ML20209A394
| ML20209A394 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/22/2020 |
| From: | Dominion Energy Nuclear Connecticut |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20209A356 | List:
|
| References | |
| 20-223 | |
| Download: ML20209A394 (192) | |
Text
Millstone Power Station Unit 3 Safety Analysis Report Chapter 2: Site Characteristics
Table of Contents tion Title Page GEOGRAPHY AND DEMOGRAPHY ..................................................... 2.1-1 1 Site Location and Description..................................................................... 2.1-1 1.1 Specification of Location............................................................................ 2.1-1 1.2 Site Area ..................................................................................................... 2.1-1 1.3 Boundaries for Establishing Effluent Release Limits................................. 2.1-1 2 Exclusion Area Authority and Control ....................................................... 2.1-2 2.1 Authority ..................................................................................................... 2.1-2 2.2 Control of Activities Unrelated to Plant Operation .................................... 2.1-3 2.3 Arrangements for Traffic Control............................................................... 2.1-3 2.4 Abandonment or Relocation of Roads........................................................ 2.1-3 2.5 Independent Spent Fuel Storage Installation (ISFSI) ................................. 2.1-4 3 Population Distribution............................................................................... 2.1-4 3.1 Population Distribution within 10 miles ..................................................... 2.1-4 3.2 Population Distribution within 50 Miles .................................................... 2.1-5 3.3 Transient Population ................................................................................... 2.1-6 3.4 Low Population Zone.................................................................................. 2.1-6 3.5 Population Center ....................................................................................... 2.1-6 3.6 Population Density...................................................................................... 2.1-7 4 References For Section 2.1 ......................................................................... 2.1-7 NEARBY INDUSTRIAL, TRANSPORTATION, AND MILITARY FACILITIES........................................................................... 2.2-1 1 Locations and Routes.................................................................................. 2.2-1 2 Descriptions ................................................................................................ 2.2-1 2.1 Description of Facilities.............................................................................. 2.2-1 2.2 Description of Products and Materials........................................................ 2.2-3 2.3 Pipelines...................................................................................................... 2.2-5 2.4 Waterways .................................................................................................. 2.2-5 2.5 Airports ....................................................................................................... 2.2-5 2.6 Highways .................................................................................................... 2.2-6
tion Title Page 2.7 Railroads ..................................................................................................... 2.2-7 2.8 Projections of Industrial Growth................................................................. 2.2-7 3 Evaluation of Potential Accidents............................................................... 2.2-8 3.1 Determination of Design Basis Events .................................................... 2.2-12 3.1.1 Missiles Generated by Events near the Millstone Site ............................. 2.2-12 3.1.2 Unconfined Vapor Cloud Explosion Hazard ............................................ 2.2-19 3.1.3 .................................................................................................................. 2.2-19 3.1.4 Hydrogen Storage at the Site .................................................................... 2.2-22 3.1.5 Toxic Chemicals ....................................................................................... 2.2-22 3.2 Effects of Design Basis Events ................................................................. 2.2-24 4 References for Section 2.2 ........................................................................ 2.2-25 METEOROLOGY ...................................................................................... 2.3-1 1 Regional Climatology ................................................................................. 2.3-1 1.1 General Climate .......................................................................................... 2.3-1 1.1.1 Air Masses and Synoptic Features.............................................................. 2.3-1 1.1.2 Temperature, Humidity, and Precipitation ................................................. 2.3-2 1.1.3 Prevailing Winds......................................................................................... 2.3-2 1.1.4 Relationships of Synoptic to Local Conditions .......................................... 2.3-3 1.2 Regional Meteorological Conditions for Design and Operating Bases ...... 2.3-3 1.2.1 Strong Winds .............................................................................................. 2.3-3 1.2.2 Thunderstorms and Lightning..................................................................... 2.3-4 1.2.3 Hurricanes ................................................................................................... 2.3-4 1.2.4 Tornadoes and Waterspouts........................................................................ 2.3-4 1.2.5 Extremes of Precipitation............................................................................ 2.3-5 1.2.6 Extremes of Snowfall.................................................................................. 2.3-5 1.2.7 Hailstorms ................................................................................................... 2.3-5 1.2.8 Freezing Rain, Glaze, and Rime ................................................................. 2.3-6 1.2.9 Fog And Ice Fog ......................................................................................... 2.3-6 1.2.10 High Air Pollution Potential ....................................................................... 2.3-6 1.2.11 Meteorological Effects on Ultimate Heat Sink........................................... 2.3-6
tion Title Page 2 Local Meteorology...................................................................................... 2.3-7 2.1 Normal and Extreme Values of Meteorological Parameters ...................... 2.3-7 2.1.1 Wind Conditions ......................................................................................... 2.3-7 2.1.2 Air Temperature and Water Vapor ............................................................. 2.3-7 2.1.3 Precipitation ................................................................................................ 2.3-8 2.1.4 Fog and Smog ............................................................................................. 2.3-8 2.1.5 Atmospheric Stability ................................................................................. 2.3-8 2.1.6 Seasonal and Annual Mixing Heights ........................................................ 2.3-9 2.2 Potential Influence of the Plant and Its Facilities on Local Meteorology .. 2.3-9 2.3 Local Meteorological Conditions for Design and Operating Bases ........... 2.3-9 2.3.1 Design Basis Tornado ................................................................................. 2.3-9 2.3.2 Design Basis Hurricane ............................................................................ 2.3-10 2.3.3 Snow Load ................................................................................................ 2.3-10 2.3.4 Rainfall...................................................................................................... 2.3-10 2.3.5 Adverse Diffusion Conditions .................................................................. 2.3-10 2.4 Topography ............................................................................................... 2.3-10 3 On-Site Meteorological Measurements Program ..................................... 2.3-11 3.1 Measurement Locations and Elevations ................................................... 2.3-11 3.2 Meteorological Instrumentation................................................................ 2.3-11 3.3 Data Recording Systems and Data Processing ......................................... 2.3-12 3.4 Quality Assurance for Meteorological System and Data.......................... 2.3-12 3.5 Data Analysis ............................................................................................ 2.3-13 4 Short-Term (Accident) Diffusion Estimates............................................. 2.3-13 4.1 Objective ................................................................................................... 2.3-13 4.2 Calculation ................................................................................................ 2.3-13 4.3 Results....................................................................................................... 2.3-13 5 Long Term (Routine) Diffusion Estimates ............................................... 2.3-14 5.1 Calculation Objective ............................................................................... 2.3-14 5.2 Calculations .............................................................................................. 2.3-14 5.2.1 Release Points and Receptor Locations .................................................... 2.3-14 5.2.2 Database.................................................................................................... 2.3-14
tion Title Page 5.2.3 Models ...................................................................................................... 2.3-14 6 References for Section 2.3 ........................................................................ 2.3-14 HYDROLOGIC ENGINEERING ............................................................. 2.4-1 1 Hydrologic Description............................................................................... 2.4-1 1.1 Site and Facilities........................................................................................ 2.4-1 1.2 Hydrosphere................................................................................................ 2.4-1 2 Floods.......................................................................................................... 2.4-2 2.1 Flood History .............................................................................................. 2.4-2 2.2 Flood Design Considerations...................................................................... 2.4-3 2.3 Effect of Local Intense Precipitation .......................................................... 2.4-4 3 Probable Maximum Flood on Streams and Rivers ..................................... 2.4-7 4 Potential Dam Failures, Seismically Induced ............................................. 2.4-7 5 Probable Maximum Surge and Seiche Flooding ........................................ 2.4-7 5.1 Probable Maximum Winds and Associated Meteorological Parameters.... 2.4-7 5.2 Surge and Seiche Water Levels .................................................................. 2.4-8 5.3 Wave Action ............................................................................................. 2.4-10 5.3.1 Deep Water Waves ................................................................................... 2.4-10 5.3.2 Shallow Water Waves............................................................................... 2.4-12 5.3.3 Wave Shoaling .......................................................................................... 2.4-13 5.3.4 Wave Refraction ....................................................................................... 2.4-13 5.3.5 Wave Runup ............................................................................................. 2.4-14 5.3.6 Clapotis on Intake Structure ..................................................................... 2.4-14 5.4 Resonance ................................................................................................. 2.4-14 5.5 Protective Structures ................................................................................. 2.4-15 6 Probable Maximum Tsunami Flooding .................................................... 2.4-15 7 Ice Effects ................................................................................................. 2.4-16 8 Cooling Water Canals and Reservoirs ...................................................... 2.4-16 9 Channel Diversions................................................................................... 2.4-16 10 Flooding Protection Requirements ........................................................... 2.4-16 11 Low Water Considerations ....................................................................... 2.4-16
tion Title Page 11.1 Low Flow in Rivers and Streams.............................................................. 2.4-16 11.2 Low Water Resulting from Surges, Seiches, or Tsunamis ....................... 2.4-17 11.3 Historical Low Water................................................................................ 2.4-18 11.4 Future Control........................................................................................... 2.4-18 11.5 Plant Requirements ................................................................................... 2.4-18 11.6 Heat Sink Dependability Requirements.................................................... 2.4-18 11.7 Dispersion, Dilution, and Travel Times of Accidental Releases of Liquid Effluents in Surface Waters ...................................................................... 2.4-19 12 Groundwater ............................................................................................. 2.4-23 12.1 Description and Onsite Use ...................................................................... 2.4-23 12.2 Sources...................................................................................................... 2.4-23 12.3 Accident Effects........................................................................................ 2.4-24 12.4 Monitoring or Safeguard Requirements ................................................... 2.4-28 12.5 Design Bases for Subsurface Hydrostatic Loading .................................. 2.4-28 13 Technical Specification and Emergency Operation Requirements .......... 2.4-28 14 References for Section 2.4 ........................................................................ 2.4-29 GEOLOGY, SEISMOLOGY, AND GEOTECHNICAL ENGINEERING ......................................................................................... 2.5-1 1 BASIC GEOLOGICAL AND SEISMIC INFORMATION ................... 2.5.1-1 1.1 Regional Geology .................................................................................... 2.5.1-1 1.1.1 Regional Physiography and Geomorphology .......................................... 2.5.1-2 1.1.2 Regional Structure ................................................................................... 2.5.1-3 1.1.3 Regional Stratigraphy .............................................................................. 2.5.1-6 1.1.4 Regional Tectonics .................................................................................. 2.5.1-6 1.1.4.1 Domes and Basins.................................................................................... 2.5.1-6 1.1.4.2 Faulting .................................................................................................... 2.5.1-7 1.1.4.3 Tectonic Summary ................................................................................. 2.5.1-10 1.1.4.4 Remote Sensing ..................................................................................... 2.5.1-10 1.1.4.5 Structural Significance of Geophysical Studies..................................... 2.5.1-11 1.1.5 Regional Geologic History .................................................................... 2.5.1-12
tion Title Page 1.2 Site Geology .......................................................................................... 2.5.1-16 1.2.1 Site Physiography .................................................................................. 2.5.1-16 1.2.2 Local Stratigraphy.................................................................................. 2.5.1-17 1.2.3 Site Stratigraphy .................................................................................... 2.5.1-17 1.2.4 Local Structural Geology....................................................................... 2.5.1-18 1.2.4.1 Site Structural Geology.......................................................................... 2.5.1-20 1.2.5 Site Geological History.......................................................................... 2.5.1-21 1.2.6 Site Engineering Geology ...................................................................... 2.5.1-24 1.3 References for Section 2.5.1 .................................................................. 2.5.1-25 2 VIBRATORY GROUND MOTION ....................................................... 2.5.2-1 2.1 Seismicity................................................................................................. 2.5.2-1 2.1.1 Completeness and Reliability of Earthquake Cataloging ........................ 2.5.2-1 2.1.2 Earthquake History .................................................................................. 2.5.2-2 2.1.3 Seismicity within 50 Miles of the Site..................................................... 2.5.2-4 2.1.4 Earthquakes Felt at the Site ..................................................................... 2.5.2-5 2.2 Geologic Structures and Tectonic Activity.............................................. 2.5.2-9 2.3 Correlation of Earthquake Activity with Geologic Structures or Tectonic Prov-inces ....................................................................................................... 2.5.2-14 2.3.1 Correlation with Geologic Structures .................................................... 2.5.2-14 2.3.2 Correlation with Tectonic Provinces ..................................................... 2.5.2-15 2.4 Maximum Earthquake Potential ............................................................ 2.5.2-16 2.4.1 Maximum Historical Site Intensity........................................................ 2.5.2-16 2.4.2 Maximum Earthquake Potential from Tectonic Province Approach..... 2.5.2-17 2.5 Seismic Wave Transmission Characteristics of the Site........................ 2.5.2-17 2.6 Safe Shutdown Earthquake .................................................................... 2.5.2-18 2.7 Operating Basis Earthquake................................................................... 2.5.2-18 2.8 References for Section 2.5.2 .................................................................. 2.5.2-18 3 SURFACE FAULTING .......................................................................... 2.5.3-1 3.1 Geologic Conditions of the Site............................................................... 2.5.3-1
tion Title Page 3.2 Evidence of Fault Offset .......................................................................... 2.5.3-1 3.2.1 Petrographic Analysis .............................................................................. 2.5.3-3 3.2.2 Clay Mineralogy, Fluid Inclusion Analysis, and Radiometric Dating .... 2.5.3-4 3.2.3 Conclusions.............................................................................................. 2.5.3-7 3.3 Earthquakes Associated with Capable Faults .......................................... 2.5.3-8 3.4 Investigation of Capable Faults ............................................................... 2.5.3-8 3.5 Correlation of Epicenters with Capable Faults ........................................ 2.5.3-8 3.6 Description of Capable Faults.................................................................. 2.5.3-8 3.7 Zone Requiring Detailed Faulting Investigation ..................................... 2.5.3-8 3.8 Results of Faulting Investigation ............................................................. 2.5.3-8 3.9 References for Section 2.5.3 .................................................................... 2.5.3-8 4 STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS ..................................................................................... 2.5.4-1 4.1 Geologic Features .................................................................................... 2.5.4-1 4.2 Properties of Subsurface Materials .......................................................... 2.5.4-2 4.2.1 Artificial Fill ............................................................................................ 2.5.4-3 4.2.2 Beach Deposits ........................................................................................ 2.5.4-3 4.2.3 Unclassified Stream Deposits .................................................................. 2.5.4-3 4.2.4 Ablation Till............................................................................................. 2.5.4-4 4.2.5 Basal Till.................................................................................................. 2.5.4-4 4.2.6 Monson Gneiss ........................................................................................ 2.5.4-5 4.3 Exploration............................................................................................... 2.5.4-6 4.4 Geophysical Surveys................................................................................ 2.5.4-6 4.4.1 Onshore Seismic Refraction Survey ........................................................ 2.5.4-7 4.4.2 Offshore Seismic and Bathymetric Survey.............................................. 2.5.4-7 4.4.3 Seismic Velocity Measurements.............................................................. 2.5.4-7 4.5 Excavations and Backfill ......................................................................... 2.5.4-9 4.5.1 Excavation ............................................................................................... 2.5.4-9 4.5.2 Backfill................................................................................................... 2.5.4-11 4.5.3 Extent of Dredging................................................................................. 2.5.4-14
tion Title Page 4.6 Groundwater Conditions........................................................................ 2.5.4-14 4.6.1 Design Basis for Groundwater............................................................... 2.5.4-14 4.6.2 Groundwater Conditions During Construction...................................... 2.5.4-16 4.7 Response of Soil and Rock to Dynamic Loading .................................. 2.5.4-17 4.7.1 Subsurface Material Properties Used in SSI Analysis........................... 2.5.4-18 4.8 Liquefaction Potential............................................................................ 2.5.4-19 4.8.1 Structural Backfill.................................................................................. 2.5.4-19 4.8.2 Basal Tills .............................................................................................. 2.5.4-19 4.8.3 Beach and Glacial Outwash Sands ........................................................ 2.5.4-20 4.8.3.1 Dynamic Response Analysis of Beach and Glacial Outwash Sands ...................................................................................................... 2.5.4-20 4.8.3.2 Liquefaction Analysis of Beach and Glacial Outwash Sands................ 2.5.4-22 4.8.3.3 Liquefaction Analyses of Beach Area Sands using 2-Dimensional Dynamic Response Analysis......................................... 2.5.4-24 4.8.4 Ablation Till........................................................................................... 2.5.4-26 4.8.4.1 Dynamic Response Analysis of Ablation Till ....................................... 2.5.4-26 4.8.4.2 Liquefaction Analysis of Ablation Till .................................................. 2.5.4-27 4.9 Earthquake Design Basis ....................................................................... 2.5.4-28 4.10 Static Stability........................................................................................ 2.5.4-28 4.10.1 Bearing Capacity.................................................................................... 2.5.4-28 4.10.2 Settlement of Structures......................................................................... 2.5.4-29 4.10.3 Lateral Earth Pressures .......................................................................... 2.5.4-30 4.11 Design Criteria ....................................................................................... 2.5.4-30 4.12 Techniques to Improve Subsurface Conditions ..................................... 2.5.4-31 4.13 Structure Settlement............................................................................... 2.5.4-32 4.14 Construction Notes ................................................................................ 2.5.4-32 4.15 References for Section 2.5.4 .................................................................. 2.5.4-33 5 STABILITY OF SLOPES ....................................................................... 2.5.5-1 5.1 Slope Characteristics................................................................................ 2.5.5-1 5.1.1 Shoreline Slope ........................................................................................ 2.5.5-1
tion Title Page 5.1.2 Containment Rock Cut............................................................................. 2.5.5-3 5.2 Design Criteria and Analysis ................................................................... 2.5.5-3 5.2.1 Shoreline Slope ........................................................................................ 2.5.5-3 5.2.2 Containment Rock Cut............................................................................. 2.5.5-6 5.3 Logs of Borings ....................................................................................... 2.5.5-7 5.4 Compacted Fill......................................................................................... 2.5.5-7 5.5 References for Section 2.5.5 .................................................................... 2.5.5-7 6 EMBANKMENTS AND DAMS ............................................................ 2.5.6-1 PENDIX 2.5A- AGE OF TILL AT MILLSTONE POINT .................................... 2.5A-1 PENDIX 2.5B- PETROGRAPHIC REPORTS, FINAL GRADE ..........................2.5B-1 PENDIX 2.5C- MINERALOGICAL ANALYSIS OF MILLSTONE FAULT GOUGE SAMPLES......................................................................................2.5C-1 PENDIX 2.5D- POTASSIUM - ARGON AGE DETERMINATION ................... 2.5D-1 PENDIX 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 PENDIX 2.5F- DYNAMIC SOIL TESTING ON BEACH SANDS...................... 2.5F-1 PENDIX 2.5G- CONSOLIDATED UNDRAINED TESTS ON BEACH SANDS2.5G-1 PENDIX 2.5H- SEISMIC VELOCITY MEASUREMENTS ................................ 2.5H-1 PENDIX 2.5I- DIRECT SHEAR TESTS ON NATURAL ROCK JOINTS .......... 2.5I-1 PENDIX 2.5J- BORING LOGS..............................................................................2.5J-1 PENDIX 2.5K- SEISMIC SURVEY...................................................................... 2.5K-1 PENDIX 2.5L- SEISMIC AND BATHYMETRIC SURVEY ...............................2.5L-1 PENDIX 2.5M- LABORATORY TEST PROGRAM FOR PROPOSED ADDITIONAL STRUCTURAL BACKFILL SOURCES.....................................2.5M-1
List of Tables mber Title 1 1990 Population and Population Densities Cities and Towns Within 10 Miles of Millstone 2 Population Growth 1960-1990 3 Population Distribution 1985 (0-20 km) 4 Population Distribution Within 10 Miles of Millstone - 1990 Census 5 Population Distribution Within 10 Miles of Millstone - 2000 Projected 6 Population Distribution Within 10 Miles of Millstone - 2010 Projected 7 Population Distribution Within 10 Miles of Millstone - 2020 Projected 8 Population Distribution Within 10 Miles of Millstone - 2030 Projected 9 Population Distribution 1985 (0-80 km) 10 Population Distribution Within 50 Miles of Millstone - 1990 Census 11 Population Distribution Within 50 Miles of Millstone - 2000 Projected 12 Population Distribution Within 50 Miles of Millstone - 2010 Projected 13 Population Distribution Within 50 Miles of Millstone - 2020 Projected 14 Population Distribution Within 50 Miles of Millstone - 2030 Projected 15 Transient Population Within 10 Miles of Millstone - 1991-1992 School Enrollment 16 Transient Population Within 10 Miles of Millstone (Employment) 17 Transient Population Within 10 Miles of Millstone State Parks and Forests (With Documented Attendance) 18 Low Population Zone Permanent Population Distributions 19 Low Population Zone School Enrollment and Employment 20 Metropolitan Areas Within 50 Miles of Millstone 1990 Census Population 21 Population Centers Within 50 Miles of Millstone 22 Population Density* 1985 (0-20 km) 23 Population Density 1985 (0-80 km) 24 Population Density Within 10 Miles of Millstone 1990 (People per Square Mile) 25 Population Density Within 10 Miles of Millstone 2030 (People per Square Mile)
mber Title 26 Population Density Within 50 Miles of Millstone 1990 (People per Square Mile) 27 Population Density Within 50 Miles of Millstone 2030 (People per Square Mile) 28 Cumulative Population Density 1985 29 Cumulative Population Density Within 50 Miles of Millstone 1990 (People per Square Mile) 30 Cumulative population Density Within 50 Miles of Millstone 2030 (People per Square Mile) 1 Description of Facilities 2 List of Hazardous Materials Potentially Capable of Producing Significant Missiles 3 Summary of Exposure Distance Calculation 4 Aggregate Probability of Explosion or Violent Rupture Capable of Missile Generation 5 Types of Tank Car Missiles 6 Tank Car Fragment Range (Feet) at 10-Degree Launch Angle 7 Estimated Ignition Probabilities 8 Probability of an Unconfined Vapor Cloud Explosion 1 Monthly, Seasonal, and Annual averages and Extremes of Temperature at Bridgeport, Conn. (1901-1981) 2 Mean Number of Days with Selected Temperature Conditions at Bridgeport, Conn.
