EVALUATION OF ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

Prepared for Entergy Nuclear Indian Point 2, LLC, and Entergy 

Nuclear Indian Point 3, LLC 

Prepared by: 

Enercon Services, Inc. 

500 TownPark Lane, Suite 275 

Kennesaw, GA 30144 

February 12, 2010 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

i 

TABLE OF CONTENTS

Attachments ............................................................................................................................... iii

Executive Summary ................................................................................................................... iv

1 Background and Introduction ................................................................................................. 1

1.1 Purpose of this Evaluation................................................................................................ 1

1.2 Scope and Design Objectives ........................................................................................... 1

2 IPEC Stations and Cooling Systems Description ................................................................... 2

2.1 IPEC Units 2 and 3 Overview .......................................................................................... 2

2.2 Description of Plant Processes ......................................................................................... 2

2.2.1 Nuclear Steam Supply System Operations ............................................................... 2

2.2.2 Condenser Operation ................................................................................................ 3

2.2.3 Effluent Treatment Operation ................................................................................... 4

2.3 Source Waterbody ............................................................................................................ 5

2.3.1 Source Waterbody Description ................................................................................. 5

2.3.2 Hydraulic Zone of Influence ..................................................................................... 6

2.3.3 Intake Volume Calculation ....................................................................................... 6

2.4 CWIS Description ............................................................................................................ 7

2.4.1 Physical Description, Location and Depth of CWIS ................................................ 7

2.4.1.1 Current Traveling Water (Ristroph) Screens ..................................................... 9

2.4.1.2 Fish Handling and Return System ................................................................... 11

2.4.2 CWIS Flow Description .......................................................................................... 13

2.4.2.1 Pump Descriptions ........................................................................................... 13

2.4.2.2 Design Intake Capacity .................................................................................... 16

2.4.2.3 Flow Reductions from Baseline ...................................................................... 17

2.4.2.4 Through-Screen Velocity ................................................................................ 19

2.4.2.5 Seasonal Changes in CWIS Operation ............................................................ 21

2.4.3 Biocide Treatment ................................................................................................... 21

2.5 Discharge System ........................................................................................................... 21

2.6 Cooling System Equipment ............................................................................................ 23

2.7 License Status ................................................................................................................. 24

3 Existing CWIS Technologies and Operational Measures that Affect I&E ........................... 25

3.1 Description of Existing CWIS Technologies and Current Operational Measures that 

Affect I&E ................................................................................................................................ 25

3.1.1 Existing Traveling Water Screens .......................................................................... 25

3.1.2 Existing Fish Handling and Return System ............................................................ 26

3.1.3 Flow Reductions ..................................................................................................... 27

3.1.3.1 Dual/Variable Speed Pumps ............................................................................ 27

3.1.3.2 Historic Flow Reductions ................................................................................ 27

3.1.3.3 Outage Schedule .............................................................................................. 29

3.2 Percent Reductions in I&E from Baseline for Existing CWIS Technologies and Current 

Operational Measures ............................................................................................................... 29

4 I&E Reduction Technologies ................................................................................................ 30

4.1 Upgrade of the Existing Fish Handling and Return Systems ......................................... 30

4.2 Traveling Water Screens ................................................................................................ 31
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4.2.1 Alternative Ristroph Screens .................................................................................. 32

4.2.2 Dual Flow Traveling Water Screens ....................................................................... 35

4.2.3 Angled Traveling Screens ....................................................................................... 39

4.2.4 WIP Screens ............................................................................................................ 43

4.2.5 MultiDisc® Screens ................................................................................................. 48

4.3 Passive Intake Systems................................................................................................... 51

4.3.1 Cylindrical Wedgewire Screens .............................................................................. 51

4.3.2 Perforated Pipe Inlets .............................................................................................. 63

4.3.3 Porous Dikes/Leaky Dams ...................................................................................... 65

4.4 Barrier Technologies ...................................................................................................... 68

4.4.1 Aquatic Filter Barriers ............................................................................................ 68

4.4.2 Fish Barrier Nets ..................................................................................................... 76

4.4.3 Behavioral Barriers ................................................................................................. 79

4.4.3.1 Light Guidance System ................................................................................... 80

4.4.3.2 Acoustic Deterrents ......................................................................................... 81

4.4.3.3 Air Bubble Curtains ......................................................................................... 82

4.4.3.4 Electrical Barriers ............................................................................................ 84

4.4.4 Louver System ........................................................................................................ 86

4.5 Alternate Intake Location ............................................................................................... 88

4.6 Flow Reduction .............................................................................................................. 90

4.6.1 Dual/Variable Speed Pumps ................................................................................... 91

4.6.1.1 Flow Reduction Parameters/Methodology ...................................................... 91

4.6.1.2 Flow Reduction Impacts .................................................................................. 93

4.6.1.3 Effects of Further Operational Flow Reductions ............................................. 97

4.6.1.4 Conversion of Unit 2 to Variable Speed Pumps .............................................. 98

4.6.2 Use of Recycled Wastewater as Cooling Water ..................................................... 99

4.6.3 Outage Timing ...................................................................................................... 101

4.6.4 Radial Wells .......................................................................................................... 102

4.7 Alternative Heat Rejection and Recirculation .............................................................. 105

4.7.1 Evaporative Ponds ................................................................................................ 105

4.7.2 Spray Ponds .......................................................................................................... 107

4.7.3 Cooling Canals ...................................................................................................... 108

4.7.4 In-River Heat Exchangers ..................................................................................... 110

5 Conclusions ......................................................................................................................... 113

6 References ........................................................................................................................... 119
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Attachments 

Attachment 1 – Major Components; Vendor Data and References 

Attachment 2 – Post-Modification Site Renderings and Conceptual Drawings 

Attachment 3 – Evaluation of VSP Performance 

Attachment 4 – Capital Costs Assessments 

Attachment 5 – Figures 

Attachment 6 – Biological Assessment 

Attachment 7 – Recycled Wastewater Cooling 
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Executive Summary

Entergy Nuclear Indian Point 2, LLC, and Entergy Nuclear Indian Point 3, LLC (collectively, 

Entergy) have submitted a timely and complete renewal application for a State Pollutant 

Discharge Elimination System (SPDES) permit (SPDES Permit NY0004472) for Indian Point 

Energy Center (IPEC) nuclear powered electric generation stations 2 and 3 (individually, Unit 2 

and Unit 3, respectively, and collectively, the Stations). The New York State Department of 

Environmental Conservation staff (NYSDEC) has proposed modifications in the Stations’ draft 

SPDES permit, including possible construction and operation of cooling towers in a closed-loop 

cooling configuration (NYSDEC Proposed Project). Consideration of closed-loop cooling is 

subject to certain feasibility and alternative technologies assessments, as directed by the 

NYSDEC Assistant Commissioner’s August 13, 2008 Interim Decision (Interim Decision). 

Accordingly, the NYSDEC may revisit its proposed modifications to the draft SPDES permit for 

the Stations and change them pursuant to Entergy’s feasibility and alternative technologies 

assessments.1

As part of the alternative technologies assessment, Entergy retained Enercon Services, Inc. 

(ENERCON) to determine whether an alternative technology exists that “will minimize adverse 

environmental impact to a level equivalent to that which can be achieved by closed-loop 

cooling” (see the Interim Decision). In order to obtain reliable aquatic information associated 

with the existing intake technologies at each Unit, closed-loop cooling, and each alternative 

technology evaluated, ENERCON relied on aquatic and biological information, including 

comprehensive entrainment and impingement data, from biological experts Lawrence W. 

Barnthouse of LWB Environmental Services, Inc., Douglas G. Heimbuch of AKRF, Inc., Mark 

T. Mattson of Normandeau Associates, Inc., and John R. Young of ASA Analysis & 

Communication, Inc. (collectively, the Biological Experts). 

This Report identifies and evaluates potential alternative technologies to closed-loop cooling, 

focusing on: (1) technological or engineering feasibility; (2) comparative effectiveness in terms 

of impingement and entrainment losses (I&E) (based on an evaluation prepared by the Biological 

Experts, Attachment 6); and (3) estimated cost, based on a detailed, site-specific conceptual 

design. 

Cylindrical wedgewire screens (CWW) are technologically feasible at the Stations. This 

technology also shows great promise in reducing I&E, based on extensive technical work 

performed by Alden Laboratories in 2003, 2004 and 2005, as analyzed by the Biological Experts. 

In addition, CWW screens have been implemented at a facility with a total intake flow rate 

comparable to the total intake flow rate at the Stations. Specifically, Oak Creek Power Plant in 

Milwaukee, Wisconsin operates the current largest installation of cylindrical wedgewire screens, 

which includes an offshore intake system that filters a flow rate of 1,560,000 gallons per minute 

(gpm) at a through-screen velocity of 0.5 feet per second (fps) with a 16% margin. The CWW 

system at Oak Creek became operational in January 2009 and is designed to operate year round. 

This new information provided ENERCON with recent valuable data to evaluate CWW at the 

IPEC Stations. 

 

1

The Interim Decision provides that NYSDEC must evaluate Entergy’s alternative technology assessment and 

commence a proceeding to modify the draft SPDES permit if it determines that the proposed alternative technology 

may be substituted for the NYSDEC Proposed Project (i.e., closed-loop cooling). 
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v 

Several conceptual CWW screening array designs, each fitting within the Stations’ exclusionary 

zone, were created. Although the United States Environmental Protection Agency (EPA) 

typically recommends cylindrical wedgewire through-slot velocities at or below 0.5 feet per 

second (fps), NYSDEC has indicated interest in through-slot velocities at or below 0.25 fps. As 

such, separate conceptual cylindrical wedgewire screen systems were designed to provide a 

maximum through-slot velocity of at or below both 0.5 fps and 0.25 fps. 

Cylindrical wedgewire screens are expected to achieve biological benefits (i.e., reductions in 

I&E) comparable to those that could be achieved by the NYSDEC Proposed Project. 

Specifically, operation of cylindrical wedgewire screens with a mesh size of 2.0 mm and 

through-slot velocity at or below 0.5 fps has the potential to reduce equivalent age 1 (EA1)2

impingement and entrainment losses from the regulatory baseline3

 by as much as approximately 

99.9% and 89.8%, respectively. In addition, the Biological Experts provided an evaluation of the 

cumulative reductions in I&E over the expected lifetimes of Unit 2 and Unit 3 associated with 

cylindrical wedgewire screens, as compared to closed-loop cooling. This analysis accounted for 

a current proposal based on cylindrical wedgewire screen studies to install this technology at 

Unit 2 by 2013 and Unit 3 by 2015.4

 Closed-loop cooling, by contrast, would not be complete 

until 2029 based on a schedule derived by ENERCON, with input from counsel and Spectra 

Energy Transmission, LLC (owner of the Algonquin Gas Transmission Pipeline, which would 

require relocation in order to construct a closed-loop cooling tower at Unit 3).5 Based on this 

evaluation, the estimated cumulative total reduction in EA1 I&E for cylindrical wedgewire 

screens (98% and 87% for EA1 impingement and entrainment losses, respectively) would be 

greater than the estimated cumulative total reduction in EA1 I&E for closed-loop cooling (86% 

and 50% for EA1 impingement and entrainment losses, respectively). 

Nonetheless, while promising, before a specific CWW array can be located and operated at the 

Stations, site-specific analyses would be required to determine the optimal location and slot 

width for reducing entrainment, with particular focus on the slot width at which fouling (i.e., the 

accumulation of matter on the screens) would not be a concern to Station operations. 

Other alternative technologies were evaluated, but were not recommended due to site-specific 

issues. As detailed in this Report, for instance, due to nuclear-safety issues, the use of aquatic 

filter barriers or other technologies that could potentially block the service water intake at each 

Unit (e.g., fish barrier nets, porous dikes) are not considered as primary alternatives. Several 

technologies (e.g., spray ponds, evaporative ponds, cooling canals, radial wells) were identified 

as infeasible due to lack of available land area. The use of coarse or fine mesh traveling water 

screens of a different mesh size than currently employed at the Stations would not be expected to 

 

2

 As noted in Attachment 6, natural mortality of early life stages of fish (i.e., eggs and larvae) is very high. 

Conversion to equivalent age-1 fish allows I&E that occur at different life stages to be combined into a single metric 

that weights the losses according to the number that could, on average, have survived to age 1. 

3

 As noted in Attachment 6, the regulatory baseline is a regulatory construct that employs certain operation and 

survival assumptions. This baseline has been used by NYSDEC in SPDES permit proceedings for other New York 

power plants. 

4

 ENERCON has reviewed the proposed schedule described in the biological cumulative analysis (Attachment 6); a 

detailed schedule for implementation of cylindrical wedgewire screens at the Stations would be created during the 

detailed design phase. 

5

 Engineering Feasibility and Costs of Conversion of Indian Point Units 2 and 3 to a Closed-Loop Condenser 

Cooling Water Configuration, Enercon Services, Inc., 2010 
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significantly reduce I&E beyond the existing screening systems. Several technologies (e.g., 

behavioral barriers) have been studied previously and identified as ineffective at the Stations and 

would require further evaluation to determine their site-specific technological feasibility. 

Upgrades to the existing fish return systems were not recommended because the Stations’ 

existing traveling water screens and fish return systems are considered state-of-the-art for 

impingement reduction. 
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AT INDIAN POINT UNITS 2 & 3 

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1 Background and Introduction 

Entergy retained ENERCON to work in conjunction with the Biological Experts to determine 

whether an alternative intake technology exists that will achieve reductions in I&E comparable 

to that of the NYSDEC Proposed Project. In order to obtain I&E information associated with the 

existing intake technologies at each Unit, the NYSDEC Proposed Project, and each alternative 

technology evaluated, ENERCON relied on aquatic and biological information, including 

comprehensive entrainment and impingement data, provided by the Biological Experts. This 

evaluation is pursuant to the Interim Decision, which provides that if Entergy proposes an 

alternative technology that reduces I&E to a level comparable to the NYSDEC Proposed Project, 

NYSDEC must commence a proceeding to modify the draft SPDES permit. 

1.1 Purpose of this Evaluation 

This Report evaluates the technological feasibility, comparative I&E reductions, and 

estimated costs of several alternative technologies. The Stations’ existing technologies and 

operational measures are also evaluated to provide a comparative basis for assessing 

alternative technologies. 

1.2 Scope and Design Objectives 

This Report provides the following: 

 In Sections 2 and 3, a detailed description of the operation and features of the existing 

cooling water intake structures (CWISs) at the Stations, intake flow characteristics, 

and recent, planned maintenance of the CWISs. These Sections also include an 

evaluation of the existing technologies and operational measures implemented at the 

Stations to reduce I&E. 

 In Section 4, an evaluation of several alternative technologies. 

 In Section 5, relevant conclusions. 
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2 IPEC Stations and Cooling Systems Description 

2.1 IPEC Units 2 and 3 Overview 

Entergy owns and operates Unit 2 and Unit 3, both located in Buchanan, New York on the 

east bank of the Hudson River. The primary activity of each Unit is the generation of electric 

power. Entergy Nuclear Indian Point 2, LLC also owns IPEC Unit 1, but it was removed 

from service in October 1974. Thus, this Report focuses on Units 2 and 3. 

Unit 2 and Unit 3 are Westinghouse Pressurized Water Reactors (PWRs) that produce steam 

for direct use in steam turbines in order to generate electricity. Unit 2 began commercial 

operation in August 1974 and currently generates electricity at a rated capacity of 

approximately 1078 MWe [Ref. 6.60]. Unit 3 began commercial operation in August 1976 

and currently generates electricity at a rated capacity of approximately 1080 MWe [Ref. 

6.64]. The CWISs provide cooling water to absorb waste heat rejected by the Stations. 

According to 40 CFR §125.93, a CWIS is defined as “the total physical structure and any 

associated constructed waterways used to withdraw cooling water from waters of the U.S. 

The cooling water intake structure extends from the point at which water is withdrawn from 

the surface water source up to, and including, the intake pumps.” Unit 2 and Unit 3 were 

designed, constructed, and licensed, and are operated, to withdraw cooling water from the 

Hudson River via two shoreline once-through CWISs. According to 40 CFR Part 125, 

§125.93, cooling water is defined as “ ...water used for contact or non-contact cooling, 

including water used for equipment cooling, evaporative cooling tower makeup, and dilution 

of effluent heat content.” 

2.2 Description of Plant Processes 

2.2.1 Nuclear Steam Supply System Operations 

PWRs are designed to produce electrical energy. Thermal energy is produced by the 

reactor and transferred to steam. The thermal energy in the steam is converted (via a 

turbine driven generator) to electrical energy. At Unit 2 and Unit 3, the exhaust steam is 

converted into water after leaving the turbine and returned to the steam generators as 

heated feedwater with dissolved and suspended solids removed. There are two major 

systems used by a PWR to convert the thermal energy of the fuel into electrical energy. 

The primary system transfers heat from the primary water to the steam generator, while the 

secondary system transfers the steam formed in the steam generator to the turbine 

generator. The expanded steam exhausted by the turbine generator is condensed into water 

by the flow of circulating water through the condenser tubes [Ref. 6.120]. 

The primary system is also called the Reactor Coolant System (RCS) and consists of four 

similar heat transfer loops connected in parallel to the reactor vessel. Each loop contains a 

reactor coolant circulation pump and a steam generator. The RCS also includes a 

pressurizer, a pressurizer relief tank, the associated piping, and the instrumentation 

necessary for operational control. The RCS transfers the thermal energy generated in the 

core to the steam generators where steam is generated to drive the turbine generator. The 

RCS also provides a boundary for containing the reactor coolant under operating 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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temperature and pressure conditions, and confines radiological materials. Demineralized 

water in the reactor coolant loops is maintained under high pressure to prevent the water 

from boiling. The pressurizer uses electrical heaters and water sprays to maintain water 

pressure in the reactor coolant loops [Ref. 6.64]. 

The secondary system is often called the Steam and Power Conversion System (SPCS). 

The SPCS is designed to remove heat from the reactor coolant in the steam generators, 

produce steam for use in the turbine-generators, condense the turbine exhaust steam into 

water, and return the condensed water to the steam generators as feedwater. The major 

components of this system include the tube side of the steam generators, the turbinegenerator, condensers, feedwater pumps, the associated piping, and the instrumentation 

necessary for operational controls. Feedwater enters the steam generators where it is 

converted into a steam-water mixture. After a steam swirl vane assembly separates the 

steam from the water particles, the steam rises through additional separators, which further 

reduce its moisture content. The saturated steam is then passed through the turbinegenerators. Each Unit has a tandem compound turbine comprised of one high pressure 

turbine and three low pressure turbines that rotate at 1800 rpm. The saturated steam is first 

passed through the high pressure turbine then through the low pressure turbines. From the 

low pressure turbines, the steam is exhausted into the condensers where it is condensed and 

de-aerated, and then returned to the cycle as feedwater to the steam generators [Ref 6.120]. 

A simplified schematic of a typical PWR plant is shown in Figure 2.1. 

Figure 2.1 Basic Arrangement of a PWR 

2.2.2 Condenser Operation 

The objective of the main condenser is to serve as a heat sink (i.e., a mechanism for heat 

removal) for turbine exhaust steam, turbine bypass steam, steam generator bypass steam, 

Hudson

River 

MSR
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

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and other flow [Ref. 6.120]. As such, cooling provided by the condenser is necessary to 

provide condensed steam (i.e., feedwater) for the steam generators. 

Although the Unit 2 and Unit 3 main condensers are not identical, they are similar in that 

they are of the single pass, divided water box, de-aerating type. Each consists of three 

shells, one for each low pressure turbine cylinder, and is located directly beneath the low 

pressure cylinders of the main turbine. The location of the condensers below the lowpressure turbines is indicative of their function, whereby the cooling water of the CW 

system condenses the steam exhausted from the turbine, which is then returned to the 

steam generators as feedwater. 

Hudson River water is the heat sink for the main condenser and its supported systems. The 

condenser hotwells are designed for 4-minute storage and are longitudinally divided to 

facilitate the detection of condenser tube leakages [Ref. 6.60; Ref. 6.64]. 

Each of the Unit 2 and Unit 3 condensers are rated at the following design parameters [Ref 

6.42]: 

Unit 2 Unit 3

Steam condensed 2.415×106 lbm/hr 2.453×106 lbm/hr 

Heat removed 2.32×109 BTU/hr 2.33×109 BTU/hr 

Absolute pressure 2.05 in-Hg 2.04 in-Hg 

Surface area 315,700 ft2

 286,125 ft2

2.2.3 Effluent Treatment Operation 

IPEC Unit 2 and Unit 3 have similar systems to process liquid radiological waste 

(radwaste). Liquid radwaste generated throughout Unit 2 is collected by the waste disposal 

system (WDS) liquid waste holdup tank (LWHT). The effluent in the LWHT is 

transferred to the Unit 1 Waste Collection System (WCS), which is comprised of four 

75,000 gallon tanks. The effluent from these tanks is sluiced to demineralizer vessels 

where it is processed using activated charcoal and anion, cation, and macro-reticular resins. 

The distillate produced by the demineralizer vessels is collected in two distillate tanks. 

One distillate tank is filled while the other distillate tank is sampled and discharged. When 

a distillate tank is ready for discharge, it is isolated and sampled to determine the allowable 

release rate. If the distillate is suitable for release, it is discharged to the Hudson River (via 

the Unit 1 discharge tunnel). If the contents of the distillate tank are not suitable for 

release, they are returned to the waste collection tanks for additional processing [Ref. 

6.60]. 

Liquid radwaste generated throughout Unit 3 is stored in three waste holdup tanks. Waste 

Holdup Tank 31 has a capacity of 24,500 gallons and Waste Holdup Tanks 32 and 33 each 

have a capacity of 62,000 gallons. If the liquid waste is suitable for discharge from the 

waste holdup tanks, it can be pumped to one of the two monitor tanks of the Chemical and 

Volume Control System. When one monitor tank is filled, it is isolated and the effluent is 

re-circulated and sampled for radiological and chemical analysis while the second tank is 

in service. If the contents of the monitor tank are suitable for discharge, the effluent is 

pumped to the Unit 3 SW discharge; otherwise the effluent is returned to the waste holdup 

tanks for additional processing. Water from the waste holdup tanks can also be pumped 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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into the demineralization system, which consists of a series of pressure vessels containing 

activated charcoal and anion, cation, and macro-reticular resins. Effluent processed by the 

demineralization system is pumped to the Chemical and Volume Control System monitor 

tanks where it is discharged through the SW discharge or returned to the waste holdup 

tanks for additional processing [Ref. 6.64]. 

Unit 2 and Unit 3 have identical systems used to process gaseous waste. Gaseous effluent 

generated by each Unit discharges to the respective waste gas compressor suction header, 

where each header flows into one of four gas decay tanks. Any moisture present in the 

waste gas compressor suction headers is drained to drain tanks that discharge to the WDSs. 

Gaseous effluent held in the decay tanks can either be returned to the Chemical and 

Volume Control System holdup tanks, or discharged to the atmosphere if the gases are 

suitable for release. Discharged gases are released from vents at a controlled rate and, in 

addition to the effects of normal dispersion, accounting for air turbulence created in the 

wake of the containment buildings [Ref. 6.60; Ref. 6.64]. 

2.3 Source Waterbody 

2.3.1 Source Waterbody Description 

The lower Hudson River, the source waterbody and heat sink for Unit 2 and Unit 3, is a 

152-mile-long tidal estuary extending from the New York Harbor to the Federal Dam at 

Troy. In the vicinity of IPEC, the Hudson River is approximately 4500 ft wide and 40 ft 

deep on average, with depths reaching over 60 ft below mean sea level (MSL) just offshore 

[Ref. 6.82]. The depth directly adjacent to the CWIS is currently dredged to 27 ft below 

MSL. 

The Hudson River in the vicinity of IPEC is subject to a substantial tidal influence and salt 

water intrusion. All of the lower Hudson River (i.e., from the Federal Dam at Troy to the 

New York Bay) is tidal, and tidal amplitudes at the Federal Dam average 4.7 ft [Ref. 6.8; 

Ref. 6.24]. Haverstraw Bay, the location of the closest station to IPEC for which the 

National Oceanic and Atmospheric Administration (NOAA) publishes data, has a tidal 

range of 3.23 ft [Ref. 6.81]. There are two flood and two ebb tides within a 24.8-hour 

interval (i.e., flow past IPEC changes direction by being pushed upstream by salt water 

tides and pushed downstream by freshwater inflow in a regular tidal rhythm every 12.4 

hours), referred to as a “semidiurnal pattern” [Ref. 6.4]. Flow past IPEC during peak tidal 

flow is approximately 80 million gallons per minute (gpm) [Ref. 6.64]. On average, only 

10% of the total lower Hudson River flow is made up by freshwater inflows [Ref. 6.116]. 

The net downstream flows due to freshwater inflow have been reported to be in excess of 

11,670,000 gpm 20% of the time and 1,795,000 gpm 98% of the time [Ref. 6.64]. IPEC is 

located within the area of the River generally considered brackish, although at certain 

times in the spring, water in the vicinity of IPEC could be considered fresh due to heavy 

spring runoff [Ref. 6.24]. 

The Hudson River can be divided into four salinity zones based on average annual 

salinities. The mid-estuary section, where IPEC is located, is generally the oligohaline 

zone (0.5 – 5 parts per thousand salinity). The northern perimeter of this zone marks the 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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seasonal inland (northernmost) extent of brackish water in the Hudson River. The limits of 

this zone vary based on the amount of freshwater inflow [Ref. 6.24]. 

2.3.2 Hydraulic Zone of Influence 

Several hydrological studies have investigated the Unit 2 and Unit 3 CWISs [Ref. 6.4; Ref. 

6.5; Ref. 6.71]. The hydraulic zone of influence establishes where the source of water 

entering the intake originates, which enables a quantification of the affected volume of the 

source water body. The combined maximum intake rate calculated for Unit 2 and Unit 3 is 

approximately 1,762,000 gpm, or just 2.2% of the 80,000,000 gpm average tidal flow rate 

of the Hudson River [Ref. 6.60]. As shown in Section 2.4.2.3.2, Table 2.1, the average 

historic combined flow rates for the Stations from 2001 to 2008 is approximately 

1,390,000 gpm (2001.2 MGD), and, therefore, makes up only 1.7% of the 80,000,000 gpm 

average tidal flow rate of the Hudson River. 

La Salle Hydraulic Laboratory created a scaled, physical hydraulic model to study Hudson 

River Flows around the IPEC Stations’ CWISs in 1976 [Ref. 6.95]. Water from both 

downstream and upstream of the Stations supplies the CWIS. The zone supplying water 

downstream of the Stations was estimated to be 300-350 ft wide. During ebb tide, the 

study concluded that all water comes to the intakes from a narrow 200-250 ft wide zone 

upstream of the Stations along the east shore. 

Current measurement data collected offshore of IPEC during three tidal cycles showed a 

maximum flood velocity of 1.5 fps and maximum ebb velocity of 3.3 fps. Based on these 

maxima, the average flood velocity is 1.0 fps, and the average ebb velocity is 2.1 fps [Ref. 

6.11]. The Unit 2 and Unit 3 CWISs have an intake water approach velocity of 

approximately 1.0 fps at full flow and approximately 0.6 fps at reduced flow [Ref. 6.24]. 

2.3.3 Intake Volume Calculation 

In order to characterize the Stations’ water use through the CWISs in terms of Hudson 

River flow, the total design intake volume over one tidal cycle of ebb and flow can be 

expressed as a percentage of the volume of water column that passes through the area 

centered about the CWIS opening (4500 ft across, average 40 ft deep). Under 40 CFR 

§125.83, 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 noted, the tidal 

currents in the vicinity of IPEC have an average 12.4 hour tidal cycle of ebb and flow. The 

maximum tidal excursion for both Units, calculated to be approximately 94,000 ft, is a 

function of the maximum flow velocity of 3.3 fps [Ref. 6.11] and the tidal period [Ref. 

6.114]. Therefore, the volume of Hudson River water flow defined by one tidal excursion 

at mean low water (MLW) is approximately 1.26×1011 gallons for each Unit. The intake 

volume of Unit 2 over one tidal cycle is approximately 6.59×108 gallons based on the 

maximum design cooling water flow of 886,000 gpm (Section 2.4.2.2). For Unit 3 the 

intake volume over one tidal cycle is approximately 6.52×108

 gallons based on the 

maximum design cooling water flow of 876,000 gpm (Section 2.4.2.2). As such, the Unit 

2 and Unit 3 intake volumes (6.59×108 and 6.52×108

 gallons, respectively) each only make 

up approximately 0.52% of the volume of Hudson River water flow defined by one tidal 

excursion (1.26×1011 gallons). Note that this percentage of the volume of Hudson River 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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7 

water flow defined by one tidal excursion is not the same as the percentage of the average 

tidal flow rate of the Hudson River discussed in Section 2.3.2. 

2.4 CWIS Description 

As noted in Section 2.1, the Stations have once-through CWISs Screens are typically placed 

within the CWISs to filter the source waterbody. After passing through the screens, water is 

pumped out of the intake structure and delivered through piping systems to the main steam 

condensers (circulating water systems) and to both the essential and non-essential service 

water headers for cooling purposes. Each Unit has a separate CWIS that houses the 

circulating water pumps and the service water pumps that are required to provide adequate 

and reliable flow to the circulating water and service water systems. In addition, several 

additional technologies are utilized at each CWIS for the purpose of reducing I&E. As further 

discussed in Section 3, the Stations’ existing traveling water screens (TWSs) and fish return 

systems are considered state-of-the-art for impingement reduction. 

2.4.1 Physical Description, Location and Depth of CWIS 

The Stations’ CWISs are located approximately 700 ft apart along the shore of the Hudson 

River. 

Unit 2

The Unit 2 CWIS is a shoreline intake structure. In contrast to Unit 3 (discussed below), 

the Unit 2 above-deck mechanical equipment is not covered by a screen house structure. 

Figures 5-1 and 5-2 of Attachment 5 show plan and section views of the Unit 2 CWIS. 

Concrete wing walls form the north and south ends of the Unit 2 CWIS. The inlet to the 

Unit 2 CWIS is a concrete manifold partitioned into seven independent intake water 

channels (screenwells). The channels are separated by three foot thick concrete walls. Six 

of the channels provide River water to the circulating water (CW) pumps. The purpose of 

the CW pumps is to provide cooling water to the circulating water system. Each CW 

channel is 13 feet (ft) 4 inches wide and 42 ft high from the back wall to approximately 11 

ft from the entrance. After that point, the channels expand outward to a width of almost 15 

ft at the entrance. [Ref. 6.48; Ref. 6.49] The center channel is partitioned into two sections 

and provides River water to the service water (SW) pumps. The purpose of the SW pumps 

is to provide cooling water to the service water system. Each SW section is 10 ft wide and 

42 ft high [Ref. 6.48; Ref. 6.49]. Gated openings are provided between the SW sections 

and the adjacent CW channels to allow SW flow to be delivered through the CW TWSs 

[Ref. 6.59]. 

The opening to the CWIS has a height of 26 ft and is completely submerged at 1 ft below 

MSL. The lowest portion of the CWIS is located at an approximate elevation of 27 ft 

below MSL and the concrete deck is at an elevation of 15 ft above MSL [Ref. 6.49]. A 

debris wall is located at the entrance to the Unit 2 CWIS. The bottom of the debris wall 

extends to 1 ft below MSL and is designed to restrict floating materials at or just below the 

surface from entering the CWIS [Ref. 6.62]. 

Each of the seven Unit 2 intake channels has a coarse bar rack installed to retain pieces of 

debris larger than 3 inches. The bar racks are constructed of 1⁄2 inch by 3 inch bars spaced 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

8 

31⁄2 inches apart. The bars are mounted vertically (narrow side toward the flow), running 

the full height of the intake structure [Ref. 6.62]. Large debris that accumulates in front of 

the bar racks is manually removed by divers. 

