REDACTED VERSION WITHOUT PROPRIETARY, COMPANY CONFIDENTIAL INFORMATION 

### ENGINEERING RESPONSE TO UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

CW A 

### 308 LETTER 

### PILGRIM NUCLEAR POWER STATION PLYMOUTH , MASSACHUSETTS

PREPARED AND SUBMITTED ON BEHALF OF: 

# nter,
Entergy Nuclear Generating Company Pilgrim Nuclear Power Station 600 Rocky Hil 

### Road Plymouth, MA 02360- 5508

By: 

### Enere.

# Oees, Inc.

500 TownPark Lane, Suite 275 Kennesaw, GA 30144

Input Provided By: Normandeau Associates, Inc. NERA Economic Consulting

June 2008Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW 308 Letter



### Table of Contents 1 Background, Introduction, and Scope..................................................................................... 

### Background and Introduction.........................................................................................

Scope............................................................................................................................... 1 PNPS and Cooling System Description.................................................................................. 2 PNPS Overview.............................................................................................................. 2 Source Water Body......................................................................................................... 2 Cooling Water Intake Structure Description.............. ..................................................... 4 Discharge System.......................................................................................................... 12 Cooling Water Process Flow Diagram ......................................................................... 13 Recent and Planned Plant Modifications ...................................................................... 13 Projected Retirement Plans ........................................................................................... 14 Description of Plant Processes............................... ,.............................................................. 15 Nuclear Steam Supply System Operation..................................................................... 15 Condenser Operation.................................................................................................... 15 CWIS Operation............................................................................................................ 16 

# 3.4 Effluent Treatment Operations..................................................................................... 16 Evaluation of Existing CWIS Technologies and Operational Measures .............................. 17 Evaluation of Existing CWIS.......... .............................................................................. 18 

# 4.2 Percent Reductions from Baseline for Existing CWIS ................................................. Evaluation Methodology for Alternatives....... ................ ............................................. 23
5 Closed- Loop Cooling............................................................................................................ 25 Meteorological Data...................................................................................................... 25 

# 5.2 PNPS Administrative/Continuous Operation Limits .................................................... 26

5 . 3 Closed- Loop Operational Parameters...................... .............. ...................... ................. 29
5.4 Closed- Loop Operational Parasitic Losses ................................................................... PEPSE ModeL............................................................................................................... 30 Baseline Closed-Loop Operation Parameters ............................................................... 31 Reduced Power Operational Parameters.................................. 00.......... ......................... 31 Summary of Reduced Power Operational Impacts....................................................... 33 Alternative Impingement/Entrainment Reduction Technologies ......................................... 35 Modified Traveling Screens and Fish Handling and Return Systems .......................... 35

-1-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

6.2 6.3 Screening/Barrier Technologies.................................................................................... 41 Alternative Intake Location.......................................................................................... 43 Flow Reduction..................................................................................................................... 45

7 . Variable Speed Pumps (VSPs)........ .................... ........................ .................................. 45 Assisted Recirculation.................................................................................................. 53 Grey Water.................................................................................................................... 54 Conclusions........................................................................................................................... 56 References.................................................................................................................... ......... 58



### List of Attachments Attachment 1 - Major Components; Vendor Data and References 

### Attachment 2 - Assisted Recirculation Attachment 3 - Closed- Loop and Variable Speed Pump Station Performance 

### Attachment 4 - Cost Assessments 

### Attachment 5 - Figures Attachment 6 - Normandeau Biological Input Attachment 7 - Grey Water Cooling Attachment 8 - Offshore Intake

-11-Figure 1

Figure 2 Figure 3 Figure 4
Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Figure 11

Table 1
Table 2
Table 3

Table 4
Table 5
Table 6
Table 7

Table 8
Table 9

Table 10

Table 11
Table 12
Table 13
Table 14 Pilgrim Nuclear Power Station

Response to United States Environmental Protection Agency CW A ~308 Letter



### List of Figures Aerial View of PNPS .................................................................................................. 3 Traveling Water Screen Operation............................................................................. 7 

### Simplified Schematic ofBWR Plant Operation ....................................................... 15 Turbine Building....................................................................................................... 28 Modified Ristroph Screen......................................................................................... 36 Multi-Disc Screen..................................................................................................... 38 Typical WIP Screen Arrangement................ .................................... ........................ 39 Typical WIP Screen - Side View................ ............................................................. 40 Typical Velocity Cap Flow Direction ............................. .......................................... 44 

### Incremental Reduction in Annual EA Entrainment Using VSP Operation Flow Reduction......................................................................................................... 51

Incremental Reduction in Anual EA 

### Impingement Using VSP Operation Flow Reduction......................................................................................................... 52



### List of Tables History of Key CWIS Components at PNPS ..........."............................................... 13 PNPS Baseline Monthly EA Entrainment and Impingement ................................... 18 

### PNPS Baseline EA Impingement Survival - Fish Return Sluiceway and Low Pressure Wash System........ ...................................................................................... 19 PNPS Flow Reduction from Baseline.................... ............................................. ...... 20 PNPS Baseline EA Entrainment Reduction by Month............................................. 21 PNPS Baseline EA Impingement Reduction by Month ........................................... Net Power Generation Loss ....... ................... ....................................................... ..... 32 Closed-Loop Limiting Operation Parameters................ ........................................... 33 

### Hourly Maximum Active Power Loss (MW 

### e) Attributed to Flow Reduction
- 118 

### F Hotwell B Limit.......................................................................................... 47 

### VSP Operation Achievable Circulating Water Flow Reduction at Specific Electrical Output Losses - 118 

### F Hotwell B Limit............................................... 48 PNPS Variable Speed Pump Thermal Discharge ..................................................... 49

Summary ofVSP Operation - Hotwell B Limit c? 118 F ........................................ NPDES Water Discharge Permit Flows ................................................................... 54 Summary of Alternatives.......................................................................................... 56

-11-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### Summary of Report Conclusions Pilgrim Nuclear Power Station (PNPS or the 

### Station), owned by Entergy Nuclear Generation Company (Entergy), consists of one Boiling Water Reactor unit in Plymouth, Massachusetts that 

### operates subject to and with the benefit of its existing National Pollutant Discharge Elimination 

### System (NPDES) permit (NPDES Permit MA0003557). This Report has been prepared by 

### Enercon Services (Enercon), a leading nuclear engineering firm

### , in response to certain requests for information from the United States Environmental Protection Agency (EP A) under Section 

### 308 of the Clean Water Act (CWA), 33 U.S. c. ~1318 , with respect to cooling water intake structures (CWIS) under CWA ~316(b), U.S. C. ~1326(b). 

### This Report relies upon an accompanying report prepared by N ormandeau Associates , Inc. 

### (Normandeau) that provides impingement and entrainment data used to characterize PNPS' current impingement and 

### entrainment mortality (I&E) reduction measures (as compared to 

### baseline), as well as to estimate 

### potential changes in 

## I&E for the potential alternative technologies evaluated herein. This Report documents Enercon s preliminary 

### feasibility and engineering analysis of the 

### customary range of technologies potentially applicable at a large-scale nuclear facility (of the configuration of PNPS) to 

### reduce I&E. Nuclear safety and technological feasibility 

### determinations are made , as well as - where achievable - measures of the estimated effectiveness and cost of the technology in 

### question. The technological feasibility standard 

### applied by Enercon allows for consideration of only those technologies the 

### installation and operation of which would be permitted under PNPS' current operating license from the Nuclear 

### Regulatory Commission (NRC) and within the operating parameters of the nuclear power industry. 

### Enercon evaluated several potentially available technologies with respect to their application to 

### reduce I&E and , based on this assessment , determined that certain technologies are not technologically feasible at PNPS. First, conversion from the current once-through to closed- loop 

### cooling would dramatically, and inappropriately, increase Station design parameters above 

### several basic equipment limitations. Moreover, the Station 

### s net thermal load would have to be 

### reduced to such an extent that nuclear safety concerns would render the Station completely 

### inoperable a minimum of 242 calendar days in a 

### typical year (based on historical ambient conditions), a configuration not acceptable in terms of current nuclear industry operating standards. As a result , closed- 

### loop conversion ofPNPS represents an infeasible circulating water cooling technology. Likewise , in addition to the fact that the fragility (i. , a characteristic of 

### aquatic species that generally are not expected to surive , in any material numbers , impingement 

### on the vast majority of screening, barrier, barricade or comparable equipment or systems) of the 

### species historically impinged at PNPS does not support resort to the suite of potential traveling 

### water screen modifications and screening/barrier technologies potentially available at other facilities , Enercon determined , as EP already has in its national rulemaking, that these technologies are technologically infeasible due both to their unproven history as retrofitted 

### technologies at comparable nuclear facilities and to the nuclear safety concerns presented specifically with respect to PNPS. 

### Aside from these exclusions , Enercon determined 

### that only four technologies are either technologically feasible , 

### at PNPS or potentially so as a general matter with respect to the goal of potential I&E reductions. The first technology, variable speed pumps (VSPs), is technologically

-lV-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter


### feasible at PNPS 

### , provided substantially increased thermal discharge limits are employed. The remaining three technologies 

### , an acoustic fish deterrent system

### , an offshore intake and assisted recirculation , are generally technologically feasible on a theoretical basis for facilities like PNPS 

### but require further evaluation to determine their site-specific technological feasibility at PNPS itself.
While an acoustic fish deterrent system is in use at 

### a sister Entergy facility, Enercon cannot assume without further study that such a system would be effective for the species impinged at PNPS , as this is a conclusion that Normandeau has yet to assess and determine. Moreover

### , the 

### technological feasibility of such a fish deterrent system at PNPS would be highly dependent on 

### the ability to ensonify the CWIS with the appropriate hardware tolerant of the harsh environmental conditions present at PNPS. As such , additional engineering studies are necessary to determine the engineering feasibility of such a system. 

### An offshore intake , likewise 

### , requires an engineering evaluation of the design and cost of a
viable location 

### , and therefore must follow Normandeau 

### s assessment and identification of the
potential locations , if any, for such a technology to reduce impingement and entrainment mortality at PNPS. 

### Lastly, assisted recirculation -- a configuration whereby a portion of the water from the Station 

### discharge canal would be routed to a cooling tower , cooled , and returned to the CWIS , is 

### untested at any nuclear facility, making a detailed cost estimate impossible at this time absent a 

### rigorous design effort not able to be performed in the timeframe contemplated by this response

and unless EP 

### A determines 

### , despite the operational impacts of such a system , that further consideration is warranted.

-v-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

## Background

## , Introduction, and Scope
1.1 

## Background and Introduction Pilgrim Nuclear Power Station (PNPS) is seeking a renewal of its existing National Pollutant 

### Discharge Elimination System (NPDES) permit (NPDES Permit No. MA0003557). This Report 

### has been prepared to provide PNPS' response to an information request letter from the United 

### States Environmental Protection Agency (EPA) under Section 308 of the Clean Water Act 

### (CWA), 33 U. C. ~1318 

### , and to confirm the Station s current compliance with CWA ~316(b), 33 U. C. ~1326(b) (i. , ~308 Letter). In the ~308 Letter, EPA requested certain technology and fisheries information from Entergy.


### 1.2 

### Scope The following information is contained in this Report: 

### A detailed description of PNPS' existing cooling water intake structure (CWIS) and other cooling systems. 

### A description of the processes employed at PNPS with regard to operation of the nuclear steam supply system , condenser, CWIS 

### , and effuent treatment. An evaluation of PNPS' current CWIS technologies and operational measures with respect to the EP A uniform baseline configuration.

### An engineering evaluation of conversion of the PNPS cooling system from the current oncethrough to closed-cycle cooling. 

### An evaluation of the customary 

### suite of impingement and entrainment mortality (I&E) * 

### reduction technologies (e. 

### traveling water screen modifications screening/barrier technologies , and an alternative intake location). 

### . An 

### evaluation of potential flow reduction options (e. , variable speed pumps , assisted recirculation, and the use of grey water). 

