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Revision 36 to Final Safety Analysis Report, Chapter 2, Site and Environment
	ML18247A223
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Site:	Millstone
Issue date:	06/18/2018
From:	; Dominion Energy Nuclear Connecticut
To:	; Office of Nuclear Reactor Regulation
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Millstone Power Station Unit 2 Safety Analysis Report Chapter 2: Site and Environment

Table of Contents tion Title Page GENERAL DESCRIPTION............................................................................... 2.1-1 1 References.................................................................................................. 2.1-1 POPULATION, LAND USE AND WATER USE ............................................ 2.2-1 1 Population .................................................................................................. 2.2-1 2 Land Use .................................................................................................... 2.2-1 3 Water Use .................................................................................................. 2.2-1 4 References.................................................................................................. 2.2-1 METEOROLOGY .............................................................................................. 2.3-1 1 Regional Climatology ................................................................................ 2.3-1 2 Local Meteorology..................................................................................... 2.3-1 2.1 Potential Influence of the Plant and Its Facilities on Local Meteorology . 2.3-1 2.2 Local Meteorological Conditions for Design and Operating Bases .......... 2.3-1 2.2.1 Design Basis Tornado ................................................................................ 2.3-1 3 On Site Meteorological Measurements Program....................................... 2.3-1 4 Short Term (Accident) Diffusion Estimates .............................................. 2.3-1 4.1 Objective .................................................................................................... 2.3-1 4.2 Calculations ............................................................................................... 2.3-2 4.2.1 Venting Point and Receptor Locations ...................................................... 2.3-2 4.2.2 Models ....................................................................................................... 2.3-2 4.3 Results........................................................................................................ 2.3-2 5 Long Term (Routine) Diffusion Estimates ................................................ 2.3-2 5.1 Objective .................................................................................................... 2.3-2 5.2 Calculations ............................................................................................... 2.3-2 5.2.1 Venting Point and Receptor Locations ...................................................... 2.3-2 5.2.2 Database..................................................................................................... 2.3-3 5.2.3 Models ....................................................................................................... 2.3-3 6 References.................................................................................................. 2.3-3 GEOLOGY ......................................................................................................... 2.4-1 1 General....................................................................................................... 2.4-1 28/18 2-i Rev. 36

tion Title Page 2 Regional Geology ...................................................................................... 2.4-1 3 Site Geology .............................................................................................. 2.4-1 3.1 Site Surficial Geology................................................................................ 2.4-1 3.1.1 Westerly Granite ........................................................................................ 2.4-1 4 Seismic Refraction Surveys ....................................................................... 2.4-2 5 References.................................................................................................. 2.4-2 HYDROLOGY ................................................................................................... 2.5-1 1 General....................................................................................................... 2.5-1 2 Public Water Supplies................................................................................ 2.5-1 3 Regional and Site Water Flow ................................................................... 2.5-1 4 Tides and Flooding .................................................................................... 2.5-3 4.1 Normal Tides ............................................................................................. 2.5-3 4.2 Tides and Flooding Due to Storms ............................................................ 2.5-3 4.2.1 Study of Flooding Potential from Design Basis Hurricane ....................... 2.5-4 4.2.2 Flood Protection for Plant Structures....................................................... 2.5-14 4.2.3 Intake Structure Flood Protection ............................................................ 2.5-17 4.2.4 Flood Protection of Electrical Equipment ............................................... 2.5-17 4.2.5 Underground Tanks ................................................................................. 2.5-18 4.3 Prevention from Icing .............................................................................. 2.5-18 5 Oceanography .......................................................................................... 2.5-19 5.1 Water Temperature .................................................................................. 2.5-19 5.2 Current Velocity and Volume Flow in Channel ...................................... 2.5-19 5.3 Effluent Dilution ...................................................................................... 2.5-19 6 References................................................................................................ 2.5-19 SEISMOLOGY................................................................................................... 2.6-1 1 References.................................................................................................. 2.6-1 SUBSURFACE AND FOUNDATIONS............................................................ 2.7-1 1 General....................................................................................................... 2.7-1 2 Exploration................................................................................................. 2.7-1 3 Site Conditions........................................................................................... 2.7-2 28/18 2-ii Rev. 36

tion Title Page 3.1 Area Geology ............................................................................................. 2.7-2 3.2 Soil Conditions .......................................................................................... 2.7-2 4 Laboratory Testing..................................................................................... 2.7-2 5 Foundations................................................................................................ 2.7-3 5.1 Structural Data ........................................................................................... 2.7-3 5.2 Foundation Evaluation ............................................................................... 2.7-3 6 Liquefaction ............................................................................................... 2.7-5 7 References.................................................................................................. 2.7-5 9 General References .................................................................................... 2.7-6 ENVIRONMENTAL MONITORING PROGRAM .......................................... 2.8-1 ENVIRONMENTAL RADIATION MONITORING PROGRAM ................... 2.9-1 1 General....................................................................................................... 2.9-1 2 Survey Program ......................................................................................... 2.9-1 28/18 2-iii Rev. 36

List of Tables mber Title 1 Distances from Release Point to Receptors 2 (Deleted) 1 Effect of Hurricane Generated Surge and Waves on Unit Number 2 Structures 2 Design Wave Conditions 3 Roof Surface Area and Number and Size of Roof Drains 4 All Catch Basins for Elevation Area Draining Into and Runoff Flowing In and Out of a Catch Basin 28/18 2-iv Rev. 36

List of Figures mber Title 1 Geological Features 2a Boring Plan 2b Test Borings 2c Boring Logs 2d Boring Logs 3 Seismic Line Location Map 4 Seismic Profiles 1 Topography in the Vicinity of Millstone Point 2 Bore Hole and Test Pit Locations 3 Test Pit Number 1 4 Test Pit Number 2 5 Relationship Between Hurricane Wind Direction and Plant Layout 6 Section Through Plant 7 Profiles of Plant 8 Surge Hydrograph for PMH 9 Bottom Profile for Surge Traverse Line 10 Storm Tracker for Probable Maximum Hurricane 11 Location of the Center of the Storm Within the Critical Area 12 Shore Protection 13 Shore Protection 14 Wave Force Diagrams For The Three Zones And Their Corresponding Bottom Profiles Near The Walls 15 Typical Anchorage Detail 16 Filter System and the Gradation of the Filter Materials 17 Scour Protection 18 Flood Protection

-19 General Roof Plan 28/18 2-v Rev. 36

mber Title 20 Drainage Plan 21 Turbine and Auxiliary Building Plans at Elevation 14 Feet 6 Inches 22 Auxiliary Building Basement Plans 23 Intake Structure 24 Louver Protection - Intake Structure 1 Excavation Plan 2 Backfill and Compaction Requirements 28/18 2-vi Rev. 36

s section contains information on the geological, seismological, hydrological, meteorological demographic characteristics of the Millstone site and vicinity to show the adequacy of the site m a safety viewpoint.

GENERAL DESCRIPTION rmation regarding the general description of the site, location, area, boundaries, exclusion

, authority, control of activities, traffic control and relocation of roads is presented in tions 2.1.1 and 2.1.2 of the Millstone 3 Final Safety Analysis Report (Reference 2.1-1). With exceptions given below, that information is incorporated herein by reference.

Exclusion Area Boundary (EAB) as shown in Figure 2.1-3 of Reference 2.1-1 is drawn for

3. For the land sectors, the EAB is equivalent for MP2 and MP3 as it is the property line. For water sectors, the EAB is assumed to be a circle, centered on the release point with a radius al to the nearest land EAB distance from the release point. The circle shown in the Reference or a MP3 containment release. The EAB distances used for accident calculations for MP2 are en in Table 2.3-1. The distances used for nearest land for normal effluent dose calculations are given in Table 2.3-1.

1 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.1 - Geography and Demography.

28/18 2.1-1 Rev. 36

1 POPULATION rmation regarding population and population distribution is presented in Section 2.1.3 of the lstone 3 Final Safety Analysis Report (Reference 2.2-1). That information is incorporated in by reference.

2 LAND USE rmation regarding land use, explosions, fire, corrosive materials, and toxic gas is presented in tions 2.2.1, 2.2.2, 2.2.3, and 2.2.4 of the Millstone 3 Final Safety Analysis Report ference 2.2-2). That information is incorporated herein by reference.

3 WATER USE rmation regarding the water use, commercial and recreational is presented in Sections 2.1.2, 4 of Reference 2.2-1, Sections 2.2.2, 2.2.3, 2.2.4, of Reference 2.2-2, and Section 2.4 of the lstone 3 Final Safety Analysis Report (Reference 2.2-3). That information is incorporated in by reference.

4 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.1 - Geography and Demography.

2 Millstone Unit 3, Final Safety Analysis Report, Section 2.2 - Nearby Industrial, Transportation, and Military Facilities.

3 Millstone Unit 3, Final Safety Analysis Report, Section 2.4 - Hydrologic Engineering.

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rmation regarding meteorology is presented in Section 2.3 of the Millstone 3 Final Safety lysis Report (Reference 2.3-1). With the exceptions given below, that information is rporated herein by reference.

1 REGIONAL CLIMATOLOGY e Section 2.3.1 of Reference 2.3-1.)

2 LOCAL METEOROLOGY e Section 2.3.2 of Reference 2.3-1.)

2.1 Potential Influence of the Plant and Its Facilities on Local Meteorology lstone Unit 2 uses a once-through cooling water system, discharging its cooling water into an ting quarry, into which Units 1 and 3 also discharge, and thence into Long Island Sound. Thin ps of steam fog occasionally form over the quarry and less frequently over the discharge me during the winter months, depending on tidal conditions and temperature differences ween air and water. This fog dissipates rapidly as it moves away from the warm water area.

areal extent of the steam fog is negligible.

2.2 Local Meteorological Conditions for Design and Operating Bases 2.2.1 Design Basis Tornado design basis tornado for Millstone Unit 2 is defined in Chapter 5. Tornado missile protection efined in Section 5.2.5.1.2.

3 ON SITE METEOROLOGICAL MEASUREMENTS PROGRAM e Section 2.3.3 of Reference 2.3-1.)

4 SHORT TERM (ACCIDENT) DIFFUSION ESTIMATES 4.1 Objective idents could result in short term releases of radioactivity from several possible venting points.

ospheric diffusion factors (X/Q) based on site meteorological data are calculated at the lusion area boundary (EAB), and low population zone (LPZ) for each downwind sector for h release point. The diffusion factors are calculated for different release time periods ending on the length of the release. The diffusion factors are used in the calculation of ological consequences.

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4.2.1 Venting Point and Receptor Locations distances from the various release points to the exclusion area boundary in each sector are d in Table 2.3-1.

Low Population Zone (LPZ) as shown in Figure 2.1-11 of Reference 2.3-1 is drawn for Unit ut closely approximates the LPZ for Unit 2. The LPZ is taken to be 3860 meters in all sectors m any Unit 2 release point.