Unit 2 has eight Ristroph-type TWSs to remove fish from the intake flow and return them 

to the Hudson River. Unit 2 has one TWS for each CW intake channel and one for each 

SW intake section, located between the bar racks and CW pumps. The Stations’ TWSs 

consist of a continuous series of wire mesh panels and curved fish handling buckets 

attached to frames and attached to two matched strands of roller chains. These panels and 

buckets are commonly referred to as Ristroph Screens. The TWSs service the six CW 

pumps (CW pumps 21 through 26) and the six SW pumps (SW pumps 21 through 26). 

The TWSs, discussed in more detail in Section 2.4.1.1, are specifically designed to remove 

fish using low pressure spray wash nozzles and return them via fish return troughs that 

have a smooth finish designed to minimize fish abrasion [Ref. 6.41]. Residual debris 

larger than 1⁄2 by 1⁄4 inch is removed using separate high pressure spray wash nozzles and 

separate debris troughs. 

Stop log gates (i.e., barriers that, when deployed, block flow through an intake channel) are 

provided for the six CW channels and two SW channel sections and are designed to allow 

inspection and maintenance of the intake channels. Each stop log gate consists of two steel 

sections. Guide channels in the intake structure walls facilitate the installation and removal 

of the stop log gates. Chains attached to the stop log gates assist with installation and 

removal. When installed, the stop log gates isolate the water intake channel from the 

Hudson River, allowing de-watering for inspection and maintenance purposes under dry 

conditions. Each CW channel has a single stop log gate located between the TWS and its 

associated CW pump. Each of the two SW sections has two stop log gates. The SW stop 

log gates are located between the TWSs and their associated bar racks and between the 

TWSs and SW pumps. 

During periods of high River water temperature when cooling water demands are the 

greatest, Unit 2 uses up to 16,000 gpm of supplemental River water from the Unit 1 CWIS. 

The Unit 1 intake structure consists of a concrete bulkhead divided into four intake 

channels. Each intake channel is 11 ft 2 inches wide and 26 ft high. The two CW pumps 

(CW 1 and CW 2) for Unit 1 are no longer in service.6

 Two SW intake channels are 

located within the Unit 1 CWIS, north and south of the CW pump bays. Each SW intake 

bay houses a River Water (RW) service pump (Pumps 11 and 12) and two TWS pumps 

(TWS Pumps 11 through 14). One RW pump is active and the other is a standby, such that 

only one ever operates. River water is supplied to Unit 2 by RW pumps 11 and 12 through 

a 10 inch pipe. 

Unit 3

The Unit 3 CWIS is also a shoreline intake structure. The screen house for Unit 3 covers 

the Unit 3 CWIS with a steel-framed structure enclosed with metal panels. Figures 5-3 and 

5-4 of Attachment 5 show plan and section views of the Unit 3 CWIS. 

 

6

 For informational purposes, Unit 1 was shut down on October 31, 1974 and currently is managed in safe storage 

condition (SAFSTOR) prior to final decommissioning. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

9 

Concrete wing walls form the north and south ends of the Unit 3 CWIS. The Unit 3 CWIS 

consists of seven intake channels. The channels are served by a common plenum that is 12 

ft wide and 120 ft long. Nine bar racks, the bottom of which are located 1 ft below MSL, 

form the north, south, and west walls of the plenum. Seven of the bar racks are at the west 

wall with a single bar rack at the north and south ends of the plenum. The opening of each 

water intake channel is located 12 ft behind the western bar racks. Each CW channel is 13 

ft 4 inches wide and 42 ft high. The center channel is partitioned into two sections and 

provides River water to the SW pumps. Each SW section is 10 ft wide and 42 ft high. 

Gated openings are provided between the SW sections and the adjacent CW channels to 

allow SW flow to be delivered through the CW TWSs. These gated openings are normally 

kept closed [Ref. 6.62]. 

The opening to the Unit 3 CWIS has a height of 26 ft and is completely submerged at 1 ft 

below MSL. The lowest portion of the CWIS is located at an approximate elevation of 27 

ft below MSL and the concrete deck is at an elevation of 15 ft above MSL. A debris wall 

is located at the entrance to the Unit 3 CWIS. The bottom of the debris wall extends to 1 ft 

below MSL and is designed to restrict floating materials at or just below the surface from 

entering the CWIS. 

Each of the seven intake channels has a bar rack installed to retain pieces of debris larger 

than 3 inches. The bar racks are constructed of 1⁄2 inch by 3 inch bars that are set 31⁄2 

inches apart. The bars are mounted vertically (narrow side toward the flow), running the 

full height of the intake structure. A PVC-coated wire mesh screen is attached to the River 

side of the bar racks and extends from 3 ft above MSL to 4 ft below MSL. This screen 

mesh prevents smaller floating debris from entering further into the intake and clogging the 

debris and fish return troughs [Ref. 6.62]. Large debris that accumulates in front of the bar 

racks is manually removed by divers. 

Eight Ristroph-type TWSs, one for each CW channel and one each for the SW intake 

sections, are located downstream of the bar racks. The TWSs service the six CW pumps 

(CW pumps 31 through 36) and the six SW pumps (SW pumps 31 thru 36). The TWSs, 

discussed in more detail in Section 2.4.1.1, are specifically designed to remove any fish 

using low pressure spray wash nozzles and return them to the River via fish return troughs 

that have a smooth finish designed to minimize fish abrasion. In addition, debris larger 

than 1⁄2 by 1⁄4 inch is removed using separate high pressure spray wash nozzles and separate 

debris troughs. Unit 3’s stop log gates are similar to those at Unit 2. 

2.4.1.1 Current Traveling Water (Ristroph) Screens 

The CWISs at Units 2 and 3 have modified vertical Ristroph-type traveling water screens. 

These screens were installed following a collaborative research effort among the former 

owners of the Stations and the Hudson River Fisherman’s Association (HRFA), now 

Riverkeeper, Inc. (Riverkeeper), directed by Dr. Ian Fletcher, then-consultant for the 

HRFA. The effectiveness of the existing Ristroph-type TWS screens at reducing 

impingement losses (as compared to angled or traditional traveling screens7

) is 

documented in Flow Dynamics and Fish Recovery Experiments: Water Intake Systems 

 

7

 These screen types are discussed in more detail in Section 4.2. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

10 

(Fletcher Article) [Ref. 6.33]. Dr. Fletcher concluded that Station improvements, beyond 

the Ristroph-type TWSs installed, were unlikely to significantly reduce impingement 

losses. Therefore, the existing screens at the Stations are state-of-the-art in terms of 

minimizing impingement [Ref. 6.33]. In addition, the Fletcher Article [Ref. 6.33] 

indicates that the NYSDEC adopted the performance of these screens as the State’s best 

technology available for reducing impingement. 

The Stations’ existing TWS assemblies in the CW intake channels are 13 ft 4 inches wide 

and 46 ft high. The heights are measured from the center of the head shaft to the center 

of the tail shaft. The TWSs in the SW intake sections are 8 ft 9 inches wide (north 

sections) or 7 ft 2 inches wide (south sections) and are each 46 ft high. Each screen is 

installed in a channel with the screening surface oriented perpendicular to the water flow 

with each screen including 52 basket segments. The chain rotates over head and foot 

sprockets, carrying the panels down into the water and around the foot sprockets, then 

back up through the water and over the head sprockets. 

Water passes first through the ascending and then the descending screen baskets, which 

are constructed of stainless steel 14-gauge oblong-shaped mesh and are framed in a 316L 

stainless steel structure [Ref. 6.41]. The basket mesh has a 1⁄4-inch wide by 1⁄2-inch tall 

spacing with a total open area of 70.6% [Ref. 6.41; Ref. 6.94]. As discussed further in 

Section 2.4.2.4, the through-screen velocity for the Unit 2 and Unit 3 CW traveling water 

screens is 1.61 fps at MLW. 

The Ristroph-type TWSs at the Stations are automatically-cleaned screening devices 

specifically designed to gently remove aquatic species from a channel of flowing water. 

The ascending basket is located on the western side of the screen facing the CWIS 

opening and collects fish as it passes up through the water. Aquatic species are collected 

in the buckets that form the lower (trailing) edge of the mesh frame. A high pressure 

spray (80-100 psi), specifically designed to avoid the contents of the fish handling 

buckets, is used to remove any debris impinged on the basket mesh into the front debris 

trough [Ref. 6.41]. As the baskets rotate around the head sprocket, the contents of the 

buckets descend on the incline of the mesh panel where three low pressure sprays (10-15 

psi) are used to direct impinged fish into the fish return trough [Ref. 6.41]. The baskets 

continue to descend towards an additional high pressure spray (80-100 psi) that removes 

any remaining debris into the rear debris trough. As the baskets continue to revolve 

towards the foot sprocket, any fish and debris that were not originally washed off the 

screens may be washed off in the flow of water. This fish and debris is considered to be 

‘carryover’ and could potentially enter the CW pump intake. 

The TWSs ordinarily operate continuously at 2.5 feet per minute (fpm). The TWSs 

operate at 10 fpm when a high differential pressure is detected across the screens, 

indicating a large buildup of debris, until that buildup is cleared. Electric radiant heating 

elements, installed in the driving head of the TWSs, are energized when the temperature 

is below 35°F to prevent ice from forming. 

Figure 2.2 shows a schematic of the Station’s TWS configuration. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

11 

Figure 2.2 TWS Operation 

2.4.1.2 Fish Handling and Return System 

The fish handling and return systems at the Stations consist of a series of low pressure 

water sprays used to transfer fish to fish return troughs that return those fish to the 

Hudson River. Residual debris is removed via separate high pressure water sprays and 

debris return troughs. Prior to the installation of each Unit’s fish return systems, 

extensive studies were conducted, and prototype fish return system models were 

designed. The design and testing of the fish return systems were conducted under the 

oversight of Dr. Ian Fletcher, consultant for Riverkeeper’s predecessor, between 1989 

and 1992, with the objective of maximizing fish survival and minimizing reimpingement 

[Ref. 6.9; Ref. 6.111]. As discussed in Section 2.4.1.1, Dr. Fletcher concluded that 

Station improvements, beyond the installed Ristroph-type TWSs, were unlikely to 

significantly reduce impingement losses. Therefore, the existing screens at the Stations 

are state-of-the-art in terms of minimizing impingement [Ref. 6.33]. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

12 

The mesh panels and buckets of the traveling water screens are lifted out of the flow and 

above the operating floor where low pressure and high pressure water spray is directed 

outward through the mesh to remove impinged fish and debris, respectively. As shown in 

Figure 2.2, each TWS has three low pressure spray nozzles (10-15 psi) (labeled as fish 

spray pipes) and two high pressure spray nozzles (80-100 psi) (labeled as debris spray 

pipes). The fish and debris handling systems consist of three different trough systems. 

The fish return troughs are located on the east side of the traveling screens. The main 

(rear) debris troughs are on the east side of the traveling screens below the fish return 

troughs. The auxiliary (front) debris troughs are located on the west side of the traveling 

screens [Ref. 6.54]. The locations and elevations of the fish return and debris return 

troughs correspond with the sequence of high pressure and low pressure spray used to 

direct fish and debris from the mesh panels. 

The Unit 2 and Unit 3 TWSs have separate fish return systems. Both of these intakes 

have rectangular fish return troughs with clear widths of 36 inches and depths of 12 

inches. Unit 2 has one fish return trough for TWSs 21 and 23 and another fish return 

trough for TWSs 24 and 26. Separate fish return troughs are provided for these adjoining 

TWS to avoid interferences with the SW TWS screens. Bends and vertical offsets are 

located south of TWS 21 and north of TWS 26 and transition the fish return troughs into 

below deck sluices (i.e., slides or chutes) that are approximately 20 inches wide and 12 

inches deep. The fish return sluices merge north of the Unit 2 TWSs and transition into a 

14-inch diameter fish return pipe that extends 185 ft into the Hudson River, north of the 

intake structure, at a depth of approximately 34 ft below MSL. 

The Unit 3 fish return trough slopes downward between TWSs 31 through 36. South of 

TWS 31, the fish return trough transitions into a fish return sluice that has identical 

dimensions. This sluice is located above the concrete deck and runs approximately 113 ft 

south before transitioning through a 20 ft section into a 10-inch fish return pipe. The fish 

return pipe runs approximately 148 ft prior to discharging at the northwest corner of the 

discharge canal at a depth of approximately 10 ft below MSL. 

The fish return troughs and sluices are fabricated from 1⁄2-inch thick fiberglass. The 

troughs are designed to maintain a design water depth of approximately 2 inches and a 

design water velocity between 2-5 fps. The fish return troughs are covered with 

removable covers or grates in areas where personnel may travel. 

Both the main and auxiliary debris troughs are rectangular and have an inner width of 22 

inches and an inner depth of 9 inches. The debris troughs are also fabricated from 

fiberglass and merge prior to transitioning through rounded elbow sections that discharge 

into the combined debris flume. The combined debris flume travels along the west side 

of each CWIS and is rectangular with a constant width of 24 inches and varying depths 

up to 36 inches, with bends ranging from 12 degrees to 45 degrees [Ref. 6.56]. The 

debris troughs and flume are constructed of fiberglass. South of the Unit 3 CWIS, the 

combined debris flume transitions into a 14-inch diameter debris pipe that discharges into 

the discharge canal approximately 217 ft south of the flume at a depth of 6 ft 3 inches 

below MSL. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

13 

2.4.2 CWIS Flow Description 

As detailed in Section 2.4.1, two primary CWISs supply the Stations with cooling water; 

one CWIS supplies cooling water to Unit 2, and the other CWIS supplies cooling water to 

Unit 3. Additional flow from the Unit 1 RW pump can be used to supplement the Unit 2 

SW System. There are two distinct cooling water flow values: the baseline flow rate (i.e., 

maximum design intake capacity) and the average actual intake flow rate. The baseline 

flow rate, or maximum design intake capacity, is used to design all CWIS screening 

technologies, and represents the maximum flow value. Baseline flow (maximum design 

intake flow) means the cooling water design flow values and consists of the following: (1) 

the condenser cooling water flow through the circulating water pumps, and (2) the service 

water flow that serves an equipment cooling function. Baseline flow equates to the value 

assigned, during the cooling water intake structure design, to the expected total volume of 

water likely to be withdrawn from a source waterbody for cooling purposes, consistent 

with 40 CFR §125.93 and both as reflected in and consistent with the Updated Final Safety 

Analysis Report (UFSAR) for each Unit [Ref. 6.60; Ref. 6.64]. The average actual flow 

rate is the average historical amount of flow entering the CWIS. The average actual flow 

rate is smaller than the design flow rate, due to lesser flows resulting from outages and 

periods of reduced cooling demands allowing flow reductions through the use of the dual 

and variable speed pumps at Units 2 and Unit 3, respectively. Cooling water flow 

diagrams for the Station’ CW and SW systems are shown in Figures 5-5 through 5-8 of 

Attachment 5. Screenwash water (i.e., water supplied to the screenwash pumps) is not 

included in the baseline flow rate or the average actual flow rate. 

2.4.2.1 Pump Descriptions 

2.4.2.1.1Cooling Water Pumps 

Unit 2

The following sets of pumps supply cooling water to Unit 2: 

 The Unit 2 dual speed CW pumps supply once-through cooling water for the CW 

system from the Unit 2 CWIS. Each of the six CW pumps has a maximum design 

intake capacity of 140,000 gpm, combining for a total of 840,000 gpm. As shown 

in Figure 5-5 of Attachment 5, the CW pumps supply Unit 2 Condensers 21, 22, 

and 23. 

 The Unit 2 SW pumps supply River water from the Unit 2 CWIS as a cooling 

medium to those systems or components requiring heat removal during normal or 

abnormal plant conditions. The Unit 2 SW pumps also provide screenwash water 

to TWSs #27 and #28 located in the SW intake channel sections. As shown in 

Figure 5-6 of Attachment 5, the SW system consists of two supply headers, 

essential and non-essential, each provided with River water by three SW pumps. 

The essential header supplies the components requiring cooling during a station 

blackout or loss of coolant accident. Each of the six SW pumps has a maximum 

design intake capacity of 5000 gpm, combining for a total of 30,000 gpm. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

14 

 The Unit 1 RW pump can supply additional cooling River water from the Unit 1 

CWIS to the non-essential Unit 2 SW header. One RW pump has a maximum 

design intake capacity of 16,000 gpm. The second RW pump is a standby pump 

and is not included as part of the baseline flow because it does not add to the 

intake capacity. 

Pump Specifications 

Dual Speed Circulating Water Pumps (6)

 Allis Chalmers Model 96 x 84 YDDVRM 

 Each pump is a dual speed pump rated for 140,000 gpm at 21 ft total dynamic 

head (TDH) when running at 254 revolutions per minute (rpm), and 84,000 gpm 

at 15 ft TDH when running at 187 rpm. Each pump is driven by a vertical solid 

shaft squirrel cage induction motor rated for 1000/400 hp at 254/187 rpm, 6600 

volts, three phase, 60 Hertz. Dual speed operation is achieved via two sets of 

motor windings. 

Service Water Pumps (6)

 Johnston Pump Company Model 18EC-2 Stage 

 Each pump is rated for 5000 gpm at 212 ft TDH and driven by a motor rated for 

350 hp at 1800 rpm, 480 volts, three phase, 60 Hertz. 

River Water Pumps (2)

 Allis Chalmers 

 The pump is rated for 16,000 gpm and driven by a motor rated for 500 hp at 600 

rpm, 440 volts. 

Unit 3

The following sets of pumps supply cooling water to Unit 3: 

 The Unit 3 variable speed CW pumps supply once-through cooling water for the 

CW system from the Unit 3 CWIS. Each of the six CW pumps has a maximum 

design intake capacity of 140,000 gpm, combining for a total of 840,000 gpm. As 

shown in Figure 5-7 of Attachment 5, the CW pumps supply Unit 3 Condensers 

31, 32, and 33. 

 The Unit 3 SW pumps supply River water from the Unit 3 CWIS as a cooling 

medium to those systems or components requiring heat removal during normal or 

abnormal plant conditions. As shown in Figure 5-8 of Attachment 5, the service 

water system consists of two supply headers, essential and non-essential, each 

provided with River water by three SW pumps. The essential header supplies the 

components requiring cooling during a station blackout or loss of coolant 

accident. Each of the six SW pumps has a maximum design intake capacity of 

6000 gpm, combining for a total of 36,000 gpm. Three SW backup pumps are 

available at Unit 3 and each can supply 5000 gpm. The SW backup pumps take 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

15 

suction from the Unit 2 discharge tunnel and provide flow to the essential and 

non-essential nuclear services headers. 

Pump Specifications 

Variable Speed Circulating Water Pumps (6)

 Allis Chalmers Model 102 x 84 YDDVRM 

 Each pump is driven by a variable speed drive and is rated for 140,000 gpm at 29 

ft TDH when running at 360 rpm and 84,000 gpm at 19.5 ft TDH when running at 

250 rpm. Each pump is driven by a vertical solid shaft squirrel cage induction 

motor rated as 1250 hp at 250 rpm, 6900 volts, three phase, 60 Hertz. 

Service Water Pumps (6)

 Ingersoll-Rand Model 26 APK-1 

 Each pump is rated for 6000 gpm at 195 ft TDH. Each pump is driven by a motor 

rated as 350 hp at 1785 rpm, 480 volts, three phase, 60 Hertz. 

Backup Service Water Pumps (3)

 Layne & Bowler Pump Company – Specification #4756-9321-05-238-22 

 Each pump is rated for 5000 gpm at 220 ft of total dynamic head. Each pump is 

driven by a Westinghouse motor rated as 350 hp at 1770 rpm, 440 volts, three 

phase, 60 Hertz. 

2.4.2.1.2Screenwash Water Pumps 

Unit 2

The following sets of pumps supply screenwash water for Unit 2: 

 The Unit 2 CW screenwash system is provided with River water by screenwash 

pumps located in the Unit 1 intake structure. Each of these 4 screenwash pumps 

is rated at 2000 gpm, combining for a total of 8000 gpm. 

 The Unit 2 SW pumps normally provide screenwash water for the TWSs in the 

SW channel sections via the SW non-essential header. TWSs #27 and #28 are 

each provided with up to 164 gpm. 

Pump Specifications 

Screenwash Pumps (4)

 Goulds Pumps Model VIT-CF 

 Each pump is rated for 2000 gpm at 234 ft of total dynamic head. Each pump is 

driven by a motor rated as 150 hp at 1780 rpm, 480 volts, three phase, 60 Hertz. 

Unit 3

The following sets of pumps supply screenwash water for Unit 3: 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

16 

 The Unit 3 screenwash pumps take suction from CW intake channels #34, #35, 

and #36 downstream of the traveling water screens. Each of the 3 screenwash 

pumps is rated for 3200 gpm, combining for a total of 9600 gpm. 

Pump Specifications 

Circulating Water Screenwash Pumps (3)

 Ingersoll-Rand Model 24 APK-1 

 Each pump is rated for 3200 gpm at 250 ft of total dynamic head. Each pump is 

driven by a motor rated as 250 hp at 1785 rpm, 460 volts, three phase, 60 Hertz. 

2.4.2.2 Design Intake Capacity 

NYSDEC regulations do not define water sources subject to 6 NYCRR §704.5. 

However, the United States Environmental Protection Agency (EPA) defines cooling 

water as “...water used for contact or non-contact cooling, including water used for 

equipment cooling, evaporative cooling tower makeup, and dilution of effluent heat 

content.” (See 69 Fed. Reg. 41576, 41684, July 9, 2004; 40 CFR Part 125, §125.93). 

Screenwash water (i.e., the water supplied to the screenwash pumps) is not regulated by 

EPA and is included here for informational purposes only. Consistent with EPA 

regulations, in this Report the baseline flow of the Stations is comprised of the cooling 

water design intake capacities. 

Cooling Water Design Intake Capacity 

Unit 2

Under normal power generating operation, the Unit 2 SW pumps and the CW pumps can 

draw in 870,000 gpm of cooling water from the Unit 2 CWIS. The Unit 1 RW pumps 

can draw in 16,000 gpm of cooling water to supplement the Unit 2 SW System. Unit 2 

has a maximum design intake capacity for cooling water as follows: 

Cooling Water Design Intake Capacity (886,000 gpm)

 Up to 840,000 gpm from the Unit 2 CW pumps is used as non-contact cooling 

water8

 in the condenser [Ref. 6.60, Section 10.2.4]. 

 Up to 30,000 gpm from the Unit 2 SW pumps is used as non-contact cooling 

water for the essential and non-essential heating loads9

 [Ref. 6.60, Section 9.6.1]. 

 Up to 16,000 gpm from the Unit 1 RW pump is used as non-contact cooling water 

for the Unit 2 non-essential SW heating loads [Ref. 6.57]. 

Unit 2 accounts for approximately 50.3% of the total cooling water design intake capacity 

for the Stations. 

 

8

 Non-Contact Cooling Water is water used to reduce temperature which does not come in direct contact with any 

raw material, intermediate product, a waste product or finished product. 

9

 The essential loads are those which must be supplied with cooling water immediately in the event of a blackout 

and/or loss of coolant accident. The cooling water for these loads is supplied by the nuclear SW header. The nonessential loads are those which are supplied with cooling water from the conventional SW header. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

17 

Unit 3

Under normal power generating operation, the SW pumps and the CW pumps can draw 

in 876,000 gpm of water from the Unit 3 CWIS. Unit 3 has a maximum design intake 

capacity for cooling water as follows: 

Cooling Water Design Intake Capacity (876,000 gpm) 

 Up to 840,000 gpm from the Unit 3 CW pumps is used as non-contact cooling 

water in the condenser [Ref. 6.64, Section 10.2.4]. 

 Up to 36,000 gpm from the Unit 3 SW pumps is used as non-contact cooling 

water for the essential and non-essential heating loads [Ref. 6.64, Section 9.6.1]. 

Backup service water pumps are standby pumps and are not included because 

they do not add to the intake capacity. 

Unit 3 accounts for approximately 49.7% of the total cooling water design intake capacity 

for the Stations. 

Screenwash Water Design Intake Capacity 

Unit 2

The Unit 2 traveling water screens (TWSs #27 and #28) can use screenwash water from 

the discharge of the Unit 2 SW pumps. Water from screen wash pumps #21 through # 24 

located in the Unit 1 CWIS is also used to supply screenwash water to Unit 2. Unit 2 has 

a design intake capacity for screenwash water as follows: 

Screenwash Water Design Intake Capacity (8328 gpm) 

 Up to 328 gpm (164 gpm per screen) can be supplied to traveling water screens 

#27 and #28 during regular operation from the discharge of the Unit 2 SW pumps.

 Up to 8000 gpm (4 pumps at 2000 gpm) from the screen wash pumps in the Unit 

1 CWIS can be supplied to the TWSs servicing the CW channels. This flow can 

also be used as a backup source of wash water to TWSs #27 and #28. 

Unit 3

The Unit 3 screenwash pumps can draw in screenwash water from the Unit 3 CWIS. 

Unit 3 has a design intake capacity for screenwash water as follows: 

Screenwash Water Design Intake Capacity (9600 gpm)

 Up to 9600 gpm (3 pumps at 3200 gpm) is supplied to the screenwash pumps 

during regular operation. The screenwash pumps take suction from circulating 

water intake channels #34 thru #36 following the traveling water screens. 

2.4.2.3 Flow Reductions from Baseline 

It is generally assumed that a direct linear (1:1) relationship exists between flow 

reduction and the number of fish entrained or impinged. Periods of reduced power at 

each Unit contribute to reduced intake flow as well as use of the Stations’ existing 

dual/variable speed pumps. When scheduled, these flow reductions represent a reduction 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

18 

in the baseline flow and are, therefore, considered to be an operational measure to reduce 

I&E. 

2.4.2.3.1Maintenance & Refueling Outages 

At the Stations, maintenance and refueling outages (i.e., scheduled outages) are 

currently scheduled to occur approximately every 24 months for each Unit, and are 

anticipated to last approximately 25 days. Scheduled outages are staggered so that both 

Units are not offline at the same time. When a Unit is offline, some CW and SW would 

still be present after shutdown and prior to startup. Adequate SW flow must also be 

provided when the Unit is offline in order to maintain essential cooling of nuclear 

safety-related systems, including the containment cooling and recirculation systems, 

component cooling systems, instrument air cooling systems, radiation monitoring 

cooling systems, and, emergency diesel generator cooling systems. Therefore, even 

during outages some flow is drawn through the CWISs for CW and SW system cooling 

needs. 

2.4.2.3.2Historic Operational Intake Flow Rate 

Outages and periods of reduced power decrease the actual amount of flow entering the 

CWIS. When scheduled, these flow reductions represent a reduction in the baseline 

flow and, therefore, are considered to be an operational measure to reduce I&E. 

The Stations supplied eight years (2001-2008) of measured intake flow data for Units 2 

and 3, in millions of gallons per day (MGD); the Unit 2 data includes CW, SW, and 

Unit 1 RW flow, and the Unit 3 data includes CW and SW flow. Table 2.1 shows the 

monthly and annual average historic flows for the Stations. The average annual historic 

(2001-2008) intake flow rate10 for Unit 211 is 1102.2 MGD, which represents a 13.6% 

reduction in flow from the baseline flow value of 1275.8 MGD. For Unit 3, the annual 

average historic intake flow rate is 899.0 MGD, which represents a 28.7% reduction in 

flow from the baseline flow value of 1261.4 MGD. 

Table 2.1 Average Historic Flow Rates (2001-2008) 

in Millions of Gallons per Day (MGD) 

Month Unit 2 Unit 3 

January 1001.1 600.1 

February 924.1 583.2 

March 908.4 500.9 

April 940.5 614.8 

May 1107.5 899.6 

June 1243.6 1199.1 

 

10 The average annual historic (2001-2008) intake flow rate is a weighted average determined using the number of 

days in each month with respect to the number of days in one year. 

11 All Unit 1 RW flow is considered to be Unit 2 historic operational SW flow. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

19 

Month Unit 2 Unit 3 

July 1248.7 1227.1 

August 1252.3 1217.4 

September 1253.2 1234.8 

October 1209.1 1170.1 

November 1007.8 806.5 

December 1115.3 715.2 

Average Annual 1102.2 899.0 

The differences in Unit 2 and Unit 3 flow rates can be attributed to several factors. 

First, the SW capacity at Unit 2 (SW is 30,000 gpm and RW is 16,000 gpm) is greater 

than the SW capacity at Unit 3 (36,000 gpm). In addition, the condensers and low 

pressure turbines at each Unit have different designs, efficiencies, and operational 

requirements that necessitate substantially different flow requirements. Furthermore, 

Unit 2 has more issues with debris loading than Unit 3, requiring more flow to clean the 

systems. 

2.4.2.4 Through-Screen Velocity 

According to 40 CFR §125.94, if a facility reduces the through-screen velocity to at or 

below 0.5 fps, it is “deemed to have met the impingement mortality performance 

standards”. Based on the maximum design intake capacity through each CWIS (cooling 

water and screenwash water) and a mean low water (MLW) elevation (i.e., 1.0 ft below 

MSL), the through-screen velocity can be approximated by using the following equation 

and inputs [Ref. 6.94]: 

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

where 

Q is the flow rate in gpm 

BW is the screen width in feet 

LW is the depth at MLW in feet (26.0 ft12) 

POA is the “percent open area” of the screen basket 

K is a conversion factor based on screen type (396 for through flow screens) 

 

12 LW depth is the difference between MLW elevation (-1.0 ft MSL) and the elevation of the bottom of the CWIS 

(-27.0 ft). 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

20 

POA for rectangular-mesh screens can be approximated by using the following equation 

and inputs [Ref. 6.94]: 

Percent Open Area = ((K*L)/(K+D)(L+d))*100 

where 

K is the width of the opening (inches) 

L is the length of the opening (inches) 

D is the warp wire13 diameter (inches) 

d is the shute wire14 diameter (inches) 

Unit 2

The maximum design intake capacity for the CW system at Unit 2 is approximately 

140,000 gpm per channel. The six traveling water screens for the CW channels in the 

Unit 2 CWIS have a screen width of 12 ft and a depth of 26 ft at MLW. The percent 

open area is 70.55% based on a warp wire diameter and shute wire diameter of 0.064 

inches (14-gauge wire) and mesh opening size of 1⁄2 × 1⁄4-inches. Based on these inputs, 

the through-screen velocity for the CW traveling water screens is 1.61 fps at MLW. 

The maximum design intake capacity for the SW system at Unit 2 is approximately 

30,000 gpm. The two traveling water screens for the SW channel sections have a screen 

width of 5 ft 11 inches and a depth of 26 ft at MLW. The percent open area is 70.55%. 

Based on these inputs, the through-screen velocity for the Unit 2 SW traveling water 

screens is 0.35 fps at MLW. 

Unit 3

The maximum design intake capacity for CW intake channels #31 through #33 is 

approximately 140,000 gpm. The maximum design intake capacity for the CW intake 

channels #34 through #36 is approximately 143,200 gpm (one CW pump and one 

screenwash pump in each channel). The six traveling water screens for the CW channels 

in the Unit 3 CWIS have a screen width of 12 ft and a depth of 26 ft at MLW. The 

percent open area is 70.55%. The through-screen velocity for the traveling water screens 

in CW channels #34 through #36 is 1.64 fps at MLW. Traveling water screens #31 

through #33 have a through-screen velocity of 1.61 fps at MLW. 

 

13 Warp wire runs the length of the mesh. 

14 Shute wire runs the width of the mesh. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

21 

The maximum design intake capacity for the SW system at Unit 3 is approximately 

36,000 gpm. The two traveling water screens for the SW channel sections have a screen 

width of 5 ft 11 inches and a depth of 26 ft at MLW. The percent open area is 70.55%. 

Based on these inputs, the through-screen velocity for the Unit 3 SW traveling water 

screens is 0.42 fps at MLW. 

2.4.2.5 Seasonal Changes in CWIS Operation 

Unit 2 and Unit 3 have dual speed pumps and variable speed pumps, respectively, that 

allow the volume of River water withdrawn to be reduced when colder River water 

temperatures are available. The Stations use best reasonable efforts to operate the Unit 2 

and Unit 3 dual/variable speed pumps so as to keep the volume of River water withdrawn 

at the minimum required for efficient operation, considering ambient River water 

temperature, plant operating status, and the need to meet SPDES permit conditions [Ref. 