### This Report relies upon an 

### accompanying report prepared by Normandeau Associates , Inc. 

### (Normandeau) that provides impingement and entrainment data used to characterize PNPS' current I&E reduction measures 

### , as well as to estimate potential changes in I&E for the potential alternative technologies evaluated herein.

. I&E mortality or I&E means impingement mortality and entrainment mortality, as adjusted to reflect site-specific or otherwise relevant impingement and entrainment survival infonnation detennined to be reasonably representative by a qualified fish biologist or ecologist.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### PNPS and Cooling System Description PNPS Overview The primary activity of PNPS is the generation of electric power. PNPS is located in Plymouth Massachusetts on the northwest shore of Cape Cod Bay. 

### PNPS began commercial operation in 1972. The PNPS Boiling Water Reactor (BWR) produces steam for direct use in the steam turbine 

### , and currently generates at a rated capacity of 711 MWe 

### (gross) with a nominal 

### capacity of 685 MWe (net). PNPS was designed, constructed , and is 

### operated to withdraw seawater from Cape Cod Bay via a once-through CWIS. The PNPS CWIS has a design intake flow

### t of 467.28 milion gallons per day (mgd). 

### The current expected operating mode for PNPS over the next ten years is at a capacity utilization 

### rate well in excess of 15% (the threshold for the applicability of certain requirements of EP A' 

### Phase II Rule promulgated under CWA ~316(b)), consistent with PNPS' role as a " base load" 

### supplier (in part, through long-

### term power purchase agreements) to New England electricity customers , under the oversight and 

### direction of among other regulators 

### , the New England Independent System Operator (ISO-New England). 

### Source Water Body Description As described in the PNPS Final Safety Analysis Report (FSAR), the Station is located on the northwest shore of Cape Cod Bay, a circular embayment of the Atlantic Ocean off the coast of eastern Massachusetts. The floor of the bay slopes gently to the north where maximum depths of 

### 180 to 190 ft are found along a line between Plymouth Bay and Race Point

### , the northern tip of Cape Cod (Ref. 10. , FSAR Section 2. 5.2. 1). The surface area of the Bay is approximately 430 and the volume is approximately 1.6x10 

### fe. About half the 

### surface area of the bay has depths greater than 100 ft and the volume-mean depth is also about 

### 100 ft. Except for the southeast comer of the bay, where Billingsgate Shoal is found , the depths generally increase rapidly from shore (Ref. 10. , FSAR Section 2.4. 1.1J. 

### As described previously by ENSR (Ref. 10.4), historical water temperature measurements of Cape Cod Bay taken together with more recent intake water temperatures recorded at PNPS from 1999- 2005 , indicate that the mean annual temperature is approximately 50 

### F in the vicinity of

t Design Intake Flow or Licensed Design Flow means the condenser cooling water design flow values: (1) calculated by qualified engineers employing the installed pmnp capacity curves at a typical discharge head (given as 27. 5 ft in the PNPS Final Safety Analysis Report (FSAR)) for the condenser cooling water; and (2) reflecting the addition of service water pumps serving an equipment cooling fuction , both as reflected in and consistent with the FSAR. Licensed Design Flow equates to the value assigned, during the cooling water intake structue design , to the

expected total volume of water likely to be withdrawn from a source waterbody, consistent with 40 CFR 125. 93. With respect to PNPS , the Licensed Design Flow is 467. 28 milion gallons per day (mgd), or 324 500 gallons per minute (gpm), including condenser cooling water flows of 447. 84 mgd, or 311 000 gpm , and service water flows of 19.44 mgd, or 13 500 gpm. t The approximate nature of this area is evident when consulting other sources , such as Emberton (Ref. 10. 20), which describes a surface area of 1300 km (501 miPilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter PNPS. Generally 

### temperatures peak in the late summer and early fall with typical maximum 

### annual temperatures in the range of 68- 7 5 F. Mixing between the 

### surface and bottom water in 

### the fall transfers some heat to deeper layers , causing bottom water to 

### show an annual peak temperature in late summer/early 

## fall. The water typically 

### becomes isothermal in late 

### November

### , and surface water temperatures typically reach their annual low in January-February (30- 

### F). Bottom salinities are uniform throughout the year (31- 

### 32 ppt), while surface and near shore salinities show seasonal variation due to spring runoff (Ref. 10.4 , citing Galya et al. 1997). 

### An aerial view ofPNPS is shown in Figure 1.

J ' '''

