped in the Discharge Tunnel Excavation, Millstone Nuclear Power Station -
Unit 3, NRC Docket No. 50-423.
2.5.3.1-12 Nuclear Regulatory Commission 1977. 6 NRC 547(1977) Atomic Safety and Licensing Appeal Board Hearings on Indian Point, Units 1, 2, and 3 (Dockets No.
50-3, 50-247), (50-286) ALAB-436.
2.5.3.1-13 Rodgers, J. 1970. The Tectonics of the Appalachians. John Wiley and Sons, Inc.,
New York, NY.
2.5.3.1-14 Rodgers, J. 1975. Oral Communication with L. Martin and P. Mayrose, Stone &
Webster Engineering Corp., Boston, Mass.
MPS-3 FSAR 06/28/18 2.5.3-10 Rev. 31 2.5.3.1-15 Skehan, J. W. 1975. Oral Communication with L. Martin and F. Vetere, Stone &
Webster Engineering Corp., Boston, Mass.
2.5.3.1-16 Skehan, J. W. 1961. The Green Mountain Anticlinorium in the Vicinity of Wilmington and Woodford, Vermont. Vermont Development Department, Bull. No.
17, Montpelier, Vt.
2.5.3.1-17 Suter, R.; deLaguna, W.; and Perlmutter, N. M. 1949. Mapping of Geologic Formations and Aquifers of Long Island, New York. New York Dept. of Conservation, Water Power and Control, Conn. Bull. GW-18, p 212, Albany, NY.
2.5.3.1-18 Sutter, J. F. 1971. K-Ar Relationships in Mylonite Rocks (Abs). A.G.U. Trans., Vol.
52, p. 367-368.
2.5.3.1-19 Velde, B. 1965. Experimental Determination of Muscovite Polymorph Stabilities, Amer. Mineral., Vol. 50, p. 436-449.
2.5.3.1-20 Yoder, H. S. and Eugster, H. P. 1955. Synthetic and Natural Muscovites, Geochim et Cosmochim Acta, Vol. 8, p. 225-280.
MPS-3 FSAR 06/28/18 2.5.3-11 Rev. 31 TABLE 2.5.3-1 LIST OF FAULTS CLICK HERE TO SEE TABLE 2.5.3-1
MPS-3 FSAR 06/28/18 2.5.3-12 Rev. 31 TABLE 2.5.3-2 LIST OF SAMPLES CLICK HERE TO SEE TABLE 2.5.3-2
MPS-3 FSAR 06/28/18 2.5.3-13 Rev. 31 TABLE 2.5.3-3 LIST OF K/AR AGE DETERMINATIONS OF FAULT GOUGE CLICK HERE TO SEE TABLE 2.5.3-3
MPS-3 FSAR 06/28/18 2.5.3-14 Rev. 31 FIGURE 2.5.3-1 T-2 FAULT ZONE, FINAL EXCAVATION GRADE - NORTHERN SECTION
MPS-3 FSAR 06/28/18 2.5.3-15 Rev. 31 FIGURE 2.5.3-2 T-2 FAULT ZONE, FINAL EXCAVATION GRADE - SOUTHERN SECTION
MPS-3 FSAR 06/28/18 2.5.3-16 Rev. 31 FIGURE 2.5.3-3 T-3 FAULT ZONE, FINAL EXCAVATION GRADE