6.86; Ref. 6.89]. 

Also, the conventional, non-essential service water header for Unit 2 can be supplied with 

supplemental River water from the Unit 1 River Water service header during periods of 

high River water temperature. This is known as three-header operation, and is the 

preferred operating mode when the River water temperature is greater than 65°F [Ref. 

6.58] (i.e., during periods of high River water temperature, additional flow is required to 

satisfy the heat rejection requirements of the SW system). 

2.4.3 Biocide Treatment 

The CW and SW systems for Unit 2 and Unit 3 are protected from marine growth (microfouling) and mussels (macro-fouling) with biofouling control. The biofouling control is 

implemented by the application of sodium hypochlorite through injection headers and 

diffusers located in the River water intake channels behind the traveling water screens and 

before the CW and SW pumps. All of the positive displacement pumps are operated 

manually and take suction from sodium hypochlorite storage tanks. 

In accordance with the SPDES permit [Ref. 6.86], the SW systems may be chlorinated 

continuously, while chlorination of the CW systems is limited to two hours per unit per 

day and a total of nine hours per week. In addition, chlorination of the CW systems must 

be performed during the day, and the CW systems for the two units cannot be chlorinated 

simultaneously. The chlorination systems are removed from service when the average 

River water temperature is below 40°F or if the onsite chemistry and engineering 

departments determine that there is no benefit from continued chlorination. 

2.5 Discharge System 

The CW Systems provide once-through cooling water to the condensers, and the SW Systems 

supply cooling water to various nuclear components and conventional components (e.g., 

Emergency Diesel Generators, Closed Cooling Water Heat Exchangers, etc.). The water from 

each system is discharged back to the Hudson River through a common discharge canal. As 

discussed in Unit 3 UFSAR, the Hudson River has been designated as the Ultimate Heat Sink 

(i.e., the source of cooling water provided to dissipate reactor decay heat and essential cooling 

system heat loads after reactor shutdown) because it is capable of supplying a reliable, long-
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

22 

term source of cooling water [Ref. 6.64]. As such, the River provides a nuclear safety 

function. 

Unit 2 

Water for the CW System passes from the Unit 2 CWIS through the condenser and is then 

discharged via six 96” outside diameter (OD) pipes into a 20 ft wide discharge tunnel, 

approximately 150 ft long running NE to SW. Water for the SW system is also discharged 

into the Unit 2 discharge tunnel. From the Unit 2 condenser outlet, the discharge tunnel turns 

and travels approximately 60 ft SE to NW to an adjustable weir. The outfall from the weir 

discharges into the common discharge canal for Units 1, 2, and 3 [Ref. 6.50; Ref. 6.51]. 

Unit 3

Water for the CW System passes from the Unit 3 CWIS through the condenser and is then 

discharged via six 96” OD pipes into a 20 ft wide discharge tunnel, approximately 140 ft long 

running NE to SW. Water for the SW system is also discharged into the Unit 3 discharge 

tunnel. From the Unit 3 condenser outlet, the discharge tunnel turns and travels 

approximately 60 ft SE to NW to an adjustable weir. The outfall from the weir discharges 

into a 100 ft long channel prior to joining the common discharge canal for Units 1, 2, and 3 

[Ref. 6.52; Ref. 6.53]. 

Common Discharge Canal

The common discharge canal for Units 1, 2 and 3 runs northeast to southwest for 

approximately 700 ft underneath and alongside the Unit 1 and Unit 3 turbine buildings, 

respectively [Ref. 6.43; Ref. 6.44; Ref. 6.53]. This portion of the discharge canal is 

approximately 36 ft wide. The common discharge canal turns towards the River after 

reaching the Unit 3 discharge tunnel inlet, running NE to SW for approximately 260 ft [Ref. 

6.45; Ref. 6.53]. The common discharge canal runs approximately 240 ft along the River 

bank prior to reaching the 255 ft wide common outfall (i.e., Outfall 001) [Ref. 6.45; Ref. 

6.86]. 

The outfall is comprised of twelve sub-surface diffuser ports (4 ft tall by 15 ft wide spaced 21 

ft apart, center to center) which are located 12 ft beneath the water surface (at MLW) along 

the west wall of the discharge canal. Two of the twelve discharge ports have fixed gates that 

are normally closed and ten have adjustable gates that are mechanically aligned to maintain a 

differential head of 1.75 ft across the outfall structure. These gates are used to assure the 

minimum discharge velocity of 10 fps required for adequate mixing of the discharge water 

with Hudson River water [Ref. 6.63]. The first port is approximately 600 ft south of the Unit 

3 intake structure [Ref. 6.24]. The separation between the intake and the discharge is 

designed to minimize recirculation of warmed discharge effluent. Discharge temperatures are 

limited in accordance with the SPDES Permit [Ref. 6.64]. 

The outfall structure and relevant land are leased to Entergy by the New York State Energy 

Research and Development Authority (NYSERDA). This lease is dated July 1, 1971 and is 

subject to renewal on March 31, 2017 [Ref. 6.92]. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

23 

2.6 Cooling System Equipment 

Table 2.2 describes the significant installation, maintenance, and replacement dates for 

equipment and components used in the Stations’ cooling systems. 

Table 2.2 History of Key CWIS Components at Unit 2 and Unit 3 

Equipment Originally 

Installed Date and Description of Component Replacement 

Unit 2

Bar Racks 1974 Original still in place. 

Service Water Sluice 

Gates 1974 

1985, Replaced the original pneumatically operated sluice gates 

installed between the service water and circulating water bays in 

the intake structure due to corrosion. 

Traveling Screens 1974 

1983, Installed fine mesh screens in the intake structure at the inlet 

to the service water pump bays. 

1984, Installed spray wash piping that is used to clean the fine 

screens. 

1985, Installed Ristroph Screen in screen well 26 for survival 

testing. 

1991, Installed Ristroph Screens. 

2007, Replaced traveling water screen 25. 

Fish Return System 1997 Original still in place. 

Screen Wash Pumps 1974 1991, Replaced with four Goulds Pumps Model VIT-CF. 

Service Water Pumps 

21 through 26 1974 

1998, Replaced Layne & Bowler and Aurora service water pumps 

with pumps manufactured by Johnston Pumps Company. Previous 

pumps required frequent maintenance. Existing motors were 

reused. 

2006, Replaced motor in SWP 25. 

Hypochlorite Injection 

Pumps 1974 

1986, Install two diffusers to continuously chlorinate service water 

bays. 

1993, Installed saran lined piping connected to diffusers located in 

stop log frames for TWSs 27 and 28. Two chlorine monitors and 

two zebra mussel monitors were also installed at this time. 

2003, Installed two 5000 gallon hypochlorite storage tanks. 

Circulating Water 

Pumps 21 through 26 1974 

1985, Installed Allis Chalmers dual speed circulating water pumps. 

1986, Installed 2 metering pumps and piping. 

1990, Installed 3 metering pumps. 

2001, Replaced SSW Hypochlorite piping. 

2003, Replaced CWP 26 Motor and expansion joint. 

2004, Replaced CWP 22 Motor rotating element. 

Unit 3 

Bar Racks 1976 

1992, Replaced upper bar racks. 

1996, Installed wire mesh above the racks to keep out floating 

debris. 

2009, Replaced upper and lower bar racks. 

Service Water Sluice 

Gates 1976 Original still in place. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

24 

Table 2.2 History of Key CWIS Components at Unit 2 and Unit 3 

Equipment Originally 

Installed Date and Description of Component Replacement 

Traveling Screens 1976 

1986, Installed traveling water screen to provide redundancy in the 

event of a blocked screen. 

1988, Replaced traveling water screen 37 and piping providing 

screenwash water to this screen due to severe deterioration. 

1989, Replaced traveling water screen 36. 

1994, Installed Ristroph Screens. 

Fish Return System 1994 Original still in place. 

Screen Wash Pumps 1976 1994, Replaced with Ingersoll Rand 24 APK-1 pumps. 

Service Water Pumps 

31 through 36 1976 

1988, Replaced existing Layne and Bowler pumps with Ingersoll 

Rand single stage pumps to prevent suction of debris from bottom 

of Intake Structure and minimize vibration. Fiberglass baffling 

added in front of new pumps to prevent hydraulic interactions 

between the pumps. Ingersoll Rank 26 APK-1 pumps are rated for 

6000 gpm at 195 ft of total dynamic head. 

Service Water Pumps 

37 through 39 1976 1994, Permanent installation of chlorination nipple, valves, and 

cap. 

Hypochlorite Injection 

Pumps 1976 

1995, Replace existing storage tank with an 1800 gallon tank 

manufactured by Composites USA, Inc. Replacement tank is 

insulated with moisture resistant insulation. 

1998, Replaced continuous chlorination pumps 31 and 32. 

2008, Replaced hypochlorite storage tank. 

Circulating Water 

Pumps 31 through 36 1976 

1989, Allis Chalmers variable speed circulating water pumps 

installed. 

1986, Installed 2 metering pumps and piping. 

1990, Installed 3 metering pumps. 

2001, Replaced SSW Hypochlorite piping. 

2003, Replaced CWP 32. 

Note that the traveling water screens and other CWIS equipment routinely undergo 

preventative maintenance and periodic refurbishments that are not accounted for here. 

2.7 License Status 

Applications were submitted to the NRC to renew the respective Unit 2 and Unit 3 operating 

licenses for an additional 20 years under 10 CFR Part 54 on April 30, 2007. For Unit 2 and 

Unit 3, the requested renewals would extend the license expiration dates to midnight 

September 28, 2033, and midnight December 12, 2035, respectively [Ref. 6.24]. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

25 

3 Existing CWIS Technologies and Operational Measures that 

Affect I&E 

This section describes existing Station intake technologies. The Stations also employ operational 

measures that can affect I&E. EPA has defined a uniform baseline configuration (40 CFR 

§125.93) designed to ensure consistent decision-making among different facilities as follows: 

...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 3/8-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. 

New York has adopted this baseline definition and endorsed full design flow on 365 days per 

year as baseline flow [Ref. 6.91]. This section discusses the following existing CWIS 

technologies and operational measures, previously described in Section 2.4, that differ from the 

EPA baseline and reduce I&E at the Stations: 

 Modified Ristroph-type traveling water screens 

 Fish handling and return systems 

 Low pressure screenwash systems 

 Flow reductions due to dual/variable speed pump operation 

 Flow reductions due to maintenance outages 

In addition to these existing CWIS technologies and operational measures, Units 2 and 3 also 

have cooling system designs (i.e., low temperature rise across condensers, rapid transit through 

cooling system, return of water near point of withdrawal) that permit entrainment survival, as 

discussed in Attachment 6. Based on the fish survival data provided for the existing Unit 2 and 

Unit 3 CWISs in Attachment 6, IPEC’s existing CWIS technologies and operational measures 

produce quantifiable reductions from the regulatory baseline I&E, as shown in Section 3.2. 

Assessments of the qualitative features of each component of the existing CWIS are provided in 

Section 3.1. 

3.1 Description of Existing CWIS Technologies and Current Operational 

Measures that Affect I&E 

3.1.1 Existing Traveling Water Screens 

As described in Section 2.4.1, the CWISs at Units 2 and 3 have modified vertical Ristrophtype traveling water screens which were installed pursuant to the Hudson River Settlement 

Agreement [Ref. 6.40]. These screens were installed following a collaborative research 

effort among the former owners of the Stations and Riverkeeper’s predecessor and directed 

by Dr. Ian Fletcher, then-consultant for Riverkeeper’s predecessor. Dr. Fletcher concluded 

that improvements beyond the screens installed at the Stations were unlikely to 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

26 

significantly reduce impingement losses and, therefore, the existing screens at the Stations 

represent the state-of-the-art in terms of minimizing adverse impacts for impingement 

[Ref. 6.33]. As discussed in Section 2.4.1.1, the traveling water screens at each Unit have 

the following features: 

 Low approach and through-screen velocities – Low through-screen and approach 

velocities increase the likelihood that fish may escape the intake flow and therefore 

reduce the potential for impingement [Ref. 6.94]. Refer to Section 2.4.2.4 for a 

thorough discussion of these velocities. 

 Continuous operation – The modified traveling screens are rotated continuously. If 

accumulation of fish and/or debris on the screens occurs, the same amount of water 

must pass through a smaller available open area, thus increasing both the throughscreen velocity and the differential head loss. As the head losses and velocities 

increase, it is more likely that fish cannot escape the screen area and become 

impinged [Ref. 6.94]. Impingement is less likely to occur when the available 

screen open area is maintained by the continuous removal of fish and/or debris 

from the screens. 

 Flow deflector lip on fish bucket – The curved lip at the leading edge of the fish 

bucket is designed to minimize vortex stresses on fish inside the buckets. The lip 

eliminates turbulent flow in the interior of the buckets, allowing fish to maintain a 

stable, upright position [Ref. 6.35]. Water is also retained by the curved lip, 

maintaining sufficient water volume for fish in the bucket. 

 Spray washes – As noted in Section 2.4.1.2, the screens encounter a series of spray 

washes in the operating rotation. First, high-pressure sprays remove debris from 

the screens; spray deflectors prevent disturbance to fish in the fish bucket from 

these sprays. Then, low-pressure sprays aid in freeing fish from the surfaces of the 

overturning screen panels by gently spraying water through the screen mesh. Due 

to the gentle nature of the flow, the low-pressure sprays lose effectiveness when 

debris covers the screen; the high-pressure sprays must wash off debris first, to 

ensure effective fish recovery [Ref. 6.35]. Finally, another series of high-pressure 

screens washes off any remaining debris before the screens rotate back to the intake 

flow. This final wash reduces ‘carryover’ debris that could potentially enter the 

pump intakes and assists in maintaining the available open area, which reduces the 

potential for impingement. 

 Smooth screen mesh – The 1⁄2 × 1⁄4-inch clear opening slot mesh on the screen 

basket panels is smooth to minimize abrasion to fish transferred into the fish return 

sluices [Ref. 6.8]. 

Each of these features contributes to the reductions in impingement losses detailed in 

Section 3.2. Alternative screening technologies to further reduce I&E are discussed in 

Section 4.2. 

3.1.2 Existing Fish Handling and Return System 

Extensive studies, conducted under the oversight of NYSDEC staff and the predecessor to 

Riverkeeper (HRFA), were performed over several years at the Stations prior to the design 

and implementation of the current fish return systems. The fish collected in the fish 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

27 

buckets attached to the traveling water screens are returned to the Hudson River by the fish 

handling and return system. The low-pressure sprays facilitate the transfer of fish to the 

fish collection sluices, which deliver fish to return pipes. The Unit 2 return pipe discharges 

into the Hudson River north of the Stations’ CWISs, and the Unit 3 return pipe discharges 

at the northwest corner of the Stations’ combined discharge canal. The discharge locations 

of the fish return pipes were selected after conducting dye and fish release studies to find 

locations that would minimize reimpingement [Ref. 6.8]. The design and testing of the 

fish return systems were conducted under the oversight of HRFA (i.e., Riverkeeper’s 

predecessor) expert, Dr. Ian Fletcher, between 1989 and 1992, with the objective of 

maximizing fish survival and minimizing reimpingement [Ref. 6.9; Ref. 6.111]. The 

current fish return systems at Unit 2 and Unit 3 incorporate several features that improve 

fish survival: 

 Removable covers or grates over fish troughs [Ref. 6.54; Ref. 6.55]. 

 Design water depth maintained at approximately 2 inches [Ref. 6.61]. 

 Design trough water velocity between 2-5 fps [Ref. 6.9]. 

 Selection of return pipe discharge locations designed to prevent returned fish from 

immediately reentering the intake structure [Ref. 6.8]. 

The fish handing and return systems at IPEC are considered state-of-the-art, and upgrades 

to the current fish return systems would not be expected to provide appreciable biological 

benefits. 

3.1.3 Flow Reductions 

Certain flow reduction strategies offer potential I&E reduction opportunities. The 

Stations’ dual/variable speed pumps allow intake flow to be minimized based on operating 

requirements. In addition, periods of reduced power at each Unit also contribute to 

reduced intake flow. 

3.1.3.1 Dual/Variable Speed Pumps 

As described in Section 2.4.2.1, Unit 2 is equipped with dual speed CW pumps, and Unit 

3 is equipped with variable speed CW pumps. The pumps can be used to minimize the 

volume of River water drawn through the CWISs, thus minimizing I&E [Ref. 6.89]. 

Required flow rates are dependent upon intake water temperature, and typically allow 

reduced flow from late October until early May, not accounting for scheduled outages 

[Ref. 6.24]. In addition to the ambient River water temperature, flow rates are influenced 

by plant operating status and SPDES permit conditions. 

3.1.3.2 Historic Flow Reductions 

The monthly baseline flows (in millions of gallons per day), and the average monthly 

historic operational flow provided by the Stations, are shown in Table 3.1 and Table 3.2 

below, along with the corresponding flow reduction percentages. As discussed in Section 

2.4.2.3.2, the Unit 2 historic flows include CW, SW, and Unit 1 RW flow, and the Unit 3 

historic flows include CW and SW flow. Historical data for Station operation and 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

28 

associated flows for the past eight years (2001-2008) indicate an average historic 

operational flow reduction of 13.6% for Unit 2 and 28.7% for Unit 3. 

Note that, as discussed in Section 2.4.2.3.2, several factors contribute to the differences in 

Unit 2 and Unit 3 flow rates. First, the SW capacity at Unit 2 (46,000 gpm; Unit 2 SW 

and Unit 1 RW) is greater than the SW capacity at Unit 3 (36,000 gpm). In addition, the 

condensers and low pressure turbines at each Unit have different designs, efficiencies, 

and operational requirements that necessitate substantially different flow requirements. 

Furthermore, more flow is required to clean the Unit 2 systems due to more debris issues 

at Unit 2 than at Unit 3. 

Table 3.1 Unit 2 Monthly Flow Reduction from Baseline 

Month Baseline Flow 

(MGD) 

Historic Operating Flow 

(MGD) 

Average 

Flow Reduction 

January 1275.8 1001.1 21.5% 

February 1275.8 924.1 27.6% 

March 1275.8 908.4 28.8% 

April 1275.8 940.5 26.3% 

May 1275.8 1107.5 13.2% 

June 1275.8 1243.6 2.5% 

July 1275.8 1248.7 2.1% 

August 1275.8 1252.3 1.8% 

September 1275.8 1253.2 1.8% 

October 1275.8 1209.1 5.2% 

November 1275.8 1007.8 21.0% 

December 1275.8 1115.3 12.6% 

Average Annual 1275.8 1102.2 13.6% 

Table 3.2 Unit 3 Monthly Flow Reduction from Baseline 

Month Baseline Flow 

(MGD) 

Historic Operating Flow 

(MGD) 

Average 

Flow Reduction 

January 1261.4 600.1 52.4% 

February 1261.4 583.2 53.8% 

March 1261.4 500.9 60.3% 

April 1261.4 614.8 51.3% 

May 1261.4 899.6 28.7% 

June 1261.4 1199.1 4.9% 

July 1261.4 1227.1 2.7% 

August 1261.4 1217.4 3.5% 

September 1261.4 1234.8 2.1% 

October 1261.4 1170.1 7.2% 

November 1261.4 806.5 36.1% 
 ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

29 

Table 3.2 Unit 3 Monthly Flow Reduction from Baseline 

Month Baseline Flow 

(MGD) 

Historic Operating Flow 

(MGD) 

Average 

Flow Reduction 

December 1261.4 715.2 43.3% 

Average Annual 1261.4 899.0 28.7% 

3.1.3.3 Outage Schedule 

As discussed in Section 2.4.2.3, periods of reduced power decrease the actual intake flow 

entering the Station’s CWISs. This flow reduction represents a reduction from the 

baseline flow and, where quantifiable and reasonably expected, is considered to be an 

operational measure to reduce I&E. Outages are scheduled, where reasonably 

practicable, in a manner sensitive to entrainment considerations, typically during the late 

spring entrainment period, with the result that only one Unit is operating during that 

approximately 25 day outage period each year [Ref. 6.24]. 

3.2 Percent Reductions in I&E from Baseline for Existing CWIS 

Technologies and Current Operational Measures 

Based on the data provided in Attachment 6, the Stations’ existing CWIS technologies and 

operational measures produce quantifiable I&E reductions from the regulatory baseline. As 

noted in Attachment 6, the regulatory baseline is a regulatory construct that employs certain 

operation and survival assumptions. This baseline has been used by NYSDEC in SPDES 

permit proceedings for other New York power plants. The reductions in I&E at the Stations 

are characterized in terms of equivalent age 1 (EA1) fish rather than as total losses summed 

over all life stages (as noted in Attachment 6, there are different life stages of fish). The EA1 

metric weights losses of different life stages according to their expected survival rates. For 

example, if only 10% of eggs for a particular species would be expected to die before 

hatching, then entraining a single larva is equivalent to entraining 10 eggs. If 0.1% of larvae 

would be expected to survive to become one-year-old fish, then entraining 1000 larvae or 

10,000 eggs would be equivalent to removing a single one-year-old fish from the population. 

Using the EA1 metric to compare technology alternatives ensures that the comparisons weight 

all life stages equally according to their potential future contributions to the population (see 

Attachment 6 for further discussion). As shown in Tables 10 and 11 of Attachment 6, 

Appendix A, the existing CWIS technologies and operational measures at the Stations reduce 

EA1 entrainment by approximately 33.8%, and reduce EA1 impingement by approximately 

80.2% compared to the regulatory baseline. According to Attachment 6, the NYSDEC 

Proposed Project would reduce EA1 entrainment losses by approximately 96.3 to 97.6% and 

EA1 impingement losses by approximately 98.9 to 99.3% compared to the regulatory 

baseline. However, NYSDEC has identified a range of acceptable technology performance, 

measured in reduced entrainment (more than 60% reduction) and impingement (more than 

80% reduction), for other existing New York power stations [Ref. 6.87]. Therefore, 

consistent with the Stations’ existing technology being considered state-of-the-art for 

impingement, impingement is limited to NYSDEC acceptable levels. For this reason, this 

Report primarily focuses on entrainment reductions. 
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4 I&E Reduction Technologies 

This section reviews potential alternative technologies and operational measures for reducing 

I&E associated with the Stations from the regulatory baseline. The evaluation focuses on 

engineering, biological, and cost factors consistent with the Interim Decision. The engineering 

factors include technological feasibility and reliability, proven installation at comparable 

facilities, and nuclear safety concerns, where relevant. If installation of the alternative 

technology is feasible based on the engineering factors, the evaluation estimates the associated 

reductions in I&E reductions from the regulatory baseline, as provided in Attachment 6. 

Technologically feasible means that a particular technology likely can be implemented at 

comparable steam-electric generating stations and, as qualified, at the Stations to reduce I&E 

without implicating nuclear safety considerations. 

For certain alternative technologies, very preliminary capital and operational costs are estimated 

using conceptual models appropriate at this stage of the analysis (see Attachment 4). However, 

costs are likely understated due to unknown site-specific conditions. For this reason, a 

Recommended Minimum Contingency of 30% was added to all cost estimates [Ref. 6.25; Ref. 

6.113]. A typical cost multiplier of 30% was employed to capture both corporate overheads and 

the cost of carrying the associated funding (i.e., a Corporate Overheads and Work In Progress 

Cost). In addition, the preliminary estimates provided in this Report do not account for several 

complicating factors, including radiological contamination, zoning restrictions and archeological 

considerations in place at IPEC. 

Potential modifications to the CWIS for a nuclear facility, such as IPEC, where each Unit’s 

CWIS combines the circulating water and service water intakes, are complicated by the fact that 

service water flow is related to nuclear safety, and must be available at all times (i.e., for normal 

operations, shutdown, and projected accident conditions). Therefore, any potential technology 

that could introduce new failure modes into the service water systems, or that could interfere 

with maintaining the service water supply, implicates nuclear safety concerns and, therefore, 

would require further evaluation. 

Technological feasibility may be qualified if the technology is unprecedented (i.e., not 

demonstrated at any comparable facility). In addition, as discussed in Section 3.2 and Section 

4.1, the Stations’ existing technology is considered state-of-the-art for impingement; this Report 

primarily focuses on entrainment reductions. As such, technologies that would not provide 

substantial reductions in entrainment are not considered as viable alternatives to the current 

intake technologies at the Stations. 

4.1 Upgrade of the Existing Fish Handling and Return Systems 

As discussed below, no improvements to the existing fish handling and return systems are 

necessary. The main objective of any fish return system is to return impinged fish to the 

water body with minimal stress. As discussed in Section 3.1.2, fish return designs vary to 

accommodate the size and type of fish being transported. The Unit 2 and Unit 3 TWSs at the 

Stations have separate fish return systems that are described in Section 2.4.1.2. 

As part of the Hudson River Settlement Agreement, consultation and mutual concurrence 

among interested environmental parties, including Riverkeeper (then known as the Hudson 
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River Fisherman’s Association), was required for the design of the fish return systems [Ref. 

6.9]. Therefore, prior to the installation of the Stations’ fish return systems, extensive studies 

were conducted, and prototype fish return system models were designed. The design and 

testing of the fish return systems were conducted under the oversight of Dr. Ian Fletcher, 

biologist for the Hudson River Fishermen’s Association (the predecessor to Riverkeeper), 

between 1989 and 1992 [Ref. 6.9; Ref. 6.111]. Offshore dye studies were conducted to 

determine the best location for the fish return pipe discharges to limit recirculation, and live 

fish release studies were performed to determine the optimum discharge depths for the fish 

return pipes. Design models of the Unit 2 and Unit 3 fish return systems were installed at a 

nearby quarry and tested. The results of these tests indicated that the full systems would not 

impose injuries to the test species (white perch, striped bass, golden shiner, and alewife) under 

expected operating conditions [Ref. 6.9]. 

Per Siemens Water Technologies (Siemens), an industry leader in the design of fish return 

systems and traveling water screens, the fish return systems at Units 2 and 3 are considered to 

be state-of-the-art. Furthermore, Siemens does not recommend any upgrades to the fish return 

systems that would improve survivability rates (see Attachment 1, Section 1). As discussed in 

Section 2.4.1.1, in the Fletcher Article [Ref. 6.33], Dr. Fletcher concluded that improvements 

beyond the screens installed at the Stations were unlikely to significantly reduce impingement 

losses [Ref. 6.33]. In addition, the Fletcher Article [Ref. 6.33] indicates that the NYSDEC 

adopted the performance of these screens as the State’s best technology available for reducing 

impingement. 

Conclusions

The Stations’ fish return systems at Units 2 and 3 are considered to be state-of-the-art, and 

Siemens does not recommend any upgrades that would improve survivability rates (see 

Attachment 1, Section 1). Based on the previous studies performed under the oversight of Dr. 

Ian Fletcher, the (relative) recent vintage of the fish return systems, and Siemens’ review, 

upgrades to the current fish return systems are not expected to provide appreciable 

impingement benefits. The system does not impact entrainment. 

4.2 Traveling Water Screens 

Traveling water screens can be designed with coarse mesh (> 2.0 mm) or fine mesh openings 

(≤ 2.0 mm) [Ref. 6.115]. Generally, entrainment decreases with smaller mesh sizes, as fine 

mesh screens impinge organisms that are typically entrained through coarse mesh screens. 

However, as discussed in Attachment 6, mortality from impingement can offset entrainment 

reductions, depending on species and life stage of the fish being impinged instead of 

entrained. Smaller mesh sizes also increase the possibility of significant fouling and heavy 

debris loading on the screening panels. Mortality of early life stage organisms impinged on 

fine mesh screens can increase due to stresses caused by the resultant higher debris loads, 

increased through-screen velocities, and increased pressure differentials. 

In certain circumstances, traveling screens, such as through flow, dual flow, and center flow 

screens, can be fitted with fine mesh screen material. Where entrainment is a seasonal 

occurrence, existing traveling water screens can be retrofitted with interchangeable fine mesh 

panels or fine mesh inserts laid over and fastened to the permanent coarse mesh screens for 
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seasonal operating requirements (e.g., a facility could replace the course mesh or install fine 

mesh inserts during the entrainment season to reduce the entrainment of eggs) [Ref. 6.115]. 

The following sections evaluate alternative screening technologies to the existing coarse mesh 

Ristroph screens. A mesh opening size of 2.0 mm was selected for the conceptual designs of 

fine mesh screening systems to provide a consistent comparison between technologies. This 

opening size was chosen as it is the smallest opening size that would likely provide reliable 

flow and avoid screen failures due to excessive debris loading and/or fouling. The biological 

information provided in Attachment 6 determines the potential reductions in EA1 I&E from 

the regulatory baseline for select opening sizes (i.e., 9.0, 6.0, 3.0, 2.0, 1.5, and 1.0 mm). 

4.2.1 Alternative Ristroph Screens 

Alternative Ristroph screens (i.e., Ristroph screens with different mesh opening sizes than 

the mesh opening size of the existing Ristroph-type TWSs) are not considered as viable 

alternatives to the current screening systems at the Stations. As shown in Attachment 6, 

the use of alternative Ristroph screens (coarse or fine mesh) would not be expected to 

provide substantial reductions in EA1 I&E from the existing TWSs and fish return 

systems, because the maximum possible reduction in EA1 entrainment losses achievable 

by fine mesh Ristroph screens (34.9%) is only 1.1% more than the current reduction in 

EA1 entrainment losses (33.8%), as shown in Section 3.2. Moreover, significant 

civil/structural modifications would be required to install fine mesh Ristroph screens at the 

Stations. 

The primary concern with fine mesh screens is that they can impinge early organism life 

stages that are entrained through coarse mesh screens. Depending on species and life 

stage, mortality from impingement can exceed entrainment mortality. In order for fine 

mesh screens to reduce entrainment losses, impingement survival of target species 

previously entrained must be substantially greater than entrainment survival through the 

circulating water system. In addition, smaller mesh sizes (i.e., < 2.0 mm) would create 

significant opportunity for fouling and heavy debris loading of the screen panels with a 

corresponding effect on survival. A study of 0.5 mm fine mesh TWSs installed at the 

Prairie Island Nuclear Generating Plant, located on the Mississippi River in Red Wing, 

Minnesota, concluded that debris volume had a significant effect on survival with mortality 

of all early life stages between 95 - 100% during high debris loads [Ref. 6.32]. Where 

debris loading is persistent, survival can be significantly impacted. 

The Consolidated Edison Company of New York (ConEd, predecessor of Entergy) 

commissioned reviews of previous fine mesh studies, surveys of existing fine mesh 

applications, and model flume trials of a fine mesh Ristroph screen between 1990 and 1991 

[Ref. 6.34; Ref. 6.32]. A field study of a fine mesh Ristroph screen installed at Unit 1 

concluded that there is no net gain when mortalities of entrained organisms are no greater 

than the mortalities imposed on the same organisms by impingement on fine mesh screens 

[Ref. 6.31]. In 1994, Dr. Ian Fletcher concluded that mesh sizes smaller than 3 mm could 

not be safely recommended due to operational/reliability issues with the fine mesh panels 

including tears, punctures, and detachment from the screen frames [Ref. 6.32]. 

Brunswick Nuclear Plant (BNP), which receives cooling water from the Cape Fear River 

near Southport, North Carolina, utilizes 1.0 mm fine mesh panels that are placed on top of 
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the permanent 9.5 mm (3/8 inch) TWS panels during periods of high entrainment to filter a 

maximum cooling water intake capacity of 1,328,000 gpm [Ref. 6.7; Ref. 6.115]. An 84% 

reduction in entrainment (compared to the permanent screen systems) was reported at BNP 

following the installation of the fine mesh inserts [Ref. 6.115]. Although EPA references 

the BNP as a successful application of fine mesh screens [Ref. 6.115], application of these 

screens at BNP has been limited. As stated in the BNP 2000 Environmental Monitoring 

Report [Ref. 6.6], “[d]uring periods of high vulnerability resulting from extreme lunar tides 

or increased sediment and debris loading, the [National Pollutant Discharge Elimination 

System] 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.” Impingement 

survival of organisms that formally would have been entrained was not determined. 