... ;( 

### , , 

## :--

~~~

Figure 1 

### Aerial View of PNPS 

### Hydraulic Zone of Influence As requested by EP A

### , the hydraulic zone of influence (HZOI) - which delineates the portion of the embayment that is potentially affected by the intake flow - at PNPS was considered. 

### A 1977 study of the HZOI performed by the Massachusetts Institute of Technology Ralph M. 

### Parsons Laboratory for Water Resources and Hydrodynamics compared the tidal flow pattern 

### with and without the influence of the intake flow. Within the study, it was determined that because " the relationship between plant flows and tidal velocities was similar in both situations the assumption of negligible modification on tidal flow by the plant intake was indeed justified" (Ref 10. 131). 

### Because influence of the intake flow is negligible 

### , further delineation of the HZOI is not necessary . 

### PNPS Tidal Influence

EP A requested a 

### calculation of the total design intake flow over one tidal cycle of ebb and flow 

### as a percentage of the volume of the water column within the area centered about the CWISPilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### opening, with a diameter defined by the distance of one tidal excursion at mean low water level. 

### Under 40 CFR ~ 125. 

### , the tidal excursion is defined as " the horizontal distance along the estuary or tidal river that a particle moves during one tidal cycle of ebb and flow. 

### " As a result such a calculation is only possible where the volume of the water column can be defined with reference to tidal estuaries or tidal rivers. As PNPS is a coastal facility that draws directly from 

### Cape Cod Bay, tidal excursion in the vicinity of PNPS cannot be calculated , and the applicable water column subject to influence by the facility cannot be defined. 

### In any event

### , PNPS' design
intake flow has virtally no influence on 

### any applicable water column defined with reference to tidal cycles in Cape Cod Bay. 

### Cooling Water Intake Structure Description As detailed below 

### , the CWIS is located along the shoreline 9 and consists of several different 

### components. It begins with an opening 

### created by two large protective breakwaters of a 

### constrcted embayment which reduce the effects of severe wave action. Seawater is drawn through the constructed embayment and along a 

### dredged intake channel (Ref. 10. , FSAR Section 2.4.4. 

### 1). Seawater flowing through the intake channel turns approximately 90 degrees at the proximal end of the 

### embayment. To restrain the seasonal ingress of horseshoe crabs , four
barriers consisting primarily of 16- 

### inch tall I-

### beams are inserted into the four stop log guides at
that point ** 

### . As shown in Attachment 5 , Figure 5. 

### , after entering the CWIS the seawater must 

### pass through trash racks before reaching the traveling water 

### screens with their screenwash 

### pumps. The CWIS ends at the Salt Service Water (SSW)tt pumps , the Circulating Water (CW)H (also known as the Seawater) pumps , the Fire Protection System pumps , and chlorination equipment. 

### A major portion

### , approximately 96%, of the seawater that passes the traveling water screens is 

### directed to the CW pumps 

### , which deliver water to the 

### main condenser. A small portion approximately 4%, of the seawater flows through the sluice gates and is used by the SSW pumps. 

### Additional flow is supplied , as demanded , to the Fire Protection 

### System pumps; however , this flow is infrequent and not continuous.

g Note that PNPS does not have a typical shoreline intake as discussed further throughout this section. .. These horseshoe crab barriers have proven to be an effective obstacle that prevents the crabs , which are unable to swim, from walking into the intake structue and becoming impinged on the traveling screens.

tt Salt Service Water or Service Water means the water withdrawn from Cape Cod Bay through the CWIS for safety-related equipment, including facility shut-down systems , via as many as five (5) service water pumps , as reflected on the PNPS NPDES Pennit Attachment B (Water Flow Diagram). Service Water is included in the calculation of Licensed Design Flow. H Condenser Cooling Water or Circulating Water means the water withdrawn from Cape Cod Bay through the CWIS for the circulating water system, which absorbs heat from PNPS' main condenser and its supported systems which in turn serve as a heat sink for turbine exhaust steam, tubine bypass steam , and other generating equipment flow , as reflected on the PNPS NPDES Pennit Attachment B (Water Flow Diagram). Condenser Cooling Water is included in the calculation of Licensed Design Flow. gg

Nonnal water supply for the Fire Protection System pumps is supplied by the Town of Plymouth.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### Physical Description, Location , and Depth of CWIS The CWIS is located on Cape Cod Bay at coordinates N41 0 56' 46" and W70 34' 

### 42" . The CWIS 

### begins with two large breakwaters (also referred to as jetties) that are designed of rubble mound construction and are 

### protected by 

### heavy capstone. The breakwater on the northwest is 

### approximately 1400 ft long, and the breakwater on the southeast is approximately 700 ft long. 

### The top elevation of both breakwaters is at + 11.2 ft mean sea level (MSL) (+ 

### 16 ft mean low water (MLW)) (Ref. 10. , FSAR Section 2.4.4. 1). The breakwaters provide a first line of defense 

### from excessive wave action

### , overtopping due to wave runup, and storm flooding of the site. The average velocity of flow at the embayment opening is 0. 05 feet per second (fps) at mid- tide level 

### with both CW pumps operating (Ref. 

### 10.4). The breakwater structures represent a difference from the EP A uniform baseline configuration as defined in Section 4. The CWIS then transitions to a screenwell that takes in seawater at its northern wall through four bays 

### , each 14 ft wide and 12 ft high topped by a skimmer wall. These openings to the bays are 

### fully submerged at mean low water level. The lowest portion of the 

### CWIS is located at an approximate elevation of 24 ft below MSL. The front of the screenwell includes a skimmer wall 

### the bottom of which is located at 12 ft below MSL , designed to restrict floating materials at or 

### just below the surface from approaching the traveling screens (Ref. 10.4). Because the skimmer 

### wall was designed and constructed to preclude surface withdrawal , it represents a difference from the EP A uniform baseline configuration as defined in Section 4. 

### The screenwell of the CWIS is a reinforced concrete substructure 

### , and a superstructure of steel 

### framing enclosed with precast panels , divided into four bays , one for each traveling screen 

### assembly. The four CW bays have steel struts on the walls to allow dewatering of the bays (Ref. 10. 

### , FSAR Section 12. 2.2. 

### 8). The SSW pump compartments are located between the two CW pumps and are constructed of solid concrete. Refer to Figure 5. 7 in Attachment 5 for a schematic of the screenwell. 

### Two independent screening systems exist at PNPS. Trash racks (also known as bar racks) are installed as a primary barricade to retain pieces of debris larger than 3 inches (Ref. 10. , FSAR Section 11.6. 

### 3). Large debris that accumulates in front of the trash racks is manually removed by 

### plant personnel (divers). Four traveling water screens 

### , two for each CW pump bay, follow the trash racks. The traveling water screens , discussed in more detail below 

### , are used to remove any

material larger than 

### by y, inch. A dual (high and low pressure) screenwash system , consisting of two pumps , duplex basket strainers , and associated piping and valves , is used to spray material 

### off the rotating screens into the fish return sluiceway. The supply to the screenwash pumps 

### comes from the SSW system , and screenwash water is dechlorinated prior to entering the 

### screenwash pumps because the SSW system is continuously chlorinated. The low pressure 

### screenwash system and fish return sluiceway were added as operational and structural controls for the purpose of reducing impingement mortality. Therefore , they also represent a difference from the EPA uniform baseline configuration as defined in Section 4.



### Traveling Water Screens PNPS has four Rex Chainbelt through- flow traveling water screens 

### , two for each CW pump, 

### consisting of a continuous 

### series of wire mesh panels bolted to frames and attached to two 

### matched strands of roller chains. They are each approximately 10 ft wide 

### , and are installed in a channel with the screening surface oriented perpendicular to the water flow. Each of the screensPilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### includes 53 basket segments (or panels). The chains operate in a vertical path overhead

### , carring the panels down into the water, around the foot sprockets , back up through the water , and over 

### the head sprockets. All the traveling screens use the same stainless steel oblong-shaped mesh with v"- inch wide by 

### inch tall spacing and are framed in a fiberglass support structure. With 

### both CW pumps running, the design flow is 81 125 gpm per screen. Using the equation below
(Ref. 10. 7), the design through-screen velocity can be calculated as follows:

Through- Screen Velocity = Q/(BW*L W*POA *K) 

### where BW is the screen width in feet , L W is the water depth in feet

### , Q is the flowrate in gpm POA is the "percent open area

### " of the screen basket, K is a conversion factor equal to 396 , and 

### the through-screen velocity is calculated in fps (Ref. 10. 7). The 

### POA of the traveling water screens with v"- inch by inch openings is approximately 68% and the screen basket width 

### (BW) is 10ft. The water depth (L W) is 19.2 ft and is based on the water depth at ML W. Based on these inputs , the through-screen velocity at ML W is calculated to be 1. 57 fps. 

### The traveling water screens 

### , which are used to remove aquatic life and/or debris from intake water

### , are operated routinely, preemptively, and in response to an alarm - which occurs when 

### there is a pressure (or level) differential between the upstream and downstream sides of the screen assembly. PNPS has six scheduled screenwashes per week to monitor fish impingement at 

### three different times of day: morning, afternoon, and evening. When the seawater temperatures fall below 30 

### , the screens are operated continuously to prevent freezing. The screens normally 

### operate at 5 feet per minute (fpm), but can run at high speed (20 fpm) during heavy debrisloading conditions. 

### Under normal operation

### , seawater passes first through the ascending, and then the descending, 

### screen baskets. The ascending basket is located on the upstream portion of the screen , and 

### collects fish and/or debris as it passes up through the water. The aquatic life and/or debris are retained on the upstream face of the wire mesh panels as well as on the horizontal surface of the 

### basket frame and the lifting lip that forms the lower

### , or trailing, edge of the mesh frame. The 

### basket continues to rotate and 

### descends into the water on the downstream side. Aquatic life and/or debris not washed off the screen basket may be washed off in the flow of water. This is considered ' 

### carrover ' and wil travel into the CW pump bays (and possibly into the SSW pump bays).
The traveling water screens represent a difference from the EP 

### A uniform baseline configuration as defined in Section 4. Figure 2 shows a schematic of the traveling water screen operation.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Figure 2 Screenwash System 

### Each traveling water screen uses dual (low and high pressure) spray washing to clean the debris and/or aquatic life that has been impinged on the screens. Initially, a low pressure jet of water is used to wash living organisms from the screen and lifting shelves. Then , a high pressure spray is used to remove debris. 

### The low pressure screenwash sprays operate at a pressure of 15-20 psi 

### , while the high pressure screenwash sprays operate at 100- 120 psi. Each of the two screenwash pumps deliver 1000 gpm 

### where approximately 100 gpm is routed to the low pressure sprays , and 900 gpm to the high 

### pressure sprays. During normal operations , the spray-wash discharge is routed to the embayment through the sluiceway on the east side of the CWIS (i. , the fish return sluiceway), which 

### empties into the embayment approximately 300 ft east of the screens. 

### During severe weather events (i. 

### , ocean storms characterized by wind-induced wave runup), the spray-wash discharge 

### is sent to the discharge canal through the concrete sluiceway on the west side of the CWIS (i. 

### the debris sluiceway) because the increased capacity is needed to handle the debris load caused by such storm events. Sodium thiosulfate is added to the spray wash water to ensure that impinged 

### organisms are not washed with chlorinated water. 

### Traveling Water Screen Operation

The screenwash system represents a difference from the EP A 

### uniform baseline configuration as defined in Section 4.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

1.3 

### Skimmer Wall The skimmer wall serves to block floating aquatic life and/or debris 

### , and is effective to a depth approximately equal to the depth of the wall itself. In addition to these benefits , the wall also has 10 inch diameter openings that act as fish 

### escape ports. Fish escape ports are located in the skimmer wall as well as in each of the four curtain walls 

### , located at the screenwells about 6 ft beyond the screens. This represents a difference from the EP A uniform baseline configuration as defined in Section 4. 

# 1.4 Fish Return Sluiceway 

### As described above 

### , aquatic life and/or debris in wash water from the traveling screens are 

### discharged into one of two sluiceways. During normal weather conditions , the discharge routed through a sluiceway (i. 

### , the fish return sluiceway) that empties into the embayment approximately 300 ft to the east of the screens 

### sufficiently far from the screens to allow 

### movement within and outside of the embayment. Throughout the length of the fish return 

### sluiceway it has several turns that vary from to 27 , and has an estimated slope of 0. 035 1/28) for most of its length (Ref. 10. 8). Due to site limitations , shortly before emptying into the 

### intake embayment, the slope of the fish return sluiceway 

### increases rapidly. The sluiceway was 

### fabricated from 18 inch corrgated metal pipe forms 

### , which were used as molds to form the 9 inch deep semi-circular trough. The corrgations provide the resistance to flow in order to maintain a design water depth of 6 inches and a design water velocity 

### less than 8 fps in the sluiceway. Also , the sluiceway is coated with water-

### based epoxy resin emulsions that are used to 

### keep fouling from forming in the sluiceway and provide a smooth 

### surface. The top of the sluiceway is covered with wire screens or heavy duty 3- inch grating covers in areas where personnel and vehicles may travel. 

### As an operational measure 

### , when the weather is severe or there is heavy loading, the screenwash 

### effuent is directed into the discharge canal via the concrete sluiceway on the west side of the embayment (i. , the debris sluiceway). This sluiceway 

## is much shorter than the eastern 

### sluiceway, and therefore does not go through many turns. Using this sluiceway during heavy loading prevents the fish return system from clogging and prevents recirculation of debris.
The fish return sluiceway represents a difference from the EP 

### A uniform baseline configuration as defined in Section 4.



### CWIS Flow Description

Pump 