4.2.2 Models ident X/Qs were calculated using the basic methods of Regulatory Guide 1.145 for elevated ases; the X/Qs for the first four hours are calculated using a seabreeze fumigation model pted from Regulatory Guide 1.3. X/Q values for the control room due to ground level releases e calculated using the guidance of Regulatory Guide 1.194, (Reference 2.3-2).

4.3 Results calculated X/Qs used in DBA radiological consequence calculations are presented with the of assumptions used in each calculation in Chapter 14.

5 LONG TERM (ROUTINE) DIFFUSION ESTIMATES 5.1 Objective levels of radioactivity are routinely released from the Millstone stack or the Unit 2 vent.

ospheric diffusion factors (X/Q) based on site meteorological data are calculated for various nwind receptor locations of interest. The meteorological data is used to calculate the dose sequences to the public from routine airborne effluents. The calculated doses are submitted ually to the Nuclear Regulatory Commission (NRC).

5.2 Calculations 5.2.1 Venting Point and Receptor Locations tine releases from the Gaseous Waste Processing System and containment ventings are tted from the Millstone stack. Routine releases of building ventilation and containment purge are emitted from the Unit 2 enclosure building roof vent. Releases from the Millstone stack are sidered elevated. Releases from the Unit 2 vent are considered to be mixed; that is, ditionally either elevated or ground level depending on ambient wind speed. The distances m the Millstone stack and Unit 2 enclosure building roof vent to the nearest site boundary, the rest land, and to the nearest residence in each sector are listed in Table 2.3-1, and used in X/Q ulations. The distance to the nearest resident in each sector may vary from those shown in le 2.3-1 as a result of the annual land use census performed in accordance with the 28/18 2.3-2 Rev. 36

5.2.2 Database culations are performed on a quarterly basis using the actual meteorology for that period.

5.2.3 Models X/Q values for elevated releases from the Millstone stack and mixed releases from the Unit 2 t are calculated from hourly onsite meteorological data via methods adapted from Regulatory de 1.111 using a conventional Gaussian plume model.

6 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.3Meteorology.

2 Regulatory Guide 1.194, Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants, June 2003.

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Distance (Meters)

Millstone Turbine Millstone Millstone St Downwind Stack to Building to Blowdown Unit 2 Vent to Unit 2 Vent to Stack to to Neare Sectors EAB EAB Vent to EAB Nearest Land Nearest Residence Nearest Land Residenc SSW 496 (2) 680 (2) 620 (2) 14,500 14,500 14,500 14,500 SW 496 (2) 680 (2) 620 (2) 3,430 3,520 3,660 3,820 WSW 496 (2) 680 (2) 620 (2) 3,100 3,140 3,270 3,290 W 496 (2) 680 (2) 620 (2) 2,830 2,930 3,050 3,070 WNW 649 680 (2) 620 (2) 2,550 2,700 2,700 2,760 NW 710 680 (2) 620 (2) 1,930 2,240 997 997 NNW 1,029 886 915 915 915 1,029 1,029 N 1,677 1,138 1,138 1,138 1,138 1,695 1,695 NNE 813 1,726 1,597 997 997 813 813 NE 496 (3) 680 (3) 620 (3) 620 620 496 736 ENE 496 (2) 680 (2) 620(2) 1,070 1,760 1,101 1,560 E 496 (2) 680 620 1,600 1,650 1,410 1,480 ESE 496 (2) 680 (2) 620 (2) 1,900 2,010 1,640 1,760 SE 496 (2) 680 (2) 620 (2) 31,700 31,700 31,700 31,700 SSE 496 (2) 680 (2) 620 (2) 12,390 12,390 12,390 12,390 S 496 (2) 680 (2) 620 (2) 13,100 13,100 13,100 13,100 The distances may vary from those shown as a result of the annual land use census.

Water Sector, so (1) is used when greater than shoreline distance.

Shortest site boundary distance in any landward sector.

06/28/18 2.3-4 Rev. 36

TABLE 2.3-2 (DELETED) 28/18 2.3-5 Rev. 36

rmation regarding the geology of the Millstone site is presented in Section 2.5 of the lstone 3 Final Safety Analysis Report (Reference 2.4-1). With the exceptions given below, that rmation is incorporated herein by reference.

1 GENERAL e Section 2.5 of Reference 2.4-1.)

2 REGIONAL GEOLOGY e Sections 2.5.1 and 2.5.3 of Reference 2.4-1.)

3 SITE GEOLOGY e Sections 2.5, 2.5.1, and 2.5.4 of Reference 2.4-1.)

3.1 Site Surficial Geology locations of borings relevant to Unit 2 are shown in Figures 2.4-1 and 2.4-2a while esentative boring logs are presented on Figures 2.4-2b, 2.4-2c and 2.4-2d. Additional logs of ngs 101 through 114 are shown in the Millstone Unit 2 PSAR; Amendment 1, Appendix 2B, C Docket Number 50-336.

contours constructed on the upper surface of the basal till have been also presented in the lstone Unit 2 PSAR, Amendment 1, Plate 2.

3.1.1 Westerly Granite old granite quarry is located at the site. This quarry was worked for over 100 years until its ndonment in 1960. The quarry excavation, some 1,200 feet in length and 300 to 400 feet in th, extends in a northwest-southeast direction in the southerly part of Millstone Point. The rry lies in a belt of the Westerly granite.

rock in the quarry is jointed. At the northwesterly end, the joints strike N15E and dip 85 NW.

he southeasterly end of the quarry are two sets of joints, one striking N70W and dipping 85

, the other striking N-S with an 85W dip. On the easterly side of the quarry is a possible very ll, geologically ancient shear, of no importance, which strikes N50E and dips 50 SE. Sheet ting, resulting from the relief of rock stress, is prominent throughout the quarry. Prior to struction of the quarry outlet channel there were seeps of water at the south end of the quarry.

y appeared to have come from the soil above the bedrock. This indicates that the rock is ervious and allows little, if any, water to seep in from Long Island Sound.

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mic surveys, both onshore and offshore, were performed by Weston Geophysical Engineers, orporated, to provide complimentary and subsurface data to evaluate site geology as well as ish supplementary soil and rock velocities. Seismic lines were positioned to detect any large malous features that might exist at the site. The land seismic lines and the locations of test ngs 1 through 5 are shown on the seismic line location map, Figure 2.4-3. An additional land mic survey was conducted during October 1971, by Weston Geophysical Engineers, Inc.,

ference 2.4-2). This survey was initiated to determine the dynamic moduli of the compacted kfill underlying the warehouse building, primary water storage tank and refueling water age tank. Data obtained were then utilized in the dynamic structural analysis of these lities. Due to their remoteness with respect to Unit 2, offshore seismic lines have not been icted.

ths to bedrock, seismic velocity data, and inferred geologic correlation are shown on the ile section, Figure 2.4-4. Geophysical refraction survey compressional wave velocity in the rock has been calculated at 13,500 to 14,000 fps. with the shear wave velocity in the same ium estimated to be approximately 5500 to 7500 fps.

seismic results indicated (and subsequently confirmed by additional borings) that the bedrock ace is covered by dense glacial overburden material and/or saturated alluvium. Since the er level in the quarry prior to excavation of the quarry discharge canal was approximately 17 lower than that of Long Island Sound, the material would appear to be dense and relatively ermeable.

rock rises and depressions appear to trend in a north-south direction, as would be anticipated normal erosional pattern.

itional information concerning site seismic refraction surveys is contained in Section 2.5.4 of erence 2.4-1.

5 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.5, Geology, Seismology, and Geotechnical Engineering.

2 Weston Geophysical Engineers, Inc., Report to Bechtel Corporation, Seismic Velocity Measurements of Compacted Fill Material, Millstone Nuclear Projects, Unit Number 2, December 1971.

28/18 2.4-2 Rev. 36

FIGURE 2.4-1 GEOLOGICAL FEATURES 06/28/18 2.4-3 Rev. 36

FIGURE 2.4-2A BORING PLAN 28/18 2.4-4 Rev. 36

FIGURE 2.4-2B TEST BORINGS 28/18 2.4-5 Rev. 36

FIGURE 2.4-2C BORING LOGS 06/28/18 2.4-6 Rev. 36

FIGURE 2.4-2D BORING LOGS 06/28/18 2.4-7 Rev. 36

FIGURE 2.4-3 SEISMIC LINE LOCATION MAP 06/28/18 2.4-8 Rev. 36

FIGURE 2.4-4 SEISMIC PROFILES 06/28/18 2.4-9 Rev. 36

rmation regarding hydrology of the Millstone site is presented in Section 2.4 of the Millstone t 3 Final Safety Analysis Report (Reference 2.5-1). With the exceptions given below, that rmation is incorporated herein by reference.

1 GENERAL lstone Point is located on the north shore of Long Island Sound. To the west of the site is ntic Bay and to the east is Jordan Cove. Figure 2.5-1 shows the general topography of the lstone area. Section 2.5.4 discusses the probable maximum hurricane used to calculate imum water levels. Millstone Unit 2 structures are protected by flood walls and gates to ation 22 feet MSL. Flooding protection of structures is discussed in Section 2.5.4.

Millstone Site has several shallow wells near it, the nearest being one third of a mile from the ion proper (see Figure 2.4-32 of Reference 2.5-1). None of these provide water for domestic poses but one is used to water a nearby baseball field and to supply a drinking fountain at the

d. Due to the relatively impervious bedrock base, it is improbable that any water accidentally ased at the site surface could reach the wells. The larger communities near the site derive most heir water from reservoirs which are outside the surface drainage from the site.

water will be pumped through the condenser to remove the residual heat from the steam austed by the turbine. This sea water will be taken from and discharged to Long Island Sound ugh lines which will be physically separated.

ce the site is a peninsula which juts into Long Island Sound, the high tides associated with icanes could produce flooding. This problem has been studied extensively, and plant dings have been designed to withstand flooding.