Although seasonal deployment of fine mesh inserts on top of the coarse mesh TWS panels 

during periods of high entrainment could provide entrainment reductions at some facilities, 

fine mesh screens inserted on permanent coarse mesh screens can increase flow resistance 

or head loss. For a 1.0 mm mesh panel installed over a 3

/8 inch coarse metal panel, the 

head loss at a through-screen velocity of 1.0 fps increases by a factor of 3.8. For a 0.5 mm 

mesh on 3/8 inch coarse metal panel, the head loss at a through-screen velocity of 1.0 fps 

increases by a factor of 4.8 [Ref. 6.34]. Increases in head loss across the screening panels 

present numerous mechanical and biological issues. The primary mechanical concern is 

that the rate of debris plugging or blinding of the screening mesh is increased dramatically 

due to the increased pressure differentials combined with the smaller sizes of debris 

impinged by fine mesh screens [Ref. 6.27]. Increased pressure differentials can cause 

smaller impinged organisms to be damaged by extrusion (i.e., the organisms are 

compressed and forced through the screening mesh). The increased debris loads also add 

weight to the TWS panels causing premature wear and failure of bearings, chains, and 

sprockets. Permanently installed fine mesh screens typically experience tearing of the 

mesh material from the panel frames caused by metal fatigue due to the flexing of the 

panels during their ascent and descent in the water column [Ref. 6.34]. These mechanical 

issues contribute to substantial increases in maintenance requirements and 

repair/replacement costs. In addition, due to the increased pressure differentials, increased 

vortexing in the Ristroph buckets can occur, causing stresses on impinged fish resulting in 

mortality [Ref. 6.27]. 

According to 40 CFR §125.94, if a facility reduces the through-screen velocity to at or 

below 0.5 fps, it is “deemed to have met the impingement mortality performance 

standards”. In order to maintain existing head loss across the screen and provide a 

through-screen velocity at or below 0.5 fps, the size of the CWISs would need to be 

expanded to accommodate fine mesh Ristroph screens. A much larger fine mesh screen 

area would be required to provide the same total open area as a coarse mesh screen. Four 

2.0 mm fine mesh traveling water screens would be required per intake channel to filter the 

required flow and provide a through-screen velocity at or below 0.5 fps. 

Attachment 2, Figures 2-1 through 2-3 depict a conceptual design for 2.0 mm fine mesh 

Ristroph screens at Units 2 and 3. The conceptual designs would require expansion of the 

existing intake structures to form new forebays. Each forebay would be dedicated to an 

existing CW intake channel and would house four 2.0 mm fine mesh TWSs near its face. 

Each 2.0 mm fine mesh TWS channel would be equipped with new bar racks and stop logs 
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providing large debris removal and isolation of the fine mesh TWSs for repair or 

maintenance. The expanded intake for fine mesh TWSs shown in Attachment 2 would not 

affect the existing operation of the SW intake channels, and would include a new or 

modified fish return system that would be required for removal of organisms and debris 

from the TWSs. As shown, significant civil/structural modifications would be required to 

install fine mesh TWSs at the Stations. 

Maintenance

The maintenance activities required for 2.0 mm fine mesh Ristroph screens would be 

similar to the current maintenance operations associated with the existing coarse mesh 

Ristroph screens, but maintenance frequency would likely increase. Due to the larger 

debris loads retained by fine mesh screens, however, wear on mechanical components 

would be expected to be greater, thus requiring a higher frequency of maintenance and 

replacement compared to the existing TWSs. As such, the overall maintenance costs and 

time would be expected to increase significantly for fine mesh Ristroph screens compared 

to the current coarse mesh Ristroph screens due to the increased debris loads and larger 

number of Ristroph screens required. At a minimum, maintenance costs required for fine 

mesh TWSs would be at least 4 times the costs required to maintain the existing coarse 

mesh TWSs. 

Because fine mesh screens are more susceptible to biofouling than coarse mesh screens, it 

is likely that a sodium hypochlorite system would be required to periodically dispense 

sodium hypochlorite in front of any fine mesh Ristroph screens to provide biofouling 

control. Any addition of sodium hypochlorite to the CW systems would need to be 

evaluated for potential impacts to the SPDES permit [Ref. 6.86]. 

Cost

The total estimated capital cost for Unit 2 and Unit 3 for the installation of the 2.0 mm fine 

mesh Ristroph screens, as shown in Attachment 2 Figures 2-1 through 2-3, would be 

approximately $373 million (see Attachment 4). 

The construction activities associated with expanding the existing Unit 2 and Unit 3 intake 

structures and the installation of 2.0 mm fine mesh Ristroph screens would take 

approximately six to nine months per Unit. As discussed in Section 2.4.2.3.1, refueling 

outages are anticipated to last approximately 25 days. Assuming that the construction 

activities could be scheduled to coincide with a routine maintenance outage for each Unit, 

there would be approximately five to eight months of lost generating capacity per Unit 

during the implementation of the evaluated 2.0 mm fine mesh Ristroph screens. As 

discussed in Section 2.1, the Stations currently generate electricity at a rated capacity of 

approximately 1078 MWe and 1080 MWe for Units 2 and 3, respectively. A five to eight 

month construction outage would result in a loss of approximately 3.9 million to 6.3 

million MW-hrs per Unit. If construction activities could not be scheduled to coincide 

with a routine maintenance outage, the costs due to construction outages would increase. 

I&E Discussion

Attachment 6 (Tables 17 and 23 of Appendix A) provides the reductions from the 

regulatory baseline in EA1 losses averaged among species and years that could be 
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35 

achieved using 9.0, 6.0, 3.0, 2.0, 1.5, and 1.0 mm Ristroph screens accounting for the 

Stations’ survival rates (Attachment 6) and average historic flow reductions (Section 

2.4.2.3.2). A summary of the information included in Attachment 6 is shown in Table 4.1. 

Table 4.1 Potential Percent Reduction of Annual EA1 I&E Losses due to 

Modified Ristroph Screens in Each Month 

Month 

EA1 Entrainment Loss Reduction EA1 

Impingement 

9.0 mm 6.0 mm 3.0 mm 2.0 mm 1.5 mm 1.0 mm Loss Reduction 

January 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 8.7% 

February 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 9.6% 

March 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 12.0% 

April 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 6.6% 

May 5.9% 6.1% 6.2% 6.1% 5.9% 4.8% 7.4% 

June 13.6% 14.3% 14.1% 12.8% 11.0% 8.7% 8.5% 

July 5.8% 6.4% 7.0% 7.0% 6.9% 6.9% 4.0% 

August 3.4% 4.1% 4.8% 4.8% 4.8% 4.8% 4.2% 

September 1.3% 1.3% 1.5% 1.5% 1.5% 1.5% 4.4% 

October 1.2% 1.1% 1.0% 1.0% 1.0% 1.0% 3.8% 

November 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 4.6% 

December 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 6.3% 

Annual 31.5% 33.8% 34.9% 33.5% 31.5% 27.9% 80.2% 

The maximum possible reduction in EA1 entrainment losses shown in Table 4.1 (34.9%) is 

only 1.1% more than the current entrainment reduction (33.8%) shown is Section 3.2. 

Additionally, the estimated reduction in impingement provided by alternative Ristroph 

screens, regardless of mesh size, is identical to the current reductions provided by the 

existing Ristroph-type TWSs. 

Conclusions

The estimated initial costs associated with the conceptual installation of the 2.0 mm fine 

mesh Ristroph screens would include approximately $373 million in capital costs and 

approximately 3.9 million to 6.3 million MW-hrs of lost generation due to the required 

construction outages. As shown in Table 4.1, none of the mesh sizes evaluated would be 

expected to reduce EA1 entrainment losses from baseline by more than approximately 

34.9%, and, therefore, would be essentially similar to current technology conditions 

(Section 3.2). As such, alternative Ristroph screens are not further considered to be viable 

alternatives to the existing intake technologies. 

4.2.2 Dual Flow Traveling Water Screens 

Dual flow traveling water screens are not considered as viable alternatives to the current 

screening systems at the Stations, because the use of dual flow traveling water screens 

(coarse or fine mesh) would not be expected to provide substantial reductions in EA1 I&E 

from the existing TWSs and fish return systems. 
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36 

In order to reduce the through-screen velocities by increasing the available screen area, and 

thus potentially reduce impingement, the existing through flow traveling water screen 

installations at many facilities can be retrofitted to use dual flow traveling water screens 

[Ref. 6.94]. As discussed in Section 4.2.1, if a facility could reduce its maximum throughscreen velocity to at or below 0.5 fps, impingement is considered to be reduced to 

acceptable levels, according to EPA. In addition, according to the Hudson River Power 

Plants Final Environmental Impact Statement [Ref. 6.88], NYSDEC has indicated interest 

in through-slot velocities of 0.25 fps. As shown in Figure 4.1, dual flow traveling water 

screens are mechanically similar to through flow screens but are rotated ninety degrees 

within the flow channel, which reduces the through-screen velocity by increasing the 

surface area and eliminating the potential for carryover. 

Figure 4.1 Typical Dual Flow Screen Arrangement [Ref. 6.94] 

The orientation of a dual flow screen allows the entire submerged screen surface to be an 

active screen area. Thus, for an identical basket width, a dual flow screen can filter twice 

the volume of water as a through flow screen. If the volume of water to be filtered is 

constant and the traveling screens have identical basket widths, the through screen velocity 

of a dual flow screen will be approximately half of the through screen velocity of a through 

flow screen. Unlike through flow screens, the configuration of dual flow traveling water 

screens (parallel to the direction of incoming flow) eliminates debris carryover to the 

condensers and reduces condenser maintenance because the screening face of the baskets 
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37 

are not rotated into the downstream flow of the intake. Figure 4.2 compares the flow 

pattern through a through flow traveling water screen with the flow pattern through a dual 

flow traveling water screen. 

Figure 4.2 Plan View of Through Flow to Dual Flow Retrofit [Ref. 6.94] 

Conversion from through flow to dual flow traveling water screens typically includes 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 channel, 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 flow 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. 

Dual flow traveling water screens have been retrofitted at nuclear power generating 

facilities, including Cooper Nuclear Station located on the Missouri River. In 2006, coarse 

mesh dual flow traveling water screens were retrofitted at Cooper Nuclear Station to 
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38 

address debris carry-over problems encountered with the original through flow traveling 

water screens [Ref. 6.83]. Each dual flow screen is equipped with fish collection baskets 

and is designed to filter a maximum flow rate of 159,000 gpm with a through screen 

velocity of approximately 2.0 fps [Ref. 6.83]. 

Fine mesh dual flow screens have been in operation since 1984 at Unit 4 of the coal-fired 

TECO Big Bend Power Station located on the Tampa Bay estuary across from Tampa, 

Florida. The six dual flow screens have a 0.5 mm mesh size and filter an intake flow of 

approximately 483,435 gpm. Biofouling control was a significant issue at TECO Big Bend 

Power Plant requiring biweekly manual cleaning of the dual flow screens by a two person 

crew [Ref. 6.14]. 

Retrofitting the Stations’ CWISs with coarse mesh dual flow traveling water screens (i.e., 

1⁄4-inch by 1⁄2-inch basket mesh openings) would only reduce the through-screen velocity 

(calculated in Section 2.4.2.4) to approximately 0.81 fps. Therefore, in order to 

accommodate fine mesh dual flow screens while maintaining the existing head loss across 

the screens and providing a through-screen velocity at or below 0.5 fps, the size of the 

CWISs would need to be expanded to accommodate fine mesh dual flow screens. 

Attachment 2, Figures 2-4 through 2-6 depict a conceptual design for 2.0 mm dual flow 

screens at Units 2 and 3. A new intake forebay would be dedicated to each existing CW 

intake channel and would house three 2.0 mm dual flow screens near its face. Per EIMCO 

Water Technologies (EWT), a leading manufacturer of dual flow screens, three 2.0 mm 

dual flow screens would be required to filter the intake water flows while maintaining a 

through-screen velocity at or below 0.5 fps (see Attachment 1, Section 2). The face of the 

expanded intake would be located between 90 and 170 ft from the face of the existing 

intake structure and would have a width of nearly 200 ft. New bar racks and stop logs 

would be installed to provide large debris removal and isolation of the screens for repair or 

maintenance. This conceptual design would not affect the existing operation of the SW 

intake channels, and would include new or modified fish return systems that would be 

required to safely return impinged organisms to the source water body. As shown, 

significant civil/structural modifications would be required to install fine mesh dual flow 

screens at the Stations. 

Maintenance

The maintenance activities required for dual flow screens would be expected to be similar 

to the current maintenance operations associated with the existing coarse mesh TWSs, 

although overall maintenance costs and time would be expected to increase significantly 

for fine mesh dual flow screens. At a minimum, maintenance costs required for 2.0 mm 

fine mesh dual flow TWSs would be expected to be at least three times the costs required 

to maintain the existing coarse mesh TWSs. However, because dual flow screens virtually 

eliminate debris carryover into the condenser, there would be reduced maintenance 

associated with cleaning the condenser. 

Because fine mesh screens are more susceptible to biofouling than coarse mesh screens, it 

is likely that a sodium hypochlorite system would be required to periodically dispense 

sodium hypochlorite in front of any fine mesh dual flow screens to provide biofouling 

control. Any addition of sodium hypochlorite to the CW systems would need to be 

evaluated for potential impacts to the SPDES permit [Ref. 6.86]. 
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39 

Cost

The total estimated capital cost for Unit 2 and Unit 3 for the conceptual installation of the 

2.0 mm dual flow screens, as shown in Attachment 2 Figures 2-4 through 2-6, would be 

approximately $350 million (see Attachment 4). 

The construction activities associated with expanding the existing Unit 2 and Unit 3 intake 

structures and the installation of 2.0 mm fine mesh dual flow screens would take 

approximately six to nine months per Unit. As discussed in Section 2.4.2.3.1, refueling 

outages are anticipated to last approximately 25 days. Assuming that the construction 

activities could be scheduled to coincide with a routine maintenance outage for each Unit, 

there would be approximately five to eight months of lost generating capacity per Unit 

during the implementation of the evaluated fine mesh dual flow screens. As discussed in 

Section 2.1, the Stations currently generate electricity at a rated capacity of approximately 

1078 MWe and 1080 MWe for Units 2 and 3, respectively. A five to eight month 

construction outage would result in a loss of approximately 4.7 million to 6.3 million MWhrs per Unit. If construction activities could not be scheduled to coincide with each Unit’s 

routine maintenance outages, the costs due to construction outages would increase. 

I&E Discussion

Any incremental impingement reductions provided by dual flow screens would not be 

expected to be appreciable, because the Stations’ existing TWSs screens and fish return 

systems already provide state-of-the-art impingement protection (Section 3.2). Attachment 

6 (Table 17 of Appendix A) provides the expected reductions in EA1 entrainment losses 

from baseline that could be achieved through the installation of fine mesh panels with 

various mesh sizes (summarized in Table 4.1). However, as discussed in Section 4.2.1, the 

maximum possible reduction in EA1 entrainment losses shown in Table 4.1 (34.9%) is 

only 1.1% more than the current entrainment reduction (33.8%). 

Conclusions

The estimated initial costs associated with the conceptual installation of the 2.0 mm fine 

mesh dual flow screens would include approximately $350 million in capital costs and 4.7 

million to 6.3 million MW-hrs of lost generation due to the required construction outages. 

Dual flow screens would not be expected to provide substantial reductions in EA1 I&E 

from the existing TWSs and fish return systems. Therefore, dual flow screens are not 

further considered as an alternative to the current screening systems. 

4.2.3 Angled Traveling Screens 

Angled traveling screens are not considered to be viable alternatives to the current 

screening systems at the Stations, because the use of angled traveling screens (coarse or 

fine mesh) would not be expected to provide substantial reductions in EA1 I&E from the 

existing TWSs and fish return systems. 

Angled traveling screens typically consist of through flow traveling screens set at an angle 

to the incoming flow. Angled traveling screens cause abrupt changes in the velocity and 

direction of the flow, creating a turbulence zone in front of the screens that fish typically 

avoid. Rather, fish tend to align themselves parallel to the incoming flow, coming in 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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40 

contact tail first with the turbulence zone. As shown in Figure 4.3, fish move away from 

the turbulence zone in a direction perpendicular to the angled traveling screens. The net 

effect of this behavioral response, after repeated excursions away from the turbulence 

zone, is a lateral displacement of fish towards the end of the angled traveling screens into a 

bypass channel that returns fish to the source waterbody [Ref. 6.35]. 

Figure 4.3 Angled Traveling Screen Guiding Fish Towards Bypass Channel [Ref. 6.35]

Modular inclined screens (MISs) are a specific variation of angled traveling screens, where 

each module consists of integrated bar racks, dewatering stop logs, inclined screens set at a 

10° to 20° angle to the incoming flow, and a bypass channel to return fish to the source 

water body. A plan view of MISs is shown in Figure 4.4. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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41 

Figure 4.4 Plan View of MISs [Ref. 6.35] 

In order to maintain existing head loss across the screen panels and provide a throughscreen velocity at or below 0.5 fps, the size of the CWISs would need to be expanded to 

accommodate fine mesh angled traveling screens. As previously determined in Section 

4.2.1, four 2.0 mm fine mesh TWSs with a wire thickness of 0.5 mm would be required per 

intake channel to filter the required flow while maintaining a through-screen velocity at or 

below 0.5 fps. 

A conceptual design for angled traveling screens at the Stations would be similar to the 

conceptual configurations for fine mesh dual flow and fine mesh Ristroph screens shown in 

Attachment 2. However, the width of the expanded intake required for angled traveling 

screens would be larger because each angled traveling screen channel would include a fish 

bypass channel. The width of the expanded intake for 2.0 mm fine mesh angled traveling 

screens providing screened cooling water to three CW channels would be approximately 

238 ft wide assuming a 1 ft wide fish bypass channel and 3 ft thick walls. Each fine mesh 

angled traveling screen would be paired with new bar racks and stop logs providing large 

debris removal and isolation of the traveling screens for repair or maintenance. Due to the 

fish bypass channels and pumps required to induce flow in the bypass channel, 

implementation of fine mesh angled traveling screens would require more civil/structural 
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and mechanical modifications than the implementation of fine mesh dual flow screens or 

fine mesh Ristroph screens. 

Maintenance

The maintenance activities required for angled traveling screens are expected to be similar 

to the current maintenance operations associated with the existing coarse mesh TWSs, 

although additional maintenance for the new pumps required to induce flow in the bypass 

channels would be required. Overall maintenance costs and time would be expected to 

increase significantly for fine mesh angled traveling screens compared to the current coarse 

mesh TWSs due to the larger number of fine mesh screens required and the addition of 

circulating pumps for the fish bypass channels. The use of fine mesh screens would create 

larger debris loads; therefore, additional wear on mechanical components would be 

expected, resulting in a higher frequency of maintenance and replacement compared to the 

existing TWSs. Due to the increased number of screens required for the implementation of 

fine mesh angled traveling screens, maintenance costs would be expected to be 

approximately four to five times the costs required to maintain the existing coarse mesh 

TWSs. 

Additionally, because fine mesh screens are more susceptible to biofouling than coarse 

mesh screens, it is likely that a sodium hypochlorite system would be required to 

periodically dispense sodium hypochlorite in front of any fine mesh angled traveling 

screens to provide biofouling control. Any addition of sodium hypochlorite to the CW 

systems would need to be evaluated for potential impacts to the SPDES permit [Ref. 6.86]. 

Cost

The conceptual installation of fine mesh angled traveling screens would require more 

civil/structural and mechanical work than the conceptual installation of fine mesh dual 

flow or Ristroph screens. Therefore, the estimated capital costs for the conceptual 

installation of 2.0 mm fine mesh angled traveling screens would be anticipated to be 

significantly higher than the estimated costs for installation of 2.0 mm fine mesh dual flow 

screens (Section 4.2.2) or 2.0 mm fine mesh Ristroph screens (Section 4.2.1). 

I&E Discussion

With respect to impingement, in a scaled hydraulic study of the biological effectiveness of 

a MIS system (i.e., an angled screen system including a bypass channel to return fish to the 

source waterbody), the Electric Power Research Institute (EPRI) concluded MIS systems 

have potential to safely and effectively divert juvenile fish at CWISs [Ref. 6.13]. 

Diversion efficiency is defined as the ratio of fish diverted into a bypass channel divided 

by the sum of fish diverted and fish impinged against the angled screens. In a full scale 

study of an MIS system installed at the oil- and gas-fired Oswego Power Generating 

Station on Lake Ontario, diversion efficiencies of 91% for alewives, 92% for rainbow 

smelt, and 93% for white perch were reported [Ref. 6.35]. However, data collected during 

the full scale study from the bypassed fish determined that 86% of the bypassed alewives 

were dead or injured on arrival in the collection basin. The corresponding immediate 

mortalities for rainbow smelt were 59%, and for the white perch 80% [Ref. 6.35]. In 

addition, any impingement reductions provided by angled traveling screens would not be 
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expected to be appreciable when compared to the impingement reductions associated with 

the Stations’ existing TWSs screens and fish return systems (Section 3.2). 

Entrainment reductions would not be appreciable. As discussed in Attachment 6, in order 

to avoid entrainment, larvae have limited capabilities to move into a sweeping flow that 

bypasses a screen. However, due to the configuration of the angled traveling screens 

inside a CWIS, no sweeping flow bypassing the screen would be present. Therefore, 

because eggs and larvae cannot swim away from the turbulence created by angled traveling 

screens, there is no substantial reduction in entrainment [Ref. 6.107]. As such, angled 

traveling screens are not expected to improve reductions in EA1 entrainment losses 

compared to Ristroph screens (see Table 4.1). 

Conclusion

Angled traveling screens would not be expected to provide substantial reductions in EA1 

I&E from the existing TWSs and fish return systems. Moreover, the capital costs and 

maintenance costs associated with angled traveling screens would be significantly higher 

than the costs associated with dual flow screens or Ristroph screens due to additional 

civil/structural and mechanical work associated with the installation of the fish bypass 

channels and their flow-inducing pumps. Therefore, angled traveling screens are not 

further considered as an alternative to the current screening systems. 

4.2.4 WIP Screens 

Beaudrey USA W Intake Protection (WIP) screens are not considered as viable alternatives 

to the current screening systems at the Stations, because the use of WIP screens (coarse or 

fine mesh) would not be expected to substantial reductions in EA1 I&E from the existing 

TWSs and fish return systems. 

The WIP screen is a modified revolving disc screen that may often be retrofitted into 

intakes that currently have through flow TWSs. The traditional revolving disc screen 

consists of a flat disc covered with screening material that rotates about a horizontal axis 

perpendicular to the water flowing into an intake. As water flows through the submerged 

portion of the disc, solids are retained on the screening media. On a traditional revolving 

disc screen, the rotation of the disc lifts the solids above the water surface where they are 

removed by spray nozzles. 

The WIP system consists of one rotating wheel, which rotates within a frame at 1 or 2 

revolutions per minute and a fish protection system. Both fish and debris are removed 

from the screen surface below the waterline by a fish pump and suction scoop. The aquatic 

organisms do not leave the water and are returned downstream of the intake structure. 

However, compared to traditional through flow traveling water screens, the WIP system 

does not utilize the entire available screen area, as shown in Figure 4.5. 

With traditional through flow traveling water screens, any fish and/or debris that are not 

washed off the screen basket would be washed off into the flow of water and carried 

through the cooling water system. The potential for debris carryover is eliminated as 

shown in Figure 4.6, because WIP screens do not rotate over into the downstream flow, 

and all flow must pass through the screen before entering the screenwell and ultimately the 

condenser. 
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Figure 4.5 Beaudrey WIP System 
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Figure 4.6 Beaudrey WIP System, Side View 

The WIP System should have appreciably easier maintenance than the existing TWSs, 

because the WIP screens can be raised out of the water for maintenance activities, do not 

contain chainbelts or links, and lack spray nozzles and headers. The WIP screens would 

also eliminate debris carryover into the condensers, reducing maintenance associated with 

condenser fouling. 

WIP screens can also be constructed with a circular fine-mesh screen designed to collect 

fish eggs and larvae and return them to the source waterbody. However, unlike Ristroph 

screens or dual flow screens, WIP Systems are not designed to have removable fine mesh 

inserts, eliminating the possibility of seasonal deployment during periods of high 

entrainment. 

As discussed in Section 2.4.2.4, the existing TWSs allow 140,000 gpm or 143,200 gpm of 

water to flow through an area defined by the current TWS basket width and the height of 

the water level, resulting in a maximum through-screen velocity of approximately 1.61 fps 

or 1.64 fps, respectively. However, as shown in Figure 4.5, a WIP system would limit the 

flow area to a circular screen section and would require the same volume of flow to pass 

through a smaller area, resulting in an increased through-screen velocity. The through-
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screen velocity of a WIP System can be calculated by replacing the basket width and mean 

low water terms in the through-screen velocity equation provided in Section 2.4.2 with the 

surface area of the screening wheel. A WIP screen designed to fit into the existing 

traveling water screen guides would have a width of 13ft 4 inches and would have a 12.5 ft 

diameter circular screen section. If the circular screen section were constructed of the 

same wire gauge and opening size as the current TWSs (14 gauge wire and a mesh opening 

size of 1⁄2 × 1⁄4-inches), the through-screen velocity would be approximately 4.08 fps at a 

flow rate of 140,000 gpm, which is 2.5 times greater than the through-screen velocity of 

the currently installed TWSs. 

In order to provide a through-screen velocity at or below 0.5 fps, the size of the CWISs 

would need to be greatly expanded to accommodate extra WIP screens at the Stations. The 

number of fine mesh WIP screen screens required to maintain a through-screen velocity at 

or below 0.5 fps can be determined by replacing the basket width and mean low water 

terms in the equation previously referenced in Section 2.4.2.4 with the surface area of WIP 

screening wheel. Ten 2.0 mm fine mesh WIP screens with 12.5 ft diameter screening 

wheels would be required per intake channel (140,000 or 143,200 gpm) to maintain a 

through-screen velocity at or below 0.5 fps. 

A conceptual design for 2.0 mm fine mesh WIP screens at IPEC would be similar to the 

conceptual configuration for fine mesh dual flow and fine mesh Ristroph screens shown in 

Figures 2-4 through 2-6 and Figures 2-1 through 2-3 of Attachment 2, respectively. 

However, the size of the expanded intake required would be significantly larger, because 

each of the new dedicated forebays would contain 10 fine mesh WIP screens. The width 

of the expanded intake for fine mesh WIP screens providing screened cooling water to 

three CW channels would be approximately 500 ft wide assuming 13 ft 4 inch wide WIP 

screen channels and 3 ft thick walls. Each fine mesh WIP screen would be paired with 

new bar racks and stop logs providing large debris removal and isolation of the traveling 

screens for repair or maintenance. Due to size of the expanded intake required, 

implementation of fine mesh WIP screens would require more civil/structural and 

mechanical modifications than the implementation of fine mesh dual flow screens or fine 

mesh Ristroph screens. 

Maintenance

The WIP screens should have appreciably easier maintenance than the existing TWSs 

because the WIP screens can be raised out of the water for maintenance purposes. In 

addition, WIP screens would eliminate debris carryover into the condensers reducing 

maintenance costs associated with the condensers. However, overall maintenance costs 

would be expected to increase significantly for WIP screens compared to the current 

TWSs, due to the number of WIP screens that would be required to screen the normal 

intake flows of Units 2 and 3 (120 total 2.0 mm fine mesh WIP screens). Due to the 

increased number of screens required for the implementation of fine mesh WIP screens, 

maintenance costs required for 2.0 mm fine mesh WIP screens would be expected to be 

approximately ten times the costs required to maintain the existing coarse mesh TWSs. 

Because fine mesh screens are more susceptible to biofouling than coarse mesh screens, it 

is likely that a sodium hypochlorite system would be required to periodically dispense 

sodium hypochlorite in front of any fine mesh WIP screens to provide biofouling control. 
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Any addition of sodium hypochlorite to the CW systems would need to be evaluated for 

potential impacts to the SPDES permit [Ref. 6.86]. 

Cost

The estimated cost for the WIP System components (i.e., screens, pumps, and controllers) 

is 3.3 times the cost of the fine mesh Ristroph screen components and 3.7 times the cost of 

the fine mesh dual flow screen components (see Attachment 1, Section 3). In addition, due 

to the larger number of fine mesh WIP screens required and the increased costs associated 

with construction of the expanded intake structures that would be required to house the 

larger number of screens, the estimated capital costs for the installation of conceptual 2.0 

mm fine mesh WIP screens is anticipated to be significantly higher than the estimated 

costs for installation of 2.0 mm fine mesh dual flow screens or 2.0 mm fine mesh Ristroph 

screens. 

I&E Discussion

A pilot study to determine impingement reductions provided by WIP screens was 

conducted at Unit 5 of the OPPD’s North Omaha Station (a coal-fired generating station) 

by EPRI [Ref. 6.12]. Unit 5 is provided with condenser cooling water from the Missouri 

River by an intake structure that is divided into six cells or channels. The flow through 

each channel is 29,385 gpm and each channel contains a bar rack, sluice gate, and traveling 

water screen [Ref. 6.12]. One of the six traveling water screens was replaced with a WIP 

screen with square 6.1 mm (0.24 inch) openings in August 2006. The results of the pilot 

study indicated that WIP screens have the potential to reduce impingement mortality of 

channel catfish and bluegill by greater than 90%, and fathead minnow and the native 

Missouri River fish group, comprised primarily of emerald shiner, by 79 to nearly 85% 

[Ref. 6.12]. However, any impingement reductions provided by WIP screens would not be 

expected to be appreciable because the Stations’ existing TWSs screens and fish return 

systems already provide state-of-the-art impingement protection (Section 3.2). 

No studies investigating entrainment mortality associated with WIP screens have been 

performed [Ref. 6.12]. In addition, other than fine mesh panels, the WIP screens do not 

utilize any entrainment reducing features and would not be expected to provide additional 

reductions in entrainment other than physical exclusion based on the size of the mesh 

opening. Therefore, it is assumed that WIP screens with various mesh sizes would provide 

similar reductions in EA1 entrainment losses as Ristroph screens (see Table 4.1); however, 

as discussed in Section 4.2.1, no mesh size would be expected to provide significant 

additional reductions in EA1 entrainment losses. 

Conclusions

The use of WIP screens at IPEC would not be expected to provide substantial reductions in 

EA1 I&E losses from the existing TWSs and fish return systems. In addition, due to the 

number of fine mesh WIP screens and the additional intake modifications required, the 

capital costs and maintenance costs associated with the installation and operation of fine 

mesh WIP screens would be significantly higher than the costs required for fine mesh dual 

flow traveling screens or fine mesh Ristroph screens. Thus, WIP screens are not further 

considered as an alternative to the current screening systems. 
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4.2.5 MultiDisc® Screens 

Geiger MultiDisc® Screens are not considered as viable alternatives to the current 

screening systems at the Stations, because the use of Geiger MultiDisc® Screens (coarse or 

fine mesh) would not be expected to provide substantial reductions in EA1 I&E from the 

existing TWSs and fish return systems. 

Geiger MultiDisc® Screens are oriented the same way as traditional through flow screens 

(i.e., installed in a channel with the screening surface oriented perpendicular to the 

incoming flow). However, MultiDisc® 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 to the 

intake structure. The center of the mesh panels are supported by rollers. Water flows 

directly through the mesh panels. Fish and debris retained at the face of the ascending 

mesh panels are transported to the floor level where they are sluiced to fish return trough 

and debris troughs, respectively, by spray nozzles. A typical Geiger MultiDisc® Screen is 

shown in Figure 4.7. 

Figure 4.7 Geiger MultiDisc® Screen [Ref. 6.96] 

MultiDisc® Screens can be modified to include provisions for reduced impingement loss of 

aquatic species. Fish buckets attached to the screen panels retain water during its upward 

travel, thereby providing captured fish with water once the fish buckets exit the water 

level. The fish buckets are surface treated with a sliding composite material to allow 

retained fish to be easily flushed from the buckets. A low pressure spray header recovers 
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organisms which are transported upwards on the screen surface into the bucket. 