### Description As stated previously, the CWIS houses two sets of cooling water *** pumps which supply all the once-

### through cooling water for both the CW and SSW systems. No other seawater is withdrawn from Cape Cod Bay by PNPS. 

### The CW system is used for condenser cooling and is supported by two (2) vertical , mixed flow 

### wet pit type CW pumps 

### , each with an intake flow of 155 500 gpm at a discharge head of 27. 5 ft. 

### The SSW system contains five (5) safety-related pumps with a combined intake flow of 13 500

... Cooling Water means the water withdrawn from Cape Cod Bay through the CWIS , including, with respect to PNPS , Condenser Cooling Water and Salt Service Water , consistent with 40 CFR S 125. 93.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter gpm. Therefore 

### , the maximum continuous combined flow (the licensed design flow , as defined 

### previously) through the traveling screens is rated at 324 500 gpm (723 cfs or 467 MGD). This licensed design flow is consistent with EP A' 

### s definition of design intake 

### flow in 40 CFR ~ 125. 93. 

### Due to its status as a baseload facility, and consistent with operational practices in the nuclear industry, PNPS pump (and CWIS) operation is continuous , except for planned refueling outages and unplanned reactor shutdowns.Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Flow Reductions 

### The actual amount of flow entering the CWIS may be reduced when any of the cooling water pumps are shut off

, although a reduction in reactor power to 50% load or less is required to shut off a CW pump. During a refueling outage at PNPS , the CW pumps are shutdown sequentially at the beginning of the outage and are restarted before the end. At least one SSW pump is kept on at 

### all times 

### , even during outages 

### , in order to maintain essential cooling of nuclear safety-related systems tH



### Because refueling outages (and unplanned outages) are an operational measure to reduce flow they represent a difference from the EP A uniform baseline configuration as defined in Section 4.

ttt Nuclear Safety means conditions , actions or considerations within the customary or exclusive jurisdiction of the Nuclear Regulatory Commission (NRC) associated with the design, construction , operation and shut down of NRClicensed nuclear electric steam generating facilities , including without limitation any and all conditions associated with the modified or altered use of equipment, or changes to facility operations , requiring assessment of a station NRC licensing basis or operating procedures.

10-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Flow Reliabilty Intake cooling water at PNPS: (1) promotes the effcient generation of electricity, and (2) ensures an uninterrpted supply of 

### cooling water for nuclear safety-related systems. Although the 

### majority of seawater entering the 

### CWIS is pumped through the main condenser via the CW system

### , the smaller portion of intake cooling water that also passes through the traveling water screens flows into SSW pump bays. The SSW system provides the ultimate heat sink for nuclear 

### safety-related systems , such as Reactor Building Closed Cooling Water and Residual Heat Removal. Due to the consequences that have resulted from either a reduction or a temporary 

### interrption of intake cooling water flow

### , NRC and the Institute of Nuclear Power Operations (INPO), the organization that sets performance objectives , criteria

### , and guidelines industry-wide for nuclear 

### power plant operations to promote operational and safety excellence , have addressed , through 

### regulation and mandatory guidance 

### , "

Intake Cooling Water Blockage. " The nuclear industry, 

### and PNPS in particular

### , have experienced events in which traveling water screens have failed to allow an adequate supply of cooling water

### , resulting in forced plant shut downs and activation of 

### emergency response systems. Viewed broadly, these requirements proscribe screen systems that may compromise the ultimate heat sink or otherwise impair water- based nuclear safety-related systems. Moreover , these requirements are in a state of flux. In 2007 

### , INPO issued a " Significant 

### Operating Experience Report" (SOER) mandating that nuclear plants evaluate and address all possible factors that could lead to Intake Cooling Water Blockage. While PNPS' response to this 

### requirement has not been finalized yet, INPO' s SOER is expected to cause existing operation 

### and maintenance practices at PNPS to be re-evaluated and may lead to design changes affecting CWIS components.



### Biocide Treatment Sodium Hypochlorite Injection The SSW system is protected from marine growth (micro- 

### fouling, a biofim deposition on heat exchanger tubes) and mussels (macro- 

### fouling) by continuous injection of sodium hypochlorite. The CW system is protected from micro-

### fouling by injecting hypochlorite for 1 hour per day (normally) per loop. This time limit reflects NPDES Permit requirements. Thermal backwashes are used to control macro- 

### fouling in the CW System and other areas of the CWIS (excluding the SSW pump bays). 

### Measurement of the concentration of total residual chlorine (TRC) in the CW System is required 

### by the NPDES Permit. Monitoring instrumentation consists of a small 

### sample pump at the discharge canal footbridge and an amperometric titrator to determine the TRC concentration in samples drawn from the effuent 

### stream. At least one CW 

### pump must be in operation for dilution. Total residual chlorine in the SSW 

### System is measured by daily grab samples and analysis. 

### A solution of sodium hypochlorite is applied to each CW pump bay 

### alternately to achieve a maximum effuent 

### concentration of 0. 

### 1 ppm (mg/L) for approximately I hr/day in order 

### control slime growth and fouling 

### organisms within pump bays and the CW system. Two 

### chemical metering pumps supply hypochlorite just downstream of the trash racks 5 to 7 days per

11-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### week during spring, summer

### , and fall. The frequency is usually reduced in the winter to reflect the decrease in biofouling 

### potential. The Station s Chemistry staff 

### (Chemistry) samples the discharge canal during periods of CW System chlorination to verify residual chlorine levels are 

### detectable but below 0. 

### 1 ppm TRC (Ref. 10.22) to ensure compliance with the NPDES Permit
(Ref. 10. 16). 

### The SSW chlorination system has three installed metering pumps , two running simultaneously 

### while the third pump acts as a spare to either of the running pumps. Hypochlorite is injected inside each of the SSW pump bays. 

### The SSW System is chlorinated 24 hours per day, 7 days per week. The SSW loops are sampled 

### by Chemistr just downstream of each Reactor Building Closed Cooling Water heat exchanger. 

### These samples are analyzed for residual chlorine and the 

### maximum must average': 1. 0 ppm TRC (Ref. 10. 22) to ensure compliance with the limits specified in the NPDES Permit.

Screenwash Dechlorination 

### System 

### There are two screenwash pumps that are supplied from the SSW headers 

### , which supply high pressure and low pressure spray headers to keep the traveling screens clean. Debris and any fish that are sprayed off of the screens are returned to the intake canal via the fish return sluiceway. 

### Because the screenwash water originates from the SSW system, which has been chlorinated, the 

### SSW system water must be treated (dechlorinated) to remove the residual chlorine prior to being entering the intake canal to comply with the limits specified in the NPDES Permit. 

### There are two dechlorination pumps , one for each screenwash pump. metered sodium 

### thiosulfate solution is injected into the screenwash pump suction. The system includes 55 gallon drums of sodium thiosulfate 

### , two positive- displacement dechlorination pumps 

### , a flow indicator 

### for each pump, and an event recorder to record operation of the traveling screens , screenwash pumps 

### , and dechlorination pumps. The pumps are equipped with a variable stroke and frequency to allow regulation of injection rate. 

### 2.4 Discharge 

### System The discharge from the condenser and from the SSW System is returned via the discharge canal to Cape Cod Bay (Ref. 10. , FSAR Section 11.6. 

### 3). The discharge structure and canal are to the 

### northwest of the CWIS. The discharge canal is approximately 870 ft long and is extended over the beach to 

### mean low water (MLW) by rock- 

### fill jetties. The jetties are of rubble mound construction and are protected by heavy capstone. The jetties have a nominal elevation of + ML W (+ 11. 2 MSL) sloping down to a height of 4 ft at ML 

### W. The elevation of the bed of the discharge canal is 0 ft ML W. 

### The discharge canal jetties also serve to promote rapid mixing in Cape Cod Bay for heat dissipation and to protect the CWIS and discharge structures from wave action (Ref. 10. , FSAR Section 2.4.4). 

### At the CW licensed design flow of 311 

### 000 gpm through the condenser and with the turbine

### generator at full power , the temperature 

### rise through the 

### condenser is typically 29 F. The maximum allowed temperature rise from the CWIS to the end of the discharge canal is limited to 

### F in the NPDES Permit , Section A.2. a (Ref. 10. 16). The permitted maximum discharge canal temperature may not exceed 102 

### F at the point of discharge to Cape Cod Bay. RTD temperature 

### sensors are located at the intake and discharge canals to provide input signals to the station

12-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### computer and an alarm display in the main control room for monitoring compliance with the NPDES Permit limits for the CW system 

### effuent temperature (Ref. 10. , FSAR Section 11.6. 3 J. 

### Cooling Water Process Flow Diagram Refer to Figure 1 of Attachment 5 , which shows the flow of cooling water through PNPS. 

### Recent and Planned Plant Modifications Modifications since January 2001 No significant modifications that changed the design or operation of the CW System , CWIS , or SSW System have been made since January 2001; rather

### , only maintenance and preventative maintenance activities have occurred. Currently, there are no substantial design changes or modifications to the CWIS planned.



### Age of Cooling System Equipment Table 1 describes the equipment and components used in PNPS' cooling system , over time.

Table 1 

### History of Key CWIS Components at PNPS
Equipment Originally

Installed Date and Description of Component Replacement

Bar (Trash) Racks 1970 1998 , Replaced in-kind lower and mid sections of racks due to cOlTosion. Top section was in excellent condition.

Traveling Screens 1970 1992 , Replaced X- l08C&D screens wi 2 speed motors head shaft roller bearings and suspension system, stainless steel baskets with
oblong (Yz x Y4 inch) mesh and stainless steel chains. 1994 , Replaced X- 108A&B screens wi 2 speed motors head shaft roller bearings and suspension system, stainless steel baskets with
oblong (Yz x Y4 inch) mesh and stainless steel chains. 1994- 1996 , Installed lifting lips on basket frames. 1998 , Changed from stainless steel basket frames to fiberglass and Nitronic 60 basket chain rollers/pins/bushings. 2005 , Replaced X- I 08C&D complete assemblies. 2007 , Replaced X- I 08A&B complete assemblies.
Spray Wash (SCREENW ASH) 1970 1994 , Replaced P-213A & P-2l3B pumps (and basket strainers) with 100 hp motors and increased impeller size to boost flow from 750 gpm up to 1000 gpm (reflected in 1994 NPDES permit modification).

13-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Table 1 History of Key CWIS Components at Equipment Originally Date and Description of Component Replacement

Installed

1986 , Replaced P- l 05A & B impellers , shroud and pump inner casing

from C-Iron to 316 SS. Circ Water Pump 2001 , Rebuilt P- l 05B pull out pump section in-kind. 105A & P- I05B 1970 2005 , Rebuilt P- 105A pull out pump section in-kind and replaced four outer pump columns due to graphitization. 105B is scheduled to have the same columns replaced in 2009 (RFO# 17). Originally a Screenwash supplied eductor system with no electric Circ Water driven pumps provided CW Hypo. Hypochlorite Injection 1970 Pump 1990 , Installed two P- I13A and P- I13B positive displacement pumps and piping.

1986 , Installed 2 metering pumps and piping. SSW Hypochlorite 1986 1990 , Installed 3 metering pumps. Injection Pump 2001 , Replaced SSW Hypo piping.

Screenwash Installed 2 metering pumps at the inlet of Screenwash pumps to de1986 chlorinate SSW supply water. Dechlorination Pumps 2006 , Replaced metering pumps. 

## Projected Retirement Plans Currently, and except as provided under applicable NRC law regarding license life

### , there are no plans to retire PNPS 

### , which is a baseload source of supply, providing critically needed reliable affordable power to ISO-New England customers.

14-Pilgrim NucJear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### Description of Plant Processes 

### Nuclear Steam Supply System Operation At its most basic , a BWR is designed to produce electrical energy through conversion 

### , via a turbine driven generator

### , of a portion of thermal energy contained m the steam supplied from the reactor; to condense the turbine exhaust steam into water; and to return the water to the reactor as heated feedwater with a major portion of the gaseous , dissolved

### , and particulate impurities removed (Ref. 10. , FSAR Section 11. 1 J. The major components of the power generation system 

### are: turbine generator

### , main condenser, condensate pumps , condensate demineralizers 

### , reactor feed pumps 

### , feedwater heaters 

### , and condensate storage system. The heat rejected to the main condenser (the waste heat inherent in any thermodynamic cycle) is removed by the CW System. 

### The saturated steam produced by the reactor is passed through the high pressure turbine where the steam is expanded and then exhausted through the moisture separators. Moisture is removed 

### in the moisture separators and the steam is then passed through the low pressure turbines where 

### the steam is again expanded. From the low pressure turbines 

### , the steam is exhausted into the 

### condenser where the steam is condensed and de-aerated , and then returned to the cycle as condensate. A simplified schematic of a BWR plant is shown in Figure 3 (Ref. 10. 19).

ContaiwnellttDty,,-ell

Turbine Building

SteamDlyer
Moisture Sepamtor Electrical Generator

-- Reactor Core condenser Jet Pump

TofFrom Ocean Recirculation Pmup Pmup Containment Suppression Chamber

Figure 3 Simplified Schematic of BWR Plant Operation 

## Condenser Operation
The pU

### fJose of the main condenser is to serve as a heat sink (i. , a mechanism for heat removal) for turbme exhaust steam

### , turbine bypass steam

### , and other flow (Ref. 10. , Sections 11. 3.

15-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter through 11.3. 

### 3). As such

### , cooling provided by the condenser to condense steam is necessary to provide feedwater for the reactor

### , moderating the neutrons to maintain the nuclear reaction and thereby generating steam to drive the turbine. 

### The PNPS main condenser is a twin shell , horizontal titanium tube 

### , seawater cooled unit and is located in the Turbine Building below the main tubine s low-

### pressure sections. The location of the condenser below the main turbine is indicative of its function

### , whereby the cooling water of 

### the CW system condenses the steam exhausted from the turbine 

### , which is then 

### retued to the reactor as feedwater. Seawater is the heat sink for the main condenser and its supported systems. Each condenser shell has divided water boxes , which permits isolation of the CW on one-

### half shell while the other half 

### remains in operation. The arrangement of CW piping allows backwashing of the condenser by section to remove possible debris accumulated on the inlet tube sheets. The main condenser is rated at the following design parameters (Ref. 10. 3): 

# a. Steam condensed - 4. 85x10 1bm/hr Heat removed - 957. 6 BTU-lbm/hr Absolute pressure - 1.49 inches Hg Vac Inlet water temperatue - 48 Sea water flow - 311 000 gpm Surface area - 400 000 fe 

### CWIS Operation Refer to Section 2. 3 for a detailed description of the CWIS. 

# 3.4 Effluent Treatment Operations No chiling or cooling of heated once-

### through cooling water is performed at PNPS. Discharged 

### cooling water is monitored for compliance with NPDES Permit limits as described in Section 2.3.3.

16-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### Evaluation of Existing CWIS Technologies and Operational 