(1966-1981) 3 Monthly, Seasonal, and Annual Averages and Extremes of Relative Humidity at Bridgeport, Conn. (1949-1981) 4 Monthly, Seasonal, and Annual Frequency Distributions of Wind Direction at Bridgeport, Conn. (1949-1980)
-5 Occurrence of Bridgeport Wind Persistence Episodes within the same 22.5-Degree Sector (1949-1965) 6 Monthly, Seasonal, and Annual Frequency Distributions of Wind Direction at Bridgeport, Conn. (1949-1980) 7 Monthly, Seasonal, and Annual Wind Speed Extremes at Bridgeport, Conn. (1961-1990)
mber Title 8 Mean Number of Days of Thunderstorm Occurrence at Bridgeport, Conn. (1951-1981) 9 Monthly, Seasonal, and Annual Averages and Extremes of Precipitation at Bridgeport, Conn. (1901-June 1982) 10 Estimated Precipitation Extremes for Periods up to 24 Hours and Recurrence Intervals Up to 100 Years 11 Monthly, Seasonal, and Annual Averages and Extremes of Snowfall at Bridgeport, Conn. (1893-June 1990) 12 Monthly, Seasonal, and Annual Averages of Freezing Rain and Drizzle at Bridgeport, Conn. (1949-1980) 13 Average Monthly, Seasonal, and Annual Hours and Frequencies (percent) of Various Fog Conditions (1949-1980) at Bridgeport, Connecticut 14 Monthly and Annual Wind Direction and Speed Distributions for Surface Winds, at Bridgeport, Conn. (1949-1980) 15 Monthly and Annual Wind Direction and Speed Distributions for 33-Foot Winds at Millstone (1974-1981) 16 Comparison of Wind Direction Frequency Distribution by Quadrant at Bridgeport, Conn. and Millstone 17 Comparison of Average Wind Speed by Quadrant at Bridgeport, Conn. and Millstone 18 Occurrence of Wind Persistence Episodes Within the Same 22.5-Degree Sector at Millstone (1974-1981)
-19 Millstone Climatological Summary (1974-2000) 20 Comparison of Monthly and Annual Average Dry-Bulb and Dewpoint Temperature Averages at Bridgeport, Conn. and Millstone 21 Comparison of Monthly and Annual Average Relative Humidity Averages at Bridgeport and Millstone
-22 Mean Number of Days with Heavy Fog at Bridgeport, Conn. and Block Island, Rhode Island (1951-1981) 23 Wind Direction/Stability Class/Visibility Joint Frequency Distribution at Millstone 24 Persistence of Poor Visibility ( 1 Mile) Conditions at Millstone (Hours) (1974-1981)
mber Title 25 Bridgeport Pasquill Stability Class Distribution (1949-1980) 26 Millstone Stability Class Distribution Using Delta-T for Stability Determination 27 Millstone Stability Class Distribution Using Sigma Theta for Stability Determination 28 Comparison of Pasquill Stability Class Distribution at Bridgeport, Conn. and Millstone 29 Persistence of Stable Conditions (E, F, and G Stabilities) at Millstone (1974-1981) 30 Seasonal and Annual Atmospheric Mixing Depths at Millstone 31 On-site Meteorological Tower Measurements 32 Millstone Meteorological Tower Instrumentation 33 Monthly Summary of Data Recovery Rates/Meteorological System 34 Distances from Release Points to Receptors 1 Connecticut Public Water Supplies within 20 Miles of Millstone 3 2 Maximum Wave Heights Generated by Slow, Medium, and High Speed Storms (Deep-Water Fetch) 3 Maximum Shallow Water Waves (after Refraction) Slow Speed Probable Maximum Hurricane 4 Maximum Shallow Water Waves (after Refraction) Medium Speed Probable Maximum Hurricane 5 Maximum Shallow Water Waves (after Refraction) High Speed Probable Maximum Hurricane 6 Lowest Tides at New London, Connecticut 1938-1974 7 Circulating Water System and Service Water System Heat Loads 8 Dilution Factors and Travel Time
- 9 Category I Structures - Roof Survey 10 Input Data to Program HEC-2 Water Surface Computations 11 Computed Water Surface Elevations at Safety-Related Structures 12 Roof Area and Ponding Level Due to PMP (1)Category I Structures 13 Overflow Length of the Parapet Wall on the Roof Used in PMP Analysis - Category I Structures
mber Title 1-1 Rock Formations of the Coastal Plain off Southern New England 1-2 Rock Formations of Western Connecticut 1-3 Rock Formations of Eastern Connecticut and Western Rhode Island 1-4 Rock Formations of Central Rhode Island (and not Included in Previous Descriptions) 1-5 Rock Formations in Northern and Eastern Rhode Island and Southern Massachusetts 1-6 Rock Formations of Central Massachusetts 1-7 East of Clinton-Newbury Fault System, Eastern Massachusetts, and New Hampshire 1-8 Descriptions of Lineaments from LANDSAT Photographs (Shown on Figure 2.5.1-10) 2-1 Modified Mercalli (MM) Intensity Scale of 1931 2-2 List of Operating Seismic Stations 2-3 Chronological Catalog of Earthquake Activity within 200 Miles of the Site 2-4 List of Earthquakes within the 50-Mile Radius 3-1 List of Faults 3-2 List of Samples 3-3 List of K/Ar Age Determinations of Fault Gouge 4-1 List of Joints - Final Grade Floors of Structures 4-2 List of Foliations - Final Grade Floors of Structures 4-3 List of Slickensides - Final Grade Floors of Structures 4-4 List of Joints - Final Grade Containment and Engineered Safety Features Building Walls 4-5 List of Foliations - Final Grade Containment and Engineered Safety Features Building Walls 4-6 List of Slickensides - Final Grade Containment and Engineered Safety Features Building Walls 4-7 List of Joints - Final Grade Walls of Structures 4-8 List of Foliations - Final Grade Walls of Structures
mber Title 4-9 List of Slickensides - Final Grade Walls of Structures 4-10 Rock Compression Test Results 4-11 Direct Shear Test Results From Joint and Foliating Surfaces 4-12 Summary of Static Soil Properties for Beach Sands
- 4-13 Natural Water Contents of Split Spoon Samples 4-14 Foundation Data for Major Structures 4-15 List of Approximate Boring Locations, Ground Elevations, and Groundwater Elevations
- 4-16 Summary of Water Pressure Test Data 4-17 Groundwater Observations 4-18 Factors of Safety Against Liquefaction of Beach Sands 4-19 In-Place Density Test Results on Category I Structural Backfill Beneath the Service Water Intake Pipe Encasement 4-20 In-Place Density Test Results at Control and Emergency Generator Enclosure Buildings 4-23 Emergency Generator Enclosure - Soil Properties with Structure Effects from SHAKE Analysis 4-24 Bearing Capacity of Major Structures 4-25 Results of Two-Dimensional Liquefaction Analysis of Beach Area Sands
List of Figures mber Title 1 General Site Location
-2 General Vicinity 3 Site Layout 4 Site Plan 5 Towns Within 10 Miles 6 1985 Population Distribution 0-20 km 7 Population Sectors for 0-10 Miles 8 Counties within 50 Miles 9 1985 Population Distribution 0-80 km 10 Population Sectors for 0-50 miles 11 Roads and Facilities in the LPZ 12 LPZ Population Sectors Distribution 1 Major Industrial, Transportation and Military Facilities 2 Instrument Landing Patterns at Trumbull Airport 3 Air Lanes Adjacent to Millstone Point 4 New London County-State Highways and Town Roads
-5 Propane Concentration Outside and Inside the Control Room 1 Topography in the Vicinity of Millstone Point 2 Topographical Profiles within 5 Miles of Site 3 Topographical Profiles within 5 Miles of Site 4 Topographical Profiles within 50 Miles of Site (Sheet 1) 5 Topographical Profiles within 50 Miles of Site (Sheet 1) 6 General Topography - 50 Miles (Sheet 1) 7 Meteorological Instrument and Data Quality Assurance Flow Diagram 1 Facilities Located on the Site 2 Public Water Supplies within 20 Miles of Site
List of Figures (Continued) mber Title 3 Locations of Hydrographic Field Survey Stations, June to October 1965 4 Tidal Currents Measured by Essex Marine Laboratory 5 Bottom Profiles Established by Essex Marine Laboratory 6 Frequency of Tidal Flooding at New London, Connecticut 7 Site Grade and Drainage Basins for PMP Runoff Analysis 8 Bottom Profile Along Path of Maximum Surface Winds 9 Coincident Wave and Surge Slow-Speed Probable Maximum Hurricane 10 Coincident Wave and Surge Medium-Speed Probable Maximum Hurricane 11 Coincident Wave and Surge High-Speed Probable Maximum Hurricane 12 Locus of Hurricane Eye, Hurricane Type: Large Radius, Slow Speed of Translation 13 Locus of Hurricane Eye, Hurricane Type: Large Radius, Medium Speed of Translation 14 Locus of Hurricane Eye, Hurricane Type: Large Radius, High Speed of Translation 15 Wave Transects on Long Island Sound 16 Areas Under Effect of Wave Shoaling and Wave Refraction 17 Wave Refraction Diagram, Block Island Sound Grid 18 Wave Refraction Diagram, Millstone Grid, Angle of Approach South 30 Degrees East 19 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 85 Degrees South 20 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 45 Degrees South 21 Wave Refraction Diagram, Millstone Grid, Angle of Approach West 17 Degrees South 22 Topography and Runup Transects, Millstone Location 23 Intake Transect A
-24 Runup Transect B (West) 25 Runup Transect C (East) 26 Wave Clapotis at Intake
List of Figures (Continued) mber Title 27 Inputs to One Dimensional Setdown Model 28 Large Radius, Probable Maximum Hurricane Isovel Field 29 Large Radius, Slow Speed of Translation Time Variant Wind Field - Millstone 30 Setdown Versus Wind Speed 31 Boundary of the Modeled Area 32 Onsite Well Locations 33 Probable Seepage Path From Boron Recovery Tank and Waste Disposal Building to Long Island Sound 34 Scupper Details - Control, Hydrogen Recombiner, and Containment Enclosure Buildings 35 Roof Plug Sealing Detail - Hydrogen Recombiner Building 36 Hatch Cover Details - Circulating Water Pumphouse Service Water Pump Cubicle 37 Hatch Cover Details - Control Building Mechanical Room 1-1 Regional Physiographic Map 1-2 Regional Pre-Pleistocene Sediments of the Continental Margin 1-3 Site Surficial Geology 1-4 Regional Geologic Map 1-5 Regional Geologic Section 1-6 Regional Tectonic Map 1-7 Stratigraphic Correlation Chart for the Site and Surrounding Region) 1-8 Regional Stratigraphic Correlation Chart (Sheet 1) 1-9 LANDSAT Photographs of Connecticut, Rhode Island, Southern Massachusetts, and Eastern New York 1-10 Lineament Map from LANDSAT Photographs 1-11 Regional Aeromagnetic Map 1-12 Regional Bouguer Gravity Map 1-13 Site Bedrock Geology 1-14 Tectonic Map of Eastern Connecticut 1-15 Contour Diagram of Poles to Foliation Planes - Final Grade
List of Figures (Continued) mber Title 1-16 Contour Diagram of Poles to Joint Planes - Final Grade 1-17 Contour Plot of Bearing and Plunge of Slickensides - Final Grade 1-18 Generalized Location of Faults 2-1 Location of Seismic Stations 2-2 Epicenters of Earthquakes within 200-Mile Radius 2-3 Location of Earthquakes within the 50-Mile Radius 2-4 Isoseismal Map, Earthquake of November 9, 1727 2-5 Isoseismal Map, Earthquake of November 18, 1755 2-6 Isoseismal Map, Earthquake of May 16, 1791 2-7 Isoseismal Map, Earthquake of August 10, 1884 2-8 Isoseismal Map, Earthquake of March 1, 1925 (February 28, 1925 EST) 2-9 Isoseismal Map, Earthquakes of December 20 and 24, 1940 2-10 Tectonic Provinces 3-1 T-2 Fault Zone, Final Excavation Grade - Northern Section 3-2 T-2 Fault Zone, Final Excavation Grade - Southern Section 3-3 T-3 Fault Zone, Final Excavation Grade 4-1 Geologic Map of Final Grade, Service Water Line Walls - East 4-2 Geologic Map of Final Grade, Service Water Line Walls - West 4-3 Geologic Map of Final Grade, South Wall of Discharge Tunnel 4-4 Geologic Map of Final Grade, North Wall of Discharge Tunnel 4-5 Geologic Map of Final Grade, East Wall of Discharge Tunnel 4-6 Geologic Map of Final Grade, Floors of Structures 4-7 Geologic Map of Final Grade, Service Water Line Floor - West 4-8 Geologic Map of Final Grade, Pumphouse Floor 4-9 Geologic Map of Final Grade, Service Water Line Floor - East 4-10 Geologic Map of Final Grade, Southeast Quadrant of Containment Walls 4-11 Geologic Map of Final Grade, Southwest Quadrant of Containment Walls 4-12 Geologic Map of Final Grade, Northwest Quadrant of Containment Walls
List of Figures (Continued) mber Title 4-13 Geologic Map of Final Grade, Northeast Quadrant of Containment Walls 4-14 Geologic Map of Final Grade, Engineered Safety Features, Building Sump Walls 4-15 Geologic Map of Final Grade, Auxiliary Building Pipe Tunnel Pit Walls 4-16 Geologic Map of Final Grade, North Wall of Excavation 4-17 Geologic Map of Final Grade, Northeast and Southeast Pumphouse Walls 4-18 Geologic Map of Final Grade Engineered Safety Features Building Wall 4-19 Geologic Map of Final Grade Discharge Tunnel Floor 4-20 Geological Map of Final Grade Discharge Tunnel Floor 4-21 Geological Map of Final Grade North Wall of Discharge Tunnel 4-22 Geological Map of Final Grade South Wall of Discharge Tunnel 4-23 Geologic Map of Final Grade Discharge Tunnel Floor 4-24 Geologic Map of Final Grade Discharge Tunnel Floor 4-25 Geologic Map of Final Grade West Wall of Discharge Tunnel 4-26 Geologic Map of Final Grade East Wall of Discharge Tunnel 4-27 Geologic Map of Final Grade Discharge Weir Rock Face 4-28 Corrected Blow Count Plot, Pumphouse Area Sands, Onshore Boring Composite 4-29 Corrected Blow Count Plot, Pumphouse Area Sands, Borings P1 to P8 Composite 4-30 Grain Size Distribution Curves (Sheet 1) 4-31 Boring Location Plan 4-32 Plot Plan Showing Locations of the Borings and the Geologic Sections 4-33 Geologic Profile, Sections A-A', B-B' 4-34 Geologic Profile, Sections C-C', D-D', E-E' 4-35 Geologic Profile, Sections F-F" and G-G' 4-36 Top of Basal Till Contour Map 4-37 Groundwater Contour Map 4-38 Groundwater Observations in Boreholes 4-39 Bedrock Surface Contour Map 4-40 General Excavation Plan
List of Figures (Continued) mber Title 4-41 Shorefront and Dredging Plan 4-42 Modulus vs Effective Confining Pressure, Structural Fill 4-43 Lateral Pressure Distribution 4-44 Gradation Curves for Category I Structural Fill 4-45 K2 vs Shear Strain for Beach Sands 4-46 Earthquake Induced Shear Stresses in Beach Sands 4-47 Cyclic Stress Ratio vs Confining Pressure for Beach Sands 4-48 Cyclic Stress Ratio vs Penetration Resistance of Sand 4-49 Factor of Safety Against Liquefaction of Beach Sands 4-50 Idealized Soil Profile Liquefaction Analysis of Ablation Till Under Discharge Tunnel 4-51 Geologic Profile, Section H-H
4-52 Geologic Profile, Section I-I
4-53 Location of Field Density Tests - Service Water Intake Line 4-54 Location of Field Density Test - Emergency Generator Enclosure and Control Building 4-55 Geologic Profile, Section J-J' 4-56 Geologic Profile, Section K-K' 4-57 Grain Size Distribution Curves - Pumphouse Area Outwash Sands (Sheet 1) 4-58 Equivalent Numbers of Uniform Stress Cycles Based on Strongest Components of Ground Motion 4-59 Plan of Settlement Monitoring Benchmark Locations 4-60 Control Building Settlement (Sheet 1) 4-61 Emergency Generator Enclosure Settlement 4-62 .Solid Waste Building Settlement 4-63 Liquid Waste Building Settlement 4-64 Fuel Building Settlement 4-65 Geologic Profile Section L-L' 4-66 Geologic Profile Section M-M'
List of Figures (Continued) mber Title 4-67 Geologic Profile Section N-N' 4-68 Geologic Profile Section O-O' 4-69 Geologic Profile Section P-P' 4-70 Geologic Profile Section Q-Q' 4-71 Geologic Profile Section R-R' 4-72 Soil-Structure Interaction Emergency Generator Enclosure 4-73 Shear Modulus Curve Type 2 Soil (Structural Backfill and Basal Till) 4-74 Damping Curve Type 2 Soil (Structural Backfill and Basal Till) 4-75 Shorefront Profile Used in Liquefaction Analyses 5-1 Section through Shorefront 5-2 Typical Wedge Geometry 5-3 Design Loads for Ring Beam 5-4 Shorefront Slope Stability Section - Sloping Rock Profile 5-5 Summary of CIU Test Results - Beach Area Outwash Sands 5-6 Potential Failure Wedges West Side of Containment Excavation 5-7 Rock Surface Near North Edge of Main Steam Valve Building
ABLE 2.4-1 CONNECTICUT PUBLIC WATER SUPPLIES WITHIN 20 MILES OF MILLSTONE 3 CLICK HERE TO SEE TABLE 2.4-1
BLE 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
TABLE 2.4-3 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION)
SLOW SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-3
TABLE 2.4-4 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION)
MEDIUM SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-4
BLE 2.4-5 MAXIMUM SHALLOW WATER WAVES (AFTER REFRACTION) HIGH SPEED PROBABLE MAXIMUM HURRICANE CLICK HERE TO SEE TABLE 2.4-5
TABLE 2.4-6 LOWEST TIDES AT NEW LONDON, CONNECTICUT 1938-1974 CLICK HERE TO SEE TABLE 2.4-6
LOCA Coincident with LOP Loss of Power (LOP Normal Normal Unit Minimum Normal Operating Cooldown Engineered Safety Engineered Safety Hot Cold Condition (1) Condition Features Features Shutdown Shutdo 6
(106 Btu/hr) (106 Btu/hr) (106 Btu/hr) (10 Btu/hr) (106 Btu/yr) (106 Btu/
Service Water 178.97 (2) (2) (2) (2) (2)
System Circulating Water 8,200 (3) 0 0 0 0 0 System (after RHR cooling commences)
TOTAL 8378.97 (2) (2) (2) (2) (2)
NOTES:
(1) These are maximum heat loads.
(2) See Table 9.2-2.
(3) An approximate value for operation with 1 to 5 inches of backpressure on the turbine.
Usage Location Dilution Factor Travel Decay Time (hr) asure Beach 12.6 0.0 rkness Memorial 36.0 0.0 aterford State Park 36.0 0.0 ean Beach Park 21.0 0.0 escent Beach 40.0 0.0 cky Neck State Park 30.0 0.0 Cook Point 43.0 0.0 ge of Initial Mixing Zone** 3.0 0.0 r Field 36.0 0.0 000 ft south of discharge)
TES:
or discharge from Millstone 2 and 3 For Millstone 2 and 3 operation within 500 to 1,000 ft from the discharge point (quarry cut)
Number and Size of Structure A* (ft) B* (ft) C* (ft) D* (lb/ft2) Scruppers ntrol Building 1.58 0.63 99 2 at 128 in2 = 256 in2 xiliary Building North 0.50 34 South 0.50 42 el 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 in Steam Valve Building El 85'-11 1/4" 0.25 35 El 71'-2" 0.25 73 gineering Safety Features ilding El 56'-9" 0.75 47 ntainment Enclosure 2.06 0.83 118 8 at 128 in2 = 1024 ilding in2 culating and Service Water mphouse (CSWP)
El 39'-0" 1.98 1.31 87 El 26'-0" 1.31 87 drogen Recombiner 0.92 57 2 at 90 in2 = 180 in2 ilding TES:
Difference between drain low point and top of parapet.
Difference between drain low point and top of lowest roof curb.
Difference between drain low point and bottom of overflow scupper.
Maximum load (lb/ft2) applied by maximum ponding (assume that roof drains are clogged);
H2O @ 4°C (62.4 pcf).
WHERE APPLICABLE A B A C
CSWP ROOF ONLY OTHER SAFETY RELATED STRUCTURE ROOFS
COMPUTATIONS Computed Flow (cfs)
Surface Area Concentration Time at Down stream End Drainage Basin (acre) (minutes) of Drainage Basin
& C1 (2) 9.58 14.8 267 6.43 12.6 351 TES:
rainage areas A and B are graded such that their flows do not contribute to the areas of safety related structures.
rainage areas C and C1 are conservatively combined to provide worst case water flows.
SAFETY-RELATED STRUCTURES Maximum W. S.
Elevation at Doors Drainage Basin Structure 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
TABLE 2.4-12 ROOF AREA AND PONDING LEVEL DUE TO PMP (1)CATEGORY I STRUCTURES Other Roof/Area Total Area Peak Elevation Top Elevat Draining to this Considered Peak Flow of Water Elevation of Bott Plan Area of Structure's Roof (3) in Flow off Q=CIA(4) Parapet (ft, Surface (5) Scup Structures Roof (2) (ft2) (Structure/Ft2) Roof (ft2) (cfs) msl) (ft, msl) (ft, Control Bldg. 5,916 Turbine Bldg. / 2,587 8,503 13.74 92'-4" 92'-5" 91'-
Auxiliary Bldg.
North End 7,956 ----- 7,956 12.86 94'-0" (6) 94'-1 1/2" (7) -----
South End 7,912 Containment Encl. 12,445 20.11 93'-6" (6) 93'-10" (7) -----
Structure /4,247 Fuel Bldg. / 286 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 17,628 28.5 86'-2" 86'-8" -----
Cont. Encl. Strt. / 2,283 El 71'-2" 928 Main. Stm. Valve / 17,628 18,556 30.0 71'-7 5/8" 72'-2" -----
Eng. Safety Feat. 6,931 Cont. Strt. Enc. / 5,628 12,559 20.3 57'-3" 57'-4" -----
Bldg.
Cont. Strt. Encl. 18,252 ----- 18,252 29.5 187'-0" 186'-10" 185
Other Roof/Area Total Area Peak Elevation Top Elevat Draining to this Considered Peak Flow of Water Elevation of Bott Plan Area of Structure's Roof (3) in Flow off Q=CIA(4) Parapet (ft, Surface (5) Scup Structures Roof (2) (ft2) (Structure/Ft2) Roof (ft2) (cfs) msl) (ft, msl) (ft, Hyd. Rec. Bldg. 2,104 Cont. Strt. Enc. / 1,327 4,029 6.5 51'-10" 51'-11" -----
ESF Bldg. / 598 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" -----
- 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.
ABLE 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
FIGURE 2.4-1 FACILITIES LOCATED ON THE SITE
LABORATORY
FIGURE 2.4-7 SITE GRADE AND DRAINAGE BASINS FOR PMP RUNOFF ANALYSIS
SLOW SPEED OF TRANSLATION MEDIUM SPEED OF TRANSLATION HIGH SPEED OF TRANSLATION
EAST SOUTH SOUTH SOUTH
FIELD WIND FIELD - MILLSTONE
FIGURE 2.4-33 PROBABLE SEEPAGE PATH FROM BORON RECOVERY TANK AND WASTE DISPOSAL BUILDIN TO LONG ISLAND SOUND
BUILDINGS BUILDING
ROOM s section provides information regarding seismic, geologic, and geotechnical characteristics of site and the surrounding region.
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.
information contained in this section was obtained from the following:
- 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.
site is located on a low peninsula on the north shore of Long Island Sound and the east shore he Niantic River. Bedrock is highest on the eastern portion of the site and dips to the west ards Long Island Sound. The reactor containment and most other Category I structures on the ern side of the site are founded on bedrock, whereas the control, emergency generator, waste osal enclosure, turbine building, are founded on dense basal till which overlies the rock. The ulating and service water pumphouse is also founded on bedrock. The bedrock surface falls sharply from the main site area to approximately el -32 feet in the area of the pumphouse.
tion 2.5.1 presents the regional and site area geology and geologic history. A discussion of onal faulting and tectonics and their relationship to rock types at the site is discussed in detail.
tion 2.5.2 presents the regional seismicity and describes the selection of the site safe shutdown hquake (SSE) of 0.17 g and the operating basis earthquake (OBE) of 0.09 g.
tion 2.5.3 describes the faulting encountered at the site during construction. A description of origin and nature of the faults mapped at final excavation grades is included in this section.
il, and stability and liquefaction analyses based on these studies are also included in this ion, as well as maps and tables from the geological mapping program.
tion 2.5.5 presents the results of stability analyses on two safety related slopes at the site: the tainment excavation and the shoreline slope.
bankments or dams (Section 2.5.6) are not included in the plant design.
shown on Figure 2.5.1-1 the site lies in the Seaboard Lowland section of the New England siographic province. The site is located in a geologically complex region characterized by amorphosed and folded rocks of Ordovician-Silurian age. This area has been affected by four genies: the Avalonian (575 million years ago m.y.a.), the Taconian (465-445 m.y.a.), the dian (400-370 m.y.a.), and the Alleghenian (230-260 m.y.a.). The surrounding region has also n affected by rifting ranging in age from Triassic to Jurassic. Since then the region has been le, with the exception of epeirogenic uplift during Cretaceous and Tertiary times, and isostatic ound, resulting from the removal of the weight of ice covering the region during Pleistocene e.
site lies in an area of low seismic activity. Only 13 earthquakes of Intensity V, Modified calli (MM) or greater, have been recorded within a distance of 50 miles of the site in more 300 years. The nearest significant earthquake was at East Haddam, Connecticut, in 1791. Its enter was approximately 25 miles north of the site. Even though this earthquake is recorded in Earthquake History of the United States (USCGS 1965) as having an intensity of VIII MM, iled studies by Rev. Linehan, Director, Weston Geophysical Observatory, based on newspaper ounts and other records of the time, indicate that the intensity was no higher than VI to VII
. Maximum intensity of ground motion experienced at the site in approximately 300 years of rded history has not exceeded Intensity V MM, which would correspond to an acceleration of to 0.03g.
lts believed to be related to Triassic tectonics have been found in the excavation for Millstone otassium-argon methods of dating clay gouge found within the faults indicate that the last vity along these faults occurred approximately 142 m.y.a.; therefore, these faults are not able features (NNECO. 1975, 1976, 1977, 1982). There is no capable fault at or near the site.
hick layer of very dense basal till blankets the site. The bedrock surface is irregular and was ially smoothed. Most major plant safety related structures are founded on hard, crystalline rock. The control building is founded on structural backfill overlying till and bedrock.
re has been no commercial mining in the area other than the now inactive granite quarry, ted approximately 1,200 feet to the southeast of the Millstone 3 plant area. The soils and rock erlying the site are strong, stable materials that are not susceptible to loss of strength, sidence, or other instabilities during earthquake motion. The gradation and the density of the are such that liquefaction is precluded. The soils and rock underlying the site are of very low meability. The groundwater table is highest in the northern part of the site and slopes gradually ards the shoreline. There are some isolated wells in the area; however, there is no industrial, estic, or municipal use of groundwater from these wells.