Organisms impinged on the screen surface below this bucket are led via an opening in the 

lower panel frame into the bucket of the following mesh panel. Due to the turning system 

of the mesh panels at the drive unit, the fish buckets are discharged, and the retained water 

and fish are sluiced to a fish return trough. 

MultiDisc® Screens can be constructed with fine-mesh screens designed to collect fish 

eggs and larvae and return them to the source waterbody. However, unlike Ristroph 

screens or dual flow screens, MultiDisc® screens are not designed to have removable fine 

mesh inserts, eliminating the possibility of seasonal deployment during periods of high 

entrainment. 

MultiDisc® Screens have been retrofitted into the existing CWISs of nuclear power plants, 

including the Donald C. Cook Nuclear Plant in Michigan, the Salem Nuclear Generating 

Station in New Jersey, and the Fort Calhoun Station in Nebraska. Typically, MultiDisc®

Screens can be retrofitted into the existing space of the current TWSs, minimizing required 

civil/structural modifications. However, MultiDisc® Screens are not available for the 

basket width required to replace the existing TWSs at the Stations. As discussed in 

Section 2.4.1.1, the Stations’ existing TWSs have a basket width of 13 ft 4 inches, but due 

to design constraints, the largest basket width manufactured by Geiger is 10 ft (see 

Attachment 1, Section 4). The deflection of the sickle-shaped panels caused by debris 

loads limits the basket width of MultiDisc® Screens, because debris-loaded panels deflect 

at their center resulting in premature wear and deterioration. Implementation of fine mesh 

MultiDisc® screens in the existing CWISs would further increase the through-screen 

velocity and impingement mortality, due to the decrease in net porosity of the screen. 

In order to provide a through-screen velocity at or below 0.5 fps, the size of the CWISs 

would need to be expanded to accommodate fine mesh MultiDisc® screens at the Stations. 

The number of fine mesh MultiDisc® screens required to maintain a through-screen 

velocity at or below 0.5 fps can be determined by using the equation previously referenced 

in Section 2.4.2.4 and multiplying the basket width and mean low water terms in the 

equation by 80 percent. The 20 percent reduction of the screening area conservatively 

accounts (i.e., understates the reduction in screening area) for submerged components of 

the MultiDisc® screen that reduce the flow area of the screen such as the base frame, 

central panel guide, and panel frames. Six 2.0 mm fine mesh MultiDisc® screens with a 

wire thickness of 0.5 mm would be required per intake channel (140,000 or 143,200 gpm) 

to maintain a through-screen velocity at or below 0.5 fps. 

A conceptual design for 2.0 mm fine mesh MultiDisc® screens at the Stations would be 

similar to the conceptual configuration for fine mesh dual flow and fine mesh Ristroph 

screens shown in Figures 2-4 through 2-6 and Figures 2-1 through 2-3 of Attachment 2, 

respectively. However, the size of the expanded intake would be larger because each of the 

new dedicated forebays would contain six fine mesh MultiDisc® screens. The width of the 

expanded intake for 2.0 mm fine mesh MultiDisc® screens providing screened cooling 

water to three CW channels would be approximately 260 ft wide assuming 11 ft 4 in wide 

screen channels and 3 ft thick walls. Each fine mesh MultiDisc® screen would be paired 

with new bar racks and stop logs providing large debris removal and isolation of the 

screens for repair of maintenance. Due to the size of the expanded intake required, 
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implementation of fine mesh MultiDisc® screens would require more civil/structural and 

mechanical modifications than the implementation of fine mesh dual flow screens or fine 

mesh Ristroph screens. 

Maintenance

MultiDisc® screens should require less maintenance than the existing TWSs because each 

screen panel can be individually removed at floor level and because the screening unit 

contains a single side bar chain. MultiDisc® screens would eliminate debris carryover into 

the condensers, reducing maintenance costs associated with the condensers. However, 

overall maintenance costs and time are expected to increase significantly for 2.0 mm fine 

mesh MultiDisc® screens, compared to the current TWSs due to the number of screens 

required to screen the normal intake flows of Units 2 and 3 (72 total 2.0 mm MultiDisc®

screens). Due to the increased number of screens required for the implementation of 2.0 

mm MultiDisc® screens, maintenance costs would be expected to be approximately six 

times the current costs required to maintain the existing coarse mesh TWSs. 

Because fine mesh screens are more susceptible to biofouling than coarse mesh screens, it 

is likely that a sodium hypochlorite system would be required to periodically dispense 

sodium hypochlorite in front of any fine mesh MultiDisc® screens to provide biofouling 

control. Any addition of sodium hypochlorite to the CW systems would need to be 

evaluated for potential impacts to the SPDES permit [Ref. 6.86]. 

Cost

The estimated cost for the MultiDisc® screen components (i.e., screens, pumps, and 

controllers) is 1.4 times the cost of the fine mesh Ristroph screen components and 1.5 

times the cost of the fine mesh dual flow screen components (see Attachment 1, Section 4). 

In addition, due to the number of MultiDisc® screens required and the extensive 

civil/structural work required for the expanded intake structures, the estimated capital costs 

for the installation of conceptual 2.0 mm fine mesh MultiDisc® screens is anticipated to be 

significantly higher than the estimated costs for installation of 2.0 mm fine mesh dual flow 

screens or 2.0 mm fine mesh Ristroph screens. 

I&E Discussion

The number of 2.0 mm MultiDisc® screens incorporated into the conceptual design is 

based on a maximum through-screen velocity of 0.5 fps. According to the EPA, if a 

facility could reduce its maximum through-screen velocity to at or below 0.5 fps, it would 

be considered to have satisfied the standard for reducing impingement mortality. 

However, any impingement reductions provided by MultiDisc® screens would not be 

expected to be appreciable compared to the Stations’ existing TWSs screens and fish return 

systems (see Section 3.2). Due to the similarities in the method of entrainment for 

MultiDisc® screens and Ristroph screens (fish pass through mesh panels oriented 

perpendicular to the flow), MultiDisc® screens would be expected to provide similar 

reductions in EA1 entrainment losses as Ristroph screens (Table 4.1). However, as 

discussed in Section 4.2.1, no mesh size would be expected to provide significant 

additional reductions in EA1 entrainment losses. 
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Conclusions

The use of MultiDisc® screens at the Stations would not be expected to provide substantial 

reductions in EA1 I&E from the existing TWSs and fish return systems. In addition, due 

to the number of screens and the additional intake modifications required, the capital costs 

and maintenance costs associated with the installation and operation of MultiDisc® screens 

would be significantly higher than the costs required for dual flow traveling screens or 

Ristroph screens. For these reasons, MultiDisc® screens are not further considered as an 

alternative to the current screening systems. 

4.3 Passive Intake Systems 

4.3.1 Cylindrical Wedgewire Screens 

Each of the cylindrical wedgewire screen (CWW) mesh sizes evaluated (2.0 mm to 9.0 

mm) would be expected to achieve substantial additional EA1 I&E reductions from the 

regulatory baseline, and would be comparable to the NYSDEC Proposed Project. 

However, because CWW screens with smaller slot sizes would create significant 

opportunity for fouling, a site-specific study of slot sizes ranging from 2.0 mm to 9.0 mm 

is proposed to determine the optimum slot width for reducing I&E at which fouling would 

not be a concern. 

CWW screens (see Figure 4.8) are designed to reduce I&E in three ways. First, depending 

on slot size, CWW screens provide a physical barrier preventing aquatic organisms larger 

than the screen slot size from being entrained. Second, CWW screens are located directly 

in a source waterbody (and not in a screen house), so sweeping flows can remove 

organisms from the intake flow field (this increases the effectiveness of avoidance 

discussed next). Sweeping flows also reduce impingement by moving organisms past the 

CWW screens, minimizing contact. Third, hydrodynamic exclusion of early life stages 

results from the low through-slot velocity of the CWW screen that is quickly dissipated, 

allowing organisms to escape the intake flow field. Larvae too small to be physically 

excluded by CWW screens have shown an active avoidance response to the changes in 

flow velocity and direction created by CWW screens [Ref. 6.39]. As discussed in 

Attachment 6, this avoidance and hydrodynamic exclusion model results in additional 

reductions in EA1 entrainment losses. 
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Figure 4.8 Cylindrical Wedgewire Screen 

CWW screens are designed to provide a large screening area, and a low through-slot 

velocity (i.e., at or below 0.5 fps) [Ref. 6.94]. The screening surface consists of “V”-

shaped “wedge wire” bars that are welded to support rods at their apex and are formed to 

maintain a uniform screen opening. The slot size is defined as the dimension of the 

opening between the wide ends of the wedge wire bars. CWW screens with slot sizes 

larger than 2.0 mm are typically considered to be wide slot screens, while CWW screens 

with slot sizes of 2.0 mm and smaller are considered to be narrow slot screens. Figure 4.9 

shows a detailed view of the wedgewire screening material. 

Figure 4.9 Wedgewire Screening Material 

As shown in Figure 4.10, the shape of the wedge wire bars increases the flow area of the 

screen surface while reducing obstruction of the screen surface by debris accumulation. 
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The sharp edges of the wire profile allow for solid particles to make only two points of 

contact with the screen surface. 

Figure 4.10 Profile of Wedgewire Material (Left) and Round Wire Material (Right) 

Debris loading and fouling can lead to higher capture velocities and damage early life stage 

organisms. As such, CWW screen systems can utilize airburst systems that release 

compressed air through the screens, forcing accumulated debris from the screen surface. 

As shown in Figure 4.11, an airburst system consists of an air compressor and receiver, a 

distribution manifold, a control system, and an individual screen air distributor. Debris 

removed from the screening surface by the airburst system is carried away by the sweeping 

current of the waterway. 

Figure 4.11 Typical CWW Screen Airburst System [Ref. 6.94] 
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Early CWW screen designs and perforated pipe intakes (obsolete intake screening systems 

the predate CWW screens, discussed further in Section 4.3.2), had inherent design issues 

that have been addressed through the development of CWW screens. These developments 

include: 

 Internal flow modifications that allow CWW screens to achieve an even velocity 

distribution across the screen surface area, avoiding areas of high flow concentration. 

The internal modifications prevent uneven flow distributions. Prior to these 

modifications, most of the flow would enter the screen through the slots nearest the 

supply pipe, creating a localized area with high through-slot velocities. In addition, 

the internal flow modifications allow the length of the screens to be increased, 

resulting in increased flow through an individual CWW screen; previously, the length 

of the CWW screens was limited to the size of the screen diameter. 

 Airburst systems designed to effectively remove debris from the screen surfaces. 

 The use of “V” shaped “wedge wire” bars to increase the flow area of the screen 

surface while reducing obstruction of the screen surface by debris accumulation. 

 The use of different screening materials to reduce biofouling. As shown in 

Attachment 1, Section 5, CWW screens constructed of a copper-nickel alloy are 

designed to provide protection against biofouling, specifically zebra mussels. 

These developments have led to improved reliability of CWW screen installations and 

increased operational effectiveness. 

There are no applications of CWW screens at nuclear power facilities. However, CWW 

screens have been effectively used in fossil-fueled power generation facilities. Oak Creek 

Power Plant in Milwaukee, Wisconsin operates the largest installation of CWW screens. It 

has four operating Units online that generate a total of 1135 MWe. The Oak Creek CWW 

screen system includes an offshore intake system situated approximately 6000-7000 ft from 

the shoreline at a depth of approximately 43 ft. According to Oak Creek (see Attachment 

1, Section 6), the CWW system became operational in January 2009 and is designed to 

operate year round. The offshore intake system uses twenty-four (24) 8-ft diameter CWW 

screens with a slot size of 0.375 inches to filter a flow rate of 1,560,000 gpm (see 

Attachment 1, Section 6). The total intake flow rate at Oak Creek is comparable to the total 

intake flow rate at IPEC Units 2 and 3. The CWW screen system at Oak Creek was 

designed to provide a through-screen velocity at or below 0.5 fps and the system was 

oversized by approximately 16% (3 additional screens) to provide a margin against fouling. 

Johnson Screens, a leading CWW screen manufacturer, supplied Oak Creek’s CWW 

screens. The entire screen assemblies are manufactured from copper-nickel alloy. The 

CWW screens are mounted to 4 manifolds; six CWW screens are mounted to each 

manifold. The manifolds are connected to drop tunnels that discharge into a single 

transmission tunnel that flows towards the shoreline into the plant’s wetwell. The 

transmission tunnel was bored into the bedrock and has a total length of 9200 ft. Cooling 

water from the wetwell is subsequently pumped to the condenser of each Unit. 

At Oak Creek, flow reductions, potentially caused by fouling and the associated differential 

pressure increases across the CWW screen system, are measured by gauging the water 

level in the wetwell. The original shoreline intake system remains operational and is 
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isolated using stop logs, so that, in the event that flow through the CWW screen system is 

not available or reduced, the stop logs can be manually opened to restore flow to the 

facility using lifts actuated by heavy-duty electric wrenches. Due to the distance of the 

offshore intake to the facility, Oak Creek’s CWW system is not equipped with an airburst 

system; however, fouling of the CWW screens is not a significant concern based on the 

characteristics of the source waterbody (Lake Michigan). Biofouling caused by zebra 

mussels has not been an issue due to the use of copper-nickel alloy screens. A frazil ice 

fouling event15 occurred early in 2009; however, flow through the CWW system was 

quickly restored without compensatory actions. 

CWW screen systems have also been installed at facilities located on the Hudson River. 

The Charles Point Resource Recovery Facility (Charles Point), formerly known as 

Westchester RESCO, is located approximately 1⁄2 mile northwest of IPEC on the eastern 

shoreline of the Hudson River. Charles Point is a waste to energy facility that produces 

approximately 60 MWe and utilizes a once-through cooling system with a flow rate of 55 

MGD. The cooling water intake utilizes 2.0 mm CWW screens installed in 1986 to draw 

water at an offshore distance of approximately 800 ft. There are eight (8) 54 inch diameter 

CWW screens constructed of a copper nickel alloy situated in four pairs on T-stands 

approximately 5 ft above of the Riverbed. According to Charles Point (see Attachment 1, 

Section 7), the CWW screens at Charles Point operate year round and utilize an airburst 

system that discharges twice daily via timers. A dive team is dispatched annually to 

visually inspect the screens. If there are local areas of debris buildup identified during the 

inspection dive, the divers will remove the debris. Flow reductions due to frazil ice were 

reported to occur during periods of extreme cold temperatures combined with low River 

water levels. These events were reported to occur every 2-3 years, and flow through the 

CWW screens is restored by using the airburst system. No other operational issues 

associated with the Charles Point CWW screens were reported. 

Two 0.125-inch slot CWW screens are installed at the IBM facility in Poughkeepsie, NY 

and provide Hudson River water for the facility’s HVAC chillers (see Attachment 1, 

Section 8). The CWW screens at the IBM facility have a maximum intake flow rate of 

60,000 gpm per screen. According to the Facility Engineer (Attachment 1, Section 8), the 

stainless steel screens were installed in the early-1980s and operate year round. The CWW 

screens are equipped with an airburst system that discharges hourly. The CWW screens 

were removed and inspected in 2004 for potential damage caused by impacts from ice 

floes. Minor dents and a small quantity of zebra mussels were identified. Flow through the 

CWW screens is maintained using the airburst system. No significant fouling issues were 

reported, although minor icing reportedly occurs during winter months. No other 

operational issues associated with the IBM facility’s CWW screens were reported. 

In order to filter the required 840,000 gpm of CW flow per Unit at IPEC, multiple CWW 

screens would be required. In addition, several different slot sizes were preliminarily 

evaluated for the Stations. Table 4.2 shows the number and size of CWW screens that 

 

15 Granular ice crystals formed in turbulent, supercooled water are referred to as “frazil ice.” Supercooled water 

occurs when the water temperature begins to drop and passes through the 32°F point. At a temperature of less than 

32°F, tiny particles of ice form quickly and uniformly through the water mass. Frazil ice is extremely adhesive and 

will stick to any solid metallic object that is at or below the freezing point. 
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would be required to maintain the CW flow while retaining a maximum through-slot 

velocity at or below 0.5 fps. 

Table 4.2 Wedgewire Screens Required to Maintain Minimum ThroughSlot Velocity of 0.5 fps 

Slot Size # of Screens Screen Length Screen Diameter 

9.0 mm (~ 3⁄8 inch) 48 257 inch 72 inch 

6.0 mm (~ 1⁄4 inch) 48 267 inch 66 inch 

3.0 mm (~ 1⁄8 inch) 72 239 inch 66 inch 

2.0 mm (0.078 inch) 72 257 inch 72 inch 

1.5 mm (0.059 inch) 60 300 inch 84 inch 

1.0 mm (0.040 inch) 72 300 inch 84 inch 

Low through-slot velocities would be used to ensure that organisms are not impinged on 

the screen because they cannot swim away from the intake velocity. According to the 

Hudson River Power Plants Final Environmental Impact Statement [Ref. 6.88], although 

EPA typically recommends CWW through-slot velocities at or below 0.5 fps, NYSDEC 

has indicated interest in through-slot velocities at or below 0.25 fps. As such, Table 4.3 

shows the number and size of CWW screens that would be required to maintain the CW 

flow while retaining a maximum through-slot velocity of 0.25 fps or less. 

Table 4.3 Wedgewire Screens Required to Maintain Minimum ThroughSlot Velocity of 0.25 fps 

Slot Size # of Screens Screen Length Screen Diameter 

9.0 mm (~ 3⁄8 inch) 96 257 inch 72 inch 

6.0 mm (~ 1⁄4 inch) 96 267 inch 66 inch 

3.0 mm (~ 1⁄8 inch) 144 239 inch 66 inch 

2.0 mm (0.078 inch) 144 257 inch 72 inch 

1.5 mm (0.059 inch) 120 300 inch 84 inch 

1.0 mm (0.040 inch) 144 300 inch 84 inch 

Because CWW screens with smaller slot sizes would create significant risk of fouling, only 

designs for CWW screen systems with slot sizes ranging from 2.0 mm (i.e., the slot size 
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used at Charles Point) to 9.0 mm (the slot size used at Oak Creek) were developed in an 

attempt to minimize both entrainment and fouling. 

 Conceptual layout drawings of potential 9.0 mm and 2.0 mm slot CWW screen 

systems sized for through-slot velocities of 0.5 fps are shown in Attachment 2, 

Figures 2-9 and 2-11, respectively. Plan and detail drawings associated with the 

layout drawings of systems sized for through-slot velocities of 0.5 fps are shown in 

Attachment 2, Figures 2-10 and 2-12. 

 Conceptual layout drawings of potential 9.0 mm and 2.0 mm slot CWW screen 

systems sized for through-slot velocities of 0.25 fps are shown in Attachment 2, 

Figures 2-13 and 2-15, respectively. Plan and detail drawings associated with the 

layout drawings of systems sized for through-slot velocities of 0.25 fps are shown in 

Attachment 2, Figures 2-14 and 2-16. 

These layouts depict arrays of CWW screens attached to transmission piping that flows into 

common headers leading into the CWISs. The CWW screen systems would be located 

within the IPEC’s existing exclusion zone; thus, implementation of the CWW screen 

systems would not limit navigability of the Hudson River. As shown in the plan and detail 

drawings, the common headers would connect to the CWISs downstream of the TWSs, 

allowing the existing screening systems to maintain operability. Newly installed stop logs 

and isolation valves would enable the CWW screen arrays to be isolated for maintenance, 

repair, or seasonal operation. 

The conceptual CWW screen systems would be equipped with sensors in the CW pump 

pits monitoring water elevation. Decreases in water elevation would typically indicate 

debris accumulation on the screen surfaces, because fouling of the CWW screen slots adds 

further resistance to the flow of intake water and results in reduced flow volumes. When a 

predetermined water elevation was reached, the airburst system would be activated. The 

airburst cycle would dislodge debris from the CWW screens, returning the water level to 

an acceptable level. The sensors would also monitor the effectiveness of the airburst 

system in removing debris from the screen surfaces by measuring the water elevation 

following an airburst cycle. If the airburst systems could not adequately remove debris 

from the CWW screen surfaces, the water elevation would continue to fall until a second, 

lower water elevation was reached. At this lower water elevation, hydraulic operators 

installed on the existing stop logs would be used to raise the stop logs allowing cooling 

water to be withdrawn from the Hudson River through the existing TWSs. The stop log 

system would ensure a reliable supply of cooling water, preventing air intrusion and 

cavitation in the CW pumps, which could lead to unnecessary, unplanned reactor 

shutdowns. 

There are several considerations with respect to the retrofit of CWW screens at the Stations 

summarized below: 

 CWW screens are susceptible to damage and clogging due to ice formation on the 

screens during the winter months. Granular ice crystals formed in turbulent, 

supercooled water are referred to as “frazil ice.” Supercooled water occurs when the 

water temperature begins to drop and passes through the 32°F point. At a 

temperature of less than 32°F, tiny particles of ice form quickly and uniformly 
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through the water mass. Frazil ice is extremely adhesive and will stick to any solid 

metallic object that is at or below the freezing point [Ref. 6.94]. CWW screens are 

highly susceptible to formation of ice on the screens, as documented by the U.S. 

Army Corps of Engineers [Ref. 6.112]. Although the Stations do not have a history 

of frazil ice issues with the existing CWISs, due to the location of the CWW screens 

and the general susceptibility of CWW screens to frazil ice, any site-specific CWW 

pilot study would evaluate potential frazil ice events. 

 Water flow through CWW screens, and their effectiveness with respect to entrainment, 

can be limited by debris buildup on the surface of the screens and siltation below the 

screens. Debris buildup can be periodically removed from the CWW screen surfaces 

by utilizing an airburst system. Without a sweeping current, the dislodged debris 

could resettle on the screen surface. A minimum sweeping current of at least 1 fps 

past the CWW screens is recommended to minimize clogging from debris 

accumulation [Ref. 6.115]. The Hudson River has two flood and two ebb tides within 

a 24.8-hour period, referred to as a semidiurnal pattern (see Section 2.3.1). The 

average sweeping current of the Hudson River is 1.0 fps for the flood tides and 2.1 fps 

for the ebb tides based on maximum observed velocities. The actual slack tide lasts 

for a short period as the tide changes between flood and ebb conditions. The sweeping 

current during the ebb and flood tides should be sufficient to facilitate adequate 

cleaning of the CWW screens using an airburst system. As shown in the layout 

drawings (Attachment 2, Figures 2-9 through 2-16), a CWW screen system at the 

Stations would require an array of screens that would be situated a minimum of 40 ft 

offshore to allow clearance for transmission piping, isolation valves, and dredging. 

 Any CWW screens used at the Stations would need to maintain the consistent intake 

flow required for cooling. Typically, smaller slot size screens are more susceptible to 

fouling, which can reduce flow. On-site physical testing would be required at the 

Stations to determine the optimum slot size that would address entrainment goals 

while ensuring a reliable flow of cooling water. 

 Adequate CW pump submergence is required to prevent air intrusion into the 

circulating water pumps, and a submergence margin is employed to prevent this 

occurrence because air intrusion and cavitation in the CW pumps could lead to 

unnecessary, unplanned reactor shutdowns. The resistance of the CWW screens 

(assumed clear of fouling or clogging) and the associated piping systems would reduce 

the water elevation within the CWISs and, therefore, the submergence of the CW 

pumps. As fouling or clogging of the CWW screens occurred, resistance through the 

screens would increase, causing additional water level drop in the pump bay and a 

reduced submergence margin for each pump. In order to avoid damage to the CW 

pumps caused by air entrainment, the evaluated design of the CWW screen systems 

require the existing CW pump pits to be excavated and deepened by approximately 6 

ft. New extended pump shafts and impellers would be installed on the existing CW 

pumps. Deepening of the existing CW pump pits, along with installation of extended 

pump shafts and impellers, would ensure the submergence margin and water level 

required to prevent the effects of air entrainment. 
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In order to establish a CWW screen system that balances biological and operational 

effectiveness, a laboratory study of CWW screen systems would be recommended prior to 

full-scale implementation of a CWW screen system at Unit 2 or Unit 3. Additionally, a 

small scale on-site pilot study would also be recommended to begin evaluating the sitespecific fouling and operational issues, including the installation of CWW screens at a 

single CW pump bay. The on-site study should continuously monitor pressure differential 

(head loss) across the screen surface as the increases in pressure differential due to fouling 

would be used to design set points and operational frequency of the air backwash system. 

The on-site study should identify the optimal location and orientation of the screen arrays 

within the River, and the optimal vertical location of the CWW screens off of the Hudson 

River bed. In particular, the minimal height off of the River bed that eliminates the 

possibility of siltation should be identified and the temperature gradient with respect to 

depth in the water column should be established. 

Test deployment of the screens should be year-round to determine if River conditions are 

acceptable for year-round CWW screen operation, similar to Charles Point and the IBM 

Facility. Several different screening materials (304SS/316L/Z-Alloy) would also be tested 

to determine the optimum material to resist corrosion and biofouling. The study should 

also attempt to identify fouling sources and fouling rates. The fouling sources and rates 

should be established for each month of operation to identify periods of high vulnerability 

(e.g., eelgrass could be problematic in the spring, while leaves could be a concern in the 

fall, or icing in the winter). 

Based on these study results, installation and operation of a full scale CWW screen system 

and airburst system at one Unit would be recommended. This installation would allow the 

Stations to more fully evaluate the performance of a CWW screening system at the 

Stations. The particular engineering parameters studied would include the frequency of 

airburst operation required to maintain a through-slot velocity at or below 0.5 fps and the 

optimum placement of the CWW screens in the water column to avoid siltation, icing, and 

fouling. 

Maintenance

The use of narrow slot openings (i.e., 2.0 mm and smaller) dictates that the screens should 

be closely monitored and inspected at more frequent intervals. When the screens are 

initially installed, they should be inspected on a quarterly basis for the first 12 to 15 

months of operation to monitor fouling/icing. Once the rate of fouling/icing has been 

established, inspection frequency should be altered to coincide with fouling/icing patterns. 

The evaluated CWW screens would have several O&M requirements as detailed below: 

 Inspect airburst systems 

 Activate air cleaning systems periodically to clean CWW screens 

 Inspect/lubricate isolation valves 

 Manually exercise isolation valves 

 Inspect CWW screens using divers or cameras 

 Manually brush and/or hydroclean CWW screens 
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When debris accumulates on the screen body, the screens would be cleaned with an 

airburst system. Operations personnel would likely perform O&M activities associated 

with maintenance of the airburst systems and isolation valves. The frequency of manual 

cleaning of the screens would need to be determined by operations after installation in 

order to account for conditions specific to the Hudson River. 

The maintenance costs would include the costs required to maintain the existing coarse 

mesh TWSs, the new airburst systems, and the new stop log systems. Additional 

underwater inspection and cleaning of the CWW screens would likely be performed by a 

subcontracted team of divers. Additionally, parasitic power losses due to the operation of 

air compressor motors for the airburst systems were evaluated. The estimated power 

requirements per Unit are based on two 35 hp motors operating continuously for 52 weeks. 

Based on these assumptions, the additional parasitic losses associated with operation of the 

air compressor motors for the airburst systems at each Unit would be approximately 456 

MW-hr per year (912 MW-hr per year, total) for a CWW system designed for a throughslot velocity of 0.5 fps. For a CWW system designed for a through-slot velocity of 0.25 

fps, the additional parasitic losses associated with operation of the air compressor motors 

for the airburst systems at each Unit would be approximately 912 MW-hr per year (1824 

MW-hr per year, total). 

Cost

The capital cost estimates for the implementation of the evaluated CWW screens at the 

Stations are detailed in Attachment 4. Equipment quotes from vendors are provided in 

Attachment 1. The total estimated capital costs for the installation of copper-nickel CWW 

screens at IPEC Units 2 and 3 with a through-slot velocity of 0.5 fps and airburst cleaning 

would be approximately $41.7 million for 2.0 mm screens, and approximately $36.5 

million for 9.0 mm CWW screens. The total estimated capital costs for the installation of 

copper-nickel CWW screens at IPEC Units 2 and 3 with a through-slot velocity of 0.25 fps 

and airburst cleaning would be approximately $63.3 million for 2.0 mm screens, and 

approximately $52.0 million for 9.0 mm CWW screens. As shown in Attachment 1 

Section 5, CWW screens constructed of copper-nickel could provide further protection 

against biofouling, specifically zebra mussels. 

Several unknown factors associated with the conceptual CWW system design developed 

above would require resolution during the detailed design phase. These factors include: (1) 

design and analysis to evaluate potential flow issues within the CWISs and vortexing by 

the CW pumps, (2) uneven bathymetry in the River in front of the Stations requiring a 

different footprint or non-standard installation techniques for the CWW screen arrays, and 

(3) the extent of laboratory and site-specific tests of the CWW screen arrays. These factors 

could more than double the costs, increasing the total cost of implementing CWW screen 

systems to more than $100 million. 

Excavation of the existing CW pump pits and the tie-in of the CWW screen headers would 

take approximately six to eight weeks per pump pit, assuming that construction activities 

are performed 24 hours per day. Excavation of a single pump pit at each Unit could be 

conducted simultaneously, allowing the Units to remain online although a reduction in load 

would result from the reduced CW flow. Therefore, the Stations would experience 

approximately 36 to 48 weeks of reduced generating capacity at each Unit during 
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construction. Note that this is a conservative construction estimate and is considered a 

‘best case’ scenario because actual construction scheduling would be dependent on 

numerous unknown factors including the geologic composition of the material below the 

pump pits, the ability of construction activities to be performed due to local weather 

conditions, and the ability to work 24 hours per day. Several excavation and tie-in 

construction tasks would require a full Unit outage to be completed; however, it is likely 

that these tasks could be scheduled to coincide with a routine maintenance outage for each 

Unit. Refueling outages are anticipated to last approximately 25 days (almost 4 weeks); 

therefore, there would be a total of approximately 32 to 44 weeks of reduced generating 

capacity at each Unit during the implementation of the evaluated CWW screen options. As 

discussed in Section 2.1, the Stations currently generate electricity at a rated capacity of 

approximately 1078 MWe and 1080 MWe for Units 2 and 3, respectively. A 32 to 44 

week period of reduced generating capacity would result in a loss of approximately 22,000 

to 30,000 MW-hrs at Unit 2, and approximately 11,000 to 16,000 MW-hrs at Unit 3. If the 

required construction and tie-in activities could not be scheduled to coincide with a routine 

maintenance outage, the construction costs would increase. 

I&E Discussion

As noted earlier, CWW screens are designed to reduce I&E in three ways. First, 

depending on slot size, CWW screens provide a physical barrier preventing aquatic 

organisms larger than the screen slot size from being entrained. Second, since CWW 

screens are located directly in a source waterbody (and not in a screen house), sweeping 

flows can remove organisms from the intake flow field (this increases the effectiveness of 

avoidance). Sweeping flows also reduce impingement by moving organisms past the 

CWW screens, minimizing contact. Third, hydrodynamic exclusion of early life stages 

results from the low through-slot velocity of the CWW screen that is quickly dissipated, 

allowing organisms to escape the intake flow field. Larvae too small to be physically 

excluded by CWW screens have shown an active avoidance response to the changes in 

flow velocity and direction created by CWW screens [Ref. 6.39]. As discussed in 

Attachment 6, this avoidance and hydrodynamic exclusion model results in additional 

reductions in EA1 entrainment losses. 

Attachment 6 (Tables 17 and 23 of Appendix A) provide the estimated reductions from the 

regulatory baseline in EA1 losses that could be achieved using 9.0, 6.0, 3.0, 2.0, 1.5, and 

1.0 mm CWW screens sized for through-slot velocities at or below 0.5 fps, including the 

Stations’ survival rates (Attachment 6) and average historic flow reductions (Section 

2.4.2.3.2). A summary of the information included in the tables is shown in Table 4.4. 