### Measures EPA prescribes a uniform baseline configuration (40 CFR ~125. 93) designed to ensure consistent decision-making among different facilities nationwide as follows: Calculation baseline means an estimate of impingement mortality and entrainment that would occur at your site 

### assuming that: the cooling water system has been designed as a once- through system; the opening of the cooling water intake 

### structure is located at , and the face of the standard 318- 

### inch mesh traveling screen is oriented parallel to 

### , the shoreline near the surface of the source waterbody; and the baseline practices , procedures 

### , and structural configuration are those that your 

### facility would maintain in the absence of any structural or operational controls including flow or velocity reductions 

### , implemented in whole or in part for the purposes of reducing impingement mortality and entrainment... 

### This section discusses the following existing CWIS technologies and operational measures at PNPS that differ from the EP A baseline , as described in Section 2.3: Breakwaters Skimmer wall
Fish escape ports
Traveling screens Low pressure screenwash Fish return system 

### Outage schedule/fow reduction 

### Based on input provided by Normandeau

### , the low pressure screenwash 

### , fish return system, and 

### flow reductions produce quantifiable 

### reductions from 

### baseline in I&E. 

### While data is not available to estimate the impacts on I&E for the other components , Normandeau has provided assessments of the qualitative features of each component. 

### The differences in I&E at PNPS 

### , while treated in this Report as percentage reductions , are 

### characterized by Normandeau in terms of equivalent adult (EA) fish to ensure comparable raw data is properly understood and evaluated. Table 2 , based on 

### information provided by Normandeau (see Attachment 6), which shows baseline fish losses and monthly fractions during recent representative years , demonstrates that entrainment accounts for 99. 

### 3% percent of the losses. The four months with the most EA entrainment are March through June , accounting for 

### more than 80% of the annual entrainment. The four months with the most EA impingement are April , August , September , and November 

### , which 

### account for more than 75% of the annual impingement

### , but only 0. 5% of total annual abundance (of combined baseline EA entrainment and impingement).

17-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Table 2 

### PNPS Baseline Monthly EA 

### Entrainment and Impingement

Monthly EA Monthly EA Monthly EA Monthly EA Month Entrainment Entrainment Impingement Impingement

Losses Fraction Losses Fraction January 236 324 1.7% February 161 822 372 March 465 612 17.4% 1529 April 385 340 14.4% 4012 21.4% May 601 582 22.4% 393 2.1% June 793 354 29. July 141 583 0.2% August 189 3494 18. September 691 2625 14. October 1888 495 November 2410 4452 23. December 2540 0.1% 1012 5.4% Annual 681 247 100. 788 100.

1.1 

### Evaluation of Existing CWIS

Traveling Water 

### Screen Low Pressure Screenwash and Fish Return 

### System As provided by Normandeau (see Attachment 6), incremental EA impingement survival due to 

### the sluiceway and the low pressure wash systems are shown in Table 3. The most incremental 

### EA impingement survival due to the sluiceway occurs in the months of May and July, with an annual EA impingement survival of 9. 7%. The annual incremental EA impingement survival due 

### to the low pressure wash system is 5. 

### 7%, where the months with the most EA impingement 

### survival are January, May, and November. Thus 

### , the cumulative EA impingement survival is 15.4%, based on the additive nature of the survival data supplied by Normandeau in Attachment

Ht Based on adjustments to design intake flow based on actual flow. Refer to Attachment 6.

18-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter


## Table 3 PNPS Baseline EA Impingement Survival 

### - Fish Return Sluiceway and Low Pressure Wash

System

Month Fish Return Low Pressure

Sluiceway Wash System January 

### 1.% February March April 3.4% May 28. June July 37. August 12. 

### 1.% September 1.4% 2.4% October 12. November December 1.0% Annual 1.2 

### Breakwaters The breakwaters creating PNPS' intake embayment provide a relatively protected area from the 

### often dynamic environment of southwest Cape Cod Bay, particularly during periods of easterly winds. Per Normandeau (Ref. 10.23), the prevailing counterclockwise net flow in Cape Cod Bay 

### is also deflected by the breakwaters , and fish that might 

### otherwise be disoriented in the Bay turbulent waters 

### , or carried along in the strong current

### , are less likely to be impinged due to the presence of the breakwater.



### Skimmer Wall The skimmer wall along the leading edge of the CWIS extends approximately 12 ft below the water 

### s surface at mean sea level. Per Normandeau (Ref. 10.23), fish traveling individually or in schools near the surface encounter and are deflected by the 

### wall and are therefore less susceptible to impingement on the traveling screens. 

# 1.4 Fish Escape Ports The PNPS intake includes a number of 10-inch fish escape ports 

### , located in the skimmer wall of the CWIS. Per 

### Normandeau (Ref. 10.23), fish that pass under the 

### skimmer wall can escape encounters with the traveling screens by passing through the openings. 

# 1.5 Outage Schedule/Flow Reduction PNPS has an annual flow reduction of 5.4% from the baseline flow (licensed design flow) of 324 500 gpm 

### , and the greatest reductions in flow occur in April and May due to the timing of

19-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### refueling outages. The other reductions from baseline flow correspond to periods of lesser flows through the 

### SSW system due to reduced cooling 

### demands and to unplanned outages. The monthly baseline flows (in milions 

### of gallons per month) and the actual monthly flows are shown in Table 4 along with the corresponding flow reduction percentages !?!?!?

Table 4 

### PNPS Flow Reduction from Baseline

Month Baseline Flow Actual Flow Flow

(MG/month) (MG/month) Reduction !?!?!?

January 486 14,104 February 084 667 March 486 970 April 018 298 26. May 486 524 13. June 018 682 2.4% July 14,486 262 1.5% August 486 300 1.% September 018 809 1.5% October 486 942 November 018 692 December 14,486 144 2.4% Annual 170 557 161 394 5.4% 

### Percent Reductions from Baseline for Existing CWIS As discussed previously, not all of the 

### existing CWIS technologies have data available to 

### quantify I&E. The EA entrainment reduction from baseline is calculated based on information provided by Normandeau

### , solely from the reduction in flows due to the refueling outages and 

### reduced cooling demands. Similarly, the EA impingement reduction and EA impingement 

### mortality reductions are calculated based on flow reduction attributable to refueling outages 

### (with respect to impingement reductions), as well as on the reductions due to the sluiceway and 

### the low pressure spray 

### wash (with respect to impingement mortality reductions). While the remaining technologies do not have quantifiable reductions in entrainment and/or impingement ~~~

This Report assumes that a direct linear (1: 1) relationship between flow reductions and the number of fish entrained and impinged exists; however, the reductions in impingement and entrainment due to flow reduction reported by Nonnandeau in Attachment 6 are slightly more conservative than the actual flow reduction from baseline and, therefore, wil be used throughout this Section. Percentage reductions in entrainment and impingement due to flow reduction differ slightly due to the conversion of sampled life stages per unit volume to total monthly life stages , and the consolidation of species and life stages into a single entrainment or impingement number per month.

20-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter mortality, each technology does have an associated reduction in entrainment and/or impingement mortality as discussed in qualitative terms above.



### Entrainment Reduction from Baseline for Existing CWIS Reduction percentages from baseline for EA entrainment are comprised of actual flows divided by baseline flows , multiplied by the monthly entrainment distribution, as shown in Attachment 6. 

### Because entrainment is not uniform throughout the year , flow-weighted annual entrainment reductions were calculated based on the results 

### of the actual pattern of intake flows in each month throughout the year. 

### The EA entrainment reduction

### , shown in Table 5 , is the product of the monthly flow reductions given in Attachment 6 , Table 6.4 and the monthly EA entrainment abundance from Table 2. 

### The months with most significant portion of EA entrainment reductions are April and May, while the EA entrainment reduction from September through January is minimal 

### , due to the fact that each of these months experience less than I % of the annual entrainment. 

### Existing operations reflect a cumulative quantified reduction of EA entrainment from baseline of approximately 8. , based on a six-year averaging of monthly EA entrainment reductions.

Table 5 

### PNPS Baseline EA Entrainment Reduction by Month

Month Monthly EA Flow EA Entrainment

Entrainment Reduction Reduction January February 3.2% 0.2% March 17.4% April 14.4% 26. May 22.4% 13. June 29. 2.4% July 

### 1.% August 1.2% September 1.5% October November 2.3% December
100. Annual (Total) (Total) (Average) 

### Impingement Mortality Reductions from Baseline for Existing CWIS

Unlike entrainment 

### , where reductions from baseline are computed based solely on the product of the flow reduction (i. 

### e. the difference between baseline or licensed design flow and actual flow) 

### and the monthly entrainment distribution , impingement mortality reductions from baseline

21-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter 

### include the effects of the fish return sluiceway and low pressure traveling screenwash as shown in Attachment 6 , Table 6. 13. 

### The incremental EA impingement mortality reductions from Table 3 (fish return sluiceway and low pressure wash system) and Attachment 6 , Table 6. 

### 13 (flow reduction) are combined (based 

### on the additive nature of the survival data supplied by Normandeau in Attachment 6) to create a 

### cumulative EA impingement reduction. The EA impingement reduction is the product of this 

### cumulative monthly EA impingement reduction (in Table 6) and the monthly EA impingement from Table 2. 

### The months with the most significant portion of cumulative monthly EA impingement reduction 

### are April through July, while the months with the most significant portion of the monthly EA 

### impingement abundance are August through November. The average cumulative monthly EA impingement reduction is 20. 

## 8%. For each month, the cumulative EA impingement reduction is 

### applied to the monthly EA impingement abundance to determine the amount of the annual EA impingement reduction that 

### occurs within that month. For example , in April there is a 

### cumulative EA impingement reduction of 

## 38.4%. This reduction in EA impingement is 

### subsequently applied to the April EA impingement abundance of 21.4% to yield an annual EA impingement reduction of 8.2% within the month of April. 

### The months with the greatest EA impingement reductions are April , August , and November 

### while the EA impingement reduction in June and July is at a minimum due to the fact that each of these months experience less than 1 % of the annual impingement. 

### Existing operations reflect a cumulative quantified reduction from baseline of approximately 18. , based on a six-year averaging of monthly EA impingement reductions.

22-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter

Table 6 

### PNPS Baseline EA Impingement Reduction by Month Monthly EA Impingement Reduction Month Monthly EA Impingement

Impingement Flow Fish Return Low Pressure

Reduction Sluiceway Wash System Cumulative Reduction January 

### 1.% 12.1 % February March April 21.4% 26. 3.4% 38.4% May 13. 28. 9.1% 51.% 

### 1.%
June 0.3% 2.4% 19.4% July 0.2% 1.0% 37. 44.4% August 18. 

### 1.% 12. 

### 1.% 14. September 14. 1.5% 1.4% 2.4% October 12. 6.2% 22. November 23. 13. December 5.4% 2.4% 1.0% 11.0%

100. 20. 18. Annual (Total) (Average) (Average) (Average) (Average) (Total) 

### Evaluation Methodology for Alternatives The assessments detailed in the following sections review potential alternate technologies and 

### operational measures for 

### reducing I&E. 

## The evaluation criteria 

### focus on engineering considerations , though noting 

### biological factors where significant. The engineering factors 

### include technological feasibility and reliability, proven installation at comparable nuclear facilities 

### , and modifications conflicting with the Station s licensing basis or implicating nuclear 

### safety concerns. After considering engineering factors , the evaluation addresses the estimated 

### ability of the technology to demonstrably reduce I&E (as determined by Normandeau based on PNPS site-specific data, relevant literature , or both). 

### Where an alternate technology or operational measure satisfies the engineering and biological criteria

### , capital and operational costs are then estimated under a conceptual model appropriate at this stage of the analysis 

### , but likely understated in terms of site-specific costs 

### , unkown at this time , that may substantial increase costs. Thus , for instance 

### , the preliminary estimates provided 

## in this Report do not account for several complicating factors , including radiological 

### contamination and the limitations on development 

### necessitated by the zoning and agricultural (forestry) restrictions in place at Entergy s property. 

### Potential modifications to the CWIS for a nuclear facility such as PNPS , which has a combined CW and SSW intake 

### , are complicated by the fact that SSW flow is related to nuclear safety, and must be available at all times (i. 

### , for normal operations , shutdown , and postulated accident

23-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A ~308 Letter conditions). Per the PNPS Salt 

### Service Water / Chlorination Reference Text (Ref. 10.2), the safety design bases of the SSW system are as follows: 

# I. SSW is designed so no single system component failure can prevent it from providing a heat sink for RBCCW **** .



# 2. SSW continuously supplies adequate cooling water to the RBCCW heat exchangers under transient and accident conditions. Therefore 

### , any potential technology that introduces new failure modes into the SSW system , or 

### could interfere with maintaining SSW supply, would implicate nuclear safety concerns and be therefore judged as technologically infeasible.

In summary, technologically feasible means a baseline determination that a particular technology 

### likely can be implemented in general at comparable steam- 

### electric generating stations and , as qualified , in a site-specific 

### manner at PNPS to reduce entrainment or impingement without 

### implicating nuclear 

### safety considerations. Site-specific technological feasibility may qualified , and therefore 

### , not technologically feasible if the technology is unprecedented (i. , not demonstrated at any comparable facility).

*... Reactor building closed cooling water.