1.1 REGIONAL GEOLOGY w England is characterized by a series of intensely folded anticlinoria and synclinoria trending he northeast. The geology of these folds has been made more complex by igneous activity, amorphism, and faulting. Extensive glaciation has modified landforms and deposited or
ions that follow.
1.1.1 Regional Physiography and Geomorphology Millstone site is located in the Seaboard Lowland section of the New England physiographic vince (Figure 2.5.1-1). The New England province is divided into five sections by Fenneman 38): the Taconic, the Green Mountain, the White Mountain, the New England Upland, and the board Lowland. The Connecticut Valley Lowland is discussed by Fenneman (1938), but not sidered as a separate province. Just southwest of Millstone Point along the coast of necticut lies the Coastal Plain province. These sections are not necessarily characterized by orm geological terrain, but are defined primarily by similar topographic expression.
tion 2.5.1.2 discusses the local physiography and its significance to the site.
Seaboard Lowland section is a smooth, low-lying belt extending from Connecticut north to w Brunswick. In Connecticut, the Lowland varies in width from 6 to 16 miles, and as it swings hward in Rhode Island and Massachusetts, it widens to approximately 50 miles in theastern Massachusetts. The relatively low altitude of the seaboard section is not primarily to a difference in rock resistance, though the parts underlain by the Carboniferous sediments lower and flatter than the rest (Fenneman 1938). Along Long Island Sound, it is probable that rrow zone was covered by Cretaceous formations of the coastal plain (Fenneman 1938). This e has a steeper seaward slope than the upland and is considered by Fenneman (1938) to be part he pre-Schooley peneplain. In the Millstone site area, this zone is characterized by glacial wash and moraines with some swamp deposits.
Taconic section, the westernmost subdivision of the New England province, extends from roximately 12 miles southeast of Poughkeepsie, New York, northward to approximately land, Vermont. The zone is fairly narrow with a maximum width of about 25 miles, and the is mostly mountainous. The mountains consist mainly of strongly metamorphosed sediments, predominantly schists and slates.
Green Mountain section borders the Taconic section to the northeast. This highland section nds from western Massachusetts into Canada. The Green Mountains are underlain by resistant talline rocks of Precambrian age.
White Mountain section consists of a series of mountain ranges from the White Mountains of w Hampshire northeastward to the Katahdin group in Maine. This section is underlain mainly metamorphosed sedimentary and volcanic rocks of Paleozoic age and igneous rocks of the ite Mountain Plutonic-Volcanic series (Billings 1956).
New England Upland section, the largest section of the New England physiographic vince, extends from Canada to the Highlands area of southeastern New York and northern w Jersey. This section typically reflects underlying fold belts and has the appearance of a eau dissected by narrow valleys and containing scattered monadnocks (Fenneman 1938). It first believed that a single peneplain existed at one time and extended from Long Island
exact origin of the peneplain is still questioned. Two hypotheses have been brought forth for origin of the plateau: marine terracing and terracing by normal erosion (Fenneman 1938).
ther explanation is widely accepted, although a combination of the two seems more plausible.
Connecticut Valley Lowland trends northerly through the New England Upland section from Connecticut shore to just north of Greenfield, Massachusetts. The Lowland is underlain by dstone, conglomerate, and shale, which is less resistant to weathering, and diabase which is e resistant. There is an abrupt change to crystalline rocks on both sides of the depression.
th of the New England Lowland section is the Atlantic Coastal Plain physiographic province.
s section (Figure 2.5.1-1) encompasses Cape Cod, Long Island, southern New Jersey, and the hore islands and shoals. In the site area, the Coastal Plain sediments are submerged by the ntic Ocean. These sediments are of late Cretaceous and Tertiary ages and thicken seaward.
ure 2.5.1-2 shows a distribution of pre-Pleistocene sediments off the New England coast. The ement is believed to be a continuation of that found underlying southern New England.
ciation has greatly changed much of New England. The rock outcrops have been rounded and othed and the valleys filled with glacial deposits. The rivers in many cases had to develop channels after being dammed by glacial deposits.
stocene glacial deposits are widespread throughout New England. End moraines occur along southern margins and are prominent along Long Island, Block Island, Martha's Vineyard, e Cod, and in southern Rhode Island and Connecticut (Schafer and Hartshorne 1965). End aines have been mapped in the site area by Flint (1975) and Goldsmith (1964) and are shown he Site Surficial Map (Figure 2.5.1-3).
1.1.2 Regional Structure Millstone site area lies in the northern portion of the Appalachian Mountain system. The alachians extend from Alabama to Newfoundland as a series of ranges formed by a number of cessive deformations during the Paleozoic era.
northern Appalachians can be separated into a number of distinct geologic sections. The ternmost area, the foreland, is relatively undeformed. This area includes the Catskill Plateau, Hudson-Champlain and the St. Lawrence Lowlands, and consists mainly of gently dipping, mentary rocks of Early Paleozoic age.
arrow belt of deformed and metamorphosed lower Paleozoic carbonate rocks, east of the land, forms the northern extension of the Valley and Ridge province. These rocks are similar hose of the Catskill Plateau: however, they have undergone at least two deformations and have n broken by thrust faults and high-angle gravity faults.
westward into place above middle Ordovician shales (Figures 2.5.1-4 and 2.5.1-5).
New England section is a series of north-south anticlinoria and synclinoria that parallel the eral trend of the Appalachian Mountain belt. They are, from west to east: the Green Mountain clinorium, the Connecticut-Gaspe synclinorium, the Bronson Hill anticlinorium, the rimack synclinorium, and the Rockingham anticlinorium, the Merrimack synclinorium, and Rockingham anticlinorium. The Merrimack synclinorium in southeastern New England ends uptly on the east along the Clinton-Newbury and Lake Char fault zones. East of the fault zone a belt of Precambrian and Lower and Middle Paleozoic igneous and metamorphic rocks of ous lithologies. Figure 2.5.1-4 shows the major stratigraphic units associated with these ctural belts and Figure 2.5.1-5 shows the structural units.
Green Mountain anticlinorium is made up of a series of massifs that are intensely sheared and amorphosed Paleozoic rocks with a Precambrian core. They are, from north to south: the en Mountain, the Berkshire, and the Housatonic massifs.
Hudson Highlands group of rocks including schists, gneisses, granites, and minor marbles of cambrian age are exposed along much of the anticlinorium. This structural high is believed to arate the miogeosynclinal sequence on the west from the eugeosynclinal sequence on the east.
eugeosynclinal sequence is generally considered as a homoclinal sequence, of intensely ed and sheared rocks of early Paleozoic age. In the trough of the Connecticut-Gaspe clinorium is a series of domes surrounded by the entire synclinorial sequence. The clinorium is a major tectonic unit that extends from Long Island Sound along the Connecticut er to the Gaspe Peninsula and into Newfoundland. The east limb is masked by the younger tic sediments and basalt flows of the Connecticut Valley Triassic Basin.
crest of the Bronson Hill anticlinorium coincides with an echelon series of Ordovician gneiss es (Naylor 1968, Thompson et al., 1968). The metamorphosed sediments and volcanic rocks rdovician and Devonian ages are stratigraphically continuous with those of the Connecticut-pe synclinorium. The gneiss domes are believed to have been the loci of volcanic islands hin the eugeosynclinal trough during Early Paleozoic time (Naylor 1968, Thompson et al.,
8).
Merrimack synclinorium shares its west limb with the Bronson Hill anticlinorium, which udes metamorphosed lower and middle Paleozoic clastic sediments. Metamorphism and onism have greatly confused the geology of the area. Metamorphic grade increases from north outh within the synclinorium. The synclinorium has been intruded by rocks belonging to the onian New Hampshire Plutonic series (Billings 1956, Page 1968, Foland et al., 1971). The thern extent of the Merrimack synclinorium is obscured by the Honey Hill fault and the local ing and refolding of the Ordovician rocks south of the Honey Hill fault.
ozoic metamorphic units of primarily sedimentary origin.
Merrimack synclinorium and the Rockingham anticlinorium end abruptly along the Clinton-wbury fault zone. East of this fault and the Lake Char fault lies a belt of Precambrian and lower middle Paleozoic igneous and metasedimentary rocks. Granites, granite gneisses, schists, and anic deposits are characteristic of this area. The Precambrian basement of southeastern New land is younger than that of the Green Mountains to the west (Naylor 1975). The geologic ain in this southeastern New England belt is comparable to that of the Avalon Peninsula in wfoundland (Rodgers 1972). A number of Late Paleozoic basins have been superimposed on e rocks: Boston, Norfolk, Woonsocket, North Scituate, and Narragansett Basins. The ragansett Basin is slightly to moderately metamorphosed with a maximum staurolite grade in southwest corner (Weston Observatory 1976). The Boston Basin is only slightly amorphosed (Rodgers 1970).
ng the southern New England coast is an east-west belt of rocks extending eastward from the ern edge of the Connecticut Valley Triassic Basin (Figure 2.5.1-4). In Connecticut, the strip is e up of complexly folded metasediments and a number of gneiss domes. The domes range in from late Precambrian to early Paleozoic (Naylor 1968, Rodgers 1970). The Millstone site is ted in this region adjacent to the Lyme Dome (Section 2.5.1.2). In Rhode Island, the strip sists of massive, relatively undeformed Late Pennsylvanian or Early Permian granites rragansett Pier and Westerly Granite) which intrude the Narragansett Basin deposits, and cambrian gneisses.
taceous and post-Cretaceous sediments have masked the seaward extension of the alachian structures to the south and east. Figure 2.5.1-2 shows the inferred distribution of the stal plain material. Figure 2.5.1-5 shows what is considered to be the seaward thickening ge of Cretaceous, Tertiary, and Quaternary sediments dipping to the southeast. These ments unconformably overlie the pre-Cretaceous rock surface that dips seaward at a low le. Recent work by Sheridan (1974) indicates that there are some very deep, possibly fault-nded basins beneath the outer shelf and beyond, containing carbonates and evaporates of ssic-Triassic and Permo-Carboniferous age (Figure 2.5.1-6). A number of somewhat lower Triassic and Permo-Carboniferous basins have been hypothesized in papers by Ballard Uchupi (1972, 1975) (Figure 2.5.1-6). Table 2.5.1-1 gives the lithologies, ages, and thickness he coastal plain sediments off the southern New England coast. Figure 2.5.1-2 shows the nt of the Cretaceous sediments and the unconformably overlying Tertiary sediments. A thin eer of reworked glacial outwash and clastic material covers most of the shelf area (Hoskins 7). Relief on the surface of the continental shelf of the Long Island, Block Island, and Rhode nd Sounds and in the Buzzards Bay area has been observed by seismic profiling. Tagg and upi (1967) believe these irregularities to be caused by fluvial erosion and modified by glacial ion and deposition.
physical studies in the Gulf of Maine indicate that its tectonic history is similar to that of the w England coast. Late Paleozoic and Early Mesozoic basins are also believed to exist in this (Ballard and Uchupi 1972, 1975). These structures are covered by differing amounts of post-
ments and the Tertiary-lower Pleistocene strata from the Pleistocene glacial deposits (Ballard Oldale 1973). Moraine deposits cover much of the Gulf of Maine and Georges Bank area llard and Oldale 1973). The topographic expression is believed by Ballard and Oldale (1973) e due to the result of stream erosion during Tertiary and early Pleistocene time.
1.1.3 Regional Stratigraphy generalized regional geologic map (Figure 2.5.1-4) shows the distribution of significant rock es in the region surrounding the Millstone site. The regional geologic section (Figure 2.5.1-5) taken trending east-west from the Appalachian Plateau in New York to the eastern edge of the ssic sediments and then southeastward through the Millstone site to the Coastal Plain ments.
regional stratigraphic correlation chart (Figure 2.5.1-7) gives a number of stratigraphic mns with correlations between regions of similar latitude as well as correlations between ons of similar longitude. Therefore, correlations are given parallel to and across the regional
- d. Figure 2.5.1-8 gives more detailed stratigraphic information for areas within the site on. A detailed description of the rock units shown on this chart is included as Tables 2.5.1-1 ugh 2.5.1-7.
1.1.4 Regional Tectonics Northern Appalachians have been affected by four major orogenies: the Avalonian, Taconian, dian, and possibly the Alleghenian. The Avalonian and the Alleghenian orogenies mainly cted the southeastern portions of New England. The first three of these orogenies have duced a complex series of anticlinoria and synclinoria that constitute the New England land
- s. The prominent structural belts are the Green Mountain anticlinorium, the Connecticut ley-Gaspe synclinorium, the Bronson Hill anticlinorium, the Merrimack synclinorium, and the kingham anticlinorium, all discussed in Section 2.5.1.1.2 and shown on Figure 2.5.1-6. These clinoria and synclinoria trend parallel to the Appalachian Mountain belt. Section 2.5.1.1.5 usses the geologic history.
etailed description of regional tectonics is included in this section, which forms the basis for subdivision of New England into tectonic provinces (Section 2.5.2.2).
1.1.4.1 Domes and Basins mentioned in Section 2.5.1.1.2, gneiss domes are present in the Connecticut Valley clinorium and the Bronson Hill anticlinorium.
se domes differ geologically because the gneiss cores of those in the synclinorium may consist ly of Precambrian basement from beneath the Paleozoic sequence, whereas, the core gneisses he anticlinorium seem to be intrusions into the pre-Silurian part of the rock sequence (Rodgers 0). The Lyme and Willimantic domes (Figure 2.5.1-5) lie east of the Bronson Hill
bron Gneiss, Brimfield Schist, Tatnic Hill Formation, and Quinebaug Formation) and have a cambrian-Cambrian core (Ivoryton Group, Plainfield Formation, and Sterling Plutonic Group) ndgren and Ebblin 1972).
most prominent basins in the region are the Triassic basins of the Connecticut Valley and w York-New Jersey and Pennsylvania areas, and the Carboniferous basins of southeastern New land (Figure 2.5.1-6). Offshore basins have been located by geophysical methods south of w England and in the Gulf of Maine (Section 2.5.1.1.2).
1.1.4.2 Faulting effects of the different stages of mountain building are widespread throughout New England.
varying types of faults present in different sections have allowed a reconstruction of the logic history and an increased understanding of the tectonic forces related to each orogeny.
racteristic crustal structures have been left by the Taconian and Acadian orogenies and later he rifting during the Triassic-Jurassic period.
area most affected by the Taconian orogeny is along the Hudson River from approximately bury, Vermont, to the vicinity of Poughkeepsie, New York, and eastward into western ssachusetts. The region exhibits a number of gravity slices that slid off an uplifted block to the during middle to late Ordovician time (Bird 1969).
umber of thrust faults are noticeable in New England. The Ammonoosuc fault in western New mpshire (Figure 2.5.1-6) trends N25E (Rodgers 1970) and dips at approximately 38 degrees to northwest. Silicified zones have been noted along the fault and the displacement has been mated to be 7,000 feet (Billings 1956). The fault offsets the metamorphic isograds associated h the Acadian orogeny: however, it is intruded by granitic rocks associated with the White untain magma series (Billings 1956). Potassium-argon studies on biotite from the Conway nite yield a radiometric age of 172 3 m.y.a. (Foland et al., 1971) indicating no movement g this fault since the granitic intrusion. Rodgers (1970) suggests that the Ammonoosuc may normal fault; however, Billings (1956) considers it a thrust fault.
ther major thrust fault system, the Lake Char-Honey Hill, lies in southern and eastern necticut. The Honey Hill, the east-west segment, extends from Chester near the Connecticut er eastward to south of Preston. The Lake Char section runs north-south from Lake Char in ssachusetts to Preston, Connecticut. The fault system is characterized by zones of cataclastic ks up to 2,500 feet thick (Dixon and Lundgren 1968). The plane of the fault is an irregular, ped surface. The dip of the Honey Hill section is generally at low angles to the north with a imum at 55 degrees in the Preston area; the Lake Char section dips westward at roximately 10 degrees (Dixon and Lundgren 1968). The Honey Hill part of the system is roximately 14 miles from the Millstone site.
thrust fault activity along the Lake Char-Honey Hill system is thought to have begun in the dle to late Devonian and continued into the Permian period (170-225 m.y.a.). Movement on
vement on the fault plane was toward the southeast (Dixon and Lundgren 1968). Dixon and dgren (1968) believe that movement associated with the Lake Char-Honey Hill system prised the last pre-Triassic activity in the area.
ently, Lundgren and Ebblin (1972) have hypothesized that the thick zones of cataclastic rock related to relative upward movement of basement at different places and at different times m late Devonian to Permian. This intense folding developed major cataclastic units in zones of h shear between mantling rock and basement complexes. Three different episodes of uplift ught about the present alignment of structure in southern Connecticut.
gers (1970) indicates that late movements occurred sometime after Carboniferous, but before late Triassic. The Honey Hill fault is cut by faulting believed to be related to Triassic rifting dgers 1970, Goldsmith 1967c).
ther to the northeast in Massachusetts is another large thrust fault system, the Clinton-wbury, paralleling the Bloody Bluff system. Skehan (1969, 1973), Castle et al. (1976), and on (1976) have suggested that the Clinton-Newbury - Bloody Bluff system is a continuation of Lake Char-Honey Hill system of Connecticut. The Clinton-Newbury -Bloody Bluff zones run heasterly from south of Worcester to Newburyport and into the Gulf of Maine (Skehan 1969).
ailed mapping linking the Lake Char to the Bloody Bluff has yet to be done. Exposures in the chusett-Marlboro tunnel indicate that these faults dip to the northwest and are reverse in nature ehan 1968). The average direction of tectonic transport is to the east, similar to that of the e Char-Honey Hill fault. The dominant faulting is later than the metamorphism and is bably late Paleozoic to mid-Mesozoic (Skehan 1968). A prominent number of northerly ding, younger, high-angle faults have been observed throughout the New England area, some ing the thrust faults associated with the Clinton-Newbury system.
northern border of the Triassic Newark Basin is bounded by a series of closely spaced parallel faults that commonly trend N30E to N50E and dip to the southeast. This Ramapo fault em has a complex history of movements dating back to late Precambrian (Ratcliffe 1971).
e Triassic rejuvenation of the old fracture system produced the Newark depositional basin.
mal faulting associated with the regional rifting and the deposition of the coarse glomerates in the basin continued into the Jurassic (Ratcliffe 1971). Page et al. (1968) have orted recent seismic activity in the vicinity of the Ramapo, but there has been no movement cted at the surface.
Triassic Connecticut Valley Basin extends from the Connecticut shore northward to the ssachusetts-Vermont border. The basin averages about 20 miles in width and exposes clastic mentary deposits interlayered with basalt flows and sills generally dipping to the east. At the ern edge, the deposits are abruptly ended by a west dipping normal fault zone. It has been erally accepted that the Connecticut portion of the basin was formed by faulting that was temporaneous with the deposition of the clastic sediments, and the fault zone of the east side gs into contact the Triassic sediments with the Paleozoic crystalline rocks to the east (Wheeler 9, Sanders 1960). The northern part of the Triassic Basin may have had a slightly different
hern portion of the basin has been established in the Mineral Hill area of Montague, ssachusetts (NUSCO. 1974). This fault has been interpreted as a thrust fault, which was later tivated with minor normal displacement. Potassium-argon radiometric dating of fault gouges nd along this fault and other small faults in the region yielded dates between 140 and 180
.a. (NUSCO. 1974). These dates reflect the movement related to the extension tectonics of the ssic-Triassic period.
umber of smaller faults are associated with the Carboniferous basins of eastern Massachusetts eastern Rhode Island. Some of these faults bound the basin. Many of the faults associated h the Boston Basin are thrust faults. These are smaller splays off the large Bloody Bluff fault em previously mentioned (Nelson 1976). These faults were originally formed during the pressional forces associated with the Acadian orogeny. Movement along the faults is believed e associated with the climax of the regional metamorphic event (Nelson 1976). Nelson (1976) cates that another near-surface fault system is post-Pennsylvanian in age, and that this system be related to the faulting of the Pennsylvanian rocks of Rhode Island.
eastern margin of the Woonsocket and North Scituate Basins is bounded by high angle faults inn and Oliver 1962). Although a short portion of the western boundary of the Narragansett in is a normal fault (Quinn 1971), silicification along this fault may indicate some association h Triassic activities (Rodgers 1970). Other small faults on the northeast edge of the ragansett Basin bring Pennsylvanian sedimentary rocks in contact with older plutonic rocks.
physical studies by Ballard and Uchupi (1975) indicate a number of basins in the Gulf of ne and the Georges Bank. These basins were postulated to be bounded by faults associated h the Triassic-Jurassic period. As shown on Figure 2.5.1-6, these authors suggest a boniferous basin extending offshore northeast of the Boston Basin. However, rock samples vered from these areas by Ballard and Uchupi (1975) fail to support the existence of these physically-inferred basins.
shore geophysical studies by McMaster (1971) indicate a fault occurring southwest of Block nd. Recent work performed by Weston Geophysical Engineers, Inc., for New England Power mpany (1976) and by the USGS (Needell and Lewis 1982) has indicated that this fault, named New Shoreham fault, lies slightly east and extends further northward then originally indicated McMaster (1971). It is a normal fault, striking approximately N30-50W and dipping at roximately 75 degrees to the northeast. The fault displaces sediments identified as Cretaceous; ever, Pleistocene deposits are undisturbed. The nearest approach of the New Shoreham fault pproximately 21 miles southeast of Millstone Point (Figure 2.5.1-6).
ny faults have recently been investigated throughout New England. These investigations cate that the last episode of movement was associated with Jurassic-Triassic tectonics. Lyons Snellenburg (1971) have investigated three normal faults in New Hampshire. The study uded the radiometric dating of the clay gouge generated during faulting. Radiometric testing ormed on the illite portion of the clay gouge yielded ages between 157 and 164 m.y.a.
4).
th-south trending high-angle faults have been analyzed in the Charlestown, Rhode Island area.
assium-argon test results on the illite clay gouge indicated dates ranging from 169 to 226
.a. (NEPCo. 1976).
h-angle, north-south trending normal faults uncovered in the excavation of Millstone 3 have been investigated (NNECO 1975, 1976, 1977) and are discussed in greater detail in tion 2.5.3.2. Radiometric age determinations on clay gouge indicate dates ranging from 109 to m.y.a.
h-angle normal faults are quite common in southern New England. Two of these faults, the tern Hill (Rodgers 1970) and the unnamed fault in the Uncasville quadrangle, (Goldsmith 7c), cut the Honey Hill fault. The unnamed fault in Uncasville (Goldsmith 1967c) dies out roximately 10.5 miles northeast of Millstone Point. These faults are believed to be related to rifting associated with the Trassic-Jurassic period because radiometric age dating indicates the last activity along some of these faults occurred in that period. Rodgers (1975), Skehan 75), and Goldsmith (1973) believe that the hydrothermal activity, typically silicification, along ts of this type represents the youngest known tectonically related event in southern New land.
1.1.4.3 Tectonic Summary structural pattern of New England (Figure 2.5.1-6) is characterized by strong north-northeast ds. The major anticlinoria and synclinoria, the alignment of domes and basins, the trend of the ting, and the alignment of most of the granitic intrusions indicate a constant and pervasive onic force acting in the same orientation for a prolonged period of time.
ny of the features are the result of compressional forces acting throughout the region during h of the Paleozoic era. The area has undergone folding, igneous intrusion, refolding, and sequently, thrust faulting.
Mesozoic era was characterized by faulting and igneous activity differing from that of the ozoic era. Normal faulting associated with extensional forces is well developed in the thern New England area. The intrusion of diabase dikes and sills is also associated can be erved, physiographic and tonal. Tonal linear features may be due to a change in vegetation, reas physiographic lineaments generally are due to topographic expression accentuated by ion. These features are probably related to structural discontinuities, chiefly faults, shear es, and joints (O'Leary et al., 1976).