Note that the maximum possible reductions in EA1 I&E shown in Table 4.4 (99.9% and 

89.8%, respectively) are substantially higher than the current EA1 I&E reductions (80.2% 

and 33.8%, respectively) shown is Section 3.2. 
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Table 4.4 Potential Percent Reduction of Annual EA1 I&E Losses due to 

CWW Screens in Each Month with Through-Slot Velocities of 0.5 fps 

Month 

EA1 Entrainment Loss Reduction EA1 

Impingement 

9.0 mm 6.0 mm 3.0 mm 2.0 mm 1.5 mm 1.0 mm Loss Reduction 

January 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 9.6% 

February 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 10.5% 

March 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 13.1% 

April 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 8.2% 

May 8.3% 8.3% 8.3% 8.3% 8.3% 7.9% 10.0% 

June 28.2% 28.2% 28.2% 28.3% 28.2% 27.7% 12.7% 

July 26.5% 26.5% 26.5% 26.5% 26.6% 26.6% 5.5% 

August 14.8% 14.8% 14.8% 14.8% 14.8% 14.8% 5.7% 

September 6.4% 6.4% 6.4% 6.4% 6.4% 6.4% 6.0% 

October 4.9% 4.9% 4.9% 4.9% 4.9% 4.9% 5.1% 

November 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 5.7% 

December 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 7.8% 

Annual 89.6% 89.6% 89.7% 89.8% 89.7% 88.8% 99.9% 

An evaluation of the cumulative benefits of reductions in I&E over the expected lifetimes 

of Unit 2 and Unit 3 was provided in Attachment 6, accounting for both expected annual 

reductions in I&E losses and for the implementation time required for the technologies. 

For the cumulative benefits analysis, it was assumed that CWW screens could be installed 

and operating at Unit 2 in 2013 and at Unit 3 in 2015, the NYSDEC Proposed Project 

would become operational at both Units in 2029, and that both Units would cease 

operation in 2035.16 As discussed in ENERCON’s Engineering Feasibility and Costs of 

Conversion of Indian Point Units 2 and 3 to a Closed-Loop Condenser Cooling Water 

Configuration [Ref. 6.22], implementation of the NYSDEC Proposed Project would 

involve extended delays due to the technical complexity of the project, permitting 

requirements, and likely litigation relating to local zoning ordinances. Other technologies 

that are nearly as effective as the NYSDEC Proposed Project at reducing I&E losses, such 

as CWW screens, could be installed much sooner; therefore, reductions in I&E losses 

could begin almost immediately rather than being deferred for an extended period while 

technical and legal issues associated with the NYSDEC Proposed Project are resolved. 

Because of the earlier installation date, cumulative reductions in I&E losses over the 

lifetimes of Units 2 and 3 could be much greater for alternative technologies than for the 

NYSDEC Proposed Project. According to Attachment 6 (Appendix A, Table 27), the 

NYSDEC Proposed Project would result in only a 50% cumulative reduction in estimated 

 

16 As discussed in Attachment 6, the installation schedule for CWW screens is consistent with a proposal based on 

studies of this technology. The installation schedule for the NYSDEC Proposed Project was derived by ENERCON 

[Ref. 6.22] with input from counsel to Entergy and Spectra Energy Transmission (owner of the gas pipeline that 

would have to be re-located in order to construct the NYSDEC Proposed Project). 
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EA1 entrainment losses and an 86% cumulative reduction in estimated EA1 impingement 

losses, compared to the regulatory baseline. The reason for this is that, for most of the 

years between 2013 and 2029, the existing technology would still be operating. In 

contrast, for CWW screens, estimated cumulative total EA1 impingement and entrainment 

losses would be reduced by approximately 98% and 87%, respectively. These results 

indicate that the CWW screens would be substantially more effective than the NYSDEC 

Proposed Project at reducing I&E below the losses associated with the existing technology. 

Conclusions

Estimated capital costs associated with the installation of CWW screens with a throughslot velocity of 0.5 fps would be approximately $41.7 million for 2.0 mm screens, and 

approximately $36.5 million for 9.0 mm CWW screens. The estimated capital costs for the 

installation of CWW screens with a through-slot velocity of 0.25 fps would be 

approximately $63.3 million for 2.0 mm screens, and approximately $52.0 million for 9.0 

mm CWW screens. As described previously, several unknown factors associated with the 

conceptual CWW system design developed above would require resolution during the 

detailed design phase. These factors could more than double the costs, increasing the total 

cost of implementing CWW screen systems to more than $100 million. There would also 

be a loss of approximately 33,000 to 46,000 MW-hrs due to the CW pump pit excavation 

and construction. As shown in Table 4.4, each of the mesh sizes evaluated would be 

expected to achieve substantial reductions in EA1 I&E, comparable to the NYSDEC 

Proposed Project. In addition, according to Attachment 6, the estimated cumulative total 

reduction in EA1 entrainment losses for CWW screens (88%) would be greater than the 

estimated cumulative total reduction in EA1 entrainment losses for the NYSDEC Proposed 

Project (55%). Because CWW screens with smaller slot sizes would create significant 

opportunity for fouling, slot sizes ranging from 2.0 mm to 9.0 mm were selected for initial 

evaluation in an attempt to minimize both entrainment and fouling. A site-specific 

engineering and biological effectiveness study would be required to determine the 

optimum slot width for reducing EA1 entrainment losses while limiting fouling. 

4.3.2 Perforated Pipe Inlets 

Perforated pipe inlets are obsolete systems that have been replaced by the development of 

CWW screens. They are not considered as viable alternatives to the existing technologies 

at the Stations, due to serious operational risks, including increased head loss across the 

screen face, poor velocity distribution across the screens, and surface profiles prone to 

clogging or snagging. 

Perforated pipe inlets draw water through round or elongated perforations in cylindrical 

plate sections placed in a water body. Perforated pipe inlets are designed to produce low 

through-screen velocities. When implementing perforated pipe inlets, the perforated 

sections are situated parallel to the ambient current in order to use the sweeping flow to 

reduce impingement. Perforated pipe inlets can be designed in multiple configurations as 

shown in Figure 4.12. Plan and profile views of a perforated pipe inlet system are shown 

in Figure 4.13, and a plan view of the perforated pipe sections is shown in Figure 4.14. 
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Figure 4.12 Plan Views of Perforated Pipe Inlet Variations [Ref. 6.2] 

Figure 4.13 Perforated Pipe Inlet System [Ref. 6.101] 
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Figure 4.14 Plan View of Perforated Pipe Inlets [Ref. 6.101] 

I&E Discussion

Due to the similarities between perforated pipe intakes and the wedgewire screen systems 

discussed in Section 4.3.1, it is expected that the I&E reductions would be similar. 

However, as discussed previously, perforated pipe intakes often have head loss, debris 

buildup, and velocity distributions issues that could attribute to increased impingement loss 

[Ref. 6.2]. 

Conclusions

Obsolescence of perforated pipe intakes has been caused by the development of CWW 

screens, which began in the late 1970s. Although perforated pipe intakes are very similar 

to the CWW screens discussed in Section 4.3.1, the perforated pipe openings increase the 

head loss across the screen face, create a poor velocity distribution, and create a surface 

profile prone to clogging or snagging when compared to the wedge-shaped wire screen 

used in CWW screens. Therefore, perforated pipe intakes are not further considered as an 

alternative to the existing intake technologies. 

4.3.3 Porous Dikes/Leaky Dams 

Although the implementation of porous dikes, also known as leaky dams or leaky dikes, 

would be theoretically possible, porous dikes are not considered as viable alternatives to 

the current screening systems at the Stations due to nuclear-safety related issues with the 

conceptual designs and the unproven nature of this technology in front of the service water 

systems at nuclear generating facilities. More specifically, because the safety-related 

service water channels would be enclosed by any of the conceptual configurations, any 

reduction in void spaces within the porous dikes caused by debris, siltation, or fouling, 
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including by colonization of fish and plant life, combined with the lack of a back flushing 

system associated with these systems, could implicate nuclear-safety related issues and 

potential interruptions in operations due to flow reliability issues with the circulating water 

system. 

Porous dikes are filters resembling a breakwater that surround a cooling water intake. The 

core of a porous dike consists of riprap stone, cobble, or gravel contained within wiremesh cages that allow for the free passage of water through the voids or pores. Porous 

dikes act as behavioral and physical barriers to juvenile and adult fish, keeping them from 

entering a CWIS. The size of the pores in the core of the dike determines the biological 

effectiveness, the through-core intake velocity, and the amount of maintenance required. 

Although smaller pores would be expected to allow fewer fish to pass through the core of a 

porous dike, the through-core intake velocity would increase, as would the amount of 

maintenance required. Figure 4.15 shows plan and section views of a typical porous dike. 

Figure 4.15 Plan and Section View of a Porous Dike [Ref. 6.2] 

Porous dikes are typically used only for low flow rate applications, and currently no porous 

dike installations exist at nuclear power generating facilities or comparatively sized fossilfuel generating facilities. The primary concern with porous dikes, particularly at nuclear 

facilities, is the potential for fouling. While fouling is a substantive issue for barrier and 

screening technologies, it is a particular issue for porous dikes, because back-flushing 

systems, commonly used in other screening technologies, are not feasible for porous dikes 

[Ref. 6.115]. Additional concerns include the buildup of ice against the porous dike walls, 

engineering practicality, and limitations to the recreational and nautical use of the 

waterway. 
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At nuclear facilities, any reduction in void spaces within the porous dikes caused by debris 

and silt and/or fouling by colonization of fish and plant life, combined with the lack of a 

back flushing system, could lead to an interruption of cooling water supply to nuclearsafety related systems and interruptions in the operation of the plant due to flow reliability 

issues with the circulating water system. The addition of this new failure mode for the SW 

system would affect the licensing basis of the plant and would therefore require an 

amendment to the Stations’ NRC licenses (License Amendment). Similarly, a redesign of 

the SW system to avoid or mitigate new failure modes would also affect the licensing basis 

of the plant and would require a License Amendment. 

The hydraulic and fouling characteristics of porous dikes were studied at a testing facility 

on the estuarine Mount Hope Bay for the Brayton Point Generating Station (BPGS), 

beginning in July 1979. The porous dike used for testing consisted of a reinforced 

concrete and steel structure with a water intake channel sectioned into three 6 ft wide and 

20 ft deep sections. The first and third sections were filled with wire-mesh cages 

containing 3 inch stone and 8 inch stone, respectively. The center section was left open 

and used as a control channel. Performance of the porous dikes was characterized by an 

increase in head loss across the upstream and downstream faces of the test sections and a 

reduction in flow volume. Daily head losses were similar for the first and third sections, 

where increases in head loss correlated with observed fouling. The maximum reported 

flow rate for the first section was approximately 23 gpm/ft2

, and the maximum reported 

flow for the third section was approximately 32 gpm/ft2. The approach velocity of the 

water entering the porous dike sections was consistent at approximately 0.1 fps; however, 

flows below 0.1 fps were obtained below the low water mark of the dikes, indicating that 

increased fouling occurred near the bottom. Tubes inserted into the test sections were used 

to measure increases in weight and biofouling, which correlated to void space reductions. 

Biological analysis of the fouling tubes indicated that approximately half of the 

accumulated materials in the porous dike sections were live organisms [Ref. 6.69]. Porous 

dikes were never implemented for full scale operation at BPGS. 

Artificial breakwaters, which are similar in construction to porous dikes, have been shown 

to increase habitat for demersal fishes and invertebrates. An artificial breakwater is used to 

protect the ocean shoreline CWIS at the Pilgrim Nuclear Power Station (Pilgrim) in 

Plymouth, Massachusetts. The presence of a breakwater, like the one at Pilgrim, attracted 

a community of macroscopic algae, hydroids and other biofouling organisms that created a 

multi-tiered and diverse habitat. In turn, this diverse habitat attracted reef-dwelling fish, 

specifically cunner (Tautoglabrus adspersans). Since porous dikes are similar in 

construction to the breakwater at Pilgrim, they may function as artificial reefs, and – when 

built in ecosystems with limiting hard substrate habitat – are likely to attract a diverse 

community. In estuarine ecosystems, like the Hudson River Estuary, the sediment burden 

carried by freshwater inflow is likely to increase the potential for clogging of the pore 

spaces needed for porous dikes to work as they were designed [Ref. 6.76; Ref. 6.98]. 

For the Stations, sizing of conceptual porous dikes was estimated using a surface area of 

120 ft2

 and the BPGS maximum flow rate of the 8 inch stone section (32 gpm/ft2) as a 

scaling factor. Water depths in the vicinity of the Stations’ CWISs range from 

approximately 12 ft to 80 ft [Ref. 6.80], and, assuming an average submerged depth of 50 

ft, a conceptual porous dike at Unit 2 would require a length of approximately 545 ft to 
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68 

filter 870,000 gpm (design CW flow of 840,000 gpm and design SW flow of 30,000 gpm). 

Unit 3 would require a conceptual porous dike with a length of approximately 550 ft to 

filter 876,000 gpm (design CW flow of 840,000 gpm and design SW flow of 36,000 gpm). 

Assuming an average submerged depth of 50 ft is conservative (i.e., understates the 

required length), because a greater average submerged depth reduces the required length of 

the conceptual porous dikes. As shown in Attachment 2, Figure 2-17, the Unit 2 and Unit 

3 porous dikes would extend approximately 125 ft and 75 ft, respectively, from the 

shoreline of the Stations into the Hudson River. The endpoints for the conceptual Unit 2 

porous dike would be the existing asphalt road north of the Unit 2 CWIS and the southern 

end of the Unit 2 wing wall, and the endpoints for the conceptual Unit 3 porous dike would 

be near the southern perimeter of the condensate polishing building and the northern end of 

the discharge canal. 

A single conceptual porous dike enclosing the CWISs for Units 2 and 3 would also include 

the CWIS for Unit 1 (i.e., the porous dike would also be required to filter the 16,000 gpm 

design flow for the Unit 1 RW pumps). In order to filter the combined flowrate of 

1,762,000 gpm, a porous dike with a total length of approximately 1110 ft would be 

required, assuming an average submerged depth of 50 ft. As shown in Attachment 2, 

Figure 2-18, the single conceptual porous dike would extend approximately 105 ft into the 

Hudson River with a shoreline distance of approximately 900 ft. The north and south 

endpoints for the conceptual porous dike enclosing the CWISs for Units 2 and 3 is near the 

north end of the Unit 2 wing wall and south end of the Unit 3 wing wall, respectively. 

I&E Discussion

At the Stations, a porous dike would be sized to produce a through-slot velocity at or below 

0.5 fps. According to 40 CFR §125.94, if a facility reduces its through-screen velocity to at 

or below 0.5 fps, it is “deemed to have met the impingement mortality performance 

standards”. Because the effectiveness of screening early life stages by porous dikes has not 

been established at any site [Ref. 6.2], a study would be required to estimate the potential 

reductions in entrainment losses. 

Conclusions

As shown in Attachment 2, Figures 2-17 and 2-18, the safety-related SW channels would 

be enclosed by either of the conceptual porous dike configurations. Therefore, any 

reduction in void spaces within the porous dikes caused by debris, siltation and/or fouling 

by colonization of fish and plant life, combined with the lack of a back flushing system 

associated with these systems, could implicate nuclear-safety related issues and potential 

interruptions in operations, due to flow reliability issues with the service water and 

circulating water systems. Based on these nuclear-safety related issues, the installation of 

porous dikes is not considered as a viable alternative to the current screening systems. 

4.4 Barrier Technologies 

4.4.1 Aquatic Filter Barriers 

Although Aquatic Filter Barriers (AFBs) are theoretically feasible and have the potential to 

reduce I&E, certain operational issues (specifically, fouling and icing concerns) could 
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prohibit their operation at the Stations throughout the year. In addition, the actual design 

and installation of an AFB at the Stations would require extensive biological, geotechnical, 

and field studies to determine the optimum curtain size, perforation size, anchoring system, 

airburst operation schedule, and maintenance schedule. Furthermore, implementation of 

AFBs at the Stations would present significant nuclear safety and licensing issues 

(including probable License Amendments) that would need to be resolved prior to 

permitting of the AFBs. AFBs are not currently installed, nor have ever been licensed or 

installed in front of a service water intake at a nuclear facility. 

The Aquatic Filter Barrier (AFB) is a relatively new technology for use at cooling water 

intake structures [Ref. 6.19]. The AFB is permeable to water but relatively impermeable to 

fish, shellfish, and ichthyoplankton, and therefore capable of reducing both I&E [Ref. 

6.19]. Gunderboom® has a patented full-water-depth filter curtain, composed of 

polyethylene or polypropylene fabric that is supported by flotation billets at the surface of 

the water and anchored to the bottom of the water body. This AFB system is referred to as 

the Gunderboom® Marine Life Exclusion SystemTM (MLESTM). The MLESTM completely 

surrounds the intake structure, preventing organisms from entering the cooling water 

intake. A deployed Gunderboom® system is shown in Figure 4.16. 

Figure 4.16 Gunderboom® MLESTM Deployed at Lovett Generating Station 

The Gunderboom® MLESTM is a permeable curtain typically constructed of two layers of 

fabric that are subdivided into vertical cells or pockets. A flotation hood keeps the system 

afloat and maintains complete coverage through the water column. Sufficient fabric is 

used to accommodate water level fluctuations [Ref. 6.99]. The fabric used to create the 

MLESTM panels is shown in Figure 4.17. MLESsTM have sizing limitations and the ability 

to interfere with or prevent other existing uses of the source waterbody [Ref. 6.115]. 
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Figure 4.17 Gunderboom® Permeable Fabric Material [Ref. 6.19] 

A MLESTM is typically sized to allow a flowrate of 5 to 10 gpm/ft2

. Loads on the curtain 

fabric are reduced by maintaining low through-curtain flow rates; however, low throughcurtain flow rates increase the size of the MLESTM required. Conversely, high throughcurtain flow rates decrease the size of the MLESTM required, but increase the possibility of 

curtain failure due to debris loading. 

The MLESTM utilizes AirBurstTM systems to routinely remove deposits on the fabric 

panels. The AirBurstTM system consists of tubing woven into the bottom of each 

Gunderboom® panel that releases compressed air to dislodge debris attached to the panels. 

Where available, a sweeping velocity in a waterway can carry dislodged debris away from 

the MLESTM. Laboratory tests conducted by EPRI concluded that the AirBurstTM system 

effectively cleaned various AFB configurations in one to three cleaning cycles under 

certain circumstances [Ref. 6.19]. 

According to the EPA’s Technical Development Document for the Final Section 316(b) 

Phase II Rule, AFBs are “experimental in nature,” and Lovett Generating Station (a coalfired plant) was the only power plant facility where an AFB has been used at a full scale 

level [Ref. 6.115]. A MLESTM was deployed from 2004 through 2008 at Units 3, 4, and 5 

of Lovett Generating Station, a now retired power plant located approximately 1.5 miles 

southwest of IPEC on the western shoreline of the Hudson River in Stony Point, NY. 

Units 3, 4, and 5 of Lovett Generating Station had a combined condenser cooling water 

intake rate of approximately 323,000 gpm (465 MGD) [Ref. 6.99]. Field and laboratory 

studies conducted from 1995 through 2001 were performed to develop and evaluate a 

MLESTM at Lovett Generating Station, prior to installation of a fully operational MLESTM 

in 2004 [Ref. 6.72; Ref. 6.73; Ref. 6.74]. Significant conclusions from these studies 

included: 

 Anchoring systems for the MLESTM must be properly engineered through 

bathymetric and geophysical studies of the waterway to prevent detachment of the 

anchors caused by debris loading on the MLESTM fabric [Ref. 6.72]. 
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 Perforation size in the MLESTM fabric is site specific and is driven by biological 

exclusion requirements, waterbody characteristics, and flow requirements [Ref. 

6.19; Ref. 6.72]. 

 AirBurstTM systems must be utilized to remove debris and sediment buildup on the 

face of the MLESTM fabric. Frequency of airburst operation is site specific 

depending on debris loading characteristics. Inadequate removal of debris from 

the MLESTM results in submergence or overtopping of flotation billets [Ref. 6.73]. 

 Fabrication of the MLESTM curtain needs to conform precisely to the maximum 

water depths along the deployment transect to ensure effective cleaning and limit 

the potential for biofouling growth [Ref. 6.74]. 

 Flow rates through the MLESTM curtain should be between 5 and 10 gpm/ft2

. 

Laboratory tests conducted in 1997 indicated that curtain fabrics tested at flow 

rates of approximately 5 gpm/ft2

 clogged slowly, but recovered well after 

cleaning. Curtain fabrics tested at flow rates of approximately 10 gpm/ft2

 clogged 

faster and the recovery rate after clogging was acceptable, but not as good as with 

flow rates of approximately 5 gpm/ft2. Curtain fabrics tested with flow rates in the 

range of 15 gpm/ft2

 clogged rapidly with poor flow rate recovery after cleaning 

[Ref. 6.73]. 

As noted in Attachment 6, the MLESTM at Lovett Generating Station had a 79% overall 

average exclusion effectiveness. According to Attachment 6, this effectiveness, and the 

absence of size selectivity, both suggest that performance of the MLESTM at Lovett 

Generating Station was directly related to its time of deployment with respect to the 

Hudson River fish spawning season, the proportion of the total intake flow drawn directly 

through the filtration mesh, and the density of ichthyoplankton in the volume of unfiltered 

water drawn into the intake when deployment fails. In addition, post-deployment 

inspections at Lovett Generating Station identified tears in the flotation billet collars, due 

to extensive flexing caused by tidal oscillations and tears in the MLESTM curtain fabric 

near airburst diffusers caused by entanglement with anchor lines or other structures [Ref. 

6.74]. IPEC is located on the Hudson River approximately 1.5 miles from Lovett 

Generating Station and, as discussed in Attachment 6, both Lovett Generating Station and 

IPEC are exposed to the same source water body population of ichthyoplankton during the 

same seasonal cycle and are likely to experience similar entrainment through an MLESTM. 

However, the MLESTM at Lovett Generating Station varied in depth from 20 to 35 ft deep, 

while an MLESTM at IPEC would have an average depth of approximately 50 ft. 

Therefore, it is the increased depth and associated stresses at IPEC would likely increase 

the occurrence and severity of tears in the flotation billet collars or the MLESTM curtain 

fabric, anchorage issues, and fouling/over-topping events. 

Individual MLESsTM for IPEC Units 2 and 3 were conceptualized using the upper limit of 

the recommended flow range, 10 gpm/ft2

, and the midpoint of the recommended flow 

range, 7.5 gpm/ft2. Individual MLESsTM using the lower limit of the recommended flow 

range, 5 gpm/ft2

, were not considered, because the dimensions of the MLESsTM required 

would extend outside of IPEC’s existing exclusion zone, further limiting navigability of the 

River. Using the upper limit of the recommended through-curtain flow rates to 
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conceptualize MLESsTM at Units 2 and 3 illustrates the minimum MLESTM dimensions 

required, while using the midpoint of the recommended through-curtain flow illustrates 

more conservative dimensions of MLESsTM. It is not likely that any MLESTM at the 

Stations would be designed using the upper limit of the recommended through-curtain flow 

rates, because some margin of increased filtration area would be desired to ensure reliable 

operation of the system during periods of heavy debris loads. A site-specific study at the 

Stations would be required to determine this margin. 

The required square footage of the curtain fabric and overall length of the conceptual 

MLESTM for each of these flow rates are shown in Table 4.5 and assume an average 

submerged depth of 50 ft. Water depths in the vicinity of the Stations’ CWISs range from 

approximately 12 ft to 80 ft [Ref. 6.80]. Assuming an average submerged depth of 50 ft is 

conservative, because a greater average submerged depth reduces the required length of the 

conceptual MLESsTM. 

Table 4.5 Conceptual MLESTM Areas and Lengths 

Design Parameter Unit 2 Unit 3 

CWIS Flow Rate (gpm) 870,000 876,000 

Through-Curtain Flow Rate (gpm/ft2) 7.5 10 7.5 10 

Curtain Fabric Area (ft2) 116,000 87,000 116,800 87,600 

Overall length of MLESTM (ft) 2,320 1,740 2,340 1,750 

As shown in Attachment 2, Figures 2-7 and 2-8, the shoreline endpoints for a conceptual 

MLESTM at each Unit were selected to avoid interferences with existing structures (i.e., the 

condensate polishing building and Unit 1 wharf) and to remain within the boundaries of the 

existing exclusion zone. Additionally, the southern endpoint of the conceptual MLESTM 

for Unit 3 was placed away from the southern end of the discharge canal to avoid 

recirculation of debris in the discharge cooling water. 

A combined MLESTM enclosing the CWISs for Units 2 and 3 would also include the CWIS 

for Unit 1. In order to filter the combined flowrate of 1,762,000 gpm, an AFB with an 

overall length of approximately 3525 ft would be required based on the upper limit of the 

recommended flow rate through the curtain fabric of 10 gpm/ft2 and an average submerged 

depth of 50 ft. This conceptual combined MLESTM for Units 2 and 3 would extend 

approximately 900 ft into the Hudson River based on a shoreline distance of approximately 

1800 ft and would occupy nearly all of the exclusion zone. A combined MLESTM 

enclosing the CWISs of Units 1, 2, and 3 with a through-curtain flow rate at the midpoint 

of the recommended flow rate of 7.5 gpm/ft2

 would require an overall length of 

approximately 4700 ft, assuming an average submerged depth of 50 ft, and would not fit 

into the existing exclusion zone. The dimensions of a combined MLESTM are larger than 

the dimensions of the individual MLESsTM and a combined MLESTM likely to be installed 

(through-curtain flow rate of 7.5 gpm/ft2

) would not fit in the existing exclusion zone. 

Additionally, a combined MLESTM would preclude the use of the Unit 1 wharf that is 

required for nautical plant security responses. Thus, a single combined MLESTM for both 

Units would provide no additional benefits to the individual MLESsTM for Units 2 and 3 

shown in Attachment 2, and is not further considered as an alternative to the existing intake 

screening systems. 
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Actual design and installation of an AFB at the Stations would require extensive biological, 

geotechnical, and field studies to determine the optimum curtain size, perforation size, 

anchoring system, airburst operation schedule, and maintenance schedule. As noted by 

EPRI in its laboratory study, the potential biological effectiveness of an AFB is related to 

the ability of the curtain material to be maintained in position with adequate control of 

debris [Ref. 6.19]. Site-specific developmental studies would be required at IPEC, similar 

to those performed at Lovett Generating Station between 1995 and 2001, to achieve the 

requisite level of certainty. Furthermore, MLESsTM are susceptible to damage and clogging 

due to ice formation on the curtain fabric during the winter months [Ref. 6.94]. As such, 

the use of any MLESTM installed would be limited to seasonal deployment, because 

mechanisms do not currently exist to heat the curtain fabric or otherwise prevent damage 

due to icing. Because IPEC is located on the shore of the Hudson River, any potential 

MLESTM would be situated in the main channel of the waterway exposing it to large 

floating or submerged debris that could cause tearing, entanglement, or overtopping of the 

MLESTM. The potential for failure or extensive damage to the MLESTM curtain fabric due 

to large debris would also have to be evaluated prior to implementation. 

An extensive anchoring system is required to secure the curtain fabric in place and to 

ensure that unfiltered water does not enter the intake area below the curtain fabric. The 

MLESTM installed at Lovett Generating Station had a length of approximately 1500 ft and 

was secured in place by 123 concrete anchors [Ref. 6.3]. Each concrete anchor was 6 ft 

long, 3 ft wide, and 3 ft tall (54 cubic feet) [Ref. 6.73]. The concrete anchor volume 

corresponds to an approximate weight of 8100 pounds per anchor. The combined length of 

the conceptual MLESsTM at Units 2 and 3 with a through-curtain flow rate of 10 gpm/ft2

would be approximately 3525 ft. Scaling from the Lovett Generating Station system, at 

least 287 concrete anchors would be required at IPEC to secure the curtain fabric to the 

floor of the Hudson River. 

The primary concern with installation of an AFB is the potential for the curtain fabric to 

detach from its anchors and block the CWIS. The conceptual MLESTM configurations 

shown in Attachment 2 Figures 2-7 and 2-8 would enclose the safety-related SW intake 

channels. Detachment of the MLESTM curtain fabric from its anchors could allow the 

curtain fabric to be drawn into the CWIS, potentially clogging the SW intake channels and 

cutting off the SW supply required for safe shutdown of the plant. In order for a MLESTM 

to be considered for deployment at a nuclear power plant, extensive testing and 

qualification of the MLESTM materials, specifically the attachments to the anchorages, 

would be required prior to the completion of a comprehensive failure modes and effects 

analysis (FMEA). Following this analysis, the NRC would require the submittal of a 

License Amendment Request (LAR) detailing the changes from the existing plant 

configuration and analysis and indicating that the ability of the plant to achieve safe 

shutdown would not be negatively affected by implementation of the MLESTM. Approval 

of the LAR by the NRC would be required prior to implementation of the MLESTM. It is 

not likely that the NRC would approve a LAR of this type, because both NRC 

requirements and the Institute of Nuclear Power Operations (INPO) guidelines prohibit 

screen systems that may compromise the ultimate heat sink or otherwise impair waterbased nuclear safety-related systems [Ref. 6.67]. 
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74 

Units 2 and 3 each have backup sources of cooling water flow for the SW systems that 

could provide SW to each Unit in the event of a blockage of the SW intake channels 

caused by a detached MLESTM. The Unit 1 RW pump can provide cooling water flow to 

the Unit 2 SW system via crossover piping and Unit 3 is equipped with three 5000 gpm 

backup SW pumps that take suction from the Unit 2 discharge canal. Extensive analysis of 

the suitability of each of these backup pumps would be required prior to the 

implementation of MLESsTM, because the backup pumps are not qualified for safetyrelated operation, and only two of the three Unit 3 backup SW pumps can currently be 

powered by the emergency diesel power generators [Ref. 6.64]. It is possible that the 

conceptual MLESsTM at Unit 2 shown in Attachment 2 Figures 2-7 and 2-8 could fail in a 

manner that would block the intake structures of both Units 1 and 2, precluding flow from 

the Unit 1 RW pump and Unit 2 SW pumps. Based on this scenario, the potential 

installation of new backup SW pumps in the Unit 2 discharge canal that could provide 

emergency cooling water flow for the SW system of Unit 2 would need to be determined 

prior to the implementation of MLESsTM at IPEC. Any redesign of the SW system to 

avoid or mitigate any new failure modes associated with the implementation of an 

MLESTM at either Unit would also affect the licensing basis and would require a License 

Amendment, as discussed previously. 

Maintenance

MLESsTM are passive barrier systems with few mechanical components; thus, periodic 

inspection and cleaning would entail the majority of the maintenance scope. However, 

MLESsTM would require seasonal installation, retrieval, and subsequent repair to the 

curtain fabric adding to the overall maintenance cost. As noted previously, at Lovett 

Generating Station, tears in the flotation billet collars due to extensive flexing caused by 

tidal oscillations and tears in the MLESTM curtain fabric near airburst diffusers caused by 

entanglement with anchor lines or other structures were identified during post-deployment 

inspections [Ref. 6.74]. The small apparent opening size of the curtain fabric material 

required to physically exclude eggs and larvae also retains higher debris loads and dictates 

that the MLESsTM be inspected in frequent intervals. When MLESsTM are initially 

installed they should be inspected on a quarterly basis for the first 12 to 15 months of 

operation to monitor fouling/growth. The conditions of MLESsTM should be well 

documented so that fouling/growth can be closely monitored. Once the rate of fouling has 

been established, the inspection frequency may be altered to coincide with the fouling rate. 

The evaluated AFBs / MLESsTM would have several operations and maintenance (O&M) 

requirements as detailed below: 

Check air cleaning systems via boat 

Clean MLESsTM using power wash system via boat deployment 

Annual deployment of MLESsTM 

Annual retrieval of MLESsTM 

 Inspect MLESsTM while deployed in River 

Repair MLESsTM after removal from River 
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The O&M estimates for the MLESsTM are in addition to the present O&M requirements for 

the existing TWSs that would operate when the MLESsTM were not deployed. When 

debris accumulates on the MLESsTM fabric, the MLESsTM would be cleaned with an 

AirBurstTM system. The frequency of cleaning would need to be determined by operations 

after installation in order to account for conditions specific to the Hudson River. 