2 PUBLIC WATER SUPPLIES e Section 2.4.1.2 (Hydrosphere) and 2.4.13 (Groundwater) of Reference 2.5-1.)

3 REGIONAL AND SITE WATER FLOW groundwater environment at the Millstone site is characterized by generally impermeable rock acquicludes overlain by soil masses of varying permeabilities. The bedrock is mostly nson gneiss, with a Westerly granite dike intruding the gneiss in the quarry area. Neither rock ermeable, and there appears to be little movement of water through fissures in either formation e the quarry did not fill with either fresh or salt water after its abandonment in 1960. The rlying soil is composed of relatively dense glacial till of low permeability surmounted by tion soils (drift) which are generally more porous and permeable. Both soils, as well as the k formations, show sharp irregularities in depth at different locations. Gneiss outcrops in the her terrain in the north part of the site indicate that this terrain is underlain by rock, creating a nage divide, with groundwater transport to the east, west and south. This transport is probably omplished mostly in the upper layers of the soil (the ablation soils and upper glacial tills being 28/18 2.5-1 Rev. 36

ilable. The aquifer systems onsite can be best described as unconfined (water table) aquifers, h pronounced variations in depth at different locations. Locally perched water table conditions ur in some areas of soil stratification and shallow ponded water is frequently visible in lized bedrock troughs. The configuration of the water table for the site, thus, cannot be drawn h any degree of accuracy, but some limited information does exist. In May 1965, water levels even dug or driven wells were measured; the level in the west part of the site (Bay Point area)

+5 feet MSL; in the east part of the site (Jordan Cove) it was +2 feet MSL. A series of borings 969 in the area now taken up by Millstone Unit 2 structures indicated water table elevations ween +4.3 feet. and +7.2 feet MSL with an average of +5.6 feet. MSL (Figure 2.5-2). These ls may have been higher than normal due to heavy rain preceding the test borings. The rage influx rate of water into two test pits located at the north end of the Millstone Unit 2 ine building (in August 1969) was approximately 8 gallons per hour over a 48 hour5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months period ures 2.5-3 and 2.5-4 show the pit locations and dimensions). The sandy soils of the shore r the Millstone Unit 2 intake structure are highly permeable, since water levels in one test hole mber 110 on Figure 2.5-2) varied with water levels in Niantic Bay; however, these coarser ds are generally restricted to the shore area, and the information derived from the less meable till material of the test pits is more characteristic of the overall permeabilities of the soils.

bedrock surface is exposed at the south end of the site but covered with a dense glacial till at north end. Since both are quite impervious, precipitation does not sink into it readily, and h of it runs off on the surface directly into Niantic Bay or Jordan Cove. Some surface water ects in depressions in the northern part of the site.

eneral, because of the complexities of achieving reliable data, the USC&GS does not attempt auge the flow in estuaries or embayments. Consequently, the fresh water discharge into ntic Bay and Jordan Cove is not measured. These are the two bodies of water adjacent to the lstone Point Site to the west and east, respectively. There are no established U.S. Geological vey gauging stations on either the Niantic River or Jordan Brook, nor has the survey ducted any short term, special gauging studies.

estimate has been made of the average flow into and out of the Niantic River due to tidal on. Assuming a mean cross-section of 1,620 square feet for the channel leading from Niantic to the Niantic River and a mean tidal current of 0.77 knot, there would be a total flow of 89,600 cubic feet per each ebb or flood tide over a six hour period (average flow about 13,000 ft/sec). This figure should be taken as an approximation only. It is based on the best data ilable. (Cross-section estimate from the USC&GS, Chart 214; current velocity is from ervations from the survey ship, MARMER during a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period in August, 1965 when it located near the entrance to the Niantic River.) It is noted that only a small fraction of the

,000 cfs tidal flow into which the discharge canal flow is diluted could possibly enter the ntic River. There are no dams on the Niantic River and due to the limited drainage area, it is mated that the most serious flood effects will come from the bay.

28/18 2.5-2 Rev. 36

4.1 Normal Tides e Section 2.4.1.2 of Reference 2.5-1.)

4.2 Tides and Flooding Due to Storms rmation regarding tides and flooding due to storms is presented in Sections 2.4.2, 2.4.3, and 5 of Reference 2.5-1. With the exceptions given below, that information is incorporated herein eference.

various surge levels and associated most severe wind generated wave action is included in le 2.5-1. Wind directions from 5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months before maximum surge (T = -5) to ten hours after imum surge (T = 10) are shown in relation to the plant layout in Figure 2.5-5.

ore maximum surge conditions occur, wave action is directed on the eastern shore, which is a icient distance from the plant such that local shore damage, if it should occur, would not affect safe operation of the plant.

T = -2 hours, the postulated surge level exceeds plant grade. However, both the Millstone Unit take structure and adjacent shoreline are protected from direct wave action by both the lstone Units 1 and 2 plant structures until the surge reaches its probable maximum. Wind nted waves directed between azimuth 130° and aximuth 160°, corresponding to T = 0 bable maximum surge) and T = 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months , respectively, pass between the Millstone Unit 1 plant cture and intake structure. During probable maximum conditions, the south wall of the intake cture would be exposed to a maximum surge level of 18.11 feet and a runup of 3.69 feet such the maximum water level would be elevation 21.80 feet MSL.

ween azimuth 160° and 170°, the Millstone Unit 1 intake structure protects the Millstone Unit take structure and adjacent shoreline. At approximately azimuth 170° (corresponding to T = 5 rs after peak conditions), direct wave action could impinge against the shoreline and the lstone Unit 2 structure but at a severe oblique angle. It is not until T = 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that waves are directed as to effectively impinge on the intake structure. However, by this time, the surge ht is reduced to elevation 6.8 feet MSL with wave heights of 7.5 feet, resulting in a total up to elevation 10.6 feet MSL. Analytical studies indicate that this wave action has no imental effect on the rip-rap.

ypical profile through the plant and intake structure is shown in Figure 2.5-6. Additional files between the plant and shoreline are shown in Figure 2.5-7. Rip-rap placed in a 1-to-1 e up to approximately elevation 13 feet MSL (and higher) extends from the Millstone Unit 1 ke structure to approximately 120 feet north of the Millstone Unit 2 intake structure. The area he east and south of the Millstone Unit 2 intake structure, between the rip-rap and the access d, is covered with bituminous paving material and graded at approximately a 1 percent slope ard the shore.

28/18 2.5-3 Rev. 36

siderably lower than 40 mph and the fetch limited by the Niantic Bay such that a clapotis ld be insignificant. However, the intake structure was conservatively designed to withstand external forces of a clapotis based upon probable maximum conditions, with the winds iented to provide perfect reflection of waves.

hose instances when wind directed waves would impinge upon the front of the intake cture, the maximum runup (at 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months after probable maximum conditions) is limited to ation 10.6 feet MSL. Since this does not exceed the bottom elevation of the operating floor, operating floor will not be exposed to the effects of hydrodynamic surging. Such possibilities further limited since water fluctuations within the intake structure would be damped by the rgy lost in passage through the restricted openings in the trash racks and traveling screens.

rnal water levels would be further attenuated due to the fact that the water must enter the cture through a submerged opening (elevation (-)10 to (-)30 feet MSL) through which the sure response factor would be less than unity.

s covered by checkered plates are provided in the operating floor to allow for the passage of storm surge (which has no dynamic effect) and to allow for the effective venting of air due to remote possibility of hydrodynamic surging.

affected plant structures are designed to accommodate the effects discussed above.

e: Information concerning Resonance Phenomena is contained in Section 2.4.5.4 of erence 2.5-1.

4.2.1 Study of Flooding Potential from Design Basis Hurricane aximum probable hurricane study for the Millstone plants was presented in Docket 50-245, endment 15, using the Hydrometeorological Section ESSA, HUR 7-97 Interim Report eteorological Characteristics of the Probable Maximum Hurricane, Atlantic and Gulf Coast of

. The conclusions reached in this study showed a stillwater level slightly in excess of 16 feet a maximum runup to elevation 17-18 feet MSL. This stillwater surge was calculated by bining the rise due to atmospheric reduction, wind set up, and an astronomical tide.

stillwater surge level analysis was performed for three possible PMH configurations as ows: large radius, slow speed of translation (LR/ST); large radius, medium speed of slation (LR/MT); large radius, high speed (LR/HT). The PMH parameters and associated water surge levels for these configurations are as follows:

H configuration LR/ST LR/MT LR/HT ntral Pressure (inches Hg) 27.26 27.26 27.26 ripheral Pressure (inches Hg) 30.56 30.56 30.56 28/18 2.5-4 Rev. 36

dius to Maximum Winds (nm) 48 48 48 gle of Radius to Direction of Translation (degrees) 115 115 115 nslational Speed (knots/hr) 15 34 51 ximum Gradient Wind (mph) 124 124 124 ximum (over water) Surface Wind (mph) 116 127 137 llwater Surge Level (feet MSL) 18.1 16.8 16.5 refore, it is observed that the large radius, slow speed of translation PMH yields the most ere design conditions.

investigation was subsequently made to determine the effects of increasing the astronomical by one foot with a coincidental two foot forerunner on sea level anomaly. A recheck has also n made using a wind stress factor of 1.10 and a slightly modified storm track. It was rmined that with a stillwater level of 19.17 feet MSL, the storm surge would exceed elevation eet MSL for 36 minutes, elevation 18 feet MSL for 108 minutes, elevation 17 feet. MSL for minutes, and elevation 16 feet MSL for 236 minutes.

PMH storm track and surge traverse line are shown in Figure 2.5-10. For purposes of imizing storm surge effects at Millstone, the PMH is required to track northwestward from open ocean across Long Island and Long Island Sound, with the storm center impacting the necticut coast just east of New Haven. Historically, most hurricane movement in coastal areas hese latitudes is more to the north or northeast (and, consequently, the surge is less), but a hwestward movement is meteorologically feasible under appropriate circumstances. With m movement in this direction, the direction of the maximum surge is approximately the same; maximum surge would follow a fetch of surge traverse line running from the open ocean near ntauk Point to the Millstone site, passing between Little Gull Island and Fishers Island. The of maximum winds during the time of maximum surge is assumed to encompass this fetch with wind direction parallel to the surge traverse line. The assumed bottom profile under the e traverse line is shown in Figure 2.5-9. This profile was actually taken along a line from terly, Rhode Island SSE to the open ocean in order to satisfy the bathystrophic model straint that the surge traverse line be perpendicular to the bottom contours; the profile location hown in Figure 2.5-10.

pertinent PMH parameters selected were as follows:

central pressure: 27.26 inches radius to maximum wind: 48 nm forward (translational) speed: 15 knots maximum gradient wind: 123 mph maximum surface wind (over water): 124 mph peripheral pressure: 30.56 inches 28/18 2.5-5 Rev. 36

he time of maximum surge, the calculated components of the surge were as follows:

wind setup 12.47 feet water level rise due to pressure drop 2.20 feet astronomical tide 2.50 feet initial rise 2.00 feet total surge stillwater increase 19.17 feet MSL er factors used were as follows:

bottom friction factor 0.0025 wind stress coefficient 1.10 total stillwater surge height of 19.17 feet was presented in Amendment 19 to Millstone Unit 1 R (Docket No. 50-245); however, the 2.00 feet initial rise postulated to account for a runner anomaly is too high for the New England Coast, and the AEC has accepted a total water surge height of 18.2 feet. (i.e., with a 1.00 feet initial rise as recommended by the stal Engineering Research Center, U. S. Army) as appropriate for the Millstone area pendix E, Docket Number 50-336, Safety Evaluation of Millstone Nuclear Power Station Unit mber 2 by the Division of Reactor Licensing, USAEC, August 7, 1970).