1.1.4.4 Remote Sensing d Satellite (LANDSAT) photographs of Connecticut, Rhode Island, southern Massachusetts, eastern New York were studied to identify linear features or lineaments. A lineament is
umably reflects a subsurface phenomenon (O'Leary et al., 1976). Two types of lineaments can bserved, physiographic and tonal. Tonal linear features may be due to a change in vegetation, reas physiographic lineaments generally are due to topographic expression accentuated by ion. These features are probably related to structural discontinuities, chiefly faults, shear es, and joints (O'Leary et al., 1976).
ure 2.5.1-9 shows the LANDSAT photographs used for the study, and Figure 2.5.1-10 shows lineaments greater than 10 miles long identified on the photographs. The explanation for the ations shown on Figure 2.5.1-10 are given in Table 2.5.1-8. The linear features shown on ure 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 lineaments shown on Figure 2.5.1-10 are, for the most part, due to differences in topography.
se differences may be due entirely to the resistance to erosion of the varying rock units. The ority of the lineaments coincide with geologic contacts which have been accentuated by the ion of rivers and streams. As can be seen on Figure 2.5.1-10 and listed in Table 2.5.1-8, es of weakness within rock masses have also accounted for a number of the lineaments.
ional joint patterns and mapped faults are easily identifiable on the LANDSAT photographs.
se often correspond to topographic lows due to the erosion of the broken and more easily thered material.
1.1.4.5 Structural Significance of Geophysical Studies physical studies have aided in the interpretation of the geology of New England. The magnetic and Bouguer gravity maps relating to regional geologic features are presented on ures 2.5.1-11 and 2.5.1-12, respectively.
aeromagnetic information shown on Figure 2.5.1-11 generally conforms to the regional logic trends observed in New England.
umber of areas exhibit strong alignment or high intensity of magnetic character. The Lake r-Honey Hill system in Connecticut and the Clinton-Newbury fault zone in Massachusetts are most prominent lineations on the aeromagnetic map. The Cape Ann area, north of Boston, is racterized by its high magnetic intensity. This is caused by the combination of the high nsities related to the basic rock of the Salem Gabbrodiorite and the existence of a highly ted and brecciated zone. The northwestern and southern boundaries of the Cape Ann area ely coincide with the Clinton-Newbury, the Bloody Bluff, and the Boston border faults
aller, less striking anomalies occur in the site area, in the Cape Cod area, and in central ssachusetts just east of the Connecticut River Valley Triassic Basin. The anomaly in the lstone area follows the folded pattern of the interlayed metasedimentary and metavolcanic ks. The rock with very high susceptibilities apparently wraps around the structural features cent to the site (Lyme dome, Figures 2.5.1-13 and 2.5.1-14) and extends out into Long Island nd (Barosh and Pease 1974). The anomalies on Cape Cod are probably due to large basic usive bodies (Barosh et al., 1974). The north-south trending anomaly east of the Triassic Basin entral Massachusetts is related to the presence of metavolcanic rocks of high magnetic ceptibility. Barosh and Pease (1974) indicate that the metavolcanic rocks to the south are less netically susceptible due to the effects of retrograde metamorphism and they are not noted on aeromagnetic map.
all isolated anomalies can be observed on the east side of the axis of the Green Mountain clinorium. A series of ultramafic bodies extending from Canada southward to Massachusetts ehan 1961) may be the cause of these anomalies.
ure 2.5.1-12 shows the regional gravity in relation to the geologic structures of New England the trend of the gravity anomalies corresponding to the differing structural alignment. The t prominent anomaly is along the axis of the Green Mountain anticlinorium. This gravity high ears to be caused by the relative uplift of a dense lower crust (Kane et al., 1972). In the eastern ion of New England, it is still apparent that the gravity anomalies follow the structural trend.
s trend is sharply broken by the large negative anomaly encompassing the White Mountains of w Hampshire. Other locally pronounced anomalies are found throughout New England and for the most part, associated with igneous masses. The large anomaly on Cape Ann is bably due to mafic rock underlying the Cape Ann series.
1.1.5 Regional Geologic History Regional Geologic Map (Figure 2.5.1-4) shows the distribution and generalized age tionships of rocks in the New England area.
geologic history of New England is complex because the region has been subject to several genies during the Precambrian and Paleozoic eras. The early and middle Paleozoic rocks esent geosynclinal sequences which have been deformed and recrystalized to varying degrees ng the disturbances discussed below.
nger, relatively unchanged rocks are found in the Carboniferous basins in southeastern New land and in the Triassic-Jurassic basins in south-central New England and New Jersey-nsylvania.
youngest igneous activity in New England took place in the Mesozoic Era. The passive lacement of the White Mountain series during the Jurassic and Cretaceous periods, and the
Precambrian erences have been recognized between the Precambrian rocks in the western part of New land and those of eastern New England. Basement rocks of western New England belong to Grenville province. The older Precambrian rocks in this province include those in the core of Adirondack Mountains and those of the Green Mountain, Berkshire, Housatonic, and Hudson hlands massifs (Figure 2.5.1-6). Isachsen (1964) considers the Manhattan Prong to be cambrian and is considered by Naylor (1975) to be part of the western basement. These rocks characterized by high temperature, high pressure (granulite facies) metamorphism at 1,100 to 0 m.y.a. and may include units that formed significantly earlier (Naylor 1976). Rodgers 68a) suggests that the eastern edge of the North American continent during the Cambrian and ly Ordovician periods coincided with the eastern edge of these massifs.
cambrian rocks of eastern New England are believed to be associated with the Avalonian geny (Rodgers 1972). At Hoppin Hill, Massachusetts, the Dedham Granodiorite is onformably overlain by lower Cambrian slate that is lithologically similar to sequences in wfoundland (Skehan 1968). The eastern basement is considered to be a thick sequence of dominantly mafic volcanic rocks with intercalated metasedimentary rocks and granitic to broic plutons lying underneath fossiliferous lower and middle Cambrian strata (Naylor 1976).
idium-strontium (Rb-Sr) whole-rock ages for the Hoppin Hill Granite, Northbridge and ford Granite, and the Dedham Granodiorite date from 514 to 591 m.y.a. (Fairbairn et al.,
7). The eastern basement is nowhere characterized by granulite facies metamorphism and has yielded zircon or rubidium-strontium whole-rock ages greater than 650 m.y.a. This basement esents a period of widespread volcanism and plutonism with peak activity between 600 and m.y.a. (Naylor 1975). The eastern basement lies, for the most part, east of the Lake Char-ton Newbury fault system. Naylor (1976) considers the gneisses along the southeastern coast onnecticut to be part of the eastern basement and not an eastward extension of the Bronson sequence. The Millstone site lies in this sequence and it is discussed in greater detail in tion 2.5.1.2. Late Precambrian through early Devonian stratified sequences occupy most of area between the eastern and western basements (Naylor 1975).
Early Paleozoic o bands of Cambrian rocks are observed in New England; one along the Hudson and mplain Valleys extending northward to Quebec, and the other in scattered outcrops along the ent-day coast (Theokritoff 1968). The western band was a sand-carbonate shelf sloping ply eastward and grading into a basin of mud deposition. The eastern band consists mainly of d deposits around nonvolcanic islands. During early and middle Cambrian, Pacific province nas occupied sites on the shelf and adjacent parts of the basin, whereas Acado-Baltic faunas upied sites around the island chains (Theokritoff 1968).
imentation continued into the Ordovician period. In early middle Ordovician, much of both platform carbonates and terrain to the east were folded and became emergent (Berry 1968).
masses to the east, and the deposition of deltaic sediments westward from these lands (Berry 8). The uplifts were the surface effects of the orogenic deformation at depth accompanied by
-grade metamorphism (Rodgers 1970). Also associated with these events, referred to as the onian orogeny, was the intrusion of plutons related to the Highlandcroft magma series (Berry 8). During much of middle Ordovician time, a series of volcanoes and islands existed along present day Bronson Hill anticlinorium. Much of eastern Connecticut is underlain by asedimentary, metavolcanic, and plutonic rocks related to this volcanic-island chain.
ivity related to the Taconian orogeny occurred as a discontinuous series of disturbances ween 450 to 500 m.y.a. with the area of maximum deformation located in western New land (Rodgers 1970).
Middle Paleozoic ing the Silurian period, those areas uplifted by the Taconian orogeny were gradually roached upon and eventually covered (Boucot 1968). Volcanic rocks continued to be deposited g the Bronson Hill anticlinorium and volcanic activity became apparent along the Avalonian from southern New Brunswick through southeastern Maine to eastern Massachusetts dgers 1970). A belt coinciding with the present-day Merrimack synclinorium was the locus of thickest sequence of Silurian sediment in the New England region (Boucot 1968).
ywackes and thick argillaceous sandstones characterize this sequence.
bonate sequences reached a maximum in the earliest part of the Devonian period in western w England (Rodgers 1970, Boucot 1968). Clastic material was deposited upon this calcareous uence as the land mass to the east expanded westward (Boucot 1968).
middle Devonian, deposition had ceased throughout the region and the area then underwent its t severe deformation, metamorphism, and granitic intrusions (Rodgers 1970). The Acadian geny is responsible for most of the folding in the rocks presently exposed through the region.
belt of maximum intensity of this activity extends southward from central Newfoundland to ern Connecticut (Rodgers 1970). Faulting related to the Acadian Orogeny is widespread ughout the region. Disturbance of the regional metamorphic isograds indicates that folding faulting continued after the peak of metamorphism (Thompson et al., 1968).
Late Paleozoic deposition of material from this period is concentrated in the southeastern part of the region.
Boston Basin of eastern Massachusetts and the Narragansett, Norfolk, Woonsocket, and uate Basins of Rhode Island and southeastern Massachusetts are the only remnants of mentation. Rocks in these basins consist generally of coarse clastic sediments of continental in. The basins are controlled by faulting; the Boston Basin by high-angle reverse faulting lson 1976) and the Narragansett by high-angle normal faulting (Weston Observatory 1976).
amorphism has only slightly affected the Boston Basin, whereas the Narragansett Basin has,
ormation during the late Paleozoic is not widespread throughout New England. The eghenian orogeny has affected some areas of southern New England. The major manifestation his orogeny is the granitic intrusion in southern Rhode Island and Connecticut. The gentle ing and the metamorphism of the Narragansett Basin sediments may also be attributed to the ghenian orogeny. Activity along the region's extensive system of thrust faults may have tinued into the Permian period. A thermal disturbance yielding K-Ar dates of 230 to 260
.a. has been observed in an area 60 to 80 miles wide extending northward from the southern necticut coast to southwestern Maine, the cause of which is still unknown (Zartman et al.,
0). The igneous activity in Rhode Island and Connecticut may account for the southern extent; ever, Permian granitic intrusions are not observed further north. Granitic and pegmatitic usions related to the Westerly Granite intrude the Monson Gneiss at the Millstone site.
assium-argon dating (NNECO. 1975) also indicates that the Monson Gneiss at the site has n affected by the thermal disturbance described by Zartman et al. (1970) (Section 2.5.1.2).
Mesozoic and Cenozoic ard the end of the Triassic period, a series of linear, generally fault-bounded troughs formed which continental clastic sediments and volcanics accumulated. Two of these basins are arent in this region: the Connecticut Valley Triassic Basin and the Newark-Delaware Basin ure 2.5.1-9). Similar basins beneath and beyond the continental shelf off the eastern and thern coasts of New England have been inferred by geophysical studies (Sheridan 1974, lard and Uchupi 1972 and 1975, Mayhew 1974). Dikes of Triassic-Jurassic age are common ughout the region. High-angle faulting related to the rifting is also widespread throughout thern New England (Section 2.5.1.1.4.2).
eous activity in the region continued with the intrusion of the White Mountain onic-volcanic series. These rocks are found from northern to southeastern New Hampshire, thern Maine, and east central Vermont. Age determinations indicate that activity associated h the White Mountain series began in the Triassic and continued into the early Cretaceous od, 216 to 112 m.y.a. (Foland et al., 1971, Armstrong and Stump 1971). This plutonism-anism represents the last known localized tectonic activity that has occurred in the region of site. Further north, igneous activity continued with the intrusion of the Monteregian Hills onic rocks. The latest activity associated with the Monteregian Hills is approximately 100
.a. (NUSCO. 1974).
Appalachian Mountains have apparently undergone continuous erosion since late Paleozoic ept in the areas of down-dropped Triassic fault blocks (Rodgers 1967). After Jurassic eplanation of the Piedmont Plateau and what presently underlies the Coastal Plain, a broad parallel to the coast was submerged. Material eroded from the exposed Piedmont was osited in the coastal area in the form of a seaward thickening wedge. This wedge is inantly Cretaceous in age (Figures 2.5.1-2 and 2.5.1-5), but includes some thin deposits of tiary age.
ept in detail, were similar to those of today (Flint 1975). The ice scoured the land leaving tered deposits throughout the area and advancing to and beyond the southern New England st. Glacial deposits are the sole rock type exposed on eastern Long Island, Cape Cod, and tucket. The ice began to retreat from the Connecticut coast approximately 15,000 years ago nt 1975). Temporary advances and retreats of the front of the glacier caused deposits of end aines prominent throughout southern Connecticut and Rhode Island (Flint 1975). Pleistocene osition on the submerged Coastal Plain is dominated by a complex series of sedimentary uences separated by unconformities. These relationships are the result of fluvial and marine cesses active during regressions and transgressions of the sea (Knott and Hoskins 1968).
1.2 SITE GEOLOGY Millstone site is located at the southern tip of Millstone Point in Waterford, Connecticut. The is a low lying peninsula within the Seaboard Lowland section of the New England siographic province. Its physiography is discussed in Section 2.5.1.2.1.
Millstone area, like the rest of New England, was covered with glacial ice until roximately 15,000 years ago. The glaciers deposited a thick layer of glacial till and, as they ded, left end moraine and outwash deposits. The surficial geology of the area surrounding the lstone site is shown on Figure 2.5.1-3.
bedrock geology is characterized by extensive deformation, metamorphism, and intrusion by ous bodies. The bedrock geology of the 5-mile radius is shown on Figure 2.5.1-13.
geology of the eastern portion of Connecticut is made difficult to decipher by the complex ing and faulting of the Late Paleozoic era. The tectonic features of the eastern section of necticut are shown on Figure 2.5.1-14. As shown on this figure, the Millstone site lies roximately 30 miles east of the Triassic Border fault, and approximately 15 miles south of the ey Hill fault. The area south of the Honey Hill fault is complexly folded. The site lies on the limb of the recumbent Hunts Brook syncline which mantles the Lyme dome. The site location h relation to these structures is shown on Figure 2.5.1-14.
1.2.1 Site Physiography Seaboard Lowland section of the New England physiographic province narrows along the necticut coast, as shown by Figure 2.5.1-1. In the Millstone Point area, this section narrows pproximately 15 miles, bordered on the north by the New England Upland section and just th of the site by the Coastal Plain physiographic province.
most striking topographic expression in the area is the north-south trending ridges and eys. The area is drained by a number of brooks and also the Thames, Niantic, and the necticut Rivers, the latter approximately 8 miles west of the site.
ptured, by weathering and rainwater runoff, essentially to its surface existing before glaciation urred (Flint 1975). End moraine and glacial stream deposits are also prevalent throughout the on (Figure 2.5.1-3).
Millstone site is located on a small peninsula near the mouth of the Niantic River. Wave on has eroded the blanket of till from the promontories of Millstone Point, exposing rock. The orked material was deposited as beach sand in the protected areas. Eolian deposits are found ome locations, and tidal marshes and swampy areas are common.
ch of the plant area has been graded and backfilled during the construction of the three units of power generating facilities now at Millstone Point.
re is no physiographic evidence indicative of actual or potential localized subsidence, mass ting, or landslides in the vicinity of the site.
1.2.2 Local Stratigraphy site surficial and site bedrock maps are shown as Figures 2.5.1-3 and 2.5.1-13, respectively.
se maps cover approximately the area within the 5-mile radius of the site. The age tionships and descriptions of the differing bedrock units found within this region are shown on ure 2.5.1-13.
site is underlain by the Monson gneiss of pre-Silurian age and the Westerly Granite of nsylvanian or younger age. The bedrock units shown on Figure 2.5.1-13 are dominated by asedimentary and metavolcanic rocks of Cambrian or possibly Precambrian or Ordovician
. The metasedimentary and metavolcanic units have been intruded by several granitic masses, which the Sterling Plutonic Group is the oldest. The granitic gneisses seem to have been laced at fairly deep levels in the crust, for they are associated with migmatites and are mately intermingled with, and grade into, some associated metasedimentary and metavolcanic isses (Goldsmith and Dixon 1968). The Sterling gneiss units have not been noted tigraphically above the Monson gneiss in the site area. The younger granitic intrusions are the ular granites located in the Lyme dome and the Westerly Granite located along the coastline.
se granites are believed to be Permian in age (Goldsmith 1967b).
distribution of Quaternary surficial material is shown on Figure 2.5.1-3. This material udes such glacial deposits as glacial till, end moraine deposits, and stream deposits. Younger mp, littoral, alluvial, and eolian deposits also occur.
1.2.3 Site Stratigraphy excavation for Millstone 3 has been extensively mapped. These maps are shown and cribed in Section 2.5.4.1. In the site area, the bedrock surface is very irregular and completely ered with glacial till. Construction activities from Millstone 1 and 2 disturbed the naturally osited material in the site area which, for the most part, was replaced with artificial fill.
ioclase (45 percent), quartz (35 percent), and biotite (15 percent). Sericite, garnet, apatite, ote-clinozoisite, and zircon are also present (NNECo. 1975). The Monson gneiss is medium-ned, light gray with strong biotite foliation. A number of biotite segregation bands were erved throughout the excavation (Section 2.5.4).
Monson gneiss is intruded by pegmatite and granite sills related to the Westerly Granite ch was quarried on Millstone Point until 1960. The distinction between a granitic and a matitic intrusion is a subtle one. Both intrusions are related to the same source and variable n sizes are inherent in each. The Westerly Granite is considered to be a dike rock consisting of y to pink, fine-to-medium-grained, equigranular granite composed of oligoclase, microcline, quartz. The pegmatitic intrusions are similar in composition to the Westerly Granite usions except for their coarser grain size. Biotite, muscovite, and accessory minerals are also ent in smaller percentages (Goldsmith 1967b, Lundgren 1967).
entire bedrock surface at Millstone is covered by a layer of glacial till consisting of both basal ablation tills. The basal till is a dense, unsorted soil material plastered and compacted into e by the weight and dynamic pressure of an actively moving glacier. The ablation till was osited as the ice retreated. It is generally an unsorted material and, because it was subjected to ghter load than the basal till, it is less dense.
basal till consists of a mixture of cobble and boulder size rock fragments, gravel size erial, sand, and some silt binder. The ablation till is irregularly stratified with lenses of sand gravel and mixtures of cobbles, gravel, sand, and silts.
cial stream deposits are also present on Millstone Point (Figure 2.5.1-3), for the most part sisting of stratified sands with some silts and gravel.
nger beach, swamp, and marsh deposits are also observed in the site area (Figure 2.5.1-3).
beach deposits are chiefly well sorted sand and pebbly gravel deposited by current and wave on.
1.2.4 Local Structural Geology Millstone site lies on the southeastern coast of Connecticut. The regional tectonic map ure 2.5.1-6) shows the location of the site with respect to the major structural features of New land. Figure 2.5.1-14 illustrates the generalized tectonic elements of eastern Connecticut and ure 2.5.1-13 shows the structure within the 5-mile radius.
tectonic map of eastern Connecticut (Figure 2.5.1-14) shows the major folds and faults that e affected the region. Three orogenies (Taconian, Acadian, Alleghenian) have structurally left r imprint on a series of complexly deformed rocks. As shown by the site bedrock geology map ure 2.5.1-13), the Lyme dome, Hunts Brook syncline, and two smaller anticlines lie within site area. The larger structural features, such as the Bronson Hill anticlinorium, the Merrimack
structural trend south of Honey Hill is generally east-west, whereas, in the remaining portions he state, the structural trends are north-south, paralleling the regional trend.
north-south and east-west structures tend to meet in the Killingworth dome. This is not a ple dome and must have reached its present form and acquired its complicated internal cture in several stages (Lundgren and Thurrell 1973). Recumbent isoclinal folds are common ughout and the dome itself may consist of a series of antiforms and synforms.
Lyme dome, east of the Killingworth dome (Figure 2.5.1-14), also appears to be a simple clinal structure; however, the dome is mantled by the folded isoclinal Hunts Brooks syncline.
extent of the dome is marked by the contact between the Mamacoke Formation, Monson iss, or the Brimfield schist with the Plainfield Formation (Figure 2.5.1-13). The broad internal cture of the dome is indicated by the pattern of the middle unit of the Plainfield Formation and alaskite units (Sterling Plutonic Group) and by the foliation pattern (Lundgren 1967).
tribution of the stratigraphic units indicates that the dome is a northward plunging anticline.
Lyme dome lies just west of the Millstone site (Figure 2.5.1-13).
Selden Neck dome, which parallels the Honey Hill fault, is the last major dome south of the
- t. This dome is essentially an overturned, possibly recumbent, anticline having a folded axial ace that dips north or northwest (Lundgren 1966).
Hunts Brook syncline, which separates the Selden Neck dome from the Lyme dome, is the prominent fold south of the Honey Hill fault. The isoclinal syncline bends around the Lyme e and the trace of the axial plane lies within the belt of the Brimfield schist and the Tatnic Hill mation. The axial plane of the Hunts Brook syncline dips away from the Lyme dome; in the lstone area, the syncline dips to the east with the site lying on the overturned limb.
Hunts Brook syncline meets the Chester syncline in the Killingworth dome area. Lundgren
- 66) has proposed two theories concerning the relationship between these two synclines. If the ts Brook syncline is a folded overturned syncline with a nearly horizontal axis, then this axis bably meets the axis of the Chester syncline at a right angle, implying that the Hunts Brook med after or during the development of the recumbent Chester syncline. However, if the Hunts ok syncline plunges steeply to the northwest, then it could merge with the Chester syncline eath the Selden Neck dome (Lundgren 1966).
Chester syncline is a recumbent isoclinal syncline trending north from the Killingworth dome on and exhibiting a complexly folded axial plane which parallels the Monson anticline until it hes a point north of the Honey Hill fault which it parallels for some distance (Figure 2.5.1-o smaller anticlines are shown on Figure 2.5.1-13. Both are overturned isoclinal anticlines h their axial planes dipping to the northwest. The area is complexly folded and it appears that two anticlines may actually be one.
Honey Hill fault (Section 2.5.1.1.4.2) lies approximately 15 miles north of the Millstone site.
closest mapped fault is approximately 10 miles northeast of the site in the Uncasville drangle (Figure 2.5.1-14). This fault trends north-south and is believed by Goldsmith (1973) e a normal fault related to Triassic tectonics. The amount of displacement is unknown, but it is wn to cut the Honey Hill fault (Goldsmith 1967c). This faulting is thought to be related to the tern Hill fault further to the east due to its similar attitude. The Triassic Border fault lies roximately 30 miles west of the site (Figure 2.5.1-14).
umber of faults have been uncovered during the construction of Millstone 3 and are discussed etail in Section 2.5.3.2.
1.2.4.1 Site Structural Geology Millstone site lies on the overturned eastern limb of the Hunts Brook syncline (Figure 2.5.1-The axial plane of the syncline in the site area dips to the east as shown on Section A-A of ure 2.5.1-13. Detailed mapping of the excavation has yielded much information on the logy of Millstone Point (Sections 2.5.3.2 and 2.5.4.1).
site is founded for the most part on the Monson gneiss which is part of a series of lower eozoic metavolcanic and metasedimentary rocks and granitic gneisses that underlie most of ern Connecticut (Goldsmith and Dixon 1968). The Monson gneiss at the site area is light gray, ium grained, thinly layered with light feldspathic and dark biotite and hornblendic layers ldsmith 1976b). It consists of plagioglase (45 percent), quartz (35 percent), and biotite (15 ent) with accessories of garnet, apatite, epidote-clinozoisite, and zircon (NNECo. 1975). The ation is a well defined alignment of biotite flakes. Figure 2.5.1-15 is a lower hemisphere plot wing the foliation readings taken from final grade mapping. The average foliation attitude for points is N67W, 48NE. Segregation bands of biotite are apparent throughout the site.