Operations personnel would likely perform O&M activities associated with maintenance of 

the AirBurstTM systems and cleaning of the MLESTM; however, deployment and retrieval 

of the MLESsTM, underwater inspection of the MLESsTM, and repair of the MLESsTM 

would likely be performed by teams of divers and specialists contracted through 

Gunderboom®. The minimum annual O&M cost for the evaluated MLESsTM is estimated 

to be approximately $3,000,000. 

Additionally, parasitic power losses would exist due to the operation of air compressor 

motors for the AirBurstTM systems. The estimated power requirements are based on six 

200 hp motors operating 4 hours per day for 24 weeks. The 24 week estimate of the 

operational period of the AirBurstTM system motors is a conservative estimate of the time 

period that MLESsTM could be deployed without being significantly affected by icing or 

fouling and corresponds to the months of May through October. Based on these 

assumptions, the additional parasitic losses associated with operation of the air compressor 

motors for the airburst systems would be approximately 601 MW-hr per year. 

Cost

The capital cost estimates for implementation of the evaluated MLESsTM are detailed in 

Attachment 4 and include design, procurement, implementation, and startup activities, 

based on the conceptual design shown in Attachment 2 Figure 2-8. The costs associated 

with permitting the MLESsTM are not included in this estimate. As shown in Attachment 

4, the total estimated capital cost for MLESsTM at the Stations would be approximately 

$67.4 million. In order to avoid interfering with normal operations, the installation of the 

anchoring systems for the MLESsTM would be recommended, but not required, to coincide 

with scheduled outages. As noted previously, the O&M and seasonal deployment, 

removal, and repair of the MLESsTM would cost, at a minimum, approximately $3 million 

annually, not including the O&M costs for the existing CWISs. 

I&E Discussion

Attachment 6 (Tables 17 and 23 of Appendix A) provides the estimated reductions from 

the regulatory baseline in EA1 I&E that could be achieved through the seasonal use of 

MLESsTM accounting for the Stations’ survival rates (Attachment 6) and average historic 

flow reductions (Section 2.4.2.3.2). A summary of the information included in the tables is 

shown in Table 4.6. Note that the maximum possible reductions in EA1 I&E shown in 

Table 4.6 (90.4% and 90.2%, respectively) are substantially higher than the current EA1 

I&E reductions (80.2% and 33.8%, respectively) shown is Section 3.2. 
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Table 4.6 Potential Reduction in EA1 I&E due to the Installation of 

MLESsTM 

Month EA1 Entrainment Loss Reduction EA1 Impingement Loss Reduction 

January 0.0% 8.7% 

February 0.0% 9.6% 

March 0.0% 12.0% 

April 0.4% 6.6% 

May 9.9% 9.5% 

June 30.2% 11.7% 

July 25.1% 5.3% 

August 13.8% 5.5% 

September 6.0% 5.7% 

October 4.8% 4.9% 

November 0.0% 4.6% 

December 0.0% 6.3% 

Annual 90.2% 90.4% 

Note: In order to avoid the months in which MLESsTM would be significantly affected by 

icing or fouling, the MLESsTM would be deployed seasonally from May through October. 

Therefore, the reductions presented for the months of November through April (shaded 

cells) indicate the reductions due to the existing TWSs and fish return systems. 

Conclusions

Although MLESsTM have the potential to reduce I&E, there are several operational issues 

(i.e., fouling and icing concerns) that could prohibit the operation of the AFBs throughout 

the year. Implementation of MLESsTM at the Stations would present significant nuclear 

safety and licensing issues (including possible License Amendments) that would need to be 

resolved prior to permitting of the AFBs. Consistent with the aforementioned conclusion, 

AFBs are not currently installed, nor have ever been licensed or installed in front of a 

service water intake at a nuclear facility. In addition, the actual design and installation of 

an AFB at the Stations would require extensive biological, geotechnical, and field studies 

to determine the optimum curtain size, perforation size, anchoring system, airburst 

operation schedule, and maintenance schedule. 

4.4.2 Fish Barrier Nets 

Fish barrier nets are not considered as viable alternatives to the current screening systems 

at Units 2 and 3 due to nuclear-safety related issues and the lack of comparable reductions 

in I&E to the NYSDEC Proposed Project or other alternative technologies. In addition, 

fish barrier nets have not been successfully implemented for protection of eggs or larvae 

and, therefore, would not be expected to provide significant reductions in entrainment 

Fish barrier nets are coarse-mesh nets that are installed in front of the entrance to an intake 

structure primarily to reduce impingement of fish [Ref. 6.2; Ref. 6.16]. The size of the 

mesh openings limits the size of the organisms that can pass through the net. Although 
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77 

finer meshes can be used to reduce entrainment of smaller species and juvenile fish, the 

larger mesh sizes are generally required to maintain low through-screen velocities (usually 

at or below 0.5 fps) and avoid excessive clogging [Ref. 6.2; Ref. 6.16]. Barrier nets with 

mesh fine enough to prevent entrainment of eggs and larvae have not been successfully 

deployed due to the challenges of keeping the mesh clean of silt and biofouling [Ref. 6.16]. 

Therefore, fish barrier nets are not considered an effective technology for reducing 

entrainment of eggs, larvae, or zooplankton [Ref. 6.2; Ref. 6.16]. 

Cooling water is drawn through the openings in the mesh before entering the plant intake. 

Several installation designs have been developed to accommodate a range of operating 

conditions. The rigid panel support system shown in Figure 4.18 is typical for large 

installations with high debris loading and/or biofouling and high ambient velocity 

conditions on large estuaries, such as at the Hudson River in front of the Stations [Ref. 

6.16]. 

Figure 4.18 Fixed Panel Standard Design Plan [Ref. 6.16] 

In a rigid net panel design, the net is supported by steel piles, sheet pile cells, and sheet pile 

isolation walls, as shown in Figure 4.19. A walkway deck typically spans the length of the 

net to facilitate cleaning and maintenance. Individual net panels are hoisted to the 

walkway level for cleaning with power sprays and brushes. Uninterrupted fish protection 

can be provided by using spare net panels lowered into place during cleaning. 
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Figure 4.19 Rigid Panel Support Design [Ref. 6.16] 

Fish barrier nets have been deployed at several large power plants. The mesh sizes 

(measured by the length of one of the four sides of the net opening) for these installations 

have ranged from 1/10 to 1-1⁄4 inch [Ref. 6.16]. Typical barrier net mesh sizes are 1⁄4-, 3⁄8-, 

and 1⁄2-inch. As discussed in Section 2.4.1.1, the existing traveling water screens at the 

Stations have a mesh size of 1⁄4-inch wide by 1⁄2-inch tall. 

Failure of a fish barrier net could present serious operational and, where applicable, 

nuclear safety concerns. At Detroit Edison’s Monroe Plant, a fish barrier net placed across 

the intake canal clogged with fish and collapsed. The net failure was attributed to high 

intake velocities greater than 1.3 fps [Ref. 6.2]. A fish barrier net is deployed seasonally to 

reduce impingement at Arkansas Nuclear One (ANO), owned and operated by Entergy 

Arkansas, Inc. [Ref. 6.16]. The fish barrier net at ANO is installed outside an intake canal 

in the Lake Dardanelle reservoir and is deployed in the winter. The net material is nylon 

with mesh sizes of 3⁄8 and 1⁄2 inch and through-net velocities of approximately 0.04 ft/s. At 

ANO, emergency SW is supplied by an emergency cooling pond through a channel 

separate from the circulating water intake, eliminating this safety concern [Ref. 6.23]. 

A fish barrier net at the Stations would be designed for lower velocities than Detroit 

Edison’s Monroe Plant, but excessive fouling and/or River flow variability at the site could 

cause a similar failure. As described in Section 2.4.1, the SW pump channel for each Unit 

has three CW pump channels located on each side. Collapse of a fish barrier net installed 

in front of the CW pump channels could clog the SW intake channels, cutting off the SW 

supply required for safe shutdown of each Unit. Both NRC requirements and INPO 

guidelines prohibit screen systems that could compromise the ultimate heat sink or 

otherwise impair water-based nuclear safety-related systems [Ref. 6.67]. Based on this 
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nuclear-safety related issue, the installation of a single barrier net spanning both intakes or 

one barrier net at each CWIS is not considered a technologically feasible means of 

reducing I&E. Placement of four smaller nets for each set of three CW pumps on either 

side of the SW channels could be possible, although the potential for net failure to affect 

SW pump operation could still exist. The addition of a new failure mode for the SW 

system would affect the licensing basis of the plant and would therefore require a License 

Amendment. Similarly, a redesign of the SW system to avoid or mitigate new failure 

modes would also affect the licensing basis of the plant and would require a License 

Amendment. 

I&E Discussion

As noted in Section 3.2, the Stations’ existing TWSs screens and fish return systems 

already provide state-of-the-art impingement protection. Therefore, it is not expected that 

implementation of fish barrier nets would be able to provide significant reductions in 

impingement. In addition, fish barrier nets have not been successfully implemented for 

protection of eggs or larvae and, therefore, would not be expected to provide significant 

reductions in entrainment [Ref. 6.2]. 

Conclusions

In addition to the nuclear-safety related issues associated with the installation of fish 

barrier nets at the Stations, fish barrier nets have not been successfully implemented for 

protection of eggs or larvae and, therefore, would not be expected to provide significant 

reductions in entrainment [Ref. 6.2]. There would be a potential for some additional 

impingement reductions with the implementation of fish barrier nets; however, due to the 

lack of significant entrainment reductions and the nuclear-safety related issues, fish barrier 

nets are not further considered as alternatives to the current intake screening systems. 

4.4.3 Behavioral Barriers 

None of the behavioral barriers evaluated (light guidance systems, acoustic deterrents, air 

bubble curtains, or electrical barriers) are considered as viable alternatives to the current 

screening systems at the Stations because these technologies would not be expected to 

provide comparable reductions in I&E to the NYSDEC Proposed Project or other 

alternative technologies. Because eggs and larvae cannot respond to the stimuli created by 

behavioral barrier systems, there would be no direct reduction in entrainment. Additional 

site-specific studies would be required to fully evaluate the effectiveness of any behavioral 

barrier systems at the Stations. 

Behavioral barriers deter fish from entering CWISs by utilizing their natural behavioral 

responses to external stimuli. In general, studies of behavioral barriers have been 

inconclusive or have shown no significant reduction in I&E across species [Ref. 6.2], but 

such systems have proved effective for certain species, because behavioral barrier 

performance is highly dependent on the CWIS site characteristics and fish species present 

[Ref. 6.2]. Consequently, there are multiple acoustic fish deterrence systems operating at 

power generation facilities, including the NYSDEC-authorized system at the James A. 

FitzPatrick Nuclear Power Plant. Therefore, the biological benefit provided by a specific 

behavioral barrier technology cannot be fully evaluated without conducting extensive field 
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and biological studies at IPEC to characterize the site conditions and the response of the 

fish species present. 

4.4.3.1 Light Guidance System 

Light guidance systems are not considered as viable alternatives to the current screening 

systems at the Stations because they are not expected to provide reductions in I&E 

comparable to the NYSDEC Proposed Project or other alternative technologies. 

Light guidance systems most commonly use xenon strobe lights or mercury lights to 

attract or repel fish. Mercury lights are typically used to attract fish; therefore, there have 

been very few studies performed in the application of mercury lights for avoidance 

purposes. Xenon strobe lights have been proven to be more effective at repelling fish 

than a continuous light and are the primary light guidance technology [Ref. 6.15]. In 

order to evaluate the behavioral response of a fish to light, three key factors must be 

considered: (1) fish species, (2) developmental stage of the fish, and (3) the level of 

adaptation [Ref. 6.28]. These factors have led to large variations in fish response to light. 

Low intensity light attracts certain fish species but repels others and high intensity light 

has shown the same pattern [Ref. 6.2]. Some species have shown no response to any type 

of light stimuli. Studies have shown inconsistency in the use of xenon strobe lights to 

reduce fish impingement and entrainment in CWISs [Ref. 6.15]. 

An investigation into the effectiveness of light deterrents using the Fish Avoidance 

Xenon System (FAXS) supplied by EG&G Electro-Optics was conducted at Roseton 

Generating Station on the lower Hudson River in 1986 and 1987 [Ref. 6.17]. The strobe 

light source was provided by a FA-125 power supply in conjunction with a FA-107 flash 

head. FAXS has multiple power settings which can be calibrated to provide the greatest 

fish deterrence. The lowest setting results in a 750 candela (cd) light output that can 

operate at a flash rate between 100 flashes per minute (fpm) to 600 fpm. The highest 

power setting results in a 4500 cd light output that can operate at a flash rate between 100 

fpm to 400 fpm. FAXS provided the greatest fish avoidance when operated at a light 

intensity of 4500 cd and a flash rate of 200 fpm. The investigation concluded that the 

effectiveness of light deterrents is highly dependent on the species and time of the day 

[Ref. 6.17]. Results of the investigation showed that FAXS successfully deterred white 

perch, but was unsuccessful at deterring alewife, American shad, blueback herring, and 

bay anchovy. Increases in turbidity led to increases in fish avoidance due to more 

scattering of light [Ref. 6.17]. 

Flash Technology Corporation (FTC) designed a light guidance system that succeeded 

the EG&G’s FAXS. FTC’s system, specifically designed for underwater use, was the 

mostly commonly used light guidance technology between 1997 and 2004 [Ref. 6.15]. 

Although FTC’s light guidance system is no longer in production [Ref. 6.30], the FTC 

strobe lights were capable of operating at depths of up to 80 meters and consisted of flash 

heads, wiring, power supplies, and a control system. Experimental results of FTC’s 

system showed inconsistencies similar to those identified with FAXS. 
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Conclusions

Many of the species present in the vicinity of Roseton Generating Station are present at 

the IPEC Unit 2 and 3 CWISs. However, species are only one relevant factor in 

effectiveness; the different locations of the Roseton and IPEC Unit 2 and 3 CWISs on the 

Hudson River could cause significant variations in the diversion effectiveness of a light 

guidance system. Therefore, site specific studies would be required to fully evaluate the 

diversion effectiveness of a light guidance system. As such, light guidance systems are 

anticipated to provide inconsistent reductions in impingement. Moreover, eggs and 

larvae cannot respond to the stimuli created by light guidance systems there would be no 

direct reduction in entrainment. For these reasons, light guidance systems are not 

expected to provide significant reductions in I&E and are not further considered as 

alternatives to the current CWIS technologies. 

4.4.3.2 Acoustic Deterrents 

Acoustic deterrents are not considered as viable alternatives to the current screening 

systems at the Stations because they are not expected to provide reductions in I&E 

comparable to the NYSDEC Proposed Project or other alternative technologies. 

Acoustic deterrents divert fish from CWISs by creating underwater sound waves that 

trigger an avoidance response. Fish have shown sudden bursts of speed and direction 

changes in response to certain sound frequencies and sound pressure levels [Ref. 6.28]. 

Sound waves can attract or repel fish from the acoustic source, and the behavioral 

response of a fish to a given frequency is dependent on various factors, including species 

and size [Ref. 6.28]. 

A study evaluating the effectiveness of acoustic deterrents called pneumatic poppers or 

“air poppers” was conducted at the Stations from July 20, 1985 to December 29, 1985 

[Ref. 6.79]. The IPEC study was modeled after a similar study performed by Ontario 

Hydro that showed success in deterring yellow perch and alewife from the CWIS. As 

part of the study, four air poppers were installed around one of the Unit 2 intake channels. 

Air poppers release pressurized air into water to create a low frequency, high amplitude 

sound wave. Air pressurized to 3000 psig was released at 5 second intervals from the air 

poppers. The air poppers were active for 48 or 72 hour periods, followed by 48 hour 

periods of inactivity. The results of IPEC’s study showed that the air poppers had no 

significant impact on the numbers or species of fish in the vicinity of the intake or 

impinged by the CWIS [Ref. 6.79]. 

Acoustic deterrents were specifically evaluated for striped bass, white perch, and tomcod 

at the Stations [Ref. 6.21], leading to the development and testing of the Sonalysts, Inc. 

FishStartleTM system at the James A. FitzPatrick (JAF) Nuclear Power Plant. The 

FishStartleTM system is currently in operation at JAF and is similar to the SPA system 

(discussed below) in that it is capable at operating at a range of frequencies. At JAF, the 

FishStartleTM system was shown to substantially reduce the fish density in the vicinity of 

the intake when compared to the periods when the FishStartleTM system was not 

operating [Ref. 6.10]. However, because the site-specific feasibility of any acoustic 

deterrent system is highly dependent on the impinged species and their contribution to 

historical impingement, as well as their response to sound, and the engineering 
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constraints associated with the aquatic environment, extensive further study would be 

required to ascertain the biological benefits at IPEC Units 2 and 3. 

Other hydroacoustic technology has been more successful at deterring fish from CWISs 

than air poppers. Fish Guidance Systems, Inc. has developed the Sound Projector Array 

(SPA) System that creates patterns of wave forms with a range of frequencies and sound 

pressure levels. The SPA System utilizes signal generators to send recorded signals 

through amplifiers that power underwater sound projectors. An acoustic modeling 

program called PrISM determines the number, location, and orientation of the sound 

projectors. PrISM predicts the particle movement field and accounts for important 

factors, such as the geometry of the intake, reflections, and potential destructive 

interference [Ref. 6.29]. The signal generators can produce multiple signals to reduce the 

chance of fish adaption to the sound. Nuclear Plant Doel (NPD), located on the Scheldt 

Estuary in Belgium, has conducted a study of the SPA System [Ref. 6.78]. The SPA 

system at NPD utilized a signal generator programmed with eight different signals 

connected to twenty 600 watt sound projectors. The sound was emitted in intervals of 0.2 

seconds and ranged in frequency from 20 Hz to 600 Hz at a sound pressure level of 174 

dB. The study also evaluated the effects of temperature and salinity changes in 

combination with the acoustic deterrents. Results of the study showed a reduction in total 

fish impingement of 59.6%. Reductions in the numbers of impinged gobies accounted 

for 78% of the total impingement reduction [Ref. 6.78]. Other species that showed 

significant reductions in impingement were herring, sprat, white bream, smelt, bass, 

perch, sole, and flounder. The reduction in herring impingement averaged 94.7% [Ref. 

6.78]. The study also determined that changes in temperature and salinity can lead to 

changes in the acoustic field generated by the SPA system; however, these changes were 

found to be insignificant [Ref. 6.78]. These SPA system results are extremely site- and 

species-specific and are not necessarily representative of the reductions that would be 

expected at the Stations. 

Conclusions

Acoustic deterrent systems have been proven effective for certain sites with specific fish 

species. However, potential effectiveness of an acoustic deterrent system is highly 

species-specific [Ref. 6.2]. As such, site-specific studies would be required to fully 

evaluate the effectiveness of any acoustic deterrent system at the Stations. In addition, 

because eggs and larvae cannot respond to the stimuli created by acoustic deterrent 

systems there would be no direct reduction in entrainment. For these reasons, acoustic 

deterrent systems are not expected to provide significant biological benefits and are not 

further considered as alternatives to the current CWIS technologies. 

4.4.3.3 Air Bubble Curtains 

Air bubble curtains are not considered as viable alternatives to the current screening 

systems at the Stations because they were previously used at the Stations and were 

determined to be ineffective. 

Air bubble curtains are designed primarily to create a visual deterrent to fish, but can also 

stimulate auditory and physical responses [Ref. 6.18]. The air bubble curtains are created 

by pumping air through a diffuser hose. As shown in Figure 4.20, nozzles in the diffuser 
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hose release a dense “wall” of air bubbles that deter juvenile and adult fish from the 

CWIS. 

Figure 4.20 Elevation View of Air Bubble Curtain [Ref. 6.2] 

Air bubble curtain systems were in operation for several years (late-1970’s through the 

mid-1980’s) at each of the Unit 1 and Unit 2 traveling water screens and one traveling 

water screen (TWS 36) at Unit 3, but were removed after yielding poor results [Ref. 6.15; 

Ref. 6.109]. The studies of the Stations’ air bubble curtain noted that the effectiveness 

was lower at night and during periods of high turbidity, which support the observation 

that fish respond to air bubbles visually and not through auditory or tactile stimuli [Ref. 

6.18]. Air bubble curtain effectiveness may also be dependent on water temperature with 

decreased effectiveness associated with lower water temperatures [Ref. 6.108]. The air 

burst curtain at the Stations proved to be ineffective against white perch, striped bass, and 

clupeids [Ref. 6.15]. In some cases, the use of air bubble curtains increased impingement 

rates [Ref. 6.108]. 

Other field studies examining the effectiveness of air bubble curtains in reducing fish 

impingement at CWISs have been completed. One study on air bubble curtains was 

conducted in 1972 at Monroe Power Plant on Lake Erie [Ref. 6.15]. The curtains were 

turned on and off for seven day intervals during the study period. Results showed that 

the air bubble curtains were ineffective and did not reduce impingement in yellow perch, 

walleye, gizzard shad, drum, alewife, or smelt. Another air bubble curtain study 

conducted at Prairie Island Nuclear Generating Station on the Mississippi River in the 

1970s showed inconsistent results [Ref. 6.15]. Small decreases in impingement of 

crappie and freshwater drum were observed; however, the number of impinged carp, 

silver chub, and white bass increased. 

Conclusions

Although dated, effectiveness studies at the Stations and elsewhere failed to establish 

reduced impingement in associated with air bubble curtains. Moreover, because eggs and 

larvae cannot respond to the stimuli created by air bubble curtains, there would be no 
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direct reduction in entrainment. For these reasons, air bubble curtains are not expected to 

provide significant biological benefits at the Stations and are not further considered as 

alternatives to the current CWIS technologies. 

4.4.3.4 Electrical Barriers 

Electrical barriers deter fish by introducing electrical currents into the waterway. An 

electrical field is created by applying a voltage across two submerged electrodes. When 

fish are caught in the electrical field their behavioral response is to turn sideways to avoid 

the stress caused by the electrical current passing through their bodies. Orienting the 

electrical field parallel to the flow direction, which is generally the same as the direction 

fish are travelling in, results in the maximum voltage being applied to the fish (i.e., 

electric field lines run head-to-tail along the fish in the same direction as the flow). By 

turning perpendicular to the flow, fish entrained in the electrical barrier cannot continue 

swimming upstream and are swept away by the waterway’s natural current as shown in 

Figure 4.21. 

Figure 4.21 Fish Path in a Graduated Electric Field [Ref. 6.104] 

Electrical barriers are most commonly installed to impede upstream migration of invasive 

fish species. However, some have been designed to deter fish from intake structures for 

hydropower facilities [Ref. 6.104]. There are no known permanent electrical barriers in 

operation at a nuclear facility’s CWIS. 

The electrical barriers designed by Smith-Root, Inc. for fish barrier and avoidance 

purposes utilize short duration direct current (DC) pulses and a graduated electrical field 

[Ref. 6.104]. Alternating current (AC) pulses and long, continuous pulses have proven to 

be more stressful to fish and are not used as a deterrent [Ref. 6.104]. The graduated 

electrical field consists of pulse generators providing a voltage to an electrode array on 

the floor of the water body as shown in Figure 4.22. 
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Figure 4.22 Graduated Electrical Field Configuration [Ref. 6.119] 

The voltages of the pulse generators are set to be successively increasing, resulting in an 

additive effect on the electrical field’s strength. Smith-Root offers output voltages of 40, 

80, 120, 160, 200, and 240 V with pulse durations ranging from 0.15 milliseconds to 10 

milliseconds. Voltage and pulse durations are chosen based on the specific species of 

fish that the barrier is aiming to exclude [Ref. 6.104]. 

Electrical barriers have been widely dismissed as a feasible alternative to reduce fish 

impingement and entrainment at CWISs due to technological reliability issues [Ref. 6.2]. 

Electrical field strength is highly dependent on the conductivity of the water. In estuarine 

applications, such as IPEC, salinity can vary greatly leading to large deviations in the 

conductivity of the water [Ref. 6.2]. Large variability in field strength can lead to 

paralysis or even mortality to the fish [Ref. 6.2]. The effectiveness of electrical barriers 

can also be reduced by variations in flow characteristics of the water body. If the natural 

flow velocity of the water body is less than the intake flow velocity, the electrical barrier 

can paralyze fish resulting in them being entrained in the CWIS. The Unit 2 and Unit 3 

CWISs have an intake water approach velocity of approximately 1 fps at full flow and 

approximately 0.6 fps at reduced flow [Ref. 6.24]. Current measurement data collected 

offshore of IPEC during three tidal cycles showed a maximum flood velocity of 1.5 fps 

and maximum ebb velocity of 3.3 fps. Based on these maxima, the average flood 

velocity is 1.0 fps and the average ebb velocity is 2.1 fps [Ref. 6.11]. In addition, a slack 

tide lasts for a short period as the tide changes between flood and ebb conditions Thus, 

there are periods where the average River velocity is less than the intake flow velocity at 

the entrance to the CWISs. Electrical barriers would likely be ineffective during these 

periods, and could increase impingement rates by reducing the ability of fish to travel 

away from the CWISs. 

The sizes of the species at the Stations vary from small bay anchovy with lengths 

approximately 100 mm to large striped bass with lengths capable of exceeding 80 cm 

[Ref. 6.118]. These differences in length can greatly hinder the performance of an 

electrical barrier. The electrical barrier voltages are calibrated to deter a specific species 

type and size. A voltage suitable for deterring one species could potentially be fatal to 

another species due to the greater stresses caused on the species by the electrical field 
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[Ref. 6.2]. Conversely, a lower voltage capable of safely deterring one species could be 

incapable of deterring another species, allowing it to travel through the electrical barrier 

and possibly be entrained in the intake. In addition, the voltages introduced in the water 

body by electrical barriers are potential hazards for humans as well as fish [Ref. 6.104]. 

Conclusions

Design and installation of an electrical barrier at the Stations would require extensive site 

specific studies to determine the optimum location, size, and electrical field strength of 

the system. The effectiveness of electrical barrier systems is highly site-specific and 

dependent upon the conductivity of the water, natural flow of the waterbody, and size of 

the species. Based on the existing intake flow rates at the entrance to the CWISs and the 

average River velocities, operation of electrical barriers could increase impingement 

mortality. Moreover, because eggs and larvae cannot swim away from the stresses 

created by an electrical barrier, there would be no direct reduction in entrainment. For 

these reasons, electrical barriers are not expected to provide significant I&E reductions 

and are not further considered as alternatives to the current CWIS technologies. 

4.4.4 Louver System 

Louver systems are not considered as viable alternatives to the current screening systems at 

the Stations because they would not be expected to provide comparable reductions in I&E 

to the NYSDEC Proposed Project or other alternative technologies. Because eggs and 

larvae cannot swim away from the turbulence created by a louver system, there would be 

no associated reduction in entrainment. Additional site-specific biological studies would 

be required to produce an optimized louver system design for the Stations. 

Louver systems are passive guidance barriers that typically consist of a series of evenly 

spaced, vertical panels aligned across the face of an intake system at an angle to the 

incoming flow to reduce impingement. The louver panels cause an abrupt change in the 

velocity and direction of the flow, creating a turbulence zone in front of the panels that fish 

avoid [Ref. 6.35]. Fish tend to align themselves parallel and headfirst with the incoming 

flow, thus coming in contact tail first with the turbulence zone. Typically, fish will move 

away from the turbulence zone in a direction perpendicular to the angled louvers. The net 

effect of this behavioral response, after repeated excursions away from the turbulence 

zone, is a lateral displacement of fish towards the end of the angled louvers into a bypass 

channel that returns fish to the source waterbody [Ref. 6.110]. A plan view of a typical 

louver array is shown in Figure 4.23. 
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Figure 4.23 Typical Louver Array [Ref. 6.110] 

Retrofitting louver systems upstream of the existing TWSs at the Stations would require 

significant civil/structural modifications. Louver arrays and a bypass channel would have 

to be constructed in each intake channel. The bypass channel would reduce the width of 

the intake channel available for flow downstream to the existing TWSs resulting in an 

increase in through-screen velocity and likely increase in impingement mortality. 

I&E Discussion

Because eggs and larvae cannot swim away from the turbulence of the magnitude created 

by louver systems, there would be no associated reduction in entrainment [Ref. 6.107]. 

EPRI indicated that louver systems could provide 80-95% diversion efficiency for a wide 

variety of species under a range of site conditions; however, latent mortality could be a 

concern [Ref. 6.107]. Fish entrained in an intake channel with a louver system typically 

spend long periods of time swimming against the flow, just ahead of the louvers. Alden 

Research Laboratory (ARL) performed a series of test flume experiments where the crosschannel width of the test flume was 6 ft and the duration of the experiments ranged from 

15 minutes to almost 13 hours. ARL found that the residence time of fish was often much 

greater than the planned duration of the experiment. In 55 of the 58 experiments 

conducted by ARL, fish remained swimming in the flume after the termination of the 

experiment. As the residence time within the intake channel increases above certain 

minimums, fish are more likely to suffer exhaustion and be impinged against the louver 

panels before reaching the bypass. The ARL study concluded that louver systems had 

marginal success in guiding fish into the bypass channel, as fish were more often impinged 

against the louvers [Ref. 6.35]. 

Additional studies conducted by Stone and Webster concluded that the angle of the louver 

system to the incoming flow (25° and 45° in their tests) had no effect on the efficiency of 

the system; however, fish suffered more physical damage in tests conducted with the 

louvers at 45° than they did with the louvers at 25° [Ref. 6.35]. The effectiveness of 
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diverting fish uninjured to the bypass is more closely related to the cross-channel distance 

of the angled louver system than the pitch of the louvers. The cross-channel distance of a 

louver system is increased by 1.41 to 2.37 times the perpendicular distance in the range of 

25° to 45° as shown in Figure 4.24. 

Figure 4.24 Cross-channel Distance of Louver Systems [Ref. 6.110] 

The CW channels of Unit 2 and Unit 3 have perpendicular cross-channel distances of 13 ft 

4 inches, approximately 2.2 times the distance of the ARL test flume. The approximate 

cross-channel distance of a louver system within a CW channel at the Stations would range 

between 18 ft 10 inches at 45° to 31 ft 8 in at 25°. The residence time of fish within a CW 

channel at IPEC equipped with a louver system is expected to be significantly greater than 

the residence times reported in the ARL study, thus increasing the possibility of fish 

impingement against the louver arrays due to exhaustion. 

Conclusions

A site-specific study would be required to produce an optimized louver system design for 

the Stations and determine the biological benefits of the system. However, based on the 

studies, louver systems would not be expected to provide any appreciable reductions in 

impingement at the Stations. Moreover, because eggs and larvae cannot swim away from 

the turbulence created by a louver system, there would be no associated reduction in 

entrainment. For these reasons, louver systems are not expected to provide significant 

reductions in I&E and are not further considered as alternatives to the current CWIS 

technologies. 

4.5 Alternate Intake Location 

In order to evaluate the engineering feasibility of an offshore intake at the Stations and the 

potential I&E reductions associated with an offshore intake location(s), further studies of the 

Hudson River adjacent to each CWIS defining the density of aquatic organisms as a function 

of horizontal distance from the shoreline and vertical depth would be required. Despite 

extensive ongoing biological analysis at the Stations, no specific studies have been undertaken 
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to identify alternative offshore intake locations for Unit 2 or Unit 3, nor is there data suitable 

for that purpose. Therefore, the engineering feasibility of an offshore intake cannot be 

determined at this time (i.e., without first conducting a biological study establishing the 

optimum location of an offshore intake for Unit 2 and Unit 3). 

As discussed in Section 2.4.1, the Unit 2 and Unit 3 CWISs currently draw water from the 

shoreline of the Hudson River through three concrete bulkheads that are subdivided into 

independent CW and SW intake channels. These are referred to as shoreline intake systems. 

In addition to shoreline intake systems, intake systems can also be located offshore. Offshore 

intake systems typically draw in water through vertical inlets located offshore from the screen 

house and slightly above the floor of the waterbody. 