.00 feet initial rise, giving a maximum stillwater level of 18.11 feet MSL is used as the basis the surge and wave calculation presented in this amendment. The components of this imum surge stillwater level are as follows:

wind setup 12.41 feet water level rise due to pressure drop 2.20 feet astronomical tide 2.50 feet initial rise (forerunner) 1.00 feet total surge stillwater level increase 18.11feet er factors used were:

bottom friction factor 0.0025 wind stress coefficient 1.10 surge hydrograph for the site for T = -5 to T = +10 hours is presented in Figure 2.5-8.

mates of waves occurring from T = -5 to T = +10 hours are shown in Table 2.5-1. Wind ctions and approach angles of these waves with respect to plant structures are shown in ure 2.5-5. These wave estimates are based on the stillwater levels shown in the foregoing e hydrograph (answer to Question 2.7.2); that is, they are based on a surge with a 1 feet runner anomaly and a maximum stillwater level of 18.11 feet MSL.

maximum wave level of 42.5 feet MSL was obtained at the vertical wall of the intake cture at T = +0.8 with a large radius (LR) high speed (HT) PMH. The resulting stillwater level h the incident was calculated to be 18.1 feet MSL. The basis for this value can be found in the 28/18 2.5-6 Rev. 36

od design considerations are discussed above and in Section 2.4.2.2 of Reference 2.5-1. Plant cedures address necessary precautions and actions to take in the event of anticipated hurricane, ado, or flood conditions.

eorological conditions are determined from weather service forcasts and / or site eorological instrumentation.

Action By Plant Personnel Upon receiving hurricane warnings from weather service providers, Millstone operators implement appropriate procedures. Actions taken on Millstone Unit 2 include:

1. All plant flood gates are closed.

2. Traveling screens are placed on continuous wash at high speed.

3. Tours are made within the fenced boundary of the site to ensure all loose material is removed or thoroughly tied down.

4. Higher plant supervision is notified of the storm warning.

5. Should a sustained wind speed of 50 miles per hour be measured at the meteorological tower, additional personnel will be called in to assist plant operators, as required.

6. Should sustained water level approach grade level due to extremely high tides, not wave action, plant management will assess the general plant condition in conjunction with the committee(s) as described in the Quality Assurance Program Description Topical Report. Typical items to be discussed would be the intensity of the storm as to whether it is building, static, or waning; status of all plant equipment and buildings; and status of any building leakage. At this time, the decision will be made as to whether to continue operations or to initiate a normal plant shutdown. In either case, Directorate of Regulatory Operations, Region 1, will be notified of plant condition and management decision.

7. One service water pump motor will be secured and protected against flooding to a minimum elevation of 28 feet MSL in accordance with the Technical Requirements Manual.

8. If the severity of the hurricane is such that the sustained water level is increasing above grade level:

28/18 2.5-7 Rev. 36

b. Station an operator inside the intake structure to monitor the intake structure water level with respect to the Service Water and Circulating Water Pump Motors.

9. As long as the 345 transmission lines remain uninterrupted and plant equipment is not endangered, the plant can continue to be operated at power until the level of water in the intake structure reaches 19.5 feet MSL which is just below the level of the Circulating Water Pump Motors. At this time, the plant would be tripped and placed in a hot standby condition in accordance with plant procedures. If outside power is lost, emergency loads would be supplied by the diesels, and additional operator response would be in accordance with plant procedures.

10. If, following the securing of the circulating water pumps, the level of water within the Intake Structure rises above 19.5 feet MSL, one diesel would be immediately secured and its cooling system realigned such that the diesel can be cooled by water supplied from the fire system in accordance with applicable operating procedures.

11. If the water level within the Intake Structure rises to 22 feet MSL, thereby endangering the service water pump motors, the diesel operating on service water would be secured and the Service Water Pumps would be tripped in accordance with plant procedures. Essential plant equipment would be powered by the diesel whose cooling system had previously been modified to use fire water. The plant would be maintained in a hot standby status. Decay heat would be transferred from the core to the steam generators by natural circulation and then be removed from the steam generators by steaming through the atmospheric dumps. The generators would be fed by either a steam-driven or electric auxiliary feedwater pump taking a suction on the condensate storage tank.

12. When the water level recedes below 22 feet MSL, the motor which was protected would be recommissioned and started in accordance with plant procedures. It would then be used to cool the diesel which had not been lined up to the fire system. The time required for this step once the water level has receded is approximately 2.0 hours0 days 0 hours 0 weeks 0 months .

13. The other service water pump motor(s) would then be removed, disassembled, steam cleaned, dried, reassembled and reinstalled, and then an additional pump would be started. This will then allow plant systems and equipment to be returned to a normal hot standby status.

14. When the water level recedes below grade elevation 14 feet 6 inches, sample/remove/verify no water in diesel fuel oil storage tank or transfer piping, and disassemble, inspect and restore transfer pump motors.

28/18 2.5-8 Rev. 36

By the actions described, plant personnel can readily maintain the plant in a safe shutdown condition through the PMH where the major concern is the removal of decay heat. The feasibility and reliability of this course of action is justified as follows:

1. Decay heat is transferred from the core to the steam generators by natural circulation and then is removed from the steam generators by steaming through the atmospheric dumps. The generators are fed by either a steam-driven or an electric auxiliary feedwater pump taking a suction on the condensate storage tank. The availability of this method of decay heat removal is justified as follows:

a. Although as previously described, plant personnel have taken action to ensure the continued operation of at least one diesel (and this is further justified in subsequent paragraphs), the incorporation of a steam-driven pump and manually positionable components into the plant design provides for decay heat removal by the method described without dependence on emergency power from the diesels.

b. Although the normal volume in the Condensate Storage Tank is at least 225,000 gallons, the Technical Specification minimum level of 165,000 gallons is sufficient to remove decay heat for a minimum period of 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months . As a reserve supply for the auxiliary feedwater system, the suction of the pumps can be supplied from the two 245,000 gallon fire water storage tanks (Section 9.10.2). Consequently, the 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months mentioned can be readily extended. Further, these tanks are supplied by the city water system which is expected to remain pressurized by diesel-driven pumps, thereby providing a virtually unlimited supply of water. Finally, the extended periods of decay heat removal provided by the sources already mentioned would provided time to restore power to the primary water transfer pumps, thereby making available the additional 100,000 gallons from the Primary Water Storage Tank although it is not felt that this would be required.

c. The two electric and one steam-driven auxiliary feedwater pumps are operationally checked quarterly to ensure their availability.

2. Although not required for decay heat removal, the emergency power from one diesel generator is maintained by shifting its cooling to the fire system. The availability of this alternate cooling is ensured as follows:

a. The fire system is pressurized by one electric-driven fire pump from Unit 3, one electric-driven fire pump from Unit 2 and a diesel-driven fire pump.

These pumps are performance tested monthly to ensure their operability.

28/18 2.5-9 Rev. 36

pump house to a level of 22.33 feet MSL is, therefore, sufficient to protect the pumps against the maximum PMH standing water level of 18.11 ft MSL. Although power for the electric-driven fire pumps may not be available, the diesel-driven fire pump remains available since both the pump and its auxiliaries are located within the flood protected fire pump house.

c. The fire water storage tanks are maintained full. The water supply is estimated to be sufficient to operate one diesel, supplying hot standby loads, for at least 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .

3. Because one diesels cooling system is modified such that it can be cooled by fire water, and especially because emergency diesel-generated power is not necessary for decay heat removal, cooling water from the service water system is not essential for decay heat removal. Nevertheless, the operability of the service water pumps is as specified and justified below:

a. Two service water pumps operating until the level of water in the intake structure reaches 22 feet MSL.

b. When the criteria specified in the Technical Requirements Manual is met, the motor for the third service water pump is secured and protected from flooding by lowering and tying down an open bottomed, closed top, can over the motor. The length of this can is designed to prevent water from rising above elevation 22.0 feet MSL inside. This treatment will assure that this service water pump will be readily available when the water recedes.

The criteria specified will give four hours lead time before water crosses plant grade. The entire operation of protecting the motor can be accomplished within two hours.

c. Thus, by the measures previously described, service water will be maintained, except for a maximum period of 4.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months . This is based on the duration of the intake water level above 22 feet MSL which is calculated to be 2.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months plus the time to recommission the previously protected motor which is 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months .

d. Additionally, the other service water pump motor(s) will be removed, disassembled, steam cleaned, dried, reassembled and reinstalled in the field. Thus, at least one additional service water pump could be placed in service.

4. Section 8.5 of the FSAR describes the loads which will be placed on the DC system on a loss of AC power. Table 8.5-1 lists the specific loads and battery discharge rate, assuming one battery is out of service and the DO1-DO2 bus tie 28/18 2.5-10 Rev. 36

necessary equipment can be supplied for a minimum period of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months without charger support. Thus, although action has been taken to maintain AC power, the capacity of the batteries provides ample time to restore AC power if it was lost.

Conclusion By the action described and the justification provided, it is concluded that the plant can readily be maintained in a safe condition throughout a PMH.

a matter of record, no such phenomenon has been evident in any of the surges along the New land coast as plotted in the Weather Bureau Technical Paper Number 48. No mention has been e of the forerunner in the Corps of Engineers hurricane studies for New London and tford, Connecticut. In Technical Paper Number 48, it is stated that, ...the data presented in report give little support for the concept of a forerunner heralding the approach of a icane and also stated that, ...short period anomalies in mean sea level not related to the icane, but not fully explained, may account for some of the reported forerunners. To our wledge, the only area where a forerunner or anomaly of two feet has been used by the Corps ngineers is in the Galveston area where the monthly mean sea level from 1919-1961 period ed by a little more than two feet. Along the New England coast during this same period, the nthly mean sea level has varied less than one foot.

he time of the peak surge, the wind is from the southeast direction, and the wave attack would long the large axis of the point. Millstone Unit 1 would, thus, shield Millstone Unit 2 from direct wave attack.

significant exposures of the site are to the southwest where the plant is located closest to the n shoreline and to the southeast where it is located closest to the quarry. On the southwest osure, the minimum distance from the plant to the shoreline is about 220 feet, and the imum distance to the top of the slope of plant fill is about 180 feet. On the southeast exposure, minimum distance from the plant to the quarry is about 400 feet. The area between the plant the quarry has been filled with high point graded to elevation 14.5 feet MSL and low point to ation 14.0 feet MSL. The pertinent elevations of the Millstone Unit 2 plant are shown in ure 2.5-6.

ns for protection of the shores immediately north and south of the Millstone Unit 2 Intake cture are shown in Figure 2.5-12. Sectional views of protective structures and bottom profiles shown in Figure 2.5-13. Wave forces for design are conservatively based upon these profiles in accordance with the procedures presented in the Shore Protection Manual, considering PMH conditions for the site. Breaking wave forces are computed as a function of the water th, wave period, and bottom profile. The design of the protective structures is based on the eria for stability as contained in Technical Report Number 4, Shore Protection Planning and ign and the Shore Protection Manual by CERC. Maximum breaking wave heights are rmined in accordance with the method presented by Weggel, ASCE Journal of Waterways, bors and Coastal Engineering, November 1972, and the Shore Protection Manual, 1974.