Monson gneiss has been intruded by a series of pegmatite and granite bodies. For the most
, these granitic intrusions are parallel to the foliation and believed to be related to the injection the Westerly Granite (Goldsmith 1967b), which is a prominent intrusion throughout theastern Connecticut and Rhode Island (Goldsmith 1967b).
ting is well developed at the site with the major joint set striking N03W and dipping 63NE.
ure 2.5.1-16 gives a contour diagram of poles to joint planes for the joints observed while ping final grade. Minor joint sets have attitudes of N02W, 78SW; N69E, 74SE; and N48W, E. The joints generally exhibit smooth, planar surfaces with a majority having a coating of rite and some showing iron oxide staining. Jointing at the site is discussed further in tion 2.5.3.2.3. Slickensides were found in 241 locations. Figure 2.5.1-17 gives the contour of these data. The points are concentrated along the east-west axis, indicating that the major ction of displacement is east-west. The points also indicate the association of the slickensides h high angle planes, thus implying a minor readjustment of dip-slip type.
d northerly and dip at high angles east or west. The other fault is a minor low angle thrust.
ure 2.5.1-18 shows the location of these faults. The faults are all incapable features with the activity occurring approximately 142 m.y.a. Slickenside information and a section through t 18 in the Millstone 2 and 3 condensate polishing facilities indicate that the faulting is of the mal type, with some oblique dip-slip movement.
1.2.5 Site Geological History geological history of southeastern Connecticut is obscured by the complex folding and amorphism that the area has undergone. The Taconian, Acadian, and Alleghenian orogenies e affected the area to a varying extent (Goldsmith and Dixon 1968).
ages of the rocks present in the site area are still in doubt. The Monson gneiss, the New don gneiss, the Mamacoke Formation, and the Plainfield Formation are pre-Silurian in age, most probably the rocks range in age from late Precambrian or Cambrian to Ordovician, ldsmith 1976). The Brimfield schist, which lies unconformably beneath the Bolton Group, is ilar to and can be traced into the Partridge Formation and the Ammonoosuc volcanics of dle Ordovician age (Goldsmith and Dixon 1968). Two major plutonic rocks are present in the area, the Sterling Plutonic Group and the Westerly Granite. The older Sterling Plutonic Group elieved to be Cambrian or older in southern Connecticut and does not occur stratigraphically ve the Monson Gneiss around Millstone Point (Goldsmith and Dixon 1968). However, the ling Group is younger that the Monson gneiss, so the Sterling may be Ordovician or younger.
youngest rock type present in the site area is the Westerly Granite, which is regarded as mian (Lundgren 1967). A granitic intrusion other than the Sterling Plutonic Group or Westerly nite occurs in the Lyme dome. This nodular granite is believed to be older than the Westerly nite and younger than the granitic intrusions of the Sterling Plutonic Group (Goldsmith 7b).
relationship of the rocks within the site area is shown on the stratigraphic chart for the ounding area (Figure 2.5.1-7) and described in Tables 2.5.1-1 through 2.5.1-7. Figure 2.5.1-hows the distribution of the bedrock units.
origin of the oldest rocks found in the site area, the Plainfield and the Mamacoke Formations, bscure. These probably were originally quartz sandstone, limestone and dolostone, and shale ndgren 1966). The age of these rocks is still questioned, although it is believed that the rocks of Cambrian age (Page 1976). The remaining rocks in the site region with the exception of the ular and Westerly Granites are probably Ordovician in age.
Monson and New London gneisses are believed to be metamorphosed andesitic and dacitic canics and associated intrusions (Lundgren 1967). As mentioned in Section 2.5.1.1.5, the ent day Bronson Hill anticlinorium was the location of a series of volcanoes and islands ch served as a source area for much of the middle Ordovician period.
contiguous granitic gneisses in southern Connecticut suggest a Cambrian or older age ldsmith and Dixon 1968). However, the Monson gneiss, outside of the site area, has been d as 472 m.y.a. +/-15 (Brookins and Hurley 1965) and radiometric work by Zartman et al.
- 65) implies that the Quinebaug Formation, correlated with the Monson, is middle Ordovician.
Sterling gneisses seem to have been emplaced at fairly deep levels in the crust, for they are ciated with migmatites and are intimately intermingled with and grade into some associated asedimentary and metavolcanic gneisses (Goldsmith and Dixon 1968). The Sterling Plutonic up is widespread in Rhode Island, underlying most of the central portion of the state and sidered to be late Precambrian or Cambrian in age.
s, the age relations are problematic and have not been resolved to date.
Brimfield schist consisted originally of shale imbedded with minor amounts of quartz, dstone, limestone, andesitic and basaltic pyroclastics, and manganese-bearing chert. The osition of this pelitic unit represents a major change in the character of sedimentation, as anic rocks are of subordinate importance in the section above the base of the Brimfield and nic Hill Formations (Lundgren 1964). The Brimfield and Tatnic Hill Formations may have n deposited as geographically separate facies of a single stratigraphic unit (Lundgren 1964).
Brimfield schist is the youngest pre-Pennsylvanian rock found within the site area.
ch of the deformation that occurred in the Millstone area has been attributed to the Acadian geny, which affected much of central and eastern New England. The initial stages in the mation of the complex structure now observed are the north-south trending recumbent isoclinal s (Monson anticline and Chester syncline) which were formed in response to an east-west pression during early stages of post-Silurian metamorphism (Figure 2.5.1-14) (Lundgren 4). Deformations continued with the development of the east-west trending anticlines and clines, the Selden Neck dome and Hunts Brook syncline, respectively. Most of the major ures of the map pattern in the rocks south of the Honey Hill fault are the combined result of formation of the Lyme dome and the antiform at Chester. This uplift deformed the Hunts ok syncline, the Selden Neck dome, and the Honey Hill fault, resulting in the present ctural configuration.
amorphism accompanied the structural development mentioned above. Metamorphism of all rocks produced assemblages characteristic of the upper amphibolite facies (Lundgren 1966).
dgren (1964) believes the metamorphism took place when the rocks were deeply buried, bably at depths of 15 to 20 kilometers where the temperature was 550 to 650°C.
amorphism presumably began during the Devonian period but may have continued into the mian (Lundgren 1963).
Honey Hill faulting also was initiated during the Acadian orogeny as part of the eastward lacement of the recumbent Chester syncline. Movement along the Honey Hill fault is believed e southeasterly, continuing beyond the period of peak metamorphism (Dixon and Lundgren 8).
ng the folding and uplifts of the Acadian orogeny. Movement along the Honey Hill fault may e continued into the Permian period.
owing the highly active Acadian orogeny was a milder period of gentle folding, granitic usion, and localized thermal activity. The Alleghenian orogeny affected only the southeastern ion of New England, mainly Rhode Island and southeastern Connecticut. The main ifestation of the Alleghenian orogeny was the intrusion of the Narragansett Pier Granite and Westerly Granite. The Pennsylvanian sediments of the Narragansett Basin of Rhode Island ibit folding associated with this orogeny. The thermal activity is exhibited by a narrow band nding from southern Connecticut to southwestern Maine. These rocks yield potassium-argon s of 230 to 260 m.y.a. The actual cause of this disturbance is still questioned although it could attributed to contact metamorphism related to contemporaneous igneous activity, alteration ciated with major faulting, regional metamorphism in late Paleozoic time, or burial followed plift and erosion (Zartman et al., 1970).
Millstone site has been affected by thermal disturbance and granitic intrusion. Granitic usions parallel to the foliation of the Monson gneiss, folded and overturned during the dian orogeny, are widespread throughout the site area.
assium-argon dating of biotite from the gneiss and the granitic intrusions at the site yielded a ge of ages from 208 to 273 m.y.a. (NNECo. 1975). At Millstone Point, the thermal disturbance ld be attributed to contact metamorphism during emplacement of the Westerly Granite.
most recently known expression of tectonic activity in the local area is faulting related to ssic-Jurassic rifting. Small high angle faults and joints associated with the larger Triassic ts of the Triassic Basin (Figure 2.5.1-14) are common in the Clinton quadrangle to the west ndgren and Thurrell 1973) and in the Moodus and Colchester quadrangles to the north ndgren et al., 1971). Goldsmith (1967a) shows two small high-angle faults in the Uncasville drangle northeast of the site, which he believes to be related to the Triassic-Jurassic tectonics ldsmith 1973). No faults are shown adjacent to the site on the quadrangle maps. In the process mapping the excavation at the Millstone site, eleven fault zones were uncovered ction 2.5.3.2). Potassium-argon dating of clay gouge from some of these fault zones indicates the last activity along these zones occurred about 142 m.y.a. Also associated with the ssic-Jurassic periods are the deposits of arkosic clastic sediments in the Connecticut Basin, usive igneous activity, and related injection of basic dikes throughout southern New England.
rothermal activity, typically silicification, is commonly found along faults related to the ssic-Jurassic tectonics. Rodgers (1975), Skehan (1975), and Goldsmith (1973) believe that the rothermal activity represents the youngest known tectonically related event in southern New land.
ent study of dikes in southwestern Rhode Island and eastern Connecticut indicates that a few prophyre dikes may be as young as Cretaceous. Their relation to hydrothermal activity is not wn.
es, and hills, similar to those of today (Flint 1975). Cretaceous and Tertiary sediments are ent south of the site (Figure 2.5.1-2). The northernmost previous extent of these deposits is nown. During Tertiary and Quaternary time, alternating periods of transgression and ession occurred along the coast of southern New England. The two major regressions took e during the Oligocene epoch and during the Pleistocene glaciation (Garrison 1970).
dence from outside the site area indicates that during the last million years or more, necticut was covered by continental glaciers at least twice, and possibly several times, ever, evidence of only one glaciation is found locally (Flint 1975). The ice at its maximum hed its outer limit along a line on, or south of, what is now Long Island and culminated roximately 18,000 years ago (Flint 1975). Pollen studies and radiocarbon dates on samples n in New London show that glaciation took place more than 13,000 years ago (Goldsmith 0, 1962a). Caldwell (Appendix 2.5A), after visiting the Millstone site, indicated that the last osition of till was approximately 18,000 years ago and that ice covered the area until about 00 years ago. The cumulative effect of the glaciation was to smooth, round off, and widen e of the valleys and to remove most of the pre-existing regolith (Flint 1975).
Millstone area is covered with glacial till, end moraine deposits, and outwash sands as shown Figure 2.5.1-3. The end moraines are common across Rhode Island and southern Connecticut.
y were deposited when the recession of the glacial margin slowed or stopped for some period nt 1975).
avations along the discharge tunnel uncovered slumped and faulted ablation till and outwash osits. These features were found to be quite common in the outwash and are believed to be ted to penecontemporaneous soft sediment deformations, in some cases associated with ting out of buried ice blocks (NNECO. 1982).
ce the glacial period, the surficial geology has been most drastically changed by the rise in sea l, which reworked the glacial outwash and eroded till and rock promontories, then depositing material on the beach to be reworked by the wind to form dunes.
1.2.6 Site Engineering Geology Category I structures at Millstone 3 are founded on rock, dense basal till, or compacted nular backfill. The properties of the subsurface materials are given in Section 2.5.4.2.
country rock at the site is the Monson gneiss. This gneiss exhibits a well-developed foliation to the alignment of biotite flakes. Segregation bands of biotite were also uncovered at the site.
ure 2.5.1-15 shows that the attitude of the foliation is quite consistent at N67E, 48NE. Jointing he site is also very well-developed. The contour plot of the Lower Hemisphere projection ure 2.5.1-16) indicates one major joint set with three minor sets. The most prominent set has verage attitude of N03W, 63NE. The minor sets have attitudes of N02W, 78SW; N69E, 74SE; N48W 07NE.
geology of the excavation is also described in Section 2.5.4.1. Maps showing the geology of floors and walls of structure excavations accompany this description. During the mapping of excavation, eleven fault zones were uncovered. The relationship between these faults is shown Figure 2.5.1-18 and shown in greater detail on the geology maps associated with tion 2.5.4.1.
old granite quarry is located in the Westerly Granite about 1,200 feet south-southeast of the t area. This quarry was in operation as an open pit, unsupported excavation from 1830 to
- 0. The rock is sound and self-supporting, and this excavation does not influence the stability he site in any way. Neither the Westerly Granite nor the Monson gneiss are ore-bearing and e are no mining activities at present and none are anticipated in the future.
h the basal and overlying ablation tills are relatively impervious. The only water flow through gneiss noted during construction was along intersecting joints that extended upward to the ace. This flow was handled quite readily by sumps located throughout the excavation.
manent sumps have been located around the structures to take care of this groundwater flow ng the operation of the plant. The site groundwater conditions are covered in detail in tion 2.4.13 and the structure dewatering system is described in Section 3.8.5.1.
1.3 REFERENCES
FOR SECTION 2.5.1 1.1-1 Armstrong, R. L. and Stump, E. 1971. Additional K Ar Dates, White Mountain Magma Series, New England. Amer. Jour. Sci., 270, p 331 333.
1.1-2 Bain, G.W. 1932. The Northern Area of Connecticut Valley Triassic. Amer. Jour.
Sci. 23, p 57 77.
1.1-3 Balk, R. 1957. Geology of the Mt. Holyoke Quadrangle, Massachusetts. Geological Soc. Amer., Bull. 68, p 481 504.
1.1-4 Ballard, R.D. and Oldale, R. N. 1973. Geology of Gulf of Maine and Adjacent Land Areas (Abs.). Amer. Assoc. Petroleum Geologists, Bull. 57, p 2146.
1.1-5 Ballard, R.D. and Uchupi, E. 1972. Carboniferous and Triassic Rifting: A Preliminary Outline of the Tectonic History of the Gulf of Maine. Geological Soc.
Amer., Bull. 83, p 2285 2302.
1.1-6 Ballard, R.D. and Uchupi, E. 1975. Triassic Rift Structure in the Gulf of Maine.
Amer. Assn. of Petroleum Geologists, Bull. 59, No. 7, p 1041 1072.
1.1-7 Banks, Paul T. Jr. 1975. A Geologic Analysis of the Side Looking Airborn Radar Imagery of Southern New England. US Geol Survey Open-File Report 75-207, 126 pp.
Open File Report 74 91, Washington, D.C.
1.1-9 Bell, K. G. and Alvord, G. C. 1976. Pre-Silurian Stratigraphy of Northeastern Massachusetts. In: Contributions to the Stratigraphy of New England. Page, L. R.
(ed.) p 179 216.
1.1-10 Berry, W. B. N. 1968. Ordovician Paleogeography of New England and Adjacent Areas Based on Graptolites. In: Studies of Appalachian Geology: Northern and Maritime. John Wiley and Sons, Inc., New York, p 23 34.
1.1-11 Billings, M.P. 1956. The Geology of New Hampshire, Part II, Bedrock Geology.
The New Hampshire Department of Resources and Economic Development, Concord, N.H.
1.1-12 Bird, J.M. 1969. Middle Ordovician Gravity Sliding-Taconic Region. In: North Atlantic Geology and Continental Drift. Mem. 12, Amer. Assn. of Petroleum Geologists, p 670 686.
1.1-13 Boucot, A. J. 1968. Silurian and Devonian of the Northern Appalachians. In Studies of Appalachian Geology: Northern and Maritime. John Wiley and Sons, Inc., New York, p 83 94,.
1.1-14 Brookins, D. G. and Hurley, P. M. 1965. Rubidium-Strontium Geochronological Investigations in the Middle Haddam and Glastonbury Quadrangles, Eastern Connecticut. Amer. Jour. Sci., 263, p 1 16.
1.1-15 Carlson, R.O. and Brown, M.V. 1955. Seismic Refraction Profiles in the Submerged Atlantic Coastal Plain near Ambrose Lightship. Geological Soc. Amer., Bull. 66, p 969 976.
1.1-16 Castle, R.O.; Dixon, H.R.; Grew, E.S.; Griscom, A.; and Zietz, I. 1976. Structural Dislocations in Eastern Massachusetts. U.S. Geological Survey, Bull. 1410.
1.1-17 Chapman, C.A. 1968. Comparison of Maine Coastal Plutons and Magmatic Central Complexes of New Hampshire. In: Studies of Appalachian Geology: Northern and Maritime. John Wiley and Sons, Inc., New York, p 385-396.
1.1-18 Dennen, William H. 1976. Plutonic Series in the Cape Ann Area. In: Geology of Southeastern New England. New England Intercollegiate Geological Conference, 68th Annual Meeting. Science Press, Princeton, NJ p 265-273.
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1.1-21 Dixon, H.R. and Lundgren, L., Jr. 1968. Structure of Eastern Connecticut. In:
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1.1-25 Feininger, T. 1964. Petrology of the Ashaway and Voluntown Quadrangles, Connecticut Rhode Island. PhD Thesis, Brown University, Providence, RI.
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1.1-59 Lundgren, L., Jr. 1963. The Bedrock Geology of the Deep River Quadrangle, State Geological and Natural History Survey of Connecticut Quadrangle, Report No. 13.
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1.1-62 Lundgren, L., Jr. 1967. The Bedrock Geology of the Old Lyme Quadrangle. State Geological and Natural History Survey of Connecticut, Quadrangle Report No. 21.
1.1-63 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.
1.1-64 Lundgren, L. and Ebblin, C. 1972. Honey Hill Fault in Eastern Connecticut:
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1.1-65 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.
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1.1-69 McMaster, R.L. 1971. A Transverse Fault on the Continental Shelf off Rhode Island. Geological Soc. Amer., Bull. 82, p 2001 2004.
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1.1-71 Moorbath, S. (ed.) 1962. Rb-Sr Investigation of the Northbridge Granite Gneiss, Massachusetts. 10th Annual Progress Report from MIT to U.S. Atomic Energy Comm., MIT, Cambridge, Mass.
1.1-72 Moore, G.E., Jr. 1959. Bedrock Geology of the Carolina and Quonochontaug Quadrangles, Rhode Island. U.S. Geological Survey, Quadrangle Map GQ 117 Washington D.C.
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1.1-74 Naylor, R.S. 1968. Origin and Regional Relationships of the Core-Rocks of the Oliverian Domes. In: Studies of Appalachian Geology: Northern and Maritime.
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1.1-75 Naylor, R.S. 1975. Age Provinces in the Northern Appalachians. Annual Review of Earth and Planetary Sciences, 3, p 387 400.
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1.1-77 Needell, S.W., and Lewis, R.S. 1982. High Resolution Seismic-Reflection Profiles and Sidescan-Sonar Records Collected on Block Island Sound by U.S. Geological Survey, R/V ASTERIAS, Cruise AST 81-2. USGS Open-File Report 82-322.
1.1-78 Nelson, A.E. 1976. Structural Elements and Deformation History of Rocks in Eastern Massachusetts. Geological Soc. Amer., Bull. 87, p 1377-1383.
1.1-79 New England Power Co. (NEPCo) 1976. Charlestown Preliminary Safety Analysis Report, Appendix 2B. Marine Geophysical Survey, New Shoreham Fault Investigation by Weston Geophysical.
1.1-80 Northeast Nuclear Energy Co. (NNECo) 1975. Geologic Mapping of Bedrock Surface, Millstone Nuclear Power Station Unit 3. NRC Docket No. 50-423, Connecticut.
1.1-81 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, Connecticut.
1.1-82 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, Connecticut.
1.1-83 Northeast Nuclear Energy Company (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.
1.1-84 Northeast Utilities Service Co. (NUSCo.) 1974. Montague Preliminary Safety Analysis Report. NRC Dockets 50 496 and 50 497.
Stratigraphy of New England. Page, L.R. (ed.) p 357-372.
1.1-86 O'Leary, D. W.; Friedman, J. D.; and Pohn, A. A. 1976. Lineament, Linear, Lineation: Some Proposed New Standards for Old Terms. Geological Soc. Amer.,
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1.1-88 Orville, P. M. (ed.) 1968. Guidebook for Field Trips in Connecticut. New England Intercollegiate Geological Conference, State Geological and Natural History Survey, Washington, D.C.
1.1-89 Page, L.R. 1968. Devonian Plutonic Rocks in New England. In: Studies of Appalachian Geology: Northern and Maritime. John Wiley and Sons, Inc., New York, p 371-383.
1.1-90 Page, L.R. (ed.) 1976. Contributions to the Stratigraphy of New England. Geol. Soc.
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1.1-91 Page, R.H.; Molnar, P.H.; and Oliver, J. 1968. Seismicity in the Vicinity of the Ramapo Fault, New Jersey-New York. Seismological Soc. Amer., Bull. 58, No. 2, p 681 687.
1.1-92 Pease, M.H., Jr. 1972. Geologic Map of the Eastford Quadrangle, Windham and Tolland Counties, Connecticut. U.S. Geological Survey, Quadrangle Map GQ 1023, Washington, D.C.
1.1-93 Quinn, A.W. 1971. Bedrock Geology of Rhode Island. U.S. Geological Survey, Bull. 1295.
1.1-94 Quinn, A.W. and Oliver, W.A., Jr. 1962. Pennsylvanian Rocks of New England. In:
Pennsylvanian System in the United States. Amer. Assn. of Petroleum Geologists, p 60 73.
1.1-95 Ratcliffe, N. M. 1971. The Ramapo Fault System in New York and Adjacent Northern New Jersey: A Case of Tectonic Heredity. Geological Soc. Amer., Bull.
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1.1-96 Rodgers, J. 1967. Chronology of Tectonic Movements in the Appalachian Region of Eastern North America. Am. Jour. Sci., 265, p 408-427.
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1.1-98 Rodgers, J. 1970. The Tectonics of the Appalachians. John Wiley and Sons, Inc.,
1.1-99 Rodgers, J. 1972. Latest Precambrian (Post-Grenville) Rocks of the Appalachian Region. American Jour. Sci., 272, p 507 520.
1.1-100 Rodgers, J. 1975. Oral Communication with L. Martin and P. Mayrose, S&W.
1.1-101 Rodgers, J.; Gates, R.M.; Cameron, E.N.; and Ross, R.J., Jr. 1956. A Preliminary Geologic Map of Connecticut. State Geological and Natural History Survey of Connecticut.
1.1-102 Rodgers, J.; Gates, R.M.; and Rosenfeld, J.L. 1959. Explanatory Text for Preliminary Geological Map of Connecticut, 1956. Connecticut Bull., No. 84.
1.1-103 Sanders, J.E. 1960. Structural History of Triassic Rocks of the Connecticut Valley Belt and Its Regional Implications. N. Y. Acad. Sci., Section of Geological Sciences, p 119 132.
1.1-104 Schafer, J.P. and Hartshorne, J.H. 1965. The Quaternary of New England. In: The Quaternary of the United States. Wright, H. E., Jr. and Frey, D. C., Princeton University Press, Princeton, New Jersey, p 113-128.
1.1-105 Schnabel, R. W. 1960. Bedrock Geology of the Avon Quadrangle, Connecticut. U.S.
Geological Survey, Quadrangle Map GQ 370, Washington, D.C.
1.1-106 Sheridan, R.D. 1974. Atlantic Continental Margin of North America. In: The Geology of Continental Margins. Burk, C.A. and Drake, C. L. (ed.) Springer-Verlag, New York, p 301 407.
1.1-107 Shride, A. F. 1976. Stratigraphy and Correlation of the Newbury Volcanic Complex, Northeastern Massachusetts. In: Contributions to the Stratigraphy of New England.
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1.1-108 Skehan, J. W. and Abu-moustafa, A.A. 1976. Stratigraphic Analysis of Rocks Exposed in the Wachusett-Marlborough Tunnel, East-Central Massachusetts. In:
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America, Mem 148, p 217 240.
1.1-109 Skehan, J. W. 1961. The Green Mountain Anticlinorium in the Vicinity of Wilmington and Woodford, Vermont. Vermont Development Department, Bull. No.
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1.1-112 Skehan, J.W. 1973. Subduction Zone between the Paleo-American and the Paleo-African Plates in New England. Geofisica Internacional, 13, No. 4, p 291 308.
1.1-113 Skehan, J. W. 1975. Oral Communication with L. Martin and F. Vetere, S&W.
1.1-114 Snyder, G. L. 1964. Bedrock Geology of the Willimantic Quadrangle, Connecticut.
U.S. Geological Survey, Quadrangle Map GQ 335, Washington, D.C.