24-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter


### Closed- Loop Cooling PNPS is water- dependent - meaning both 

### that it requires a specific quantity and quality (measured by temperature) of water , here consistently cold seawater. Closed-cycle cooling 

### reduces water use with respect to the temperature of that water. Thus , any analysis of closed

### cycle cooling requires consideration of how these changes in water temperature will affect plant systems , operation 

### , and output. The retrofitting of nuclear facilities of comparable size , age and 

### configuration to PNPS to closed-

### loop cooling is untried. Thus 

### , this assessment is subject to the
caveats that it is 

### performed without any actual confirmatory data

### , and reflects the inherent uncertainties with novel applications of a technology intrusive to fundamental station operations. Additionally, PNPS 

### , as with all nuclear power plants , is designed to operate on a continuous and
consistent basis , and is not configured to allow frequent dramatic short-

### term power reductions. 

### Significant power reductions at PNPS require initiating and concluding procedures varying in length but often extending over numerous hours. In other words 

### , dramatic reductions in power 

### while short in duration , may have longer-term operational ramifications 

### , effectively extending the power reduction period. 

### With these caveats 

### , this section provides a preliminary engineering evaluation on the potential impact of converting PNPS from a once-through cooling water system into a closed- loop cooling water system. For this evaluation , the basic plant operational 

### parameters are first defined and then applied to calculate the effects 

### , including the expected power generation loss 

### , associated with PNPS operating under a retrofitted closed- loop cooling water design. 

### More specifically, Enercon obtained, reviewed

### , and analyzed local (meteorological) data for use 

### as an input to the state-of-

### the-art site 

### performance evaluation of power system effciency (PEPSE) model. The PEPSE model is a power plant performance modeling software that uses among other things , cooling water 

### intake temperature and flow rates to calculate plant 

### operational parameters and the resulting net power generated. The 

### PEPSE model provides the 

### expected plant operational parameters and power reductions necessary to theoretically operate 

### PNPS without exceeding equipment limitations 

### resulting in nuclear safety considerations. Likewise

### , the PEPSE model is used to analytically define the hypothetical circumstances in 

### which PNPS is incapable of mitigating nuclear safety concerns through operational measures (i. , where the Station is rendered inoperable). 

### Meteorological Data The performance of any closed-

### loop cooling water system is primarily driven by the ambient weather conditions at the site and the inlet water temperature values. Cooling towers define their performance via an approach to wet 

## bulb temperature. The wet bulb temperature , a 

### meteorological measurement which incorporates both moisture content and temperature of the ambient air , is necessary for closed- 

### loop cooling analysis , as cooling towers utilize an 

### evaporative process to remove heat from the continuously 

### recirculated cooling water. The approach to wet bulb describes the number of degrees above the ambient wet bulb temperature by which the cooling tower can be expected to reduce the cooling water temperature, whereby a lower approach equates to lower cooling water temperature 

### exiting the cooling tower. The approach to wet bulb is a value that is based on the size and effciency of the cooling tower, and essentially represents the cooling ability of the equipment. Any data set used to predict the

25-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### performance of PNPS relies heavily on the presence of either historical wet bulb temperature 

### measurements or a combination of values that can be used to calculate the wet bulb temperature (e. , dry bulb temperature and relative humidity, dry bulb temperature and dew point, etc. 

# 1.1 Meteorological Data Sources Wet bulb temperature data has been recorded for over a decade at a first order National Weather Service (i. 

### , staffed by National Weather Service employees) observatory located less than 10 

### miles from PNPS at the Plymouth Municipal Airport. This site-representative data was retrieved from the National Weather Service (NWS) via the National Climatic Data Center (Ref. 10. 5). 

# 1.2 Meteorological Data Analysis The NWS records meteorological data both hourly and during special weather conditions. Once the data is retrieved from the NWS 

### , a thorough review is conducted to normalize the hourly data 

### ensuring that a uniform hourly data set with no erroneous data is used as the basis for analysis. 

### As even minor errors present in the meteorological data 

### would propagate throughout the analysis 

### , particular focus is paid to the review and acceptance of the meteorological data. Furthermore 

### , there is almost always some degree of data loss attributed with meteorological monitoring. This 

## data loss may be due to a number of causes (equipment failure 

### biological/human interference , etc. ); however , a general guideline for meteorological data acceptance is that the data maintain an average 90% data recovery rate (Ref. 10. 14). The average recovery rate for the ten year period analyzed (1997- 2006) was 99. 1 % as shown in Attachment 3 Table 3. 1; therefore 

### , the data gathered from the Plymouth Municipal Airport greatly exceeds the threshold for validity. 

# 1.3 Inlet Water Data Analysis PNPS supplied ten years (1997-

### 2006) of measured CW inlet temperatures identical to that 

### provided for NPDES permit 

### compliance. This data was normalized into hourly segments to 

### create a uniform hourly data set with no erroneous data used as the basis for analysis. The 

### average recovery rate for the ten year period analyzed was 97. , representing an extremely robust data set. The monthly recovery rate per year is shown in Attachment 3 , Table 3.2. 

## PNPS Administrative/Continuous Operation Limits PNPS equipment operation is governed by a set of administrative limits 

## tttt used to ensure 

### adequate reliability and safety. Specifically, BWRs are subject to nuclear safety constraints on operations of various Station equipment, including pump net positive suction head requirements overall plant control characteristics , core thermal power limits , and core thermal- hydraulic 

### stability. PNPS equipment operation must be thoroughly analyzed in regard to the modifications 

### required to convert PNPS from once- through to closed- loop cooling, in order to ensure these administrative limits are not exceeded. 

### If it is expected that these administrative limits may be exceeded

### , PNPS is required to operate atypically under various levels of restriction that decrease 

### the net power generated by PNPS and ultimately implicate nuclear safety concerns. Because

tttt Administrative limits are PNPS-proceduralized limits used to prevent encroachment ofNRC licensed limitations (e. , technical specification limitations , FSAR limitations , etc. ), which require a documented Limited Condition of Operation when exceeded.

26-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter

these administrative limits implicate nuclear-safety concerns 

# , a slightly more conservative 

### continuous operation limit is used to ensure that these administrative limits are not exceeded. This approach is consistent with longstanding plant and industry operational practices , and meets industry expectations for established safety and nuclear margins.



### PNPS Cooling Water 

### Equipment Changes to the PNPS cooling water equipment that would result in performance gains are restricted by the size and configuration of the equipment within the turbine building, particularly the condenser and the surrounding components. 

### PNPS' condenser was sized to reflect the intended use of a stable and cold seawater source. The net result is that conversion to closed

### cycle cooling would require modification (through a 

### size increase) of the condenser.
condenser modification of this sort is unprecedented (i. , implementation of a condenser 

### redesign of this magnitude has never occurred at an operational nuclear power plant). Due to the 

### magnitude of this redesign and the lack of any history of a nuclear plant undertaking such a modification

### , it is concluded that the current cooling water equipment configuration could not be modified in such a way that enhances its cooling performance. 

### As shown in Figure 4 , the orientation of the PNPS main condenser is such that the entire turbine 

### building is built on top of , and around 

### , the main condenser. The net result of the main condenser location is that any increase to the size of the condenser would require a complete disassembly of 

### the turbine building, along with the accompanying modifications/additions to the turbine building following condenser modification. Because the turbine building contains the second half 

### of the reactor power conversion system (the reactor itself being the first half), the scale of a 

### turbine building modification/addition of this kind is also unprecedented (i. 

### , implementation of a complete turbine building redesign has never occurred at an operational nuclear power plant).

27-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter

.....

Figure 4 

### Turbine Building 

### Main Condenser Vacuum The objective of the main 

### condenser is to provide a heat sink for the tubine exhaust steam 

### turbine bypass steam

### , and other related flows. The main condenser is of the single pass , divided 

### water box

### , de-aerating type. It consists of two shells , one for each low pressure turbine cylinder and is a seawater cooled unit located directly 

### beneath the low pressure cylinders of the main 

### turbine as shown in Figure 4 (Ref. 10. 1) The 

### administrative limit given in the PNPS Main Condenser Vacuum System Procedure (Ref. 10. 

### 6) requires that the main condenser vacuum be below 4 in-Hg absolute.

28-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### Hotwell Temperature The main condenser hotwells provide the input flow for the condensate demineralizer system. 

### Variations in hotwell temperature have a direct impact to the performance and longevity of the 

### condensate demineralizer system. The hotwells have an average administrative limit of 120 As hotwell temperatures approach the 120 

### F administrative limit , the condensate demineralizer resins are subject to 

### reduced service life and impeded performance. According to the Main 

### Condenser Vacuum System Procedure (Ref. 10. 6), if these administrative 

### limits cannot be maintained the power must be reduced in accordance with the Station Power Procedure (Ref. 10. 17). To provide an operational margin against the administrative limit

### , a continuous operation limit of 118 F is evaluated in the 

### PEPSE analysis to ensure instantaneous ambient variations are not 

### capable of causing the administrative limit to be exceeded. This 

### continuous operation limit is consistent with sound nuclear engineering practice and 

### industr standards. 

### 2.4 

### Power/Flow Operating Map To satisfy nuclear safety constraints , BWRs must operate under numerous restrictions , including 

### pump net positive suction head requirements , overall plant control characteristics , core thermal power limits , and core thermal-

### hydraulic stability considerations. The power/flow operating map 

### for PNPS is included as Attachment 5 , Figure 5.2. Constraints imposed by equipment 

### , alarms reactor scrams initiated by protective instrumentation 

### , and operator actions based upon written operating procedures maintain PNPS within the bolded boundary lines shown on this map for an allowable region of operation, bounded by a monitored region that prevents high power/low flow conditions that increase the likelihood of a thermal-

### hydraulic instability resulting in power 

### oscilations (transients), which are generally proscribed because they require the use of control 

### rods as a remedial measure. Using control rods to regulate reactor power implicates nuclear 

### safety concerns due to the increased potential for transients and could not be employed under normal or 

### acceptable operational conditions. Thus , monitored operations are not considered 

### allowable on a routine basis 

### , and therefore may be employed only on a limited basis 

### , such as weekly control rod swaps or more infrequent condenser backwashing, both typical of industrywide operations. 

### A reactor power level of greater than approximately 80% is necessary to operate within the allowable region of operation , i. , outside the monitored region , thereby preventing the use of control rods to regulate reactor power. 

### Closed-

## Loop Operational Parameters As stated in Section 5.2. , conversion of a nuclear 

### power plant designed for once- through cooling to closed- 

### loop cooling has never occurred. Nonetheless , the theoretical effect on PNPS converting from once-through to closed-loop cooling is evaluated herein and requires that certain closed-

### loop operational parameters be defined. Due to their lower 

### effciency, evaporative ponds 

### spray ponds , cooling canals , and dry cooling towers are not capable of providing suffcient 

### cooling to support the condenser temperature required by the PNPS turbine design. Therefore none of these are considered feasible technologies. As such , evaporative cooling towers are the most appropriate potential closed- loop cooling mechanism for consideration at PNPS.

29-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### SPX Cooling Technologies , a leading cooling tower design vendor, was consulted on similar 

### northeastern United 

### States power plant installations and subsequently supplied baseline 

### performance of evaporative cooling towers considered here for use at PNPS. Utilizing this range 

### of performance and taking into account the site conditions and operational restrictions present at PNPS , a tower with a 12 F approach was considered appropriate for evaluation purposes. 

### 5.4 

### Closed- Loop Operational Parasitic 

### Losses All forced draft cooling towers require input electricity to perform their cooling operation. This resulting loss of electricity, referred to as a parasitic loss , is extremely taxing to the net electrical output of a plant 

### , and increases as a function of the cooling provided. Cooling tower parasitic 

### losses include those losses directly attributed to the 

### cooling tower 

### fans and any required 

### additional CW pump horsepower necessary to overcome the increase in static head added by the cooling tower. 

### Taking PNPS' 

### site-specific characteristics into account , complete closed- loop conversion of PNPS utilizing a 12 

### F approach to wet bulb hybrid cooling tower would include a continuous 20 MWe aggregate parasitic 10ss 

### PEPSE Model
The performance evaluation of power system effciency (PEPSE) model is a state-of-the-art power plant performance modeling software used by the nuclear power industry to estimate plant operational parameters and net 

### power generated using system inputs such as CW inlet temperature. The most recent PNPS PEPSE model was reviewed 

### , updated

### , and run to produce 

### the results discussed herein. A diagram of the PNPS PEPSE model has been included in
Attachment 5 , Figure 5.