28/18 2.5-11 Rev. 36

imum dynamic forces on the structure. The wall between the two intakes is divided into three es for design purposes. The wave force diagrams for the three zones and their corresponding om profiles near the walls are shown in Figure 2.5-14. The breaking wave height for the shore h north of the Millstone Unit 2 intake, excluding the area of the wing wall, is based on the imum allowed breaker controlled by bottom topography as obtained in the PMH study for the

. However, the bottom topography allows a non-breaking wave to reach the wall for the reach ediately north of the Millstone Unit 2 intake. Wave force diagrams for the wall and the wing l north of the Millstone Unit 2 intake are also shown in Figure 2.5-14.

le 2.5-2 presents a summary of surge levels and wave conditions which were used in the gn. Wave periods, other than the design period of 9.4 seconds, were considered and were rmined to yield maximum effect on the dynamic force of +/- 10 percent.

shores are protected by post-tensioned, reinforced concrete walls which are founded upon rock. In consideration of the large magnitude of the computed wave forces due to the PMH ditions, the post-tensioned system was selected as a feasible and positive method by which e extreme forces could be sustained. The anchorage system consists of five to eleven strands, sisting of seven wires per strand, which are anchored into bedrock by drilling and grouting.

n completion of the post-tensioning operation, the anchorages are also encased in concrete. A cal anchorage detail is shown in Figure 2.5-15.

ing installation, each anchorage is prestressed to 80 percent of the guaranteed minimum mate material strength and relaxed to 70 percent and allowed to remain in place for twelve rs, at which time the anchorage is checked at lift-off to insure integrity of the anchorage load.

ign value for each anchorage is 60 percent of guaranteed minimum ultimate material strength.

walls are designed to be stable against all forces, including buoyancy, which may possibly ur from extreme low water to the PMH condition. The area immediately back of the walls is ected with quarry stones having a gradation designed to prevent scour that may possibly result m overtopping waves. Wall stability is not dependent on fill material, i.e., the wall is stable in a standing condition under wave attack. The wing walls (transition areas), which are located ediately north and south of the Unit 2 intake, were analyzed in consideration of all additional s imposed by the added sea walls and are stable as composite sections under all loadings. The t-tensioning anchorage system in these areas extends through all previously placed concrete, the structural anchorage is developed in bedrock as shown in the typical anchorage details.

existing stones within the immediate vicinity of the intake are removed.

walls are provided with drainage pipes located approximately fifteen feet apart at the base of walls. A filter system is provided behind the walls, having a gradation designed to prevent loss oil material, and to provide relief against permanent hydrostatic pressure build up (even ugh the walls are designed to resist such pressure as stated previously). The filter system and gradation of the filter materials are shown in Figure 2.5-16. The graded materials are quality trolled in accordance with the method as outlined in ASTM Specification D-2940-71T.

28/18 2.5-12 Rev. 36

ased on the results of laboratory studies reported in Beach Erosion Board (CERC) Technical morandum No. 134, entitled Beach Profiles as Affected by Vertical Wall. The maximum uring velocity is estimated using solitary wave theory. The size of stone as shown in ure 2.5-16 is obtained from the Shore Protection Manual (CERC). For the corners around lstone Unit 2 and north corner of Millstone Unit 1 intake, stones having a weight of 600 nds minimum and 1,000 pounds maximum are provided.

struction materials for the sea walls are as follows:

1. Concrete shall have a specified minimum compressive strength of 5,000 psi at 28 days.

2. Reinforcing steel shall conform to Specification ASTM A615, Grade 60, except that bent ties shall meet the provisions of Specification ASTM A615, Grade 40.

3. Post-tensioning anchorage material shall conform to Specification ASTM A-416, Grade 270, Uncoated stress-relieved strand for prestressed concrete.

4. Screens at drainage pipes shall conform to Specification ASTM A240, Type 304.

5. Gradation of fill material is shown in Figure 2.5-16.

ms approaching the site from (1) the east, (2) the north, or (3) the southeast could conceivably vide the mechanisms to produce setdown at the site. However, because of the location of lstone Point in a relatively open area of Long Island Sound and because of prior effects that PMH would have to have caused before getting into a position where it could produce own, the phenomenon appears unlikely to occur to any significant extent at Millstone.

following is a general discussion of the three storm tracks and possible setdown effects.

re is no specific or definitive information available in the form of mathematical models giving erical values for setdown in an open coast situation, nor can be bathystrophic surge prediction del used to predict maximum stillwater level be applied in reverse to this kind of phenomenon.

e 1: A hurricane approaching from the east, tracking along the Atlantic coast of Long Island, from east to west, is not common but can be postulated. Its maximum wind field, oriented from east to west over Long Island, would build a surge along the length of the Sound directed toward the New York City area. However, any water outflow from the Millstone area to support this surge would be balanced by an inflow from the open ocean simply due to level difference. This inflow would be augmented by a local water rise due to low pressure and by concurrent onshore transport of water by southeast winds, all of which would tend to keep the stillwater level at Millstone elevated even in the event of some loss of water to a westward moving surge. Also, the prior locations of the storm would have favored 28/18 2.5-13 Rev. 36

e 2: A hurricane approaching from the north is unlikely. The upper wind structure guiding hurricanes at this latitude is generally strong enough so that the looping tracks occasionally seen in lighter (tropical) wind regimes do not occur. However, postulating a loop and a northerly approach to Millstone from the Boston area, with passage of the storm from north to south approximately over Providence, strong northwesterly offshore winds could occur at Millstone. Because of the friction effects of an overland trajectory and a partial cutoff of the hurricane from its energy source (warm water), these northwesterly winds would no longer be at hurricane force and would probably be similar in intensity to those of a strong wintertime extratropical coastal cyclone passing to the east of the site. Since several of these storms pass up the coast in a normal winter, available historical records of minimum low water should be indicative of the setdown effects of a hurricane with this orientation.

In addition, water outflow from the Millstone area would be partially compensated for by inflow from the western portion of Long Island Sound, and the pressure effect on stillwater level would be opposition to the wind effect, both factors mitigating setdown.

e 3: A hurricane approaching from the southeast would have to move northwestward over Providence so that the maximum offshore winds would occur at Millstone.

However, in this orientation, prior locations of the storm would have favored net transport of water into the Sound; that is, east and northeast winds would have preceded the storm. In addition, the pressure effect in favor of stillwater level increase is operative, and a net inflow of water to the Millstone area from the western part of the Sound would occur, both factors working against setdown. The offshore winds might be stronger than in Case 2, but the attenuating effects of overland friction would still result in considerable reduction of wind speeds. As in Case 2, available historical records of minimum low water should be indicative of the setdown effects of a hurricane with this orientation.

discussed in Section 2.5.4.2.3 of the FSAR the only safety-related equipment housed in the ke structure is the service water cooling pumps. The historical low tide at New London was ut minus 4.37 feet MSL on December 11, 1943. Additionally, extreme low water as shown on C&GS Chart 214 is minus 3.5 feet MLW (minus 4.47 feet MSL). The Applicants conclude that icient margin exists between historical low water and the service water pump design low er level of minus 7 feet MSL to assure continuous operation under maximum setdown ditions.

4.2.2 Flood Protection for Plant Structures design of Millstone Unit 2 reflects the decision to provide flood protection up to elevation 22 MSL minimum for the containment, turbine, and auxiliary buildings. The containment is 28/18 2.5-14 Rev. 36

iliary and turbine buildings are to elevation 22 feet MSL.

penetrations into the auxiliary and turbine buildings are provided with hinged flood gates or logs to elevation 22 feet MSL to assure water tightness against both the water and any debris he water.

od gates, with sealing compressive membranes, are used wherever possible. If the gates at any ning pose an operational encumbrance, stop logs with equivalent sealing capability are used in e locations. The openings which have protection are shown in the plan review, Figure 2.5-18.

he event of severe local flooding or when standing water crosses the plant, appropriate cedures will be implemented.

e drainage system throughout the Millstone Unit 2 site, including the roof and yard drainage, is gned based on an intensity of three inches per hour rainfall.

roof area is divided into four subareas, relative to the place where the header drains are nected to the underground storm drain system as shown in Figure 2.5-19. The protected roof ace area, number and size of roof drains are given in Table 2.5-3.

prevent an accumulation of water which could exceed the design load of the roof, if roof drains clogged, the parapet walls are provided with scuppers.

yard, immediately adjacent to Millstone Unit 2 buildings, is similarly divided into ten areas, each one draining into a catch basin as shown in Figure 2.5-20. All catch basins, except number 1, are connected by a storm sewer system draining into Niantic Bay next to the north of Millstone Unit 2 intake structure. Catch Basin number 1 is connected to the existing Catch in number 1 of Millstone Unit 1.

le 2.5-4 includes all catch basins, top elevation, area draining into each and runoff flowing in out of each catch basin.

rational method is used to determine the runoff within the Millstone Unit 2 site.

h a rainfall intensity of 9.4 inches per hour, the total runoff is 60.0 cfs. Inlet times are very ll, therefore, their effect on the rainfall intensity is neglected. The runoff coefficient is mated to be equal to 1.0, considering the entire area is paved and the infiltration losses are nil.

storm sewer from Catch Basin CB number 9 to its outfall into Niantic Bay adjacent to the ke structure is twenty-four inches in diameter and has a maximum flow capacity of 8.8 cfs.

ing the maximum rainfall, the capacity of the sewer will be exceeded. Excess runoff will be umulated in the yard area until it reaches elevation 14.5 feet MSL and will overtop the road.

er will then flow out into Jordan Cove on the east and Niantic Bay on the west.