1.1-115 Snyder, G. L. 1970. Bedrock Geology and Magnetic Maps of the Marlborough Quadrangle, East-Central Connecticut. U.S. Geological Survey, Quadrangle Map GQ 791, Washington, D.C.
1.1-116 Stanley, R. S. 1964. The Bedrock Geology of the Collinsville Quadrangle. State Geological and Natural History Survey, Connecticut, Quadrangle Report No. 16, Washington, D.C.
1.1-117 Stetson, H. C. 1949. The Sediments and Stratigraphy of the East Continental Margin; Georges Bank to Norfolk Canyon. Contribution No. 487 from the Woods Hole Oceanographic Institution, Woods Hole, Mass., No. 2, p 1 34.
1.1-118 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, Connecticut, Bull. GW-18, p 212.
1.1-119 Sutter, J.F. 1971. K-Ar Relationships in Mylonite Rocks (Abs). A.G.U. Trans., V. 52,
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1.1-120 Tagg, A.R. and Uchupi, E. 1967. Subsurface Morphology of Long Island Sound, Block Island Sound, Rhode Island Sound and Buzzards Bay. U.S. Geological Survey, Prof. Paper 575 C, p C92 C96.
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1.1-127 Weed, E.G.A.; Minard, J.P.; Perry, W.J., Jr.; Rhodehamel, E.C.; and Robbins, E.I.
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Geol. Survey Open-File Report, 12 sheets.
ABLE 2.5.1-1 ROCK FORMATIONS OF THE COASTAL PLAIN OFF SOUTHERN NEW ENGLAND CLICK HERE TO SEE TABLE 2.5.1-1
TABLE 2.5.1-2 ROCK FORMATIONS OF WESTERN CONNECTICUT CLICK HERE TO SEE TABLE 2.5.1-2
BLE 2.5.1-3 ROCK FORMATIONS OF EASTERN CONNECTICUT AND WESTERN RHODE ISLAND CLICK HERE TO SEE TABLE 2.5.1-3
ABLE 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
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
TABLE 2.5.1-6 ROCK FORMATIONS OF CENTRAL MASSACHUSETTS CLICK HERE TO SEE TABLE 2.5.1-6
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
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
FIGURE 2.5.1-1 REGIONAL PHYSIOGRAPHIC MAP Revision 3306/30/20 MPS-3 FSAR 2.5.1-45
FIGURE 2.5.1-2 REGIONAL PRE-PLEISTOCENE SEDIMENTS OF THE CONTINENTAL MARGIN Revision 3306/30/20 MPS-3 FSAR 2.5.1-46
Revision 3306/30/20 MPS-3 FSAR 2.5.1-47 FIGURE 2.5.1-3 SITE SURFICIAL GEOLOGY
Revision 3306/30/20 MPS-3 FSAR 2.5.1-48 FIGURE 2.5.1-4 REGIONAL GEOLOGIC MAP
FIGURE 2.5.1-5 REGIONAL GEOLOGIC SECTION Revision 3306/30/20 MPS-3 FSAR 2.5.1-49
Revision 3306/30/20 MPS-3 FSAR 2.5.1-50 FIGURE 2.5.1-6 REGIONAL TECTONIC MAP
FIGURE 2.5.1-7 STRATIGRAPHIC CORRELATION CHART FOR THE SITE AND SURROUNDING REGION)
Revision 3306/30/20 MPS-3 FSAR 2.5.1-51
FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 1)
Revision 3306/30/20 MPS-3 FSAR 2.5.1-52
FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 2)
Revision 3306/30/20 MPS-3 FSAR 2.5.1-53
FIGURE 2.5.1-8 REGIONAL STRATIGRAPHIC CORRELATION CHART (SHEET 3)
Revision 3306/30/20 MPS-3 FSAR 2.5.1-54
FIGURE 2.5.1-9 LANDSAT PHOTOGRAPHS OF CONNECTICUT, RHODE ISLAND, SOUTHERN MASSACHUSETTS, AND EASTERN NEW YORK Revision 3306/30/20 MPS-3 FSAR 2.5.1-55
FIGURE 2.5.1-10 LINEAMENT MAP FROM LANDSAT PHOTOGRAPHS Revision 3306/30/20 MPS-3 FSAR 2.5.1-56
Revision 3306/30/20 MPS-3 FSAR 2.5.1-57 FIGURE 2.5.1-11 REGIONAL AEROMAGNETIC MAP
FIGURE 2.5.1-12 REGIONAL BOUGUER GRAVITY MAP Revision 3306/30/20 MPS-3 FSAR 2.5.1-58
Revision 3306/30/20 MPS-3 FSAR 2.5.1-59 FIGURE 2.5.1-13 SITE BEDROCK GEOLOGY
FIGURE 2.5.1-14 TECTONIC MAP OF EASTERN CONNECTICUT Revision 3306/30/20 MPS-3 FSAR 2.5.1-60
Revision 3306/30/20 MPS-3 FSAR 2.5.1-61 FIGURE 2.5.1-15 CONTOUR DIAGRAM OF POLES TO FOLIATION PLANES - FINAL GRADE
Revision 3306/30/20 MPS-3 FSAR 2.5.1-62 FIGURE 2.5.1-16 CONTOUR DIAGRAM OF POLES TO JOINT PLANES - FINAL GRADE
Revision 3306/30/20 MPS-3 FSAR 2.5.1-63 FIGURE 2.5.1-17 CONTOUR PLOT OF BEARING AND PLUNGE OF SLICKENSIDES - FINAL GRADE
Withhold under 10 CFR 2.390 (d) (1)
FIGURE 2.5.1-18 GENERALIZED LOCATION OF FAULTS Revision 3306/30/20 MPS-3 FSAR 2.5.1-64
site region is characterized by earthquakes of low to moderate intensity. During the past 300 rs, only 13 earthquakes greater than or equal to Intensity V Modified Mercalli (MM) have n reported within 50 miles of the site. The site lies in the Southeastern New England-Maritime tonic Province. The largest earthquake in this province was an Intensity VI (MM) event which urred in 1904 east of Eastport, Maine. Two moderate size earthquakes have occurred in the odus, Connecticut area, located in the adjacent New England Province, in 1568 (Intensity VII M)) and 1791 (Intensity VI-VII (MM)). The maximum earthquake potential at the site is med to be due to an earthquake of Intensity VII (MM) occurring close to the site. This esponds to a peak ground acceleration of 0.10 g. The safe shutdown earthquake (SSE) has servatively been specified as 0.17 g. The operating basis earthquake (OBE) has been specified
.09 g, which corresponds to approximately half the SSE.
2.1 SEISMICITY st of the information on earthquake activity in the northeastern United States is based on orical reports, old diaries, and newspaper accounts. These earthquakes are classified on the s of intensity corresponding to the Modified Mercalli scale. This scale, developed in 1931 and cribed in Table 2.5.2-1, is based on observations of the effects of earthquakes and damage to ctures. The instrumental monitoring of earthquakes began in the mid 1920s in the northeastern ted States. Magnitude, a measure of earthquake energy, is determined from instrumental data.
number of seismographic stations has greatly increased in recent times. At present, Weston ervatory of Boston College, Lamont-Doherty Geological Observatory of Columbia versity, Massachusetts Institute of Technology, University of Connecticut, Pennsylvania State versity, and Delaware Geological Survey operate seismographic stations in the northeast and rdinate the publication of the Northeastern United States Seismic Network (NEUSSN) etin. Figure 2.5.2-1 shows the location of stations in this network and Table 2.5.2-2 lists the tions and other pertinent data for these stations. Historical reports of earthquakes and rmation obtained from instrumental coverage in recent years form the basis of this mination of the seismicity of the site region.
2.1.1 Completeness and Reliability of Earthquake Cataloging n though major historical catalogs carry entries dating back almost three centuries, the erage of this period is not continuous. The completeness and reliability of the data are related population distribution and, recently, to the seismograph network coverage. Therefore, uracy of epicentral coordinates and the assigned maximum intensities must be evaluated fully.
the earlier historical events, epicenters were located closer to population centers due to the ence of reports from the true epicentral area. The intensity of an earthquake at a given location ends not only on accurate and complete human observations, but also on foundation ditions, design, type, and quality of building construction. Construction practices, particularly himneys in the earlier centuries, were certainly not those envisioned in the Modified Mercalli
mological information for the instrumental period (since 1900) must also be evaluated fully. Seismic instrumentation began in the early 1900s in the United States and Canada with gressively improved quality of earthquake data. Epicentral locations based on felt reports were plemented and somewhat controlled by instrumental data. From the 1900s until the 1960s, y a few seismographs operated in the eastern United States. Most of these stations were part of regional network operated by the Jesuit Seismological Association. In the early decades, erous factors, such as the type of instrumental response, lack of accurate time control, ward configuration, use of graphical methods, and limited knowledge of crustal velocities e potential sources of errors. These produced large uncertainties in the epicentral coordinates ch, in many cases, amounted to tens of kilometers.
ce the 1960s, increased interest in understanding local seismicity has resulted in the lementation of dense seismographic networks. Seismic data in the northeastern United States now gathered by NEUSSN and reported in its bulletin. NEUSSN reports earthquake ocentral locations and magnitudes determined through the cooperation of several institutions.
hough the coverage of this network is uneven, it is now capable of detecting and locating all hquakes in New England of magnitude greater than or equal to 2.0 (Chiburis 1979; Sbar and es 1977). Chiburis (1979) has recently examined the seismicity of New England based on nt earthquakes and has reevaluated the location and intensity of several earlier events.
2.1.2 Earthquake History dies of the earthquake history of the site region are based on the Chiburis (1979) catalog.
le 2.5.2-3 lists all earthquakes with intensity greater than or equal to IV (MM) within 200 es of the site and all instrumentally located earthquakes regardless of magnitude. The table lists the date, origin time, epicentral coordinates, epicentral intensity, magnitude, seismic ment, and a description of location. Except for the seismic moments, which were determined Street and Turcotte (1977), all other information is from Chiburis (1979). The earthquakes d 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 oderate seismicity.
cumulative historical seismicity data (Figure 2.5.2-2) reveal the presence of several distinct s of concentrated seismic activity. They are: Moodus, Connecticut; Narragansett Bay, Rhode nd; Cape Ann, Massachusetts; the area around Ossipee, New Hampshire; northern New York; theastern New York; northeastern New Jersey; and the Hudson River Valley. These are ussed in terms of their location, areal extent, level of historical seismicity, and their tectonic ework as inferred from current research.
Activity in Southern New England as of central Connecticut, near East Haddam and Moodus, and the region near Narragansett in Rhode Island and southeastern Massachusetts have experienced a low level of activity.
nts ranging in magnitude to approximately 3.5.
Activity in Southeastern New York and Northeastern New Jersey seismic activity in southeastern New York, eastern Pennsylvania, and New Jersey is racterized by several repeated occurrences of Intensity VII (MM) earthquakes. Three of these nts occurred near New York City in 1737, 1884, and 1927. Two others occurred in thwestern New Jersey in 1840 and 1871. Several Intensity VI events are also distributed ughout this area of low level activity.
ent investigations by Page et al. (1968), Aggarwal and Sykes(1978), and Sbar and Sykes
- 77) propose a spatial correlation of instrumentally recorded, small earthquakes with the apo fault system, which extends in a northeasterly direction parallel to the Appalachian trend his region. Available focal mechanism solutions for this area, by Aggarwal and Sykes (1978),
gest high angle reverse faulting along planes that parallel mapped or inferred segments of the heast-trending Ramapo system.
White Mountains Plutons area of central New Hampshire and northeastern Massachusetts, including the Cape Ann
, once considered to be a segment of a continuous Boston-Ottawa seismic trend by Sbar and es (1973), is presently interpreted as a separate seismic region. Recently, Sbar and Sykes
- 77) have recognized the presence of a seismicity gap in Vermont and western New Hampshire.
ensive regional investigations, geological and geophysical, conducted for the Preliminary ety Analysis Report (PSAR) of Pilgrim Unit 2 (BECo 1976a), have stressed the individual ty of this seismic zone. The largest events to affect this region are the Intensity VIII (MM) e Ann earthquake of 1755 and three Intensity VII (MM) events, one near Cape Ann in 1727, two near Ossipee, New Hampshire on December 20 and 24, 1940. Street and Turcotte (1977) gest a magnitude of 5.4 for the Ossipee events, based on reanalysis of several seismograms.
larger earthquakes in the Ossipee and Cape Ann areas have been individually correlated to ain plutons of the White Mountains series in combination with anomalous country rock ting in the Pilgrim Unit 2 PSAR (BECo 1976a), whereas the Nuclear Regulatory Commission associated these earthquakes with a larger zone of weakness, and the United States Geological vey, following Hadley and Devine (1974), has correlated the earthquakes with northeast-ding faults.
ent activity in this region, including central New Hampshire and the Cape Ann area, appears e low. Two events ranging in magnitude to just over 3.0 have been reported in the last decade.
seismicity of Maine, characterized by a maximum Intensity VI (MM), is spatially distributed he central and west-central regions, the New Brunswick border area, and the Quebec border on near northern New Hampshire.
o Intensity VI (MM) earthquakes, one located in the ocean off Portland in 1957 and the other r the Maine-Quebec border in 1973, are both assigned magnitudes of 4.8. For the 1973 event, tmiller (1975) determined an oblique strike-slip focal mechanism with nodal planes oriented 4E and N37W.
Hudson River Valley earthquake epicenters have been located in the Hudson River Valley. The largest of these hquakes was Intensity VII (MM) near Lake George, New York, on April 20, 1931.
hough a number of large earthquakes (Intensity IX-XI (MM)) have occurred in the St.
rence River Valley, these earthquakes fall outside the 200-mile radius and, therefore, are ussed in Section 2.5.2.4 with relation to maximum earthquake potential at the site.
cumulative historical seismicity data, carefully interpreted, can yield valuable information on spatial and temporal distribution of larger and more significant earthquake events and the tion of zones of concentrated activity. Four years of operation of the NEUSSN have produced mplete record of accurately located events of magnitude 1.8 to 2.0 and larger in the region.
r and Sykes (1977) and Chiburis (1979) have noted that the spatial distribution of this rumental seismicity closely tracks the distribution of less accurately located historical events, reinforcing confidence that older events are fairly well located and that areas of seismic vity are relatively stationary.
2.1.3 Seismicity within 50 Miles of the Site thquake activity within 50 miles of the site is listed in Table 2.5.2-4 and shown on ure 2.5.2-3. There have been 50 earthquakes of intensity greater than or equal to Intensity IV M). Almost half of this earthquake activity has occurred in the Moodus-East Haddam area, ut 25 miles northwest of the site. A temporary microearthquake network (five stations) has n installed in this area by Professor E. Chiburis of Weston Observatory to examine the nature significance of this activity.
ge earthquakes have occurred in the Moodus area in 1568, with epicentral Intensity VII (MM),
on May 16, 1791, with Intensity VI-VII (MM) (Chiburis 1979). The earthquake of May 16, 1, was felt over an area of 35,000 square miles extending from Boston to New York. Several rshocks were reported for the next few days.
ce 1791, at least 40 earthquakes have been lightly felt in the East Haddam-Moodus area. A derate earthquake took place in the same epicentral area on November 14, 1925 and, although portedly did some minor damage at Hartford and Windham, it was not strong enough to be
rmined epicenter about 19 miles northwest of the site. The earthquake had a maximum nsity of IV (MM) and was generally felt from Old Lyme, Connecticut, on the south to East tford on the north. The most recent earthquake in the Moodus area was of magnitude 2.2 in 6.
thquake activity within 10 miles of the site has been limited to four very slight earthquakes h maximum intensities of Intensity III (MM). Two of these earthquakes occurred in New don on November 23, 1894 and August 9, 1935; one occurred in Groton on August 1, 1852; the fourth was felt in Mystic, Moodus, and Norwich on September 20, 1938.
2.1.4 Earthquakes Felt at the Site determine the earthquake hazard at the site, it is necessary to examine how severely the site has n affected by large earthquakes in the past. This examination for Millstone 3 is based on ilable historical records. A discussion of these earthquakes follow.
June 11, 1638 (46.5°N, 72.5°W, Intensity IX (MM))
s earthquake, centered in the St. Lawrence River Valley, probably near Three Rivers, Quebec, felt throughout New England with no damage reported except to chimneys at Plymouth and m, Massachusetts. Perley (1891) described the chimneys at Plymouth as follows: The mneys of the first houses here were built on the outside at the ends of the houses, with the tops ng just above the roof. They were massive piles of rough and uneven stones, generally some feet square, besides being nearly perpendicular. Imperfectly built, without mortar except for ng, they readily yielded to the terrible shaking they received, and the tops of many of them fell striking on the house or on the ground. Felt (1899) reported that the shock was felt in necticut, Narragansett, Pascataquack, and surrounding areas. Based on available reports and intensity attenuation characteristics of other earthquakes occurring in the vicinity of the St.
rence River Valley, the estimated maximum intensity of the earthquake at the site was IV-V M).
February 5, 1663 (47.6°N, 70.1°W, Intensity X (MM))
s earthquake was centered in the St. Lawrence River northeast of Quebec City and was felt r a 750,000-square-mile area of eastern North America, accompanied by landslides along the Maurice, Batiscan, and St. Lawrence Rivers. Other damage was confined to cracked chimneys the like. Effects in New England were similar to those of the 1638 earthquake. Brigham
- 71) reported that on the shore of Massachusetts Bay, houses were shaken so that pewter fell m the shelves and the tops of several chimneys were broken. Based on available reports and nsity attenuation characteristics of other earthquakes occurring in the vicinity of the St.
rence River Valley, the estimated maximum intensity of this earthquake at the site was IV-V M).
epicenter of this earthquake was located off the coast of northeastern Massachusetts.
ximum damage in the intensity range of VI to VII (MM) occurred near the mouth of the rimack River where no buildings were thrown down but parts of walls of several cellars fell nd the tops of many chimneys were shaken off (Crowell, 1868). Slight damage equivalent to nsity V (MM) consisting of cracked chimneys was noted as far north as Portsmouth, New mpshire; as far west as Lowell, Massachusetts; and as far south as Boston, Massachusetts. The hquake was felt over an estimated area of 75,000 square miles from the Kennebunk River in ne to the Delaware River south of Philadelphia. The intensity distribution of this earthquake is wn on Figure 2.5.2-4. Based on available reports, the estimated maximum intensity of this hquake at the site was IV (MM).
September 16, 1732 (45.5°N, 73.6°W, Intensity VIII (MM))
s earthquake was centered near Montreal where 300 homes were damaged and 7 people were ed. It was felt in Boston and throughout New England and possibly as far south as Maryland.
ed on available reports and the intensity attenuation characteristics of other earthquakes urring in the vicinity of the St. Lawrence River Valley, the estimated maximum intensity of earthquake at the site was IV (MM).
December 18, 1737 (40.8°N, 74.1°W, Intensity VII (MM))
s earthquake appears quite similar to the earthquake of August 10, 1884, in that it was felt m Boston, Massachusetts, to New Castle, Delaware and the epicenter was located in the New k City area where some chimneys were thrown down and bells rang. Although the damage in epicentral area appears similar, it is possible that the epicentral intensity of the 1737 hquake may have been one intensity less (or Intensity VI (MM)) due to the difference in the struction quality over the 147-year interval between earthquakes. Based on available reports a comparison of this earthquake with the 1884 earthquake, the probable intensity in the nity 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))
s earthquake had its epicenter off the Massachusetts coast, east of Cape Ann. It was felt over stimated area of 300,000 square miles from the Chesapeake Bay in Maryland on the south to Annapolis River in Nova Scotia on the north and from Lake George in New York on the west pproximately 200 miles east of Cape Ann (ship thought to have run aground). Most of the age (Intensity VI (MM) or greater) from this earthquake occurred along the coast from the w Hampshire-Massachusetts line south to the Boston area. Some slight damage to chimneys ensity V (MM)) occurred as far north as Portland and Brunswick, Maine; as far south as uate, Massachusetts; and as far west as the Lowell, Massachusetts and Nashua, New mpshire area. The intensity distribution for this earthquake is shown on Figure 2.5.2-5.
orts, 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))
epicenter of this earthquake was located in the vicinity of East Haddam, Connecticut. This hquake was felt over an area of 35,000 square miles extending from Boston to New York.
mination of the dates and times mentioned in the technical references suggests that a number arthquakes occurred; the first and largest on May 16, 1791, at 8:00 pm, with a number of rshocks during the next few days.
only reports of damage were from the East Haddam area where stone walls and the tops of mneys were thrown down and latched doors were thrown open. Linehan (1964) reports that a up of professors from Wesleyan University visited the East Haddam area in 1841 and was able onfirm these reports. However, contrary to the original reports, the professors found that only large stone had been displaced (it was in a tenuous position to begin with) and that no fissures opened in the earth.
ty houses of pre-1791 construction were still occupied in the East Haddam-Middletown area ate as 1938. A study of the houses in the East Haddam area shows that they were not of sturdy struction nor had deep foundations, yet none were structurally damaged in the 1791 hquake. The fact that some stone walls or chimneys might have been damaged could be buted to an earthquake of intensity not more than V (MM), as there was little brick used and stones were glacial cobbles. Clay and fibers made up the morta (Linehan 1964).
vious reports of this earthquake placed the intensity at VIII (MM). However, Linehan (1964) cludes that the intensity of the seismic event which was felt in East Haddam on May 16, 1791 no greater than V-VI (MM). If the disturbance was of Intensity VIII (MM), the damage ld have been considerable in ordinary substantial buildings, with partial collapse, as defined he MM scale. There is no record of any damage to buildings, even though most of these were rly constructed. Therefore, the intensity of these earthquakes could have been no higher than VII (MM).
wspaper accounts indicate that the earthquake was strongly felt without any reported damage artford or New Haven, Connecticut. The intensity distribution for this earthquake is shown on ure 2.5.2-6. Based on Linehan's analysis of the earthquake's effects in the East Haddam-odus area and other available accounts, the estimated maximum intensity of the earthquake in vicinity of the site was V (MM).
October 17, 1860 (47.5°N, 70.1°W, Intensity VII to IX (MM))
s earthquake had its epicenter in the St. Lawrence River Valley, northeast of Quebec City, and felt over an area of 700,000 square miles extending as far south as Newark, New Jersey, and ar west as Auburn, New York and included most of New England. The earthquake was ngly felt in Maine, but no damage was reported there or elsewhere in New England. Based on
site was IV (MM).
October 20, 1870 (47.4°N, 70.5°W, Intensity IX (MM))
s earthquake was centered near Baie-St. Paul, Quebec, and was felt over a 1,000,000 square-e area of eastern Canada and the northeastern United States. The damage reported in the ted States included some bricks thrown from chimneys in Lewiston, Maine and some window s broken in Portland, Maine. In Springfield, three distinct periods of vibration were noticed h the longest estimated at 7 to 8 seconds; while at Hartford, a single shock lasting a minimum 0 seconds was felt.
ed on available reports, the estimated maximum intensity of this earthquake at the site was IV M).
August 10, 1884 (40.6°N, 70.4°W, Intensity VII (MM))
s earthquake was felt over an estimated 70,000 square-mile area of the northeastern United es and had its epicentral location in the New York City area. The greatest damage occurred in aica and Amityville on western Long Island, New York, where some walls were cracked, ounting for the epicentral intensity of VII (MM). The epicentral location is further evidenced moderate aftershock which took place on August 11, 1884, and was felt in a number of towns western Long Island.
analysis of this earthquake by Rockwood (1885) resulted in the isoseismal map shown on ure 2.5.2-7. Rockwood's map was based on more than 215 observations, of which 30, all hin Rockwood's Isoseismal IV, reported some damage such as fallen bricks and cracked ter. As shown on the figure, the site is located within Rockwood's Isoseismal III.
he southern Connecticut area, damage included some bricks shaken from chimneys and a few ked walls at New Haven, and dishes thrown from shelves and broken at Bridgeport. The ck was strongly felt at Hartford, but no damage was reported.
ew London, the earthquake was felt by everyone and the water in the harbor was reportedly ated. Reports also indicate a few instances of cracked and fallen plaster but no damage to mneys (The Day 1884).
ed on Rockwood's data and other available reports, the estimated maximum intensity in the area was V (MM).