### PEPSE Analysis - Baseline Closed- Loop Operation As described above , the current PNPS PEPSE model was updated and run over a bounding range of CW inlet temperatures (32 

### F to 94 , in 2 

### F increments) to calculate the baseline closed- loop operation of PNPS (i. , the theoretical performance of PNPS if it were to be converted to closed

### loop operation). At each CW inlet temperature , the net 

### power generated (MWe), hotwell temperatures (O F)/condenser backpressures (in-

### Hg) for each main condenser shell , and the condenser output temperatures (O F) were recorded. These outputs were in turn used to correlate 

### quadratic fit equations for each output as a function of continuously 

### variable CW inlet temperatures (see Attachment 3 , Figures 3. 

### 2 and 3.3). These correlations ultimately allow for the limiting PNPS operational conditions to be calculated for all feasible CW inlet temperatures.



### PEPSE Analysis - Reduced Power Operation The PEPSE model allows for the calculation of system outputs and operational conditions as a direct function of various system inputs; however, these system outputs are fixed and may not be 

### used as an input variable to calculate operating conditions of the system (i. , the PEPSE model is limited to the unidirectional calculation of operational conditions via system input). To

UU This estimate utilizes components and operating procedures typically selected for 12 F ilpproach to wet bulb cooling towers.

30-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### evaluate performance in the full range of operating conditions 

### , the net thermal input (MWt) for 

### the system was iterated over a series of CW inlet temperatures to define quadratic correlations used to calculate the system output and operational conditions (i. , net power generated (MWe), hotwell temperatures (O F)/condenser backpressures (in-

### Hg) for each main condenser shell

### , and
the condenser output temperatures (O F)). Overall , the CW inlet temperature for each hour is input into a set of quadratic correlations 

### , which in turn allows for the calculation of the limiting operational parameters. 

### Baseline Closed-

## Loop Operation Parameters Using the 

### NWS meteorological data to calculate the hourly closed- loop cooling tower performance , and following the baseline 

### PEPSE analysis methodology described above , the bounding baseline closed-loop limits are described below.



### Condenser Vacuum As stated in Section 5.2 

### , the limiting parameters for a theoretical closed- loop conversion of 

### PNPS are a condenser vacuum of 4 in- Hg and a continuous operational hotwell temperature of 118 

## F. At baseline conditions , the condenser 

### vacuum and hotwell temperature are highly correlated (see Attachment 3 , Figure 3. 1). As a result, comparisons between the two can be made 

### on general basis to define the limiting parameter. According to Attachment 3 , a condenser vacuum of 4 in-

### Hg is comparable to a hotwell temperature of approximately 125 

### F. As such , the hotwell temperature of 118 

### F is determined to be more bounding than condenser vacuum, and therefore used as the continuous operation limit in this analysis.



### Hotwell Temperature Hotwell A and B temperatures were evaluated at the continuous operation limit of 118 F. Per 

### this PEPSE model analysis , the baseline closed- 

### loop operation of hotwell B 

### bounds that of
hotwell A. Therefore , throughout the 

### following analysis , the more 

### limiting hotwell B temperature has been selected as operative. 

## Reduced Power Operational Parameters

Similar to the baseline closed- 

### loop operational parameters , the reduced 

### power operational 

### parameters use the NWS meteorological data , along with the hourly inlet water temperature. 

### These parameters are used to calculate the theoretical power generation lost in order to maintain 

### plant operational parameters 

### below their continuous operation limits. Per the methodology 

### described in Section 5. , the CW input temperature is used to create a quadratic correlation 

### allowing for the calculation of the limiting system operational parameters. The power reduction 

### is calculated hourly by deducting the theoretical power produced at the closed- loop continuous 

### operation limit from the operating power level generated under the current once- through 

### configuation. PNPS 

### , as with all nuclear power plants 

### , is not configured in such a way that enables dramatic short-

### term power 

### reductions. Significant power reduction at 

### PNPS requires initiating and concluding procedures varying in length but often extending over beyond the stated hourly 

### power loss event. This manner of operation is disruptive of station operations and may extend power losses. As a result, calendar days (i. 

### , days experiencing at least one hour of power loss) are more representative of the power loss duration likely to be experienced at PNPS.

31-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### Hotwell Temperature As previously discussed

### , the hotwell B temperatue bounds the hotwell A temperature and the 

### condenser pressure. Limited to the bounding hotwell B operation , Table 7 was created , and 

### contains the number of hours and calendar days with a net power generation loss experienced by PNPS.

Table 7 Net Power Generation Loss
Hotwell B :5 118 Power Loss Required Hours Calendar Days Power;: 20 MWe 8083 356 Power;: 40 MWe 8054 356 Power;: 60 MWe 7604 346 Power;: 80 MWe 7040 330 Power;: 100 MWe 6411 308 Power;: 120 MWe 5816 285 Power;: 140 MWe 5240 262 Power ;:160 MWe 4716 240 As shown in Table 7 , an ambient power reduction greater than 20 MWe (i. , those times with an active thermal reduction 9m ) occurs an average of 8083 hours at the continuous operation limit
of 118 

### F. The limiting power reduction necessary to maintain hotwell B' s temperature less than 118 F is 441 MWe. Likewise , an active thermal reduction 

### occurs an average of 356 calendar days per year to maintain the continuous operation limit of 118 

### For determining the time in which active power reduction is required to limit hotwell B below the continuous operation temperature , Tables 3. 

### 3 through 3. 

### 6 of Attachment 3 were created to list the frequency of consecutive occurrences requiring active power reduction. Per Attachment , continuous active power reduction is required for an average of 304 days per year to limit the hotwell B temperature to 118



### Power/Flow Operating Map 

### As discussed in Section 

### 5.2.4 a BWR must operate with certain restrictions , whereby the constraints imposed by equipment are used to 

### create a power/fow map for the operation of PNPS 

### , included as Attachment 5 

### , Figure 5.2. The PNPS power/fow operation map mirrors the 

### PEPSE model results such that a decrease in core flow rate yields a proportional decrease in net
thermal load

### , which in turn yields a decrease in net power generated. As such

### , the power/fow operating map validates the PEPSE results obtained and provides baseline operational values for the core flow rate pump.

m Active power reduction is defined as the time at which power losses are beyond the summation of parasitic losses and those directly associated with higher inlet temperatures.

32-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### In addition to analyzing the reduction in net power generation

### , analysis of the hours of operation at less than 80% net thermal load (i. , the monitored region threshold) is conducted. To this end 

### hotwell B experiences an average of 4787 hours per year at 118 

### F operating at less than 80% net 

### thermal load. Additionally, hotwell B experiences an average of 242 calendar days limited at 118 

### F operating a minimum of one hour at less than 80% net thermal load. Exceeding the 80% thermal limit would implicate nuclear safety concerns and ultimately result in a shutdown of the 

### plant. As a result , the calculated calendar days with 

### active power reduction provide a conservative estimate that includes the extensive time required to bring the Station to normal operation after a shutdown.

Seasonal/Daylight Closed-

### Loop Power Reduction As the operation of cooling towers is driven primarily by ambient environmental temperatures 

### seasonal and daylight conditions have a significant impact on PNPS closed-loop operation. Attachment 3 

### , Section 2 defines the net power loss attributed to conversion to a closed- loop cooling system on a monthly and hourly basis (i. 

### , monthly figures/tables are provided listing average closed- 

### loop power loss for each I-hour period of the day). On average 

### , July and August experience the greatest power reduction, with an average monthly 

### power loss of approximately 291 MWe occurring at a hotwell B limit of 118 F. Examining July 

### and August further

### , the greatest hourly power reduction occurs between 9am and 4pm

### , with an hourly power loss of approximately 309 MWe occurrng at a hotwelllimit of 118 

### F during this time period. 

## Summary of Reduced Power Operational Impacts The limiting 

### operational parameter (hotwell B 

### temperature) for PNPS baseline closed- loop operation was analyzed using the PEPSE model and the results displayed in Table 7. 

### Conversely, to evaluate the effect exceeding these limits has on PNPS operation , the overall heat 

### load was varied to calculate the power reduction necessary to maintain parameters at or below their operational limits. The power reductions necessary to limit hotwell B temperatures below the primary bounding and 

### power/fow map thermal limits are summarized in Table 8 below.

Table 8 

### Closed-

### Loop Limiting Operation Parameters Hotwell B :: 118 Operational Limit 1997-2006 Average Description Hours Calendar Days Power Loss )0 100 MW e 

### MIl 308 Heat Loss 0: 80% MWt 4787 242 As shown in Table 8 , the overall effect of a closed- loop conversion on plant operation, examined 

### using the PNPS power/fow operating map, is a net thermal load reduction of such an extent that 

### nuclear safety concerns occur during a significant portion of the year. Taking into account the extensive amount of time required to return the Station to operation after a plant shutdown, the 

### calculated calendar days of active power reduction are conservatively understated. To this extent

### , operation of PNPS below a net thermal load of 80% is not feasible , and operation of 

### PNPS near the conditions above increases the likelihood of transients , implicating nuclear safety

33-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter concerns. Based on this analysis 

### , closed-

### loop conversion of PNPS represents an infeasible CW cooling technology.

34-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

## Alternative Impingement/Entrainment Reduction Technologies This section evaluates the following alternative technologies in three categories , with the primary focus of the technology (reducing either 

### impingement mortality or entrainment mortality) indicated.
1) Modified traveling screens and fish handling and return systems a. Upgraded fish return trough (impingement)

b. Coarse mesh Ristroph screens (impingement)

c. Fine mesh Ristroph screens (entrainment)

d. Dual- flow conversion traveling screens (impingement)

e. Multi- disc screens (impingement)
f. WIP screens (impingement) g. Angled traveling screens and modular inclined screens (impingement) 

## 2) Screening/barrier systems

a. Fish net barriers (impingement) b. Wedgewire screens ( entrainment/impingement)
c. Aquatic micro 

### fitration barriers (impingement)

d. Behavioral barriers (impingement)
3) Alternative intake location (impingement/entrainment) 

## Modified Traveling Screens and Fish Handling and Return Systems According to Normandeau (Ref. 10.23), ten different species of fish account for approximately 

### 98% of recent (i. 

### , 2002 through 2007) impingement events at PNPS. Approximately 89% of this impingement involves two species (Atlantic menhaden and silversides) that Normandeau has advised do not

### , and are not expected to 

### , survive screen impacts associated with impingement , no 

### matter the screening technology employed. Therefore , reductions in impingement mortality with modified traveling screens are expected to be minimal at PNPS. Nonetheless , for completeness , a suite of alternative screening technologies are evaluated below. Moreover , as discussed below

### , the fish return trough is consistent with the current industry standard. Therefore , consideration of additional fish return technology is not warranted. 1.1 

### Upgraded Fish Return Trough During normal (i. , non-severe weather event) operations 

### , the fish return sluiceway, which was 

### added in 1980 and designed to maximize survivability of the impinged fish (Ref. 10. 8), is used. 

### As explained previously, the existing fish return sluiceway was designed to minimize the stress to impinged fish and maximize their surivability through the sluiceway, and 

### remains consistent with standard industry specifications for such sluiceways , given site constraints at PNPS. Therefore , no upgrades to the fish return sluiceway are warranted.

35-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### Coarse Mesh Ristroph Screens Modified Ristroph buckets can be and, in certain instances , have been retrofitted onto existing 

### traveling water screens , including at nuclear facilities 

### , to work in conjunction with the debris removal function of the existing traveling water screens. With the addition of Ristroph screens , shown in Figure 5 , the fish trough for the sluiceway would
need to be 

### restructured. The Ristroph screen would unload the impinged fish to a location 

### opposite to where they are currently 

### unloaded. This is because the current traveling screens 

### unload fish while they are ascending, but the Ristroph modified screens are unloaded while the screens are descending. Therefore 

### , a new trough would need to be constructed to collect the fish
and carr them down to the fish return sluiceway.

Lo, ; Pr swre spra,s

Fish FlelurnTrough

Captured Fish/De bris

High Pf' sS:lJre Spray, Debris Trough



### Figure 5 Modified Ristroph Screen 

### Approximately 89% of the impinged 

### aquatic organisms would not experience decreased impingement mortality by adding Ristroph buckets. Thus , Ristroph buckets are not further considered here. 1.3 

### Fine Mesh Ristroph Screens At certain facilities , traveling water screens can be further modified to incorporate screen meshes 

### with openings as small as 0. 

### 5 mm to collect fish eggs and larvae and return them to the source water body. As Normandeau indicates (Ref. 10. 

### 23), for many species and early life stages , mesh

sizes of 0. 5 to 1. 

### 0 mm are required for effective screening. Such screening presents several biological and engineering concerns. 

### Per input from Normandeau

### , the primary biological concern with fine mesh screens is that they function by impinging early organism life stages that are entrained through coarse mesh screens. Depending on 

### species and life stage , mortality from impingement can exceed entrainment

36-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### mortality. In order for fine mesh screens to provide a meaningful benefit in protecting fish 

### impingement survival of target species and life stages must be substantially greater than survival through the CW system, circumstances not demonstrated here. Generally and at PNPS in particular

### , to accommodate fine mesh screens while maintaining 

### existing head loss across the screen, the size of the intakes would need to be greatly expanded because a much larger fine mesh screen would be required to provide the same total open area as the coarse mesh screens. The primary engineering concern implicates nuclear safety. Although
EP A references the Brunswick Nuclear Plant as though fine mesh screens have been successfully applied there (Ref. 10. , Chapter 4 