28/18 2.5-15 Rev. 36

flood gates are provided at all entrances to prevent water from flowing in.

he winter, combined precipitation and ice accumulation in excess of the design load are vented by the provision of scuppers in the parapet walls. Therefore, it is concluded that all the ty-related structures and equipment are capable of withstanding PMP without loss of safety-ted functions.

he interface between Millstone Units 2 and Unit 1, the flood protection capability of Millstone t 1 was originally credited in the evaluation of Millstone Unit 2 flood protection capability.

entire periphery of Millstone Unit 1 was flood protected. However, with the ommissioning of Millstone Unit 1, the flood boundary was revised to support the ommissioning effort. As shown in Figure 2.5-18 a flood wall is provided to a minimum ation of 22 feet 0 inches along the common area between Unit 1 and Unit 2 Turbine ldings. Protection for the Millstone 2 Auxiliary Building is provided by the adjacent Millstone t 1 Control Building which is provided with flood protection on the south and east walls to a imum elevation of 22 feet 0 inches and at the 14 feet 6 inches floor elevation. Therefore the re southern interface between Millstone Units 2 and 1 is flood protected to a minimum ation of 22 feet 0 inches.

ather service forecasts provide adequate hurricane status such that there will be sufficient time ecure the plant against flooding. Securing the plant will be done at the discretion of the shift ervisor and can be accomplished by one man who would close and lock all of the hinged gates install the flood logs. The flood logs will be specifically designated as pieces of flood ection equipment and stored in the vicinity of the place where they will be used.

ing a hurricane, the plant operations will be in accordance with normal, abnormal and/or rgency operating procedures.

lstone Unit 2 can be brought safely from an operating condition to either a hot or cold tdown condition with the equipment listed in Tables 7.6-1 and 7.6-2. The philosophy of flood ection has evolved from the need to protect this required equipment which is shown at its ous elevations, in Figures 2.5-21 and 2.5-22.

as been seen that Millstone Unit 2 is extremely well protected against flooding, even on the which adjoins Millstone Unit 1. All emergency shutdown equipment, including the auxiliary er sources are flood protected.

average ground elevation around the plant buildings is at elevation 14.0 feet MSL. With the imum surge stillwater elevation of 18.1 feet MSL, based on three possible PMH figurations, the maximum depth near the building (except for the intake structure) is equal to feet. A wave height equal to 78 percent of the maximum available depth or 3.2 feet could be erated anywhere around the buildings (except for the intake structure). These waves could duce runup to elevation 25.1 feet MSL. The containment building, auxiliary building and the ehouse building have exterior concrete walls up to elevation 54.5 feet MSL minimum. The 28/18 2.5-16 Rev. 36

nected to the flood wall with waterproof caulked connections. Although runup to elevation feet MSL could be generated, the siding would prevent water resulting from splashing effects m entering the building. It is concluded that there can be no adverse effects on any of the ty-related buildings due to the design waves.

4.2.3 Intake Structure Flood Protection intake structure, as shown in Figure 2.5-23, is constructed of reinforced concrete with an rt Elevation of minus 27 feet MSL, operating deck at elevation 14 feet MSL, and a cutoff wall levation minus 10 feet MSL, all based on mean sea level being at zero feet.

only safety-related system in the intake structure is the service water system. The service er pump motors and associated electrical and control equipment are protected to elevation 22 MSL. The service water cooling pumps are also designed for a low water of elevation minus et MSL which is 2.2 feet lower than the extreme low water shown on USC&GS Chart 214.

intake structure was analyzed both statically and dynamically for the standing wave effects.

maximum and minimum pressures at the foot of the intake structure 30 feet below the mean level were calculated to be 3,960 and 2,220 psf, respectively. The net uplift pressure on the rating floor was found to be 930 psf. The stability of the structure was studied and found stable er these conditions. The louvers in front of the structure are protected by specially designed ctural frames which are shown in Figure 2.5-24 and are capable of withstanding a maximum sure of 1,120 psf due to pressure from a non-breaking wave.

maximum water level inside the intake structure caused by the standing wave condition is ulated to reach elevation 26.5 feet MSL. The analysis was performed utilizing an unsteady e mathematical model that takes into account the profile of the incident wave, inleakage ugh the louvers and system headloss. One service water pump motor is protected.

bable minimum low water level at the intake structure resulting from an occurrence of a bable maximum hurricane (PMH) oriented so as to cause maximum depression of the water ace (setdown) at the site is calculated to be minus 5.85 feet MSL as indicated in Section 2.4.11 he Millstone Unit 3 Final Safety Analysis Report (Reference 2.5-1).

design low water level of the circulating water pump is minus 3.5 feet MSL, and the service er pump level is minus 7.0 feet MSL. The fire water pumps are supplied from two 245,000 on storage tanks connected to the public water system of the town of Waterford. The probable imum low water has no effect on the service water pump.

4.2.4 Flood Protection of Electrical Equipment h the provision for concrete flood protection walls around the enclosure building, turbine ding and auxiliary building up to elevation 22 feet MSL, and with flood gates or logs at any rnal openings in these walls, overflow into and subsequent accumulation of flood water 28/18 2.5-17 Rev. 36

panels located below elevation 22 feet MSL are in close proximity to stairways or other nings to lower floors to render accumulation of water at a given location impossible. Where is not the case the equipment is mounted on a four inch raised pad.

er and control cables, cable terminations and any electrical devices required for the trouble-operation of the service water pumps in the intake structure are located above elevation 22 MSL where possible. Any of these located below this point are of tight construction.

sical separation is provided between redundant essential electrical equipment and circuits uired for safe shutdown.

ry of cables connecting outdoor equipment to equipment within the flood protected areas is so gned to preclude leakage or overflow of flood water into these areas by provision of proper s and/or by carrying cable raceways to elevation 22 feet MSL. Outdoor transformers and tchgear are protected to elevation 19.5 feet MSL.

4.2.5 Underground Tanks ere are no underground storage tanks to supply fuel at Millstone Unit 2.

4.3 Prevention from Icing highly unlikely that the formation of ice would occur in front of the intake structure in such a ner as to obscure flow. The design of the intake structure, its entrance velocity, and rakes on trash racks prevent ice formations from obscuring flow. Typical types of ice that could be ent at the intake structure are: surface ice and frazil ice.

face ice is prevented from obscuring flow due to the submerged opening entrance to the intake cture. The entrance is located at an elevation of -10 to -27 ft MSL. In order to obscure flow, ther temperatures would have to be cold enough to freeze the external sea water in the area of intake greater than 10 feet at MSL. This has not happened in the history of operation of lstone Unit 2.

zil ice (needle-shaped ice crystals suspended in water) occurs in the presence of supercooling n turbulence is too great to allow surface ice to form. Frazil ice can build on surfaces, such as h racks and walls, which have a temperature at or below freezing thereby obscuring flow into nstream components and systems such as the SW and CW Systems.

wever, frazil ice only remains suspended and submerged in a flow of water if velocity is ter than 2 fps. At the entrance of the intake structure water velocity is significantly below this

e. Since the water velocity is below the minimum velocity needed to keep frazil ice pended and submerged, it will raise to the surface prior to contact with the trash racks.

28/18 2.5-18 Rev. 36

5.1 Water Temperature e Section 2.4.11.6 (Heat Sink Dependability Requirements) of Reference 2.5-1.)

5.2 Current Velocity and Volume Flow in Channel e Section 2.4.1.2 (Hydrosphere) of Reference 2.5-1.)

5.3 Effluent Dilution e Section 2.4.12 (Dispersion, Dilution, and Travel Times of Accidental Releases of Liquid uents in Surface Waters) of Reference 2.5-1.)

6 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.4-Hydrologic Engineering.

28/18 2.5-19 Rev. 36

MPS-2 FSAR TABLE 2.5-1 EFFECT OF HURRICANE GENERATED SURGE AND WAVES ON UNIT NUMBER 2 STRUCTURES Surge Stillwater Level Significant Wave Maximum Wave Safety Related Wind Wind Wind Fore- Runup to Structure Time Direction Speed Setup Pressure Astrotide Runner Total Height Period Length Height Period Length Elevation Affected Hour Azimuth MPH feet Drop feet feet feet feet feet feet feet feet feet feet feet Breaking Location Impact Point of Runup (Unit 2 Only)

T-5 076° 67 5.98 0.86 2.50 1.00 10.34 2.4 2.7 37 4.0 4.3 95 11.3 Jordan Cove Shore Shore Line None T-4 079° 75 7.34 1.02 2.50 1.00 11.86 2.7 2.9 43 4.5 4.5 104 12.9 Jordan Cove Shore Shore Line None T-3 081° 84 9.06 1.23 2.50 1.00 13.79 3.0 3.0 46 5.0 4.8 118 15.1 Jordan Cove Shore Shore Line None T-2 084° 93 10.86 1.54 2.50 1.00 15.90 1.1 1.6 13 1.5 2.4 29 16.6 East Faces of Plant East Walls of Unit 1 Rad. Diesel Generator Buildings Waste Storage Building &

Unit 2 Auxiliary Building T-1 102° 94 12.10 1.92 2.50 1.00 17.52 2.3 2.8 40 3.1 3.2 52 18.9 East Faces of Plant East Walls of Unit 1 Rad.

Buildings Waste Storage Building &

Unit 2 Auxiliary Building T-0 132° 90 12.41 2.20 2.50 1.00 18.11 2.8 2.9 43 3.7 3.8 74 21.8 Unit 1 Buildings. & South Wall of Unit 1 None for Unit 2 Discharge Structures Reactor Building Warehouse and Unit 1 & 2 Discharge Structures T+1 140 86 12.20 2.00 2.50 1.00 17.70 2.5 2.6 35 3.3 3.4 59 19.9 Unit 1 Buildings & South Wall of Unit 1 None for Unit 2 Discharge Structures Reactor Building Warehouse and Unit 1 & 2 Discharge Structures T+2 148 83 11.19 1.62 2.50 1.00 16.31 1.4 2.3 27 1.9 2.6 35 17.3 Unit 1 Buildings & South Wall of Unit 1 None for Unit 2 Discharge Structures Reactor Building Warehouse and Unit 1 & 2 Discharge Structures T+3 157 81 9.88 1.29 2.50 1.00 14.67 0.2 0.8 4 0.3 1.1 6 14.8 Unit 1 Buildings & South Wall of Unit 1 None for Unit 2 Discharge Structures Reactor Building Warehouse and Unit 1 & 2 Discharge Structures T+4 168 81 8.50 .05 2.50 1.00 13.05 10.5 6.2 197 17.5 9.0 415 18.4 Unit 1 Warehouse and South Wall of Unit 1 None for Unit 2 Intake Structure Warehouse and Intake Structure T+5 179 75 6.72 0.88 2.50 1.00 11.10 9.5 6.1 191 19.9 8.5 370 15.9 Unit 1 Warehouse and South Wall of Unit 1 None for Unit 2 Intake Structure Warehouse and Intake Structure T+6 191 66 5.21 0.77 2.50 1.00 9.48 9.0 6.0 184 5.0 8.3 353 14.0 Unit 1 & 2 Intake South Wall of Unit 1 Intake Structure Structure Warehouse and Intake Structure 06/28/18 2.5-20 Rev. 36

MPS-2 FSAR TABLE 2.5-1 EFFECT OF HURRICANE GENERATED SURGE AND WAVES ON UNIT NUMBER 2 STRUCTURES (CONTINUED)

Surge Stillwater Level Significant Wave Maximum Wave Safety Related Wind Wind Wind Fore- Runup to Structure Time Direction Speed Setup Pressure Astrotide Runner Total Height Period Length Height Period Length Elevation Affected Hour Azimuth MPH feet Drop feet feet feet feet feet feet feet feet feet feet feet Breaking Location Impact Point of Runup (Unit 2 Only)