February 10, 1914 (45N, 76.9°W, Intensity VII (MM), Magnitude 5.5) s earthquake had its epicenter about 25 miles west of Lanark, Ontario, and was felt over a
,000 square-mile area including New England, New York State, and Pennsylvania. Some age was reported in New York State with minor damage noted as far east as Albany. The
vailable 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) s earthquake, which had its epicenter in the St. Lawrence River Valley northeast of Quebec
, was felt over approximately 2,000,000 square miles of North America, extending as far th as Virginia and west to the Mississippi River. Important damage was confined to a narrow along the St. Lawrence River Valley. Isoseismals prepared by the Dominion Observatory of ada and shown on Figure 2.5.2-8 indicate that most of New England experienced intensities II and IV (MM), the exception being extreme northern Maine, which probably experienced an nsity of V to VI (MM). The shock was generally felt throughout Connecticut with a maximum nsity of IV (MM) in the site area.
November 14, 1925 (41.5°N, 72.5°W, Intensity V to VI (MM))
s earthquake was felt over an 850 square-mile area of central Connecticut. Minor damage was orted at Hartford where some plaster fell and at Windham where dishes fell from shelves.
wspaper reports indicated that the earthquake was strongly felt from the Haddam-Middletown to Hartford.
ng the southern Connecticut coast, the earthquake was generally felt but no damage reported.
ilable 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) epicenters of these earthquakes were located near Lake Ossipee, New Hampshire. Damage of nsity VII (MM) occurred at Tamsworth and Wonalancet, New Hampshire, while damage of nsity VI (MM) was noted in a dozen localities in central New Hampshire and western Maine.
shocks were felt over a 150,000 square-mile area of the United States including all of New land, New York, and New Jersey. The earthquakes were noticeably felt in the vicinity of the but no damage was reported.
isoseismal map prepared by the Northeast Seismological Association, Figure 2.5.2-9, cates that the intensity of these earthquakes in the vicinity of the site was IV (MM).
2.2 GEOLOGIC STRUCTURES AND TECTONIC ACTIVITY site region encompasses a large segment of the northern Appalachian region. This region has ergone at least four orogenies, Mesozoic rifting and igneous activity, epeirogenic uplift, and iation. The tectonics and geologic history are discussed in Section 2.5.1. Figure 2.5.2-2 ws the regional geologic structure and the locations of epicenters within the 200 mile radius of site.
White Mountains Plutonic Province -- comprise most of the area. The remaining provinces the Coastal Plain, the Blue Ridge and Piedmont, the Northern Valley and Ridge, the alachian Plateau, the Central Stable Region, the Grenville, and the Monteregian Plutonic vince. 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 se provinces are shown on Figure 2.5.2-10.
Southeastern New England-Maritime Province site is located in the southwestern edge of the Southeastern New England-Maritime Province.
western boundary follows the Honey Hill Lake Char-fault system northward into ssachusetts. The rock fabric and structural trends are different than those of the New England vince to the west. The province is characterized by Late Precambrian basement rock overlain mildly metamorphosed rocks of Carboniferous age. Unlike the remainder of New England, the cts of the Alleghenian orogeny are apparent within the province.
Southeastern New England area is considered by Skehan (1973) to be a piece of the Paleo-ican continental plate with the Clinton-Newbury fault zone being the collision boundary.
gers(1970) considers the rocks east of the Clinton-Newbury fault to be similar to those of the lon Peninsula of Newfoundland. The reopening of the Atlantic Ocean, which began in the sozoic, isolated the pieces of the African continent. Gravity and magnetic data also indicate the province boundary represents a juncture between two discrete crustal blocks in near tatic equilibrium.
erse faulting is prominent in the intensely faulted zone between the Clinton-Newbury and e Char faults and the Boston Border fault, although transcurrent or strike-slip components exist. Northeastward along the Norumbega fault, the movement has been right lateral and exceed several hundred kilometers. Skehan (1973) considers the area to be an ancient duction zone, although all the elements have not been demonstrated. Certainly, large scale erthrusting has played a major role in the development of the province.
New England Province west of the Southeastern New England-Maritime Province lies the New England Province, nding southward to 4030'N latitude. The New England Province is structurally similar to the dmont. The region has been strongly affected by the Taconic and Acadian Orogenies, whereas Blue Ridge and Piedmont Province and the Valley and Ridge Province to the south were cted by the Alleghenian orogeny. Grenville-age basement is exposed in the cores of the
cambrian basement disappears beneath the high grade metamorphic rocks of the Merrimack clinorium to the east. The structural fabric of the province suggests a Paleozoic compressive ss directed from the east or southeast. The presence of the New Hampshire Plutonic series laced during the Acadian Orogeny aids in distinguishing the New England Province from the theastern New England-Maritime Province.
White Mountains Plutonic Province emplacement of magmas of the White Mountains Plutonic-Volcanic Series began in the sozoic and overprinted the Paleozoic effects. The series was intruded along a north-northwest d extending offshore of Cape Ann, Massachusetts, into northern New Hampshire, Vermont, southern Quebec, crossing the older structural grain of the Appalachians. Radiometric dating shown that the igneous activity began in and continued sporadically throughout the Mesozoic (BECo 1976a). All the plutons are related in age, shape, magnetic signature, gross eralogy, and mode of intrusion. The zone has been spatially correlated with a region of mic activity in New Hampshire and Massachusetts.
s zone is defined to include all mapped occurrences of White Mountains Plutonic-Volcanic es rocks and is extended offshore to include a group of magnetic anomalies similar to the hore structures. It extends northwestward to include Mt. Ascutney in Vermont and northward ncompass Mt. Megantic in southern Quebec. Southeastward, it includes the Agamenticus plex and Cape Nedick pluton.
Monteregian Plutonic Province s province, which represents an overprinting similar to the White Mountains intrusives, is posed mainly of alkaline, basic, and ultrabasic intrusives of Cretaceous age. They intrude y Paleozoic folded metasedimentary and undeformed sedimentary rocks of the New England vince. The trend of the plutonic belt cuts across the Paleozoic structural grain. The Cretaceous
, duration and mode of emplacement, size of plutons, extreme alkalic nature, contact tionships, and evidence of explosive activity distinguish the Monteregian plutons from the ite Mountain Series. The zone is defined to include all known occurrences of Monteregian rocks including several subsurface magnetic anomalies. It extends to the Oka Complex on northwest and surrounds Mt. Shefford and Mt. Brome on the northeast. The zone includes the tingsville stock near Rutland, Vermont, and all known alkalic dike occurrences in the mplain Valley. It has also been the site of a moderate amount of seismic activity and includes September 16, 1732, Intensity VIII (MM) event near Montreal.
Coastal Plain Province Atlantic Coast section of this province lies seaward of the Piedmont, New England, and theastern New England-Maritime Provinces. It is characterized by gently seaward-dipping, onsolidated Jurassic, Cretaceous, and Tertiary sediments overlying Precambrian or Early
tonically, the province is characterized as a zone of subsidence, occurring mainly since the ssic and persisting through most of the Tertiary. Several arches and embayments exist in the ement rocks and serve to subdivide the Coastal Plain into distinct sedimentary basins, some of ch contain between 10 and 12 km (32,800 and 39,400 ft) of sediments of Jurassic age and nger. Most of the deposits were placed in relatively shallow water indicating a progressive nwarping of the edge of the continent toward the oceanic floor.
Grenville Province Grenville Province borders the New England Province on the northwest and forms a belt 250 es wide from Lake Huron to the Atlantic in Labrador. The rocks of the province are divided ost evenly between medium grade marbles, quartzites and gneisses, and higher grade gneisses plutonic rocks of a slightly older series. An appendage of the Grenville Province occurs in w York State as the Adirondack uplift. Distinctive anorthosite bodies of the Adirondacks are uded in the Grenville Province because they were deformed during the Grenville orogeny ween 1.1 and 1.3 billion years ago. The Grenville Province appears to be an orogenic belt built inst the stabilized older part of the shield and is more nearly comparable to the orogenic belts he Paleozoic.
er Paleozoic platform rocks do exist in the Ottawa-Bonnecherre graben west of Logan's Line thin veneer on Grenville basement rocks. They represent a portion of the Central Stable ion which has been isolated by the uplift of the intervening Adirondacks. Their tectonic ility is related to the general stability of the underlying Grenville and, therefore, for simplicity, are included in the Grenville Province.
Piedmont-Blue Ridge Province Piedmont-Blue Ridge Province is characterized by metamorphosed Precambrian and Early ozoic eugeosynclinal rocks which were deformed during the Taconic and Alleghenian genies and may have been recrystallized during the Acadian orogeny. It includes the Blue ge anticlinorium, a relatively narrow belt of folded and faulted upper Precambrian crystalline sts and gneisses which were thrust westward several kilometers over the rocks of the valley ridge. Terrains of intrusive igneous rocks are notable in the Piedmont of Virginia and North olina. Long, narrow, graben structures filled with continental deposits of late Triassic age are erimposed intermittently on the crystallines from Pennsylvania to South Carolina. The effects each orogeny had on the rocks in the Piedmont are not yet fully understood due to the lack of rop, lack of fossils, and the strong recrystallization.
southern and eastern boundaries of the Piedmont are drawn at the present westward limit of taceous Coastal Plain deposits. Piedmont geology certainly continues beneath the Coastal n for some distance but the line where Coastal Plain mobility becomes the dominant force is ently not well established. The northern boundary of the Piedmont with the New England vince is hidden beneath the Triassic Newark Basin.
Appalachian Plateau Province borders the Central Stable Region on the east and on the south ts limit in New York. Geologically, the province is a broad, gentle, elongated basin whose ngest rocks are of probable Early Permian age. The basin forms the western part of the former alachian geosyncline with sediments thickening generally southeastward from the Cincinnati-dlay arch. Grenville basement dips beneath the province in the same direction. The basement dient steepens through central Ohio demarking the westernmost edge of Appalachian Plateau vince (USNRC 1977). Deformation of the province had its greatest development during the t-Early Permian Allegheny orogeny and resulted in gentle folding and uplift of the mentary pile with perhaps some decollement movements along weak units within the section.
d epeirogenic movements have been the only tectonic events to affect the province since Late ozoic time.
Valley and Ridge Province Valley and Ridge Province lies east of the Appalachian Plateau except at the north end where New England Province intervenes. The Valley and Ridge Province contains the major portions he sediments which were deposited in the Appalachian geosyncline, of which it comprises the theastern part. The province is characterized by unmetamorphosed Paleozoic sediments that e tightly folded and faulted during the Allegheny orogeny, about 250 million years ago.
nse pressure exerted from the southeast folded the sediments into large synclines and clines, some strongly overturned to the northwest. Thrust faults were commonly developed, icularly south of Central Virginia. The Valley and Ridge Province has been divided into hern and southern sections based on the difference in structural styles. The northern section is inated by folding, whereas the southern section is characterized by thrust faulting. In ition, the southern section has historically experienced a higher level of seismic activity while northern section is nearly aseismic (USNRC 1977, USNRC 1978). The boundary between the provinces is somewhat indistinct but is believed to occur between Roanoke and the James er in Central Virginia, roughly along latitude 37°-45' north. A striking change in the trend of ley and Ridge structures also occurs at this line; the folds to the north trend about N25 E, reas the faults to the south trend N70°E. The nature of the structural discontinuity is not wn but may be related to basement transcurrent faulting (Cardwell, et al., 1968).
Central Stable Region Central Stable Region is the westernmost tectonic province of concern to the analysis tained herein. The province is bounded on the east by the Appalachian Plateau Province and north and northeast by the Grenville Province and the New England Province. The Coastal n bounds the province on the south. The Central Stable Region extends westward to the east k of the Rocky Mountains and includes a wide variety of morphology and structure. The vince is made up of a foundation of Precambrian crystalline rock with a veneer of sedimentary er which varies widely in thickness. It represents the craton or central stable area of the North erican crustal plate. Deformation since the Precambrian has been restricted to the elopment of several broad basins, arches, domes, and similar features. Several of the basins
nwarps followed by long periods of erosion. The eastern boundary of the province represents western limit of effects from the Allegheny orogeny. The boundary follows the steepening of basement contours as the gradient increases to form the Appalachian Basin.
2.3 CORRELATION OF EARTHQUAKE ACTIVITY WITH GEOLOGIC STRUCTURES OR TECTONIC PROVINCES relationship between earthquake locations and geologic structures is important in assessing hquake hazard for a particular site. The absence of major spatial displacements through orical times that might be associated with tectonic activity in eastern United States makes the ciation of larger historical earthquakes with specific structures difficult. Only during the past to 15 years have seismologists been able to determine earthquake locations with sufficient ision to relate them to geologic structures.
2.3.1 Correlation with Geologic Structures White Mountain Plutons majority of the significant seismic activity in New England has been associated with the ite Mountains Plutonic Province. The strong concentration of events in southern New mpshire and northeastern Massachusetts has been spatially associated with plutons of the ite Mountains (Figure 2.5.2-2). A detailed investigation of the White Mountains Plutons has cated that the Ossipee, New Hampshire, earthquakes and the Cape Ann earthquake are ciated with the plutons (BECo 1976a). The largest activity was located off Cape Ann in 1755.
as assigned Intensity VIII (MM). Also, there have been a number of Intensity VII (MM) nts, two in Ossipee, New Hampshire in December 1940, and another located off Cape Ann in 7.
Ramapo Fault Ramapo fault system, which bounds the Triassic-Jurassic Newark graben on its northwest in northeastern New Jersey and southeastern New York, has been known for about 100 years has been commonly presumed to be an inactive fault. Aggarwal and Sykes (1978) have erved a spatial correlation of some epicenters in southeastern New York with surface traces of ts in the area. A large majority of events lie on or very close (0.5 to 1.2 miles) to the faults.
thermore, an examination of focal mechanism solutions shows that for each of the solutions, of the nodal planes trends north to northeast, which is also the predominant trend of the faults his area. The spatial correlation of one nodal plane with the trend of the mapped faults suggests earthquakes in this area occur along pre-existing faults.
sidering both geology and seismicity, the Ramapo fault is not considered capable in ordance with the criteria for capable faults in 10 CFR 100, Appendix A. This was established he Atomic Safety and Licensing Board (USNRC 1977) in 1977, after extensive hearings on issue.
most earthquake activity in the site region cannot be correlated with geologic structures, it is med (in accordance with 10 CFR 100, Appendix A) that these earthquakes are associated h the tectonic provinces (Figure 2.5.2-10) in which they occur. A discussion of earthquake vity in various tectonic provinces follows.
ch of the seismicity of the Grenville Province is associated with the LaMalbaie seismic zone the Monteregian Plutonic Zone, considered to be separate source areas and described below.
remaining activity is confined to a broad belt of epicenters extending from the Adirondack ft northwestward into southwestern Quebec and eastern Ontario to the vicinity of Kirkland
- e. The largest historical events in this province were the 1944 Cornwall-Massena event of nsity VIII (MM) and the 1935 Timiskaming, Quebec earthquake of magnitude 6.2 which had picentral intensity of VII (MM).
Monteregian Plutonic Province overprints the older structural features of the Grenville and w England Provinces. Its seismicity includes the easternmost part of the prominent belt of enters which trends northwestward across the Grenville Province. The largest historical hquake within the Monteregian Plutonic Province occurred at Montreal in 1732. Earlier logs have listed this event as Intensity IX (MM); however, recent evaluations of original ounts (Chiburis 1979; NYSE&G 1978) conclude that the epicentral intensity did not exceed I (MM).
LaMalbaie Seismic Zone lies outside the 200-mile radius on the boundary between the nville Province and the New England Province. It occurs as a distinct concentration of enters extending northeast from Quebec City. The LaMalbaie Zone is the most important mic source in the northeast in terms of energy released. Historically, numerous large hquakes have occurred in this zone with intensities ranging from VII to X (MM). A junction of the Charlevoix meteoritic impact structure with the tectonic boundary between the nville Province and the Appalachian structures of the New England Province has been cribed by Leblanc and Buchbinder (1977) as a likely structural basis for the concentration of in release in this zone.
major seismicity of the New England Province is related to the White Mountains Plutonic vince described above. The remainder of the province is characterized by a band of activity ch trends along the coast from northern New Jersey to eastern Connecticut. This area has erienced earthquakes up to Intensity VII (MM). These have occurred in 1737 and 1884 at New k City and 1791 at Haddam, Connecticut. Another diffuse pattern of epicenters of maximum nsity VI (MM) occurs in coastal and central Maine. Minor microearthquake activity is also orted to originate along the Ramapo fault in New Jersey and New York (Aggarwal and Sykes 8).
thquakes in 1568 and 1791 near East Haddam, Connecticut, are also part of the New England vince since these have not been associated with any specific geologic structures or faults. An stigation is currently in progress to study the Moodus noises. However the noises have not n associated with specific faults.
nsity V (MM). The largest earthquake in this province was an Intensity VI (MM) event which urred in 1904 east of Eastport, Maine.
Atlantic Coastal Plain Province has experienced a number of minor earthquakes throughout historic record. Exclusive of the Charleston, South Carolina area, the largest events have been ntensity VII (MM). These occurred in 1871, 1884, and 1927 near the boundary with the New land and Piedmont Provinces in northern New Jersey and near New York City.
Piedmont-Blue Ridge Province exhibits a fairly low level of seismicity throughout its length h diffuse areas of higher activity in central Virginia and western South Carolina. The largest orical earthquake in the province was of Intensity VII (MM). It occurred in central Virginia in 5.
2.4 MAXIMUM EARTHQUAKE POTENTIAL maximum earthquake potential for the site is evaluated by utilizing maximum earthquakes ciated with all nearby tectonic provinces and geologic structures. This analysis is made for different sets of conditions. First, actual site intensities resulting from larger historical hquakes are determined. Second, the maximum potential site intensities resulting from othetical events are calculated. These hypothetical events are specified as the largest known hquakes in each adjoining tectonic province. Each is postulated to occur at the point where its vince or structure most closely approaches the site.
2.4.1 Maximum Historical Site Intensity etailed analysis of large historical earthquakes in the northeastern United States indicates ction 2.5.2.1.4) that four earthquakes have been felt with intensities of V (MM) or greater at site. The 1755 Cape Ann earthquake caused damage corresponding to Intensity V-VI (MM) at ns near the site. The East Haddam-Moodus earthquake of 1791 was reportedly felt strongly no damage resulted at such localities as Hartford and New London, indicating an intensity of roximately V (MM). A similar intensity value is indicated for the Millstone site. Data ected by Rockwood indicate that the 1884 earthquake, with an epicenter approximately in the w York City area, was felt at the site with a probable intensity of V (MM). Bricks were thrown m chimneys and a few walls were cracked at New Haven, and plaster was cracked and odged at New London. The 1737 earthquake with epicentral location also in the New York area appears similar to the 1884 earthquake and may have been felt with an intensity of V at site.
clear that these four earthquakes in the site region caused Intensity V or V-VI (MM) at the
. The epicentral intensity of these four earthquakes was either VII, VI-VII, or VIII (MM). In site region, the 1755 Cape Ann earthquake was of highest intensity (VIII (MM)). Earthquakes er than the 1755 Cape Ann, for example, have all occurred outside the site region in the albaie area of the St. Lawrence River Valley. Large earthquakes in this zone are estimated to e caused Intensity IV-V (MM) at the site. The 1886 Charleston earthquake of Intensity X
2.4.2 Maximum Earthquake Potential from Tectonic Province Approach account for the possibility of large errors in epicentral determination, especially for events urring prior to 1950 and in the absence of capable faults, the largest known earthquake in each vince was attenuated to the site from points of nearest approach of the tectonic province in ch the earthquakes occurred, using the conservative attenuation relationship of Howell and ultz (1975). Justification for this procedure is that individual epicenters are not properly ted and, therefore, cannot be associated with specific structures.
site is located in the Southeastern New England-Maritime Tectonic Province. The largest hquake in this province was of Intensity VI (MM). The New England Tectonic Province is y near the site and several earthquakes of Intensity VII (MM) have occurred in this province 68 and 1791 at Moodus and 1737 and 1884 at New York City). Assuming that these hquakes occur at the nearest approach point of the New England Province to the site (20 km),
nsity at the site would be VII (MM). The Coastal Plain Province is also close to the site (about km). The 1927 earthquake near Asbury Park, New Jersey, was in the Coastal Plain Province had an epicentral intensity of VII (MM). A similar earthquake in the Coastal Plain Province r the site would cause Intensity VII (MM) at the site. Only one earthquake of Intensity VIII M) is associated with any of the provinces or structures in the site region. This earthquake urred near Cape Ann, Massachusetts, in the White Mountains Plutonic Province. Such an hquake occurring in that province at a minimum distance from the site (170 km) would cause intensity of V-VI (MM). In other tectonic provinces in the site region, the maximum intensity arthquakes was VII (MM). Therefore, the effect of these earthquakes would be less than VII M).
he eastern United States, earthquakes with intensities greater than VIII (MM) have occurred y in LaMalbaie, Quebec; Charleston, S.C.; and New Madrid, Missouri. Earthquake activity at e places is assumed to be associated with specific structures and, based on historical data, ld not cause greater effects at the site than Intensity IV-V (MM). Therefore, the maximum hquake potential at the site due to earthquakes occurring within 10 to 20 km of the site is nsity VII (MM).
2.5 SEISMIC WAVE TRANSMISSION CHARACTERISTICS OF THE SITE perties of subsurface materials at the site are discussed in detail in Section 2.5.4. The pressional and shear wave velocities of in situ materials are tabulated in Section 2.5.4.4.3 and r properties of the in situ materials are described in Section 2.5.4.2. The groundwater ditions at the site are discussed in Section 2.5.4.6.
safe shutdown earthquake (SSE) value of 0.17 g is applied to the bedrock surface. For ctures founded on soils, the effect of the overburden on the earthquake motion has been sidered in soil-structure interaction computations, as discussed in Section 3.7B.2.4.
discussed in Section 2.5.2.4, the maximum earthquake potential at the site is an Intensity VII nt occurring 10 to 20 km from the site. Murphy and O'Brien (1977) have published an analysis cceleration-intensity correlations using a new worldwide data base and a variety of statistical dels. Their correlation equation relating Intensity I (MM) and peak horizontal ground eleration (Ah) is:
log Ah = 0.25 I + 0.25 re Ah is in cm/sec2. For a Modified Mercalli Intensity VII earthquake, this equation gives an rage horizontal component peak acceleration of 0.10 g. In order to be conservative in the lstone 3 plant design, the SSE is specified as 0.17 g. The duration of strong ground motion ciated with an Intensity VII earthquake is estimated at 6 seconds using an assumed threshold eleration value of 0.05 g according to Bolt (1973).
2.7 OPERATING BASIS EARTHQUAKE tudy of the earthquake history of the site region has shown that the maximum historical nsity at the site has been V-VI (MM), corresponding to a peak horizontal ground acceleration 0.05 g (Murphy and O'Brien 1977). In accordance with 10 CFR 100, Appendix A, the rating basis earthquake is taken to be at least one half of the SSE, or 0.09 g.
2.8 REFERENCES
FOR SECTION 2.5.2 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.
2.1-2 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.
2.1-3 Boston Edison Company 1976a. Summary Report - Geologic and Seismologic Investigations. Pilgrim Unit 2, USNRC Docket No. 50-471. Boston, Mass.
2.1-4 Boston Edison Company 1976b, Historical Siesinicity of New England. Pilgrim Unit 2, USNRC Docket No. 50-471.
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.
2.1-6 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.
2.1-8 Chiburis, E. C. 1979. Seismicity of New England. (In press).
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.
2.1-10 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.
2.1-11 Felt, J. D. 1899. Annals of Salem, Boston. James Munroe & Company, Boston, Mass.
2.1-12 Hadley, J. B. and Devine, J. F. 1974. Seismotectonic Map of the United States.
USGS Miscellaneous Field Studies, Map MF-620.
2.1-13 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.
2.1-14 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.
2.1-15 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.
2.1-16 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.
2.1-17 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.
2.1-18 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.
2.1-19 Perley, S. 1891. Historic Storms of New England. Salem Press Publishing and Printing Company, Salem, Mass.
2.1-20 Rockwood, C. G., Jr. 1885. Notices of Recent Earthquakes. American Journal of Science and Arts, Third Series, Vol 29, p 425.
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.
2.1-23 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.
2.1-24 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.
2.1-25 Smith, W. E. T. 1966. Earthquakes of Eastern Canada and Adjacent Areas, 1928-1959. Dom. Observ. Publ., Vol 32, p 87-121.
2.1-26 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.
2.1-27 The Day 1884. New London, Conn., August 11.
2.1-28 United States Earthquakes 1940. U.S. Dept. of Commerce, U.S. Coast and Geodetic Survey, Washington, D.C.