### , Section 2.3.2), their application has been limited. As stated in the Brunswick 2000 Environmental Monitoring Report (Ref. 10. 21), " (d)uring periods of high 

### vulnerability resulting from extreme lunar tides or increased sediment and debris loading, the NPDES permit allows for removal of a portion of the fine-mesh screens to prevent plant scrams. High vulnerability conditions existed for most of the year. Installation of non safety-related 

### components with the potential to increase reactor scrams (shutdowns) is contrary to current operational standards in the nuclear industry. 

## For these reasons , fine mesh screens are not 

### considered technologically feasible for implementation at PNPS. 

## 1.4 Dual- Flow Conversion Traveling Screens At some facilities 

### , including at nuclear facilities , existing through- 

### flow traveling screen installations can be retrofitted to use dual- 

### flow traveling water screens (Ref. 10. 

### 7), which because of the increased area used to pass water through the screens , can reduce the through

### screen velocity. Conceptually, a dual-

### flow traveling water screen is mechanically similar to a through- 

### flow screen that has been rotated ninety degrees in the flow channel. The modification 

### consists of the installation of a special wall plate mounted perpendicular to the flow in place of the existing screen. The dual- 

### flow screen is then lowered into the well , with baskets parallel to the flow , on the upstream side of the wall 

### plate. An inlet opening in the wall plate allows 

### screened water to pass to the pumps. An alternative arrangement uses a specially constructed 

### screen mainframe that includes a wall plate made as an integral part of the screen frame with extensions or " wings " that fit into existing embedded guides. 

### Approximately 89% of the curently impinged aquatic organisms at PNPS would not experience 

### decreased impingement mortality by replacing the existing through-flow screens with dual-flow screens. Thus , dual flow screens are not further considered here. 

### It must be noted that the existing penetrations in the CWIS deck for the traveling screens are not 

### of adequate size to accommodate a reduction in velocity if retrofitted with dual- flow traveling screens. As stated in Section 2. 

### , the through-screen velocity with the existing through- flow traveling screens is 1.57 fps , which would increase to 1.77 fps with dual flow screens of the same 

### mesh sizing (due a reduction in screening width from 10 ft to 4. 75 ft). Alternatively, a reduced 

### velocity with dual flow screens would require a new CWIS or extensive modifications to the existing CWIS; such an implementation would require an extended forced outage.

37-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### Multi-Disc Screens Multi- 

### disc screens can , and in certain instances , have been retrofitted onto existing traveling 

### water screens at nuclear facilities. However, the use of such screens has been targeted from the perspective of Station performance (debris removal) rather than as a fish protection measure. Multi- disc screens 

### , shown in Figure 6 (Ref. 10. 9), are oriented the same way as traditional through- flow screens. Multi- 

### disc screens are comprised of circulating sickle shaped mesh panels 

### that are connected to a frame via a revolving chain. The linked mesh panels are guided on each 

### side forming a unit together with the support. The forces applied by the flowing water to the center of the mesh panels are transmitted via supporting beams into the supporting structure. In
the center 

### , the mesh panels are supported by rollers. Raw water flows directly through the mesh 

### panels. The debris retained at the face of the ascending mesh panels is transported with debris carriers to floor level. There 

### , it is removed by means of a spray-water device. This reduces the amount of carrover into the condenser intake stream.



## Figure 6 Multi-Disc Screen Approximately 89% of the currently impinged aquatic organisms at PNPS would not experience 

### decreased impingement mortality by adding multi- disc screens. Thus 

### , this technology is not further considered here. 1.6 

### WIP Screens At some facilities , existing through-

### flow traveling screen installations can be retrofit to use WIP screens; however

### , there have been no instances of such a 

### retrofit at a United States nuclear facility, and therefore the technology is unprecedented in the domestic nuclear industry.

38-

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### screen face that fish may avoid as they are directed to the escape bypass. Modular inclined 

### screens (MIS) are a variation of the angled screens whereby modules are provided which consist 

### of an entrance with trash racks 

### , dewatering stop logs in slots , an inclined screen set at a 10- degree angle to the flow , as well as a bypass to direct fish back to the source water body. In order to install angled traveling screens or modular inclined screens at PNPS , the entire CWIS 

### would have to be replaced because all of the components of the intake are oriented perpendicular to the shoreline. Moreover

### , the bypass system is an integral part of the intake. The installation of 

### modular inclined 

### screens requires a nearly complete CWIS replacement because modular 

### inclined screens are only supplied as complete systems. In addition

### , an extended forced outage would be required to modify/replace the CWIS and install the modular inclined screens. 

### Because of the unproven nature of this kind of CWIS change 

### , retrofit of the PNPS CWIS to 

### accommodate the installation of angled traveling 

### screens or modular inclined screens is considered technologically infeasible. Moreover

### , approximately 89% of the currently impinged aquatic organisms at PNPS would not experience decreased impingement mortality by adding angled traveling screens or modular 

### inclined screens. Thus , these technologies are not further considered here.
Screening/Barrier Technologies
Fish Net Barriers 

### Fish net barriers are wide-mesh nets that are installed in front of CWISs. The water entering the CWIS must first pass through the openings in the mesh. The size of the mesh openings limits the 

### size of the organisms that can pass through the net. According to Normandeau (Ref. 10.23), in 

### order to be successful 

### , the nets must have a large surface area such that the velocity through the net is very small (usually :s 0. 5 fps). Otherwise , organisms would become impinged on the screen. Barrier nets have not been used at nuclear facilities 

### , due to nuclear safety concerns associated *****



### with the deployment of such a net. Dunng a heavy ocean storm, the net may become loose and clog the intake , cutting off the 

### SSW supply required for safe shutdown of the plant. Therefore 

### , the deployment of a barrier net at 

### PNPS is considered technologically infeasible because it implicates nuclear safety concerns.



### Cylindrical Wedgewire Screens Cylindrical wedgewire screens are designed to reduce entrainment and impingement in two ways. First

### , organisms susceptible to entrainment cannot pass through the small slot size in the

***** The installation of equipment either in the embayment or lodged to the protective breakwaters has proved diffcult at PNPS. For example , during the summer of 2002 , in response to an order from the NRC mandating security enhancements to address concerns arising from September 11 , 200 I , PNPS installed barrier booms across the entrance to the intake embayment and across the discharge canal. The intake boom was anchored in stone at each end of the of the embayment jetties and was also anchored to the bottom of the embayment from buoys located
at 100- foot intervals on the boom. The discharge boom was anchored in stone at each end but was free floating in the canal. A strong Northeaststorm that year destroyed both booms , which NRC did not require PNPS to attempt to replace.

41-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter 

### screen. Screen mesh sizes range from 0. 5 to 10 mm 

### , with the most common slot sizes in the 1.0

to 2. 0 mm range. Wedgewire 

### screens have two principal configurations: wide-slot screens with 

### larger screen mesh sizes that primarily seek to reduce impingement mortality, and narrow slotscreens with small screen mesh sizes that primarily seek to reduce entrainment mortality.
EP A has expressed significant reservations about the application of wedgewire screens at nuclear facilities comparable to PNPS. As stated in Section 2.2. 3 of EPA' 

### s TDD (Ref. 10. 12), " (fJinemesh wedgewire screens (0. 5 - 

### 1 mm) also have the potential 

## for use to control both 

### impingement and entrainment. EP 

### A is not aware of the installation of any fine-mesh wedgewire 

### screens at any power plants with high intake flows (:: 100 MGD). However

### , such screens have 

### been used at some power plants with lower intake flow requirements (25 to 50 MGD), which 

### would be comparable to a very large power plant with a closed-cycle cooling system. With the 

### exception of Logan, EP A has 

### not identified any full-scale performance data for these systems. 

### They could be even more susceptible to clogging than wide-mesh wedgewire screens (especially in marine environments). It is unclear whether clogging would simply necessitate more intensive maintenance or preclude their day-to- day use at many sites. 

### In the current CWIS configuration

### , a nuclear safety concern is associated with the installation of 

### wedgewire screens. During severe ocean storms , the wedgewire screens may be dislodged damaged

### , or clogged due to excessive 

### debris. This would likely lead to the intake becoming clogged

### , which would cut off the SSW supply, which is required for safe shutdown of the plant; as EPA noted at page 4- 

### 13 of its TDD (Ref. 10. 12), there are no full-scale data regarding 

### wedgewire screens 

### available for marine environments where biofouling and 

### clogging are significant concerns. 

## For all of these reasons , the installation of 

### wedgewire screens at 

### PNPS is considered 

### technologically infeasible. In any event , to address these concerns 

### , a new CWIS or extensive
modifications to the 

### existing CWIS would be required to isolate the 

### SSW supply from the wedgewire screens used for the CW system. An extended forced outage would be required to implement these changes to the CWIS.



### Aquatic Microfiltration Barriers Aquatic micro fitration 

### barrier systems (e. 

### , Gunderbooms) are barriers that employ a filter fabric designed to allow for passage of water into a CWIS 

### , but to exclude aquatic organisms. These systems are designed to be placed 

### some distance from the CWIS within the source 

### waterbody and to act as a filter for the water that enters into the cooling water system. These 

### systems may be floating, flexible 

### , or fixed. Because these systems generally have such a large surface area, the velocities that are maintained at the face of the permeable curtain are very low. Similar to a fish barrier net, a nuclear safety concern is associated with the deployment of aquatic
micro filtration barriers. During a severe ocean storm , the net may 

### become loose and clog the intake 

### , cutting off the SSW supply required for safe shutdown of the plant. Therefore , aquatic

micro fitration barriers are not considered technologically feasible for use at PNPS ttttt

tttt For these nuclear safety-related reasons , the New York State Department of Environmental Conservation (NYSDEC) has adopted the conclusion that aquatic micro fitration barriers and similar technologies are not feasible at Indian Point Energy Center, a nuclear facility with a CWIS along the Hudson River in Buchanan , New York (Ref. 10.24 , p. VII-43, as adopted by NYSDEC in Ref. 10.25).

42-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter

Behavioral Barriers Behavioral barriers use a fish' 

### s natural reactions to stimuli to deflect it away from intakes. The 

### three main behavioral barrier systems are 

### bubble barriers , artificial lighting arrays , and underwater acoustic fish deterrence systems. There are at least two installed operating acoustic 

### fish deterrence systems: one at the D. C. Cook Nuclear Plant in Bridgman

### , Michigan (Lake Michigan), and the other at the Entergy s J. 

### A. FitzPatrick Nuclear Power Plant (JAFNPP) near Oswego , New York (Lake Ontario). JAFNPP operates a state-of-the-art Fish Deterrent System (FDS) deployed at the offshore CWIS 

### typically from the first week in April into October of each year. The sonic FDS consists of nine projector housings symmetrically installed on top 

### of the offshore velocity cap and employed 

### during the spring, summer

### , and fall months. The projectors are removed for the winter months due to the potential damage from ice packs , then redeployed in the spring. 

### The FDS system emits a high frequency broadband sound (122 - 128 KHz) at a source level of 190 decibels. According to Normandeau (Ref. 10.23), alewife , and perhaps other clupeids , may avoid this high frequency broadband sound, because Clupeiformes have swim bladders and inner ear specializations that enable these fish to detect sounds (Ref. 10. 

### 10), with the result that the high frequency sound of the FDS triggers an avoidance mechanism in such species. The site-specific feasibility of a FDS is 

### highly dependent on the impinged species and their 

### contribution to historical impingement

### , as well as their response to sound , and the engineering 

### constraints associated with the harsh marine environment. Extensive further study is required to ascertain the feasibility of this technology. 

### Alternative Intake Location As discussed in Section 2. 

### , the CWIS at PNPS draws water from Cape Cod Bay through an embayment formed by two substantial breakwaters. EP 

### A has asked PNPS to consider extending its intake 

## fuher offshore. 

### Offshore intakes typically draw in water via vertical inlets with velocity caps placed on top. These intakes are located far from the screen house and slightly above the floor of the source body of water. Velocity caps are covers that are placed over vertical inlets at offshore intakes; 

### they are used to reduce I&E by reducing fish, eggs 

### , and larvae drawn into the intake system. As 

### shown in Figure 9 

### , a velocity cap slows and converts vertical flow into horizontal flow at the
entrance of the intake (Ref. 10. 11).

43-Pilgrim Nuclear Power Station Response to United States Environmental Protection Agency CW A 9308 Letter

SEA BED (II

. . '" . . " ...

' : ''' . . t . . VELOCITY

1'1" '1" 1'"

FLOW FLOW

'01 ::: 

## . ' . ' ' . .. . : . . . . .:



### Figure 9 Typical Velocity Cap Flow Direction 

### Velocity caps are sized to achieve a low intake velocity between 0. 5 and 1. 5 fps 

### , which may reduce impingement (Ref. 10. , Chapter 4 , Appendix A). In order to connect the velocity cap to the screenwell of the existing CWIS , a large diameter intake tunnel would need to be constructed 

### underneath the floor of the bay. The design, location, and depth of such an offshore intake would 

### be dependent on technological limitations and the site-specific location selected with respect to potential biological benefits. 

### Per Normandeau (Ref. 10.23), no site-specific fisheries data are available with which to assess potential I&E at an offshore intake location. Detailed field studies of ichthyoplankton and local fish distribution are required to establish whether an offshore location is preferable and what that 

### location would be. The engineering feasibility of an offshore intake cannot be evaluated without first establishing this location.

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