T+7 203 58 4.04 0.67 2.50 1.00 8.21 8.5 6.1 191 14.2 8.1 336 12.5 Unit 1 & 2 Intake South Wall of Unit 1 Intake Structure Structure Warehouse and Intake Structure T+8 209 51 2.74 0.59 2.50 1.00 6.83 7.5 5.8 172 12.5 7.5 288 10.6 Unit 1 & 2 Intake Southwest Corners of Unit Intake Structure Structure 1 & 2 Intake Structure T+9 211 46 1.59 0.53 2.50 1.00 5.62 6.8 5.7 166 1.3 7.2 265 9.3 Unit 1 & 2 Intake Southwest Corners of Unit Intake Structure Structure 1 & 2 Intake Structure T + 10 213 41 0.52 0.49 2.50 1.00 4.51 6.0 5.5 155 10.0 6.8 237 8.0 Unit 1 & 2 Intake Southwest Corners of Unit Structure 1 & 2 Intake Structure 06/28/18 2.5-21 Rev. 36

Profile Storm Surge Wave Wave Period Designation Reach Type of Wave Level (feet) MSL Height (feet) (Seconds)

A-A Between Units 1 and 2 Breaking 14 14 9.4 B-B Thru South Wing Wall Unit 2 Non Breaking 12.7 19.3 9.4 C-C Thru North Wing Wall Unit 2 Non Breaking 12.7 19.3 9.4 D-D North of Unit 2 Approximately 120 feet Breaking 12.7 19.3 9.4 North of the Wing Wall 06/28/18 2.5-22 Rev. 36

Surface Area Number of Roof ubarea Number (square feet) Drains Size of Roof Drains 1 25980 29 4 inches 2 21890 8 4 inches 3 16098 4 4 inches 4 22085 12 4 inches Totals 86053 53 28/18 2.5-23 Rev. 36

RUNOFF FLOWING IN AND OUT OF A CATCH BASIN Top Outlet Catch Basin Elevation Drainage Runoff Total Runoff Capacity Number Feet (MSL) Area Acres CFS CFS a (CFS) tch Basin 13.5 0.26 2.44 2.44 2.86 mber1 tch Basin 13.5 0.20 1.88 1.88 2.33 mber 2 tch Basin 13.5 0.39 3.67 5.55 4.57 mber 3 tch Basin 13.25 0.57 5.36 10.91 6.87 mber 4 tch Basin 13.25 1.21 11.37 22.28 5.69 mber 10 tch Basin 13.25 1.52 14.29 36.57 8.69 mber 5 tch Basin 13.5 1.17 11.00 47.57 11.24 mber 6 tch Basin 13.5 0.39 3.67 51.24 13.44 mber 7 tch Basin 13.5 0.25 2.35 53.59 8.77 mber 8 tch Basin 13.5 0.69 6.49 60.08 8.77 mber 9 Includes runoff from upstream and any possible roof drain connection.

28/18 2.5-24 Rev. 36

FIGURE 2.5-1 TOPOGRAPHY IN THE VICINITY OF MILLSTONE POINT 06/28/18 2.5-25 Rev. 36

FIGURE 2.5-2 BORE HOLE AND TEST PIT LOCATIONS 06/28/18 2.5-26 Rev. 36

FIGURE 2.5-3 TEST PIT NUMBER 1 06/28/18 2.5-27 Rev. 36

FIGURE 2.5-4 TEST PIT NUMBER 2 06/28/18 2.5-28 Rev. 36

FIGURE 2.5-5 RELATIONSHIP BETWEEN HURRICANE WIND DIRECTION AND PLANT LAYOUT 06/28/18 2.5-29 Rev. 36

FIGURE 2.5-6 SECTION THROUGH PLANT 06/28/18 2.5-30 Rev. 36

FIGURE 2.5-7 PROFILES OF PLANT 28/18 2.5-31 Rev. 36

FIGURE 2.5-8 SURGE HYDROGRAPH FOR PMH 28/18 2.5-32 Rev. 36

FIGURE 2.5-9 BOTTOM PROFILE FOR SURGE TRAVERSE LINE 06/28/18 2.5-33 Rev. 36

FIGURE 2.5-10 STORM TRACKER FOR PROBABLE MAXIMUM HURRICANE 06/28/18 2.5-34 Rev. 36

FIGURE 2.5-11 LOCATION OF THE CENTER OF THE STORM WITHIN THE CRITICAL AREA 06/28/18 2.5-35 Rev. 36

06/28/18 2.5-36 Rev. 36 FIGURE 2.5-13 SHORE PROTECTION 06/28/18 2.5-37 Rev. 36

GURE 2.5-14 WAVE FORCE DIAGRAMS FOR THE THREE ZONES AND THEIR CORRESPONDING BOTTOM PROFILES NEAR THE WALLS 28/18 2.5-38 Rev. 36

FIGURE 2.5-15 TYPICAL ANCHORAGE DETAIL 28/18 2.5-39 Rev. 36

FIGURE 2.5-16 FILTER SYSTEM AND THE GRADATION OF THE FILTER MATERIALS 28/18 2.5-40 Rev. 36

FIGURE 2.5-17 SCOUR PROTECTION 06/28/18 2.5-41 Rev. 36

FIGURE 2.5-18 FLOOD PROTECTION 28/18 2.5-42 Rev. 36

FIGURE 2.5-19 GENERAL ROOF PLAN 28/18 2.5-43 Rev. 36

FIGURE 2.5-20 DRAINAGE PLAN 28/18 2.5-44 Rev. 36

FIGURE 2.5-21 TURBINE AND AUXILIARY BUILDING PLANS AT ELEVATION 14 FEET 6 INCHES 06/28/18 2.5-45 Rev. 36

FIGURE 2.5-22 AUXILIARY BUILDING BASEMENT PLANS 06/28/18 2.5-46 Rev. 36

FIGURE 2.5-23 INTAKE STRUCTURE 28/18 2.5-47 Rev. 36

FIGURE 2.5-24 LOUVER PROTECTION - INTAKE STRUCTURE 28/18 2.5-48 Rev. 36

rmation regarding the seismology of the Millstone Site is presented in Section 2.5 of the lstone 3 Final Safety Analysis Report (Reference 2.6-1). That information is incorporated in by reference.

1 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.5, Geology, Seismology, and Geotechnical Engineering.

28/18 2.6-1 Rev. 36

1 GENERAL s summarizes the results, analysis and evaluation of the subsurface and foundation stigations. The field exploration and the laboratory testing conducted for Unit 2 were done er the supervision and direction of Bechtel Corporation. These studies included site and area nnaissance, field supervision of the boring operations, a review of pertinent literature, and the ndation analysis and evaluation. Graphic boring logs, laboratory test data, and a list of rences cited were previously presented in the Millstone Unit 2 PSAR, Docket mber 50-336, subsequent submittal, or are referenced here. Additional information is also ented in Section 2.5.4.3 of the Millstone 3 Final Safety Analysis Report (Reference 2.7-1).

2 EXPLORATION ddition to general area and site reconnaissance work, the site was examined through an nsive subsurface drilling program. Previous investigations (in conjunction with Unit 1) uded a preliminary subsurface investigation made by Soil Testing, Inc., of Ansonia, necticut, in May, 1965, and a geological-geophysical survey conducted by Weston physical Research, Inc., Weston, Massachusetts, in October 1965. These efforts were owed in 1966 by two series of additional borings by the C. L. Guild Drilling and Boring mpany, Inc., of Braintree, Massachusetts.

itional test borings test pits, geophysical refraction surveys, and a plate load test study were e to further define the actual soil, rock, and groundwater conditions (both on and offshore),

to verify the previous interpretation of subsurface conditions within the Unit 2 area.

dler Foundation and Exploration Company, Clearwater, Florida, completed a preliminary hore and onshore subsurface investigation during the period of June through August 1969.

o, Weston Geophysical Engineers, Inc., Weston, Massachusetts, conducted an offshore physical survey during the same period.

shore borings were made by the American Drilling and Boring Company, East Providence, de Island, during the month of July 1970 to obtain additional information in the vicinity of the t 2 intake structure (Reference 2.7-2).

American Drilling and Boring Company concluded the subsurface exploration work in ember 1970, with a series of onsite borings for transmission tower structures (Reference 2.7-eotechnical representative from Bechtel Corporation was continuously in the field during the t 2 drilling operations to provide technical review, inspection, direction, and to advise the ling contractor of the boring locations and alterations made as the data was received. Frequent d visits were made by supervisory personnel from Bechtel Corporation to review boring gress and modify the boring program.

28/18 2.7-1 Rev. 36

ber of hammer blows required to drive the sampler one foot was recorded and is designated penetration resistance. The boring procedure and penetration resistance were taken in ordance with ASTM Specification D 1586-67. The penetration resistance is a simple in-place ar test, and as such is an index of soil strength, consistency and density.

soil samples obtained in the field were examined by the Bechtel geotechnical representative.

ected samples were shipped directly from the field to the testing laboratory. The jar samples m the split-spoon penetration tests were returned to the Bechtel Corporation Washington Area ineering Office and the classifications were verified.

drilling program was supplemented by test pit excavations at selected locations. The test pits vided an additional opportunity for examination of the principal soil types and observations of und water behavior.

3 SITE CONDITIONS 3.1 Area Geology e Sections 2.5.1 and 2.5.4 of Reference 2.7-1.)

3.2 Soil Conditions e Section 2.5.4 of Reference 2.7-1.)

4 LABORATORY TESTING laboratory testing program provided foundation engineering data and physical characteristics necessary to design foundations resting on soil. The testing was conducted in accordance h currently accepted procedures (References 2.7-4 through 2.7-7).

testing program generally was confined to the determination of the soil parameters of olded (fill) soil. The laboratory program included grain size and specific gravity tests to rmine particle size and distribution.

erberg limit tests to determine soil plasticity characteristics, static triaxial shear tests to aid in evaluation of fill foundation bearing capacity and elastic settlement properties, compaction s, and numerous moisture-density, void ratio and relative density determinations.