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.
2.1-30 U.S. Nuclear Regulatory Commission 1978. Safety Evaluation Report, Erie Power Station, Docket No. 50-580, 50-581.
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.
2.1-32 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.
TABLE 2.5.2-1 MODIFIED MERCALLI (MM) INTENSITY SCALE OF 1931 CLICK HERE TO SEE TABLE 2.5.2-1
TABLE 2.5.2-2 LIST OF OPERATING SEISMIC STATIONS CLICK HERE TO SEE TABLE 2.5.2-2
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
TABLE 2.5.2-4 LIST OF EARTHQUAKES WITHIN THE 50-MILE RADIUS CLICK HERE TO SEE TABLE 2.5.2-4
FIGURE 2.5.2-1 LOCATION OF SEISMIC STATIONS FIGURE 2.5.2-2 EPICENTERS OF EARTHQUAKES WITHIN 200-MILE RADIUS FIGURE 2.5.2-3 LOCATION OF EARTHQUAKES WITHIN THE 50-MILE RADIUS FIGURE 2.5.2-4 ISOSEISMAL MAP, EARTHQUAKE OF NOVEMBER 9, 1727 FIGURE 2.5.2-5 ISOSEISMAL MAP, EARTHQUAKE OF NOVEMBER 18, 1755 FIGURE 2.5.2-6 ISOSEISMAL MAP, EARTHQUAKE OF MAY 16, 1791 FIGURE 2.5.2-7 ISOSEISMAL MAP, EARTHQUAKE OF AUGUST 10, 1884 FIGURE 2.5.2-8 ISOSEISMAL MAP, EARTHQUAKE OF MARCH 1, 1925 (FEBRUARY 28, 1925 EST)
IGURE 2.5.2-9 ISOSEISMAL MAP, EARTHQUAKES OF DECEMBER 20 AND 24, 1940
FIGURE 2.5.2-10 TECTONIC PROVINCES e of the published geology maps show faults in the vicinity of the site. Figure 2.5.1-13 shows mposite bedrock geologic map for the area surrounding the site. The closest mapped fault to site is in the Uncasville quadrangle, 10.5 miles northeast of the Millstone site (Goldsmith 7a). Faulting has also been observed in the Clinton quadrangle, approximately 17 miles west he site, and in the Moodus and Colchester quadrangles, approximately 15 miles north of the (Lundgren et al., 1971; Lundgren and Thurrell 1973). These faults are all believed to be high-le faults related to extension tectonics of Late Triassic-Jurassic time (Lundgren et al., 1971; dgren and Thurrell 1973; Goldsmith 1973).
y-two faults were found during the mapping of the rock excavation for Millstone 3 between 1979 and July 1982. Forty of the faults have apparent displacements equal to or less than one with the remaining faults exhibiting apparent displacements greater than one foot. The extent he areas mapped shows eleven separate fault zones with numerous minor associated faults.
ure 2.5.1-18 shows the general location of these faults. Table 2.5.3-1 lists the faults mapped at site and provides a reference for those faults discussed in previous reports (NNECo. 1975; 6; 1977; 1982).
ples from the gouge zone of faults T-2, T-3, 1541, and 2819 were taken at final excavation de in the containment structure and discharge tunnel excavations. Petrographic analyses, x-ray raction studies, and potassium-argon radiometric dating were performed on these samples.
ay diffraction studies were performed on material from faults 1940, 2282, 2339, and 2781 ch indicated that the material was not suitable for age dating. The results of these tests are ussed in detail in Section 2.5.3.2. Table 2.5.3-2 describes the samples and shows the tests ormed. The analyses and tests show excellent agreement with previous studies performed at site (NNECo. 1975; 1976; 1977).
3.1 GEOLOGIC CONDITIONS OF THE SITE tion 2.5.1.2 discusses the stratigraphy, structural geology, and geologic history of the site area etail. The bedrock geologic map and cross section of the site area and the tectonic setting of ern Connecticut are shown on Figures 2.5.1-13 and 2.5.1-14, respectively.
3.2 EVIDENCE OF FAULT OFFSET published geologic maps which include the site area do not indicate the presence of faulting.
study of LANDSAT photographs (Figure 2.5.1-9) of southern New England identifies ineaments greater than 10 miles long. None falls within the 5-mile radius of the site.
ure 2.5.1-10 shows the lineaments and Section 2.5.1.1.4.4 discusses them.
umber of small faults were uncovered at the site during excavation and were mapped in detail.
larger faults were observed and mapped both at top of rock and at final excavation grade. One t (508) (NNECo. 1975) was mapped at top of rock and not observed at final grade; others nd at final grade were not observed at the rock surface. Figure 2.5.1-18 shows all of the faults overed during the mapping at the site. The larger faults exhibiting brecciated and silicified
ven fault zones (T-1, T-2, T-3, 18, 471-1541, 1599, 1940, 2250, 2282-2295, 2339-2347, and
- 0) have been found in the main site area and pumphouse excavations. Figure 2.5.1-18 also ws the remaining ancillary faults. Two of the smaller faults, 508 and 368, terminate within the ts of the main site excavation. Fault 508 is the only fault that was mapped at top of rock that not noted at final grade. The other faults extend beyond the boundary of the excavation at t in one direction. Fault 1541 in the auxiliary building was mapped as fault 461 in the tainment excavation. Displacement along this fault dies out before intersecting the thwestern wall of the containment.
st of the faults trend to the north and dip at high angles either to the east or to the west.
le 2.5.3-1 lists their characteristics. Slickenside information (Figure 2.5.1-17) indicates that sense of movement was in an east-west direction (dip slip). Slickenside information in the T-2,
, and 2339 fault zones indicates that the motion along the fault was oblique. Exposures of the ts (T-2, 18, and 1541) in the excavation walls indicate that they are normal (gravity) faults.
refore, the oblique motion along the larger faults has a greater dip slip component.
o of the larger faults, T-2 and T-3, were previously studied in detail immediately after their overy during the mapping of the bedrock surface (NNECo. 1975). Figures 2.5.3-1 through 3-3 show the detailed maps of these faults at final excavation grade. Both faults are racterized by a zone of gouge, breccia, microbreccia, and cataclasite derived from the Monson iss and igneous rocks which intrude the Monson Gneiss. Hydrothermal fluids have permeated gouge zones of these faults. Free-growing crystalline quartz was found in the T-2 zone, and sy quartz coated the fracture surfaces and vugs in the breccias and cataclasite of the T-3 fault
- e. Drusy quartz was also found in open cavities adjacent to T-2.
brecciated zone of T-2 varies in thickness from 4 to 6 inches. However, in some areas the e widens to 1.5 feet, and in others narrows to a single, nearly clean fracture. For the most part, breccia is partially to completely rehealed. The clay gouge varies in thickness along the fault e although it rarely exceeds 1.0 inch. The T-3 brecciated zone is similar to that of T-2, except imensions. The fault zone varies in thickness from 6 inches to 2 feet, and the clay gouge cally forms a thin, 0.5 to 2 inch, continuous seam. It is occasionally found as a thin filling ween brecciated blocks. Both zones are moderately to severely weathered with much of the stained by iron oxide.
lt T-2 trends N15W, dips at 70 degrees to the east, and is located on the eastern side of the tainment excavation. The geologic maps of the walls of the containment and of the discharge nel, Figures 2.5.4-11 through 2.5.4-14 and 2.5.4-3 through 2.5.4-5, respectively, show a ion across the fault in four locations. The largest fault at the site, T-3, lies on the western edge he rock exposure in the excavation. T-3 strikes N28W and dips 70 degrees to the east.
le 2.5.3-1 shows the apparent displacements of the faults in the horizontal plane and lists the ulated displacements, determined from the offset pegmatite veins and from slickenside rmation. The eastern blocks of T-3, T-2, 1599, and most of the faults in the pumphouse appear
omplex irregular pegmatitic intrusion has obscured the contacts in the vicinity of faults 2250 2282 making it impossible to determine the sense of development.
lt 1940 shows low-angle thrust displacement of between 1.0 and 2.0 inches toward the heast. The southwest dipping fault zone consists of a zone of weathered and fractured rock clay varying from less than 1.0 inch to about 10 inches thick. The fault ends at joint 198 but is lleled by a similar zone about 3 feet below it. This parallel zone crosses joint 198 but ends at t T-2 in a southwesterly direction. Projection of 1940 updip places the intersection of the fault h the rock surface in the vicinity of the demineralized water storage tank. Geologic mapping of area did not reveal the trace of the fault at the surface. Hydrothermal activity along the fault is ent by the presence of smectite clay in the gouge which is probably related to the same period ydrothermal activity shown in the high angle faults at the site.
r separate fault zones were uncovered in the pumphouse excavation (2250, 2282, 2330 plus 7, and 2380) with smaller faults splaying from these zones, as shown by Figures 2.5.1-18 and 4-8. These faults are similar in trend, fault zone composition, and amount and type of lacement to those faults uncovered in the main excavation. The shear zones of the faults in the phouse were characterized by hydrothermal quartz. Clay gouge was generally restricted to y thin coatings on fracture surfaces.
r other faults (2781, 2817, 2818, and 2819) were found in the discharge tunnel excavation and included in Figure 2.5.1-18 and in Figures 2.5.4-19 through 2.5.4-22. A separate report has n submitted detailing the investigation of these faults (NNECo. 1982).
lt 2781 dips 45 degrees to the west and shows reverse displacement of a biotite seam of 2.5 es. Clay from the 0- to 4-inch thick fault zone was found unsuitable for age dating. Till and wash directly overlying the fault was examined and found to be not disturbed. The largest fault overed in this portion of the discharge tunnel consists of three related faults, numbers 2817, 8, and 2819. Offset of pegmatite veins up to 1.5 feet were observed across 2817 and 2818, reas no continuity could be determined across 2819 in the width of the excavation. Fault ge material from 2819 produced a K/Ar age date of 142 million 6 million years. The zone was d with undisturbed drusy quartz and also showed no disruption of overlying stratified and tratified glacial deposits. Faults 2894 and 2899 (NNECo. 1982) show 4-inch and 0.5-inch lacements, respectively, on very narrow fault zones. Displacements on both faults were erved to end within the excavation.
3.2.1 Petrographic Analysis samples were taken from the T-2 and T-3 fault zones at final excavation grade to determine geologic history of the faulting. Figures 2.5.3-1 through 2.5.3-3 show the location of these ples. Table 2.5.3-2 lists the samples and gives a general description of each.
endix 2.5B includes a report on the petrographic analyses performed by Dr. Reinhard A.
bus of Williams College, Williamstown, Massachusetts. The work described herein
ographic analyses of the samples indicate that the fault zones have undergone at least one od of deformation, and possibly more. The cataclasite samples (2F, 5F, 6F, 9F, and 11F) sist mainly of a very fine-grained matrix of subhedral quartz prisms. For the most part, these ms exhibit no preferred orientation. Chlorite is also common in the matrix, along with some mose muscovite. The remainder of the cataclasite is made up of quartz, plagioclase, and mica ments. The fragments indicate that large pieces have undergone some deformation. The rtz crystals are highly strained and the plagioclase twin lamellae have been deformed. All of larger fragments have been altered and chlorite is present between many of the crystals.
orite has replaced the plagioclase in many places, and, where it has not been replaced, the ioclase has been altered to a highly-birefringent clay (Appendix 2.5B).
ple 12F is a sample of the Monson Gneiss taken adjacent to the T-3 fault zone. Hand cimens of the gneiss appear to be sheared. The analysis indicates that quartz present in the thin ion is very highly strained and that the plagioclase has been altered to highly birefringent clay.
bus (Appendix 2.5B) classifies this as an altered biotite-quartz-andesine gneiss.
petrographic analysis by Wobus (Appendix 2.5B) indicates that the material from the two erent fault zones, T-2 and T-3, is similar. He has classified the material in the zones as rothermally altered and silicified cataclasite. Samples taken from the bedrock surface ping also indicate the same results (NNECo. 1975).
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.
3.2.2 Clay Mineralogy, Fluid Inclusion Analysis, and Radiometric Dating ples of the clay gouge in the fault zones were taken at final excavation grade. Table 2.5.3-2 these samples, their location, and the tests performed. Six samples were analyzed by x-ray raction and radiometrically dated using the potassium-argon (K/Ar) method. Five of the ples (7F, 10F, 13F, 14F, and 15F) were taken from the larger T-2 and T-3 fault zones. Sample was taken from a small fault shown as 1541-461 on Figures 2.5.1-18 and 2.5.4-6. The
samples were analyzed to determine their composition by x-ray diffraction techniques prior eing radiometrically dated. Dr. R. T. Martin of the Massachusetts Institute of Technology, bridge, Massachusetts performed these analyses. His report is included as Appendix 2.5C.
r studies made by Dr. Martin on clay gouge materials have been reported in detail in Geologic pping of the Bedrock Surface (NNECo. 1975) and Report on Small Fault in Warehouse 5 -
lstone 2 and Condensate Polishing Facility (NNECo. 1976).
samples were comprised mainly of quartz and clay. Feldspar is noted in three of the samples
, 13F, and 14F); however, the amount is small enough to have no effect on the age determined K/Ar methods. The clay portion of the gouge consists of smectite, chlorite, and illite.
1Md, 1M, and 2M polymorphs are the mica polymorphs (illite) of the clay size fraction. The tive amounts of the polymorphs are summarized below from Dr. Martin's report pendix 2.5C):
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 mplete loss of argon is possible as a result of intense cataclastic deformation (Sutter 1971).
ns and Snellenburg (1971) have previously performed K/Ar dating of illite gouge and have cated that the 1Md mica polymorphs are developed at the time of faulting and are authigenic.
1Md polymorph is a low temperature mineral. Both the 1Md and the 1M polymorphs appear e metastable, even at low temperatures (Velde 1965). With increasing temperature, the 1Md,
, 2M reaction takes place (Yoder and Eugster 1955). The temperature necessary for the ation of the reaction from 1Md to 1M at low pressures is no greater than 250°C (Velde 1965).
rtz crystals found in the brecciated zones of T-2 and T-3 at the bedrock surface were tested to rmine their temperature of formation by Dr. Earl Ingerson of the University of Texas at Austin ECo. 1975). The temperature range for the hydrothermal formation of these quartz crystals is
°C to 198°C. This information, together with Dr. Martin's analysis indicating the relative unts of the mica polymorphs, infers that some of the 1Md polymorphs may have reverted to 1M polymorph. Apparently, the hydrothermal activity was not intense enough or long enough omplete the reaction.
2M polymorph was noted in only one sample, 7F. Because it appears in only one sample, it ms unlikely that the 2M polymorph is caused by the completion of the reaction. The 2M ymorph is common in most igneous and metamorphic rocks (Velde 1965). Since both rock es are involved in the faulting at Millstone, the 2M polymorph in Sample 7F may be a
chron Laboratories, Cambridge, Massachusetts, dated the samples analyzed by Dr. Martin.
results of the potassium-argon testing performed by Geochron Laboratories on samples from l excavation grade are included in Appendix 2.5D and are summarized in Table 2.5.3-3. The ples ranged in age from 109 to 200 m.y.a. Three samples from T-3 (10F, 13F, and 15F) were lyzed and yielded dates of 182+/-7, 155+/-6, and 178+/-7 m.y.a. Dates of 200+/-7 and 165+/-6 m.y.a.
e obtained on samples taken from T-2 (7F and 14F). Sample 1F was taken from a smaller t, 1541. The age indicated by the K/Ar method for this sample was 109+/-5 m.y.a.
of the samples tested yield results that are consistent with previous tests performed on samples m Millstone, with the exception of 1F. Table 2.5.3-3 lists the dates of samples previously ed at Millstone. These samples had a range of ages between 168 to 198 m.y.a. Excluding the from Sample 1F, the average age of faulting from all tests performed on the clay gouge from Millstone site is 176 m.y.a.
date on Sample 1F is considerably lower than the other dates. Compared to the other samples n at final grade, this sample had considerably smaller amounts of the illite fraction pendix 2.5C), and a higher ratio of smectite to illite. The smectite may have formed after the ge material, due to weathering, hydration of the illite, or by hydrothermal alteration. The nger date may reflect the interference of the smectite portion of the sample. As mentioned in tion 2.5.3.2.1, hydrothermal alteration is quite prominent, and the fault zone has been uenced by weathering.
e samples of gouge were taken from fault 1940 in the engineered safety features building and ts 2282 and 2339 in the Millstone 3 pumphouse. Dr. R. C. Reynolds of Dartmouth College lyzed the clay mineralogy of these samples. His reports are included as Appendix 2.5E.
ge amounts of smectite and little illite were present in the samples (B, C, and D) from fault 0 which precluded K/Ar dating of the material. Samples P-1 and P-2, taken from faults 2282 2339, respectively, were composed mostly of kaolinite with a small percentage of ntmorillinite (Appendix 2.5E). A trace of illite was noticed in sample P-2 but neither sample ld be dated.
form and quantity of the smectite present in the samples from fault 1940 does, however, cate a probable hydrothermal origin for the material. The kaolinite from the faults in the phouse (P-1 and P-2) was found to have a crystalline structure, also indicative of a rothermal origin. The date of the last hydrothermal event, as indicated by the studies of faults, and T-3, is between 168 and 198 m.y.a.
y gouge samples from faults 2781 and 2819 (NNECo. 1982) in the discharge tunnel were also lyzed by Dr. R. C. Reynolds. His study indicated the material from fault 2781 was not suitable age dating, as it comprised mostly original micas from the parent rock. The material from 9 was found to contain sufficient authigenic illite and was suitable for age dating. It produced
/Ar age date of 142 million +1-6 million years.
K/Ar age dating, petrographic analysis, x-ray diffraction studies, soils mapping, and the iled mapping of the fault zones indicate that the faults at the Millstone site are incapable ures. The petrographic analysis shows that the cataclasite has been silicified and rothermally altered, and that the fractures and cracks have been filled with chlorite. Prismatic rtz crystals, drusy quartz, and the silicified cataclasite found in the fault zones would be tured and/or granulated if any additional movement had occurred.
radiometric age dates on the fault gouge indicate that the last activity along the faults urred approximately 142 m.y.a. Silicified breccias, microbreccias, and cataclasites within the and T-3 zones indicate that earlier episodes of movement and silicification occurred. The ence of the 1M mica polymorph indicates that the unordered 1Md has undergone changes ated by the heat associated with the introduction of hydrothermal fluids along the fault zones.
tabulation in Section 2.5.3.2.2 summarizes the relative amounts of polymorphs from the y diffraction analysis reported in Appendix 2.5C. It was found that the clay gouge is prised mainly of 1M and 1Md polymorphs. Therefore, the dates obtained by radiometric lysis indicate some hydrothermal heating of the clay gouge zone - the last activity along the ts.
petrographic and radiometric studies are reinforced by the published geologic history of the on (Section 2.5.1.1.5) and of the site area (Section 2.5.1.2.4.1). Detailed mapping of the avation showed that the most prominent joint set trends northerly and dips at high angles to the or west, as shown on Figure 2.5.1-16. All of the smaller faults parallel the prominent ting, indicating that the same tectonic forces were responsible for their formation. Slickenside rmation (Figure 2.5.1-17) and exposures in the excavation indicate that the major component movement is down-dip. Regionally, a prominent northerly joint set exists. Many of these aces also exhibit slickensides (Lundgren et al., 1971; Lundgren and Thurrell 1973). West of site, the Triassic-Jurassic Basin is bordered by a northerly trending, high angle fault (Rodgers 0). The Clinton quadrangle to the west and the Moodus and Colchester quadrangles to the h of the site are cut by numerous high-angle faults related to the major Triassic faults to the t (Lundgren et al., 1971; Lundgren and Thurrell 1973). All available information indicates the forces necessary to develop most of the jointing and faulting at Millstone Point are related he extensional regime of the Juro-Triassic period. The compressional forces evident by faults 0 and 2781 may have resulted from shear couples associated with the tensional forces or may e been the result of pre-Triassic tectonism during the Allegheny Orogeny. Hydrothermal vity along the faults represents the youngest known fault-related event in southern New land (Goldsmith 1973; Skehan 1975; Rodgers 1975).
lstone Point, like much of New England, is covered by a layer of glacial till. The till has been erved to overlie several faults at the site. No disturbance of the till has been noted (NNECo, 5, 1982). Caldwell (Appendix 2.5A) estimated the age of the till at the site to be roximately 18,000 years old. Flint (1975) estimates that the margin of the glacier had melted k to the line of the present Connecticut coast about 15,000 years ago.
faulting at the site is related to the Triassic-Jurassic rifting as stated in Section 2.5.1.1.4.2 or r events as in the case of fault 1940.
3.3 EARTHQUAKES ASSOCIATED WITH CAPABLE FAULTS re is no evidence of capable faults within the 5-mile radius of the site. As stated in tion 2.5.2.3.1, the majority of the significant seismic activity has been associated with the ite Mountain Plutonic Province. Some activity has been associated with the Ramapo fault em (Aggarwal and Sykes 1978); however, the fault is not considered capable (NRC 1977).
3.4 INVESTIGATION OF CAPABLE FAULTS re are no capable faults within the site area. The faults uncovered in the excavation are ussed in Section 2.5.3.2.
3.5 CORRELATION OF EPICENTERS WITH CAPABLE FAULTS discussed in Section 2.5.2.3.2, there has been no spatial correlation between earthquakes and ts in the site region. Some correlation has been suggested with the Ramapo fault in New York New Jersey. As discussed in Section 2.5.2.3.1, however, the Ramapo is not considered able (NRC 1977).
3.6 DESCRIPTION
OF CAPABLE FAULTS re are no capable faults within 5 miles of the site.
3.7 ZONE REQUIRING DETAILED FAULTING INVESTIGATION ven incapable fault zones have been uncovered during excavation at the site. These faults have n mapped in detail and are discussed in Section 2.5.3.2. Figure 2.5.4-6 shows the map of the rs of structures. There are no other zones requiring detailed investigation.
3.8 RESULTS OF FAULTING INVESTIGATION re is no evidence of capable faulting within the 5-mile radius of the site. The faults at the site related to the rifting associated with the Triassic-Jurassic Period or older, with the last activity urring approximately 142 m.y.a.
3.9 REFERENCES
FOR SECTION 2.5.3 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.
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.
3.1-4 Goldsmith, R. 1973. Oral Communication with L. Martin and D. Carnes, Stone &
Webster Engineering Corp., Boston, Mass.
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.
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.
3.1-7 Lyons, J. B. and Snellenberg, J. 1971. Dating Faults. Geological Soc. Amer., Bull.
82, p 1749 1752.
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.
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.
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.
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.
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.
3.1-13 Rodgers, J. 1970. The Tectonics of the Appalachians. John Wiley and Sons, Inc.,
New York, NY.
3.1-14 Rodgers, J. 1975. Oral Communication with L. Martin and P. Mayrose, Stone &
Webster Engineering Corp., Boston, Mass.
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.
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.
3.1-18 Sutter, J. F. 1971. K-Ar Relationships in Mylonite Rocks (Abs). A.G.U. Trans., Vol.
52, p. 367-368.
3.1-19 Velde, B. 1965. Experimental Determination of Muscovite Polymorph Stabilities, Amer. Mineral., Vol. 50, p. 436-449.
3.1-20 Yoder, H. S. and Eugster, H. P. 1955. Synthetic and Natural Muscovites, Geochim et Cosmochim Acta, Vol. 8, p. 225-280.
TABLE 2.5.3-1 LIST OF FAULTS CLICK HERE TO SEE TABLE 2.5.3-1
TABLE 2.5.3-2 LIST OF SAMPLES CLICK HERE TO SEE TABLE 2.5.3-2
TABLE 2.5.3-3 LIST OF K/AR AGE DETERMINATIONS OF FAULT GOUGE CLICK HERE TO SEE TABLE 2.5.3-3
FIGURE 2.5.3-1 T-2 FAULT ZONE, FINAL EXCAVATION GRADE - NORTHERN SECTION Revision 3306/30/20 MPS-3 FSAR 2.5.3-14
FIGURE 2.5.3-2 T-2 FAULT ZONE, FINAL EXCAVATION GRADE - SOUTHERN SECTION Revision 3306/30/20 MPS-3 FSAR 2.5.3-15
FIGURE 2.5.3-3 T-3 FAULT ZONE, FINAL EXCAVATION GRADE Revision 3306/30/20 MPS-3 FSAR 2.5.3-16