28/18 2.7-2 Rev. 36

5.1 Structural Data following is a summary of the major structural components of the plant, foundation type, ndations elevation, supporting material, and foundation static contact pressure for settlement luation which represents conservative estimates of long term static loadings:

Structure and Foundation Supporting Foundation Maximum Static Type Material Elevation (feet) Pressure (psf) actor Building Mat Unweathered rock (-)33 7,500 rbine Pedestal Mat Unweathered rock (-)5 to (-)18 3,600 rbine Buildings Columns Unweathered rock (-)2 to (-)22 25,000 xiliary Building Mat (west of Unweathered rock (-)50 20,000 umn line M-7) rehouse Area of Auxiliary Controlled select 2 foot 6 inches to 8 2,400 ilding Mat (east of column compacted fill foot 6 inches e M-7) closure Building Caissons Unweathered rock (-)18 to (-)26 130,000 ake Structure Mat Unweathered rock (-)30 15,660 fueling Water Storage Tank Controlled select 11 3,000 compacted fill ndensate Storage Tank Glacial till 11 3,000 ndensate Surge Tank Glacial till 11 3,000 5.2 Foundation Evaluation soils and bedrock at this site were suited for construction of the plant without adverse lements. The bedrock provides excellent support for structures, under both static and dynamic ditions. Applied foundation bedrock contact pressures are all well below the allowable bearing sure of 200,000 psf.

in situ glacial till material is uniformly very dense in consistency, with an allowable bearing acity in excess of 10,000 psf. The applied contact pressures, which are approximately one-rter of the allowable bearing pressure, resulted in negligible settlement.

compacted backfill material was a select, processed free draining, offsite borrow material.

soil is a well-graded fine to coarse sand with some gravel. A typical grain size distribution ld be:

28/18 2.7-3 Rev. 36

Sieve Accumulative (% passing) 2 inch 100.0 1.5 inch 99.0 1 inch 91.2 0.75 inch 84.3 0.5 inch 77.1 3/8 inch 71.9 Number 4 60.1 Number 10 51.7 Number 40 29.4 Number 100 11.8 Number 200 6.6 imum Standard Proctor dry density (ASTM D-698) for the material was approximately 132 nds per cubic foot. Optimum Modified Proctor dry density (ASTM D-1557) was roximately 137 pounds per cubic foot.

following allowable bearing pressures were assigned to structural fill areas utilizing the select kfill:

Fill Compaction (Minimum) Type of Backfill and Allowable Bearing Capacity

% Standard Proctor General, nonstructure supporting, fill areas and plant STM D-698; AASHO T-99) parking lot

% Standard Proctor Structural backfill areas supporting facilities with contact pressures of 3000 psf or less

% Modified Proctor Structural backfill areas supporting facilities with contact STM D-1557; AASHO T-180) pressure of 4000 psf or less se criteria covered the majority of the backfill conditions. Unique conditions of footing size load were evaluated on an individual basis. Plate load tests and triaxial shear data indicate that allowable select backfill bearing pressures are conservative. Excavation and backfill uirements are shown in Figures 2.7-1 and 2.7-2 respectively.

to the free draining characteristic of the backfill material, settlement was elastic rather than e depended or hydrodynamic settlement, and essentially complete following construction.

lement of foundations on select backfill was small.

28/18 2.7-4 Rev. 36

lement would be less than one-half inch. Settlement joints between the warehouse portion and remainder of the auxiliary building were provided to accommodate this settlement.

6 LIQUEFACTION loose saturated sandy soil is subjected to ground vibrations, as during an earthquake, it tends ompact and decrease in volume. If the soil cannot drain during the rapid load fluctuations osed by an earthquake, there is a buildup in pore pressure until it is equal to the overburden sure. The effective stress then becomes zero, the soil looses its strength, and develops a ick or liquefied condition. If this condition is of general extent and the pressure is not rwise relieved, it can cause a flow or bearing capacity failure.

phenomenon of liquefaction is generally not applicable to this site as critical structures are nded on bedrock.

evaluation of the liquefaction potential of those soils supporting foundation loads, the glacial and select granular backfill, data from standard penetration tests in the glacial till and in-place sity tests in the fill were examined.

ndard penetration tests (ASTM D-1586-67) in the glacial till ranged from a minimum of 58 ws per foot with an average value in excess of 100 blows per foot. All compacted fill porting foundation slabs were compacted to at least 95 percent Standard Proctor which is roximately equal to 80 percent relative density (Reference 2.7-8). Therefore, the soils at the are not susceptible to liquefaction during the design basis earthquake. Additional information so presented in Section 2.5.4.8 of Reference 2.7-1.

7 REFERENCES 1 Millstone Unit 3, Final Safety Analysis Report, Section 2.5, Geology, Seismology, and Geotechnical Engineering.

2 Offshore Subsurface Investigation at Millstone Nuclear Power Station Unit 2, Report prepared by Bechtel Corporation for the Millstone Point Company, September 1970.

3 Switchyard and Transmission Tower Foundations, Reported prepared by Bechtel Corporation for the Millstone Point Company, et al., April 1971.

4 Procedure for Testing Soils, American Society for Testing and Materials, Fourth Edition, Philadelphia, 1964.

5 Akroyd, T. N. W., Laboratory Testing in Soil Engineering, Geotechnical Monograph Number 1, Soil Mechanics Standard, London, 1964.

28/18 2.7-5 Rev. 36

7 Lambe, T. W., Soil Testing for Engineers, John Wiley & Sons, Inc., New York, 1951.

8 Lee, K. L., and Singh, A., Relative Density and Relative Compaction, Journal of Soil Mechanics and Foundations, New York, 1971.

9 GENERAL REFERENCES d, H. B. and Wilson, S. D., The Turnagain Heights Landslide, Anchorage, Alaska, Journal oil Mechanics and Foundations, ASCE, Paper No. 5320, New York, 1967.

sen, W. R., et. al., The Alaska Earthquake March 27, 1964: Field Investigations and onstruction Effort, U.S. Department of Interior, Geological Survey Professional Paper 541, hington, D.C., 1966.

e, C. M. and Leeds, D. J., Response of Soils, Foundations, and Earth Structures, Bulletin of Seismological Society of America, Special Issue - An Engineering Report on the Chilean thquakes of May 1960, Vol. 53, No. 2, February 1963.

r, William C., Dynamic Response of a Particulate Soil System, Department of Civil ineering, March 1964.

obsen, L. L., Motion of a Soil Subject to a Simple Harmonic Ground Vibration, Bulletin of Seismological Society of America, Volume 20, 1930.

sner, G. W., Geotechnical Problems of Destructive Earthquakes, Geotechnique, London.

itman, R. V., Analysis of Foundation Vibrations, Department of Civil Engineering, Boston, 2.

sner, G. W., Behavior of Structures During Earthquakes, Journal of the Engineering chanics Division, Proceeding Papers 2220 with discussions 2455, 2532, and 2632, ASCE, w York, 1959 and 1960.

sner, G. W., Vibrations of Structures Induced by Seismic Waves, Part I, Earthquakes, Volume Handbook of Shock and Vibration, Edited by C. M. Harris and C. E. Crede, McGraw Hill k Company, Inc., New York, 1961.

ss, I. M. and Seed, H. B., Response of Earth Banks during Earthquakes, Journal of Soil chanics and Foundations, ASCE, Paper 5232, New York, 1967.

wmark, N. M., Design Criteria for Nuclear Reactors Subjected to Earthquake Hazards, ana, Illinois, 1967.

28/18 2.7-6 Rev. 36

mposium of Earthquake Engineering, Proceedings, Vancouver, B.C., 1965.

, K. L., and Seed, H. B., Cyclic Stress Conditions Causing Liquefaction of Sand, Journal of Mechanics and Foundations, ASCE, Paper 5058, New York, 1967.

d, H. B., and Idriss, I. M., Analysis of Soil Liquefaction: Niigata Earthquake, Journal of Soil chanics and Foundations, ASCE, Paper 5233, New York, 1967.

, K. L., and Seed, H. B., Dynamic Strength of Anisotropically Consolidated Sand, Journal oil Mechanics and Foundations, ASCE, New York, 1967.

d, H. B., and Lee, K. L., Liquefaction of Saturated Sands during Cyclic Loading, Journal of Mechanics and Foundations, ASCE, Paper 4972, New York, 1966.

d, H. B., and Idriss, I. M., Influence of Soil Conditions on Ground Motions during thquakes, Journal of Soil Mechanics and Foundations, ASCE, Paper 6347, New York, 1969.

cock, W. H. and Seed, H. B., Sand Liquefaction under Cyclic Loading Simple Shear ditions, Journal of Soil Mechanics and Foundations, ASCE, Paper 5957, New York, 1968.

bs, H. J. and Holtz, W. G., Research on Determining the Density of Sands by Spoon etration Testing, Proceedings, 4th International Conference on Soil Mechanics and ndation Engineering, Volume I, London, 1956.

ton Geophysical Engineers, Inc., Report to Bechtel Corporation, Seismic Velocity asurements of Compacted Fill Material, Millstone Nuclear Project, Unit No. 2, December 1.

28/18 2.7-7 Rev. 36

FIGURE 2.7-1 EXCAVATION PLAN TE:

Elevations shown are based on MSL datum elevation 0.00 feet.

Unless otherwise noted, slopes are 1-1/2:1 in earth and 1:3 in rock.

Locations and elevations of excavation limits in containment and lower auxiliary building allow 6 inches between outside face of concrete walls or bottom of slabs and rock to allow for placing concrete forms or mud mat for waterproofing membrane. The coordinates location limits of excavation in other areas are approximate and may have required some local excavation when construction began.

Construction slopes are protected against surface drainage and excessive erosion.

28/18 2.7-8 Rev. 36

FIGURE 2.7-2 BACKFILL AND COMPACTION REQUIREMENTS 06/28/18 2.7-9 Rev. 36

te oriented multifaceted environmental monitoring program was begun at the Millstone site in 8 several years prior to the startup of Unit 1. This period provided the base line data necessary dentify and evaluate any changes in the indicator organisms which might occur due to the ration of the nuclear plant or from any other cause. The program now in effect will continue to erience modifications as additional information is gained.

development of the existing program, the base line data it has obtained and the results are y described in annual reports entitled Monitoring the Marine Environment of Long Island nd at Millstone Nuclear Power Station, Waterford, Connecticut, submitted to the Connecticut artment of Environmental Protection (CT-DEP) in fulfillment of the National Pollutants charge Elimination System (NPDES) requirements.

28/18 2.8-1 Rev. 36

1 GENERAL tudy of environmental radiation levels was started during April 1967. This program was ted before any of the units were or became operational on the site. It provided a baseline from ch any changes in radiation, due to station operation or other causes, can be detected and luated.

2 SURVEY PROGRAM preoperational radiological monitoring program for Millstone Unit Number 2 was the same hat for Millstone Unit Number 1. This program which began in April 1967 ended when Unit mber 1 became operational in July 1970. The program and the results obtained are described in il in Section 5.2.1 of Millstone Unit Number 2 Environmental Report Operating License ge (EROLS).

Operational Radiological Environmental Monitoring Program is described in detail in the iological Effluent Monitoring and Offsite Dose Calculation Manual (REMODCM) and in h Annual Radiological Environmental Operating Report as submitted to the Nuclear ulatory Commission. This program is designed to detect potential radiological consequences tation operation.

28/18 2.9-1 Rev. 36

ML18247A223

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