Velocity caps can also be placed on top of the vertical inlets. Velocity caps are covers placed 

over the vertical inlets that convert vertical flow into horizontal flow. Velocity caps are sized 

to achieve a low intake velocity between 0.5 and 1.5 fps [Ref. 6.115]. Fish impingement is 

reduced through the use of velocity caps because fish tend to avoid changes in horizontal flow 

but are less able to detect and avoid changes in vertical flow. However, velocity caps provide 

no significant reduction in entrainment of larvae or eggs [Ref. 6.115]. As shown in Figure 

4.25, a velocity cap reduces the approach velocities, and converts vertical flow into horizontal 

flow at the entrance of the intake [Ref. 6.26]. 

Figure 4.25 Typical Velocity Cap Flow Direction 

Locations of offshore intakes, where feasible, are determined by various site-specific factors. 

Extensive studies generally are conducted to determine the optimum offshore location of the 

vertical inlets to minimize I&E. In estuaries, species distribution and abundance are 

determined by a number of physical and chemical attributes including geographic location, 

salinity, temperature, oxygen level, currents, and substrate. These factors, along with the 

degree of vertical and horizontal mixing in the estuary, dictate the spatial distribution and 

movement of organisms [Ref. 6.115]. 

An alternative offshore intake location would require significant modifications to the CWISs, 

including potential significant modifications to the River bed directly adjacent to the CWISs. 

In order to connect the velocity cap(s) to the intake channels of the existing CWISs, a large 
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diameter intake tunnel would need to be constructed below the floor of the Hudson River. 

The design, location, and depth of an offshore intake would be dependent on technological 

limitations and potential biological benefits. 

JAF is located on the southeastern shore of Lake Ontario. The CWIS at JAF consists of an 

offshore submerged velocity cap that feeds an underground D-shaped tunnel running beneath 

the lake bed to an in-shore screenwell building that contains the majority of supporting intake 

equipment. Three 120,000 gpm circulating water intake pumps and three 18,000 gpm service 

water pumps (two are required for normal operation) draw water through the offshore intake 

into the in-shore screenwell building. The offshore intake is located over 900 ft from the 

shoreline of Lake Ontario in approximately 25 ft of water. The offshore intake has four 

segmented shore-facing openings that feed a D-shaped intake tunnel that runs beneath the lake 

bed approximately 1150 ft to the in-shore screenwell building. Attached to the velocity cap 

are 88 internally heated bar racks used to prevent intake clogging due to frazil ice or excessive 

icing [Ref. 6.68]. 

I&E Discussion

In order to determine the potential I&E reductions at IPEC an extensive site-specific study 

would be required to determine the optimum location. A three year biological study to assess 

the possible extension of the cooling water intake structure at JAF began in early 2009 and is 

scheduled to conclude in late 2011. In accordance with the study plan submitted to the DEC, 

the fish species type and density at each sampling location is determined through scheduled 

hydroacoustic surveys and physical sampling using trawl and gill nets [Ref. 6.93]. A similar 

study would be required at IPEC. 

Conclusions

Despite extensive ongoing biological analysis, no specific studies have been undertaken to 

identify alternative offshore intake locations for Unit 2 or Unit 3, nor is there data suitable for 

that purpose. Thus, further studies of the Hudson River adjacent to each CWIS defining the 

density of aquatic organisms as a function of horizontal distance from the shoreline and 

vertical depth would be required to evaluate the potential I&E reductions associated with an 

offshore intake location(s). Therefore, the engineering feasibility of an offshore intake cannot 

be determined at this time (i.e., without first conducting a biological study establishing the 

optimum location of an offshore intake for Unit 2 and Unit 3). 

4.6 Flow Reduction 

Flow reductions at the Stations could be achieved through the use of new or existing 

technologies (i.e., dual/variable speed pumps), operational measures (i.e., outage timing), or 

by replacing some or all of Hudson River water used for cooling water with an alternative 

source of cooling water (i.e., recycled wastewater or water from radial wells). However, 

additional flow reductions via new or existing technologies (i.e., dual/variable speed pumps) 

or operational measures (i.e., outage timing) would not be expected to provide significant 

biological benefits over the current flow reductions achieved by using the existing 

technologies and operational measures. In addition, due to insufficient amounts of recycled 

wastewater in the vicinity of the Stations and the limited sources of available groundwater and 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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91 

land space at the Stations, the use of recycled wastewater or radial wells are not considered a 

technologically feasible means of significantly reducing I&E. 

4.6.1 Dual/Variable Speed Pumps 

Currently, the Stations reduce flow through the use of operational measures and flow 

reduction technologies (i.e., dual speed pumps at Unit 2 and variable speed pumps at Unit 

3). The historical flow reductions (from baseline) at the Stations are described in Section 

2.4.2.3. The potential for further operational flow reductions is based on equipment 

operational limits and operating performance impacts. Current operation is governed by 

limitations used to ensure adequate reliability and safety, among other factors. If it is 

expected that these limits may be exceeded, the Stations are required to operate atypically 

under various levels of restriction that decrease the net power generated. 

To evaluate the potential impact of further operational flow reductions, limits on the 

condenser pressure and cooling water velocity were used to develop the maximum flow 

reductions available. A computational model of each Unit was then used to determine the 

operational impacts of flow reductions up to the developed limits at each Unit. 

4.6.1.1 Flow Reduction Parameters/Methodology 

4.6.1.1.1Main Condenser Pressure Limit 

As described in Section 2.2.2, the objective of the main condenser is to provide a heat 

sink for the turbine 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 River-water-cooled unit 

located directly beneath the low pressure cylinders of the main turbine. 

The Unit 2 condenser low vacuum alarm is set at 25 in-Hg vacuum, or approximately 5 

in-Hg atmospheric [Ref. 6.65], and the Unit 3 low vacuum alarm is set at no lower than 

26 in-Hg vacuum, or approximately 4 in-Hg atmospheric [Ref. 6.66].17 If the condenser 

low vacuum alarm points are exceeded, the Unit is forced into a loss of condenser 

vacuum abnormal operating procedure (AOP). The loss of condenser vacuum AOP 

prompts actions to stabilize the condenser vacuum, determine the cause of loss of 

vacuum, and return the vacuum to normal. The AOP could lead to a required manual 

reactor shutdown if the condenser vacuum cannot be restored. 

4.6.1.1.2Cooling Water Velocity Limit 

The thermal performance of the condenser is dependent on the cooling water velocity 

through the condenser tubes, in conjunction with the amount of fouling of the tubes. 

According to the Heat Exchange Institute (HEI) [Ref. 6.38], water velocities of less than 

3 fps through the condenser tubes do not build up enough flow resistance within the 

condenser to ensure a uniform quantity of water through all of the tubes. Without 

 

17 The pressure setpoints listed in the Alarm Response Procedures [Ref. 6.65; Ref. 6.66] are 25 and 26 in-Hg 

absolute for Units 2 and 3, respectively. Subtracting each of these setpoints from a standard atmospheric pressure of 

29.92 in-Hg results in the main condenser vacuum setpoints of 3.92 and 4.92 in-Hg for Units 2 and 3, respectively. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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92 

sufficient flow resistance in the condenser tubes, heat transfer through the tubes would 

not be uniform and there would be an increased potential for fouling. Condenser 

performance under such conditions cannot be accurately predicted, and any correlation 

resulting from calculations or modeling using an input velocity below 3 fps cannot be 

regarded as a valid analysis [Ref. 6.38]. In addition, reduced flow velocities through the 

condenser tubes would be expected to increase fouling in the tubes [Ref. 6.103]. 

Fouling increases resistance to heat transfer and could affect the performance of the 

condenser. Therefore, in order to maintain plant performance and safety standards, the 

minimum sustained condenser tube velocity considered for flow reductions at each Unit 

is 3 fps [Ref. 6.38]. 

Unit 2 and Unit 3 are designed for maximum condenser tube water velocities of 4.1 fps 

and 6.0 fps, respectively [Ref. 6.42]. Limiting the condenser tube water velocity to 3 

fps would result in a maximum available circulating water flow reduction of 27% at 

Unit 2 and 50% at Unit 3. The maximum available design flow reduction (i.e., 

circulating water flow and service water flow; see Section 2.4.2.3) resulting from 

condenser tube water velocities of 3 fps would be approximately 25% at Unit 2 and 

45% at Unit 3. 

4.6.1.1.3Inlet Water Temperature 

Eight years (2001 through 2008) of measured daily circulating water inlet temperatures 

were provided by the Stations. An algorithm was run to remove erroneous values, with 

a resulting inlet water temperature data recovery rate of 99.8%, as shown in Attachment 

3, Table 3-1. 

4.6.1.1.4PEPSE Model 

The performance evaluation of power system efficiency (PEPSE) model is a state-ofthe-art power plant performance modeling software used by the power industry to 

estimate plant operational parameters and net power generated, using system inputs 

such as circulating water inlet temperature. The most recent PEPSE models for each 

Unit18 were reviewed, updated, and run to produce the results discussed herein. 

Diagrams of the Stations’ PEPSE models have been included in Attachment 3, Figures 

3-1 through 3-12. 

The inlet water temperature data received from the Stations was input into the updated 

PEPSE models, and the circulating water flow was reduced in 5% circulating water 

flow increments and run over a bounding range of circulating water inlet temperatures 

(32°F to 84°F, in 2°F increments). By varying the circulating water flow rate, the 

impacts of flow reductions on the Stations operation were calculated. When required, 

the net thermal input was varied for each circulating water inlet temperatures in order to 

 

18 The Stations supplied a Unit 2 PEPSE model updated in 2006 and a Unit 3 PEPSE model updated in 2007. While 

finalizing the Report analysis, updated versions of the PEPSE models were developed by the Stations. The new 

models were reviewed and compared to the PEPSE models originally used for this Report. It was determined that 

using the new PEPSE models would not result in any significant differences in the analysis and any difference 

would result in greater power losses due to additional flow reduction at the Stations. Therefore, the PEPSE models 

used for this analysis produce conservative results. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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93 

achieve condenser vacuum levels above the alarm set points discussed in Section 

4.6.1.1.1. 

4.6.1.2 Flow Reduction Impacts 

4.6.1.2.1Flow Reduction Analysis 

Using the daily measured cooling water intake temperatures at each percentage of flow 

reduction from baseline, the Stations’ PEPSE models were used to determine the hourly 

operational power loss attributed to each defined design flow reduction. Operational 

power loss is defined here as a loss of generating capacity due to the thermodynamic 

effects of reduced cooling water flow through the condenser. In contrast, a parasitic 

loss is the electric power load required to operate the cycle under the changed 

conditions. 

The annual average operational power losses at Units 2 and 3 are listed in Table 4.7 and 

Table 4.8, respectively. As shown, various levels of flow reduction from baseline could 

occur at each Unit without operational power losses in November through May. From 

June through October, however, even small amounts of flow reduction would result in 

operational power losses at both Units. The maximum operational power losses at 

Units 2 and 3 are provided in Attachment 3, Tables 3-2 and 3-3, respectively. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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Table 4.7 Unit 2 Average Power Loss (MWe) Attributed to 

Design Flow Reduction

Month 

Design Flow Reduction 

5% 10% 15% 20% 25% 

January -0.1 -0.3 -0.5 -0.7 -0.9 

February -0.1 -0.3 -0.4 -0.7 -1.0 

March -0.1 -0.3 -0.5 -0.7 -0.9 

April -0.1 -0.1 -0.2 -0.2 -0.1 

May 0.4 0.9 1.7 2.9 4.5 

June 1.5 3.3 5.4 8.0 11.2 

July 2.1 4.6 7.4 10.7 14.6 

August 2.2 4.8 7.8 11.2 15.2 

September 2.0 4.3 7.0 10.2 13.9 

October 1.0 2.4 4.0 6.1 8.7 

November 0.0 0.1 0.3 0.7 1.3 

December -0.1 -0.2 -0.3 -0.4 -0.4 

Average Annual 0.7 1.6 2.7 4.0 5.6 

Notes: 

1

 Based on daily inlet water temperature measured from 2001 through 2008. 

2

 Atypical inlet water temperatures less than 40°F excluded to remove effect of unstable 

cooling proprieties of water near the freezing point. 3

 The maximum available design flow reduction would be approximately 25% at Unit 2 

based on the HEI-defined 3 fps limitation. 
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Table 4.8 Unit 3 Average Power Loss (MWe) Attributed 

to Design Flow Reduction

Month 

Design Flow Reduction 

5% 10% 15% 20% 25% 30% 35% 40% 45% 

January -0.2 -0.4 -0.6 -0.8 -1.3 -2.3 -3.5 -4.2 -4.4 

February -0.1 -0.3 -0.6 -0.8 -1.1 -2.0 -3.3 -4.2 -4.5 

March -0.2 -0.4 -0.6 -0.8 -1.3 -2.3 -3.5 -4.2 -4.3 

April -0.3 -0.7 -1.1 -1.6 -2.1 -2.7 -3.1 -3.2 -2.6 

May -0.2 -0.2 -0.1 0.1 0.4 1.0 2.2 4.2 7.9 

June 0.6 1.3 2.4 3.8 5.7 8.3 11.9 16.8 23.4 

July 1.5 3.3 5.6 8.4 11.7 15.9 21.0 27.4 36.9 

August 1.7 3.8 6.4 9.4 13.0 17.4 22.8 29.5 42.3 

September 1.2 2.8 4.7 7.1 10.2 14.0 18.8 24.8 32.8 

October 0.2 0.6 1.2 2.0 3.2 5.0 7.6 11.4 17.0 

November -0.4 -0.8 -1.3 -1.7 -2.0 -2.1 -1.9 -1.2 0.3 

December -0.2 -0.5 -0.8 -1.3 -1.9 -2.7 -3.3 -3.6 -3.2 

Average Annual 0.3 0.7 1.3 2.0 2.9 4.0 5.5 7.9 11.9 

Notes: 

1

 Based on daily inlet water temperature measured from 2001 through 2008. 2

 Atypical inlet water temperatures less than 40°F excluded to remove effect of unstable cooling proprieties of water near the 

freezing point. 

3

 The maximum available design flow reduction would be approximately 45% at Unit 3 based on the HEI-defined 3 fps 

limitation 

The negative power loss values shown in Table 4.7 and Table 4.8 correspond to 

potential power gains that could be achieved through flow reductions from baseline. 

Note that the Stations already achieve these power gains through operational flow 

reductions that currently occur in the winter months. These gains result from reduced 

subcooling of the condensate water. When subcooling occurs, the feedwater heater duty 

increases and turbine output is reduced. Therefore, when subcooling is reduced, turbine 

output and power production increase. The ability to increase power generated due to 

reduced subcooling is reflected in the efficient flow schedule currently in place at each 

Unit [Ref. 6.89]. 

However, the thermodynamic advantage resulting from a reduction in condensate 

subcooling would be somewhat counteracted by a parasitic pump load increase. As 

flow is reduced from 140,000 gpm to 70,000 gpm, the power load required to operate 

the Unit 3 variable speed pumps increases, with peak required load at approximately 

95,000 gpm [Ref. 6.63]. The power load increase is due to decreasing pump efficiency 

and increasing total dynamic head as flow is reduced. The motor efficiency and drive 

efficiency would also be expected to decrease as flow is reduced [Ref. 6.102], further 

increasing the power load required to operate the pumps. The total power load increase 

is estimated to be less than 1 MWe at each Unit for the majority of operating conditions. 

Therefore, the parasitic power load increase has been neglected to ensure a conservative 

estimate (i.e., the net power loss at each Unit would actually be slightly more than 

predicted here). 
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96 

4.6.1.2.2Power Reduction Analysis 

Using the PEPSE modeling output previously described, the daily flow reduction 

available was calculated given an available threshold power loss. Table 4.9 and Table 

4.10 provide the incremental reductions in design flow for reductions of active power in 

5 MWe increments at Units 2 and 3, respectively. The tabulated values depict the 

average percentage of circulating water reduction available, given the HEI defined 3 fps 

condenser flow velocity restriction [Ref. 6.38]. Due to the condenser flow velocity 

limit of 3 fps, no additional reductions in flow could be achieved, and, therefore, no 

additional losses in active power above 20 MWe and 40 MWe for Units 2 and 3, 

respectively, would be warranted. 

Table 4.9 Unit 2 Average Design Flow Reduction Available at Defined 

Power Loss

Month 

Power Loss Threshold (MWe) 

0 5 10 15 20 

January 25.0% 25.0% 25.0% 25.0% 25.0% 

February 25.0% 25.0% 25.0% 25.0% 25.0% 

March 25.0% 25.0% 25.0% 25.0% 25.0% 

April 18.4% 25.0% 25.0% 25.0% 25.0% 

May 1.3% 23.5% 25.0% 25.0% 25.0% 

June 0.0% 14.5% 22.5% 25.0% 25.0% 

July 0.0% 10.7% 18.9% 24.9% 25.0% 

August 0.0% 10.3% 18.3% 24.6% 25.0% 

September 0.0% 11.3% 19.7% 24.9% 25.0% 

October 0.3% 17.9% 24.0% 25.0% 25.0% 

November 10.1% 24.9% 25.0% 25.0% 25.0% 

December 22.8% 25.0% 25.0% 25.0% 25.0% 

Average Annual 10.6% 19.8% 23.2% 24.9% 25.0% 

Notes:

1

 Based on daily inlet water temperature measured from 2001 through 2008. 2

 Atypical inlet water temperatures less than 40°F excluded to remove effect of unstable cooling proprieties 

of water near the freezing point 

3

 Values highlighted yellow represent those months restricted solely by the HEI-defined 3 fps limitation. 
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97 

Table 4.10 Unit 3 Average Design Flow Reduction Available at 

Defined Power Loss

Month 

Power Loss Threshold (MWe) 

0 5 10 15 20 25 30 35 40 

January 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

February 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

March 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

April 44.9% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

May 16.9% 41.9% 44.4% 44.9% 45.0% 45.0% 45.0% 45.0% 45.0% 

June 0.2% 24.5% 33.3% 38.6% 42.2% 44.7% 45.0% 45.0% 45.0% 

July 0.0% 13.9% 22.6% 29.0% 34.1% 38.9% 44.2% 45.0%4 45.0% 

August 0.0% 12.4% 20.9% 27.3% 32.5% 36.7% 42.5% 45.0%4 45.0% 

September 0.0% 15.9% 24.9% 31.1% 36.4% 41.8% 44.5% 45.0% 45.0% 

October 4.5% 31.7% 38.6% 42.5% 44.1% 45.0% 45.0% 45.0% 45.0% 

November 40.0% 44.8% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

December 44.9% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% 

Average Annual 23.7% 34.1% 37.8% 40.2% 42.0% 43.5% 44.7% 45.0% 45.0% 

Notes:

1

 Based on daily inlet water temperature measured from 2001 through 2008. 2

 Atypical inlet water temperatures less than 40°F excluded to remove effect of unstable cooling proprieties of water near 

the freezing point 

3

 Values highlighted yellow represent those months restricted solely by the HEI-defined 3 fps limitation. 

4

 Values round-up to 45.0%, but include days which were not limited by the HEI-defined 3 fps limitation. 

4.6.1.3 Effects of Further Operational Flow Reductions 

As described in Section 2.4.2.1, Unit 2 is currently equipped with dual speed CW pumps, 

and Unit 3 is equipped with variable speed CW pumps. The Stations utilize both the dual 

speed (Unit 2) and variable speed (Unit 3) CW pumps to provide significant reductions in 

CW flow rates. 

I&E Discussions

Attachment 6 (Tables 17 and 23 of Appendix A) provide the estimated reductions from 

the regulatory baseline in EA1 losses that could be achieved using the flow reductions 

associated with the defined power losses presented in Table 4.9 and Table 4.10. These 

reductions also account for the Stations’ survival rates (Attachment 6) and average 

historic flow reductions (Section 2.4.2.3.2). From Attachment 6 (Tables 17 and 23 of 

Appendix A), Table 4.11 presents the potential reductions in EA1 I&E corresponding to 

various active power reductions. As discussed in Section 4.6.1.1.2, the available design 

flow reduction would be limited to approximately 25% at Unit 2 and 45% at Unit 3, due 

to the HEI-defined 3 fps limitation. Because no additional reductions in flow could be 

achieved, no additional losses in active power above 20 MWe and 40 MWe for Units 2 

and 3, respectively, would be warranted. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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98 

Table 4.11 Potential Percent Reduction of Annual EA1 I&E Losses at Defined Power 

Losses in Each Month 

Month 

Power Loss Threshold (Unit 2 / Unit 3)

0 / 0 MWe 20 / 20 MWe 20 / 40 MWe 

EA1 

Entrainment 

EA1 

Impingement 

EA1 

Entrainment 

EA1 

Impingement 

EA1 

Entrainment 

EA1 

Impingement 

January 0.0% 8.8% 0.0% 8.8% 0.0% 8.8% 

February 0.0% 9.6% 0.0% 9.6% 0.0% 9.6% 

March 0.0% 12.0% 0.0% 12.0% 0.0% 12.0% 

April 0.4% 6.7% 0.4% 6.7% 0.4% 6.7% 

May 6.3% 7.4% 6.5% 7.9% 6.5% 7.9% 

June 14.9% 8.5% 17.2% 9.9% 17.2% 10.0% 

July 7.3% 4.0% 11.8% 4.4% 13.0% 4.5% 

August 4.2% 4.2% 7.0% 4.5% 7.6% 4.7% 

September 1.4% 4.4% 2.7% 4.8% 2.9% 4.9% 

October 1.2% 3.9% 2.2% 4.4% 2.2% 4.4% 

November 0.0% 4.7% 0.0% 5.0% 0.0% 5.0% 

December 0.0% 6.5% 0.0% 6.5% 0.0% 6.5% 

Annual 35.7% 80.7% 47.8% 84.7% 49.9% 85.0% 

The maximum possible entrainment reduction shown in Table 4.11 (49.9%) is only 

16.1% more than the current entrainment reductions based on the historic flow reductions 

discussed in Section 3.2 and would require substantial continuous losses in generation. 

In addition, the EA1 I&E reductions presented in Table 4.11 remain well below the 

potential percent reduction that could be achieved through conversion of IPEC to closedloop cooling. 

Conclusions

The maximum available reductions from baseline in EA1 I&E associated with reductions 

in the design flow rates would be approximately 85.0% and 49.9%, respectively. In 

addition, these reductions would correspond to continuous active power reductions of up 

to 20 MWe at Unit 2 and 40 MWe at Unit 3. As discussed in Section 4.6.1.2.2, additional 

losses in active power would not produce additional reductions in the design flow rates. 

These reductions would not be comparable to those potentially achievable by the 

NYSDEC Proposed Project, and a significant cost would be associated with the active 

power reductions resulting from the flow reductions. 

4.6.1.4 Conversion of Unit 2 to Variable Speed Pumps 

Both dual speed pumps and variable speed pumps allow reduced intake flow rates when 

ambient River temperatures are low, although variable speed pumps would provide 

significantly greater flow control, as the flow can be varied continuously between the 

maximum and minimum flow rates. The Unit 2 dual speed pumps operate at 140,000 

gpm or 84,000 gpm [Ref. 6.60]. Therefore, each dual speed pump allows for reductions 

in flow of 0% (full flow), 40% (reduced flow), and 100% (pump offline). Reducing the 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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99 

flow rate of individual dual speed pumps allows incremental flow reductions from 

baseline flow (i.e., maximum design flow for the Unit 1 RW and Unit 2 SW and CW 

pumps) of 6%, 13%, 19%, 25%, 32%, and 38% per Unit. Although the dual speed pumps 

have the capabilities of significantly reducing the intake flow rates at Unit 2, flow 

reductions of more than 25% would violate the condenser tube water velocity limit 

discussed in Section 4.6.1.1.2. 

Conclusions

Although the use of variable speed pumps at Unit 2 would provide significantly greater 

flow control and smoother transitions between flow rates, the existing dual speed pumps 

provide sufficient flow reduction increments up to, and including, the maximum flow 

reduction of 25% allowable at Unit 2. Therefore, conversion of the Unit 2 dual speed 

pumps to variable speed pumps is not likely to provide any appreciable biological benefit. 

4.6.2 Use of Recycled Wastewater as Cooling Water 

Reductions in the amount of Hudson River water used for cooling at the Stations, 

constituting a reduction in flow, could be achieved through the replacement of some or all 

of Hudson River water with an alternative source (i.e., recycled wastewater or water from 

radial wells). However, the use of recycled wastewater from waste treatment facilities, 

frequently referred to as grey water, as an alternative to using River water for thermal 

rejection from the each Unit’s condensers is not considered as a viable method of flow 

reduction due to the lack of available sources in the vicinity of IPEC. To fulfill the 

Stations’ heat transfer requirements using recycled wastewater as an alternative to Hudson 

River water, the approximate volume and flow required would have to be the same or 

greater than the volume and flow needed when using Hudson River water as the CW 

source. 

In order to determine the availability of recycled wastewater in the vicinity of IPEC, the 

permitted discharge flow rates were determined for the SPDES-permitted Westchester 

County wastewater treatment facilities (with their distance from IPEC established). The 

discharge flows listed in the SPDES Permits for all wastewater treatment facilities in 

Westchester County are included in Table 4.12 (see Attachment 7). 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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Table 4.12 SPDES Water Discharge Permit Flows 

Facility 

(SPDES Permit) Flow % Req’d CW Flow 

Driving 

Distance to 

IPEC (approx.) 

Direct 

Distance 

(approx.) 

Buchanan WWTP 

(NY0029971) 

0.5 MGD 

(347.2 gpm) 

0.02% <1 mi. <1 mi. 

Peekskill WWTP 

(NY100803) 

10 MGD 

(6,944.4 gpm) 0.41% 4 mi. 3 mi. 

Ossining WWTP 

(NY108324) 

7 MGD 

(4,861.1 gpm) 0.29% 10 mi. 9 mi. 

Yorktown Heights WWTP 

(NY0026743) 

1.5 MGD 

(1,041.7 gpm) 

0.06% 13 mi. 9 mi. 

North Castle WWTP 

(NY109584) 

0.38 MGD 

(263.9 gpm) 0.02% 25 mi. 16 mi. 

Wild Oaks WWTP 

(NY0065706) 

0.06 MGD 

(41.7 gpm) 

0.0025% 29 mi. 16 mi. 

Port Chester WWTP 

(NY0026786) 

6 MGD 

(4,166.7 gpm) 

0.25% 30 mi. 25 mi. 

Oakridge WPCF 

(NY0030767) 

0.08 MGD 

(55.6 gpm) 

0.0033% 31 mi. 23 mi. 

Yonkers Joint WWTP 

(NY0026689) 

92 MGD 

(63,888.9 gpm) 3.8% 31 mi. 25 mi. 

Blind Brook WWTP 

(NY0026719) 

5 MGD 

(3,472.2 gpm) 

0.21% 32 mi. 26 mi. 

Mamaroneck WWTP 

(NY0026701) 

18 MGD 

(12,500.0 gpm) 0.74% 34 mi. 26 mi. 

New Rochelle WWTP 

(NY0026697) 

13.6 MGD 

(9,444.4 gpm) 0.56% 38 mi. 27 mi. 

Total 154.12 MGD 

(107,027.8 gpm) 6.37% 278 mi. 206 mi. 

The closest wastewater treatment facility, Buchanan Wastewater Treatment Plant, is 

located less than 1 mile away from IPEC and discharges on average only 347.2 gpm. 

Yonkers Joint Wastewater Treatment Plant discharges 63,888.9 gpm, far more than any 

plant in Westchester County; however, it is located approximately 25 miles away and 

discharges only 3.8% of the 1,680,000 gpm required for normal CW flow. Furthermore, if 

the discharge from every wastewater treatment facility in Westchester County were 

combined, the amount of River water needed as a circulating fluid would be reduced by 

only 6.37% for both Units, or 12.74% for one Unit only, and would require between 205 

and 277 miles of pipeline. 
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Conclusions

Due to the limited sources of recycled wastewater in the vicinity of IPEC, recycled 

wastewater is not considered a technologically feasible means of significantly reducing 

I&E. 

4.6.3 Outage Timing 

The strategic timing of maintenance outages would not be able to significantly reduce EA1 

I&E over the Stations’ existing technologies and operational measures. As discussed in 

Section 2.4.2.3, maintenance outages at the Stations have the potential to significantly 

reduce the flow entering a CWIS during the outage periods. When a Unit is offline, a 

minimal amount of flow enters the CWIS as some CW would still be required after 

shutdown and prior to restart. Adequate SW flow must also be provided when the Unit is 

offline in order to maintain essential cooling of nuclear safety-related systems. 

Currently, scheduled maintenance outages at each Unit occur every 24 months and are 

anticipated to approximately 25 days. The outages are staggered so that the Units are not 

offline at the same time. The current outage schedule for Unit 2 and Unit 3 calls for spring 

outages for each Unit. A three year schedule of requested outage dates is filed annually 

with New York Independent System Operator (NYISO), which reviews the requested 

schedule and approves or disapproves the outage dates [Ref. 6.85]. Maintenance outages 

are typically scheduled between seasons of peak electrical demand, between the high use 

winter months (December, January, and February) and the high use summer months (June, 

July, and August). As discussed in Section 3.2, the Stations’ existing technology is 

considered state-of-the-art for impingement; therefore, and outage timing considerations 

focus on minimizing entrainment. 

Attachment 6 (Tables 17 and 23 of Appendix A) provide the potential reductions in each 

month due to a one Unit outage at IPEC. Table 4.11 provides the potential incremental 

reductions a one Unit outage would have to reduce EA1 I&E when compared to the 

Stations’ existing reductions. These reductions would be similar for an outage at either 

Unit 2 or Unit 3. 
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Table 4.13 Potential Incremental Reductions in EA1 I&E Losses 

Due to Outage Timing at One Unit From the Existing Technologies 

and Operational Measures

Month EA1 Entrainment EA1 Impingement 

January 0.0% 0.3% 

February 0.0% 0.2% 

March 0.0% 0.3% 

April 0.1% 1.0% 

May 2.1% 1.5% 

June 9.7% 2.9% 

July 10.7% 1.2% 

August 5.3% 0.9% 

September 2.6% 1.2% 

October 1.8% 0.6% 

November 0.0% 0.5% 

December 0.0% 0.3% 

As shown in Table 4.11, outages taken in the months of June, July, or August would have 

the highest potential to provide incremental EA1 entrainment reductions. However, while 

scheduling each Unit’s outages for the months of June, July, or August would coincide 

with the optimum period for EA1 entrainment reduction, this period also reflects peak 

summer demand. NYISO historically has underscored the importance of the Stations’ 

generation during this period. As such, I&E reductions associated with scheduled outage 

shifting to June, July, or August are not further considered. The only remaining months 

that would have the potential to reduce EA1 entrainment are May, September, and October 

where the highest incremental reduction in EA1 entrainment and impingement over the 

Stations’ current technologies and operational measures would be 2.6% and 1.2%, 

respectively, in the month of September. 

Conclusions

Assuming approval from NYISO, each Unit having bi-annual outages in September would 

result in potential incremental EA1 entrainment and EA1 impingement reductions of up to 

approximately 2.6% and 1.2%, respectively, and would not provide comparable reductions 

to closed-loop cooling or other alternative technologies. As such, a change in the current 

schedule outage timing is not further considered as an alternative to the current 

technologies and operational measures utilized at the Stations. 

4.6.4 Radial Wells 

Radial wells are not considered as a viable method of flow reduction due to the limited 

sources of available groundwater and land space at IPEC. 

Radial wells are underground horizontal wells that draw water from the surrounding 

aquifer. Typical radial well systems consist of a concrete pump-well caisson installed in 
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the ground with several perforated collector screen pipes (laterals) protruding through wall 

ports into the surrounding aquifer. Radial wells draw water at low velocities through many 

feet of porous material, reducing the flow through the CWISs and, therefore, I&E. A 

typical plan and section view of a radial well system is shown in Figure 4.26. 

Figure 4.26 Radial Well – Section and Plan Views [Ref. 6.2] 

Radial wells have been installed successfully at utility and municipal facilities, producing 

water flow rates of up to 50 MGD [Ref. 6.100]. The success of radial well technology is 

highly site specific and limited by the following: 

 Radial wells are only suitable where there is a porous aquifer with the capacity to 

provide the quantity of water required. Test wells must be drilled and pump-tested to 

determine the exact characteristics of the aquifer and size of the required radial well 

system. Installation and testing of wells would take at least two to four months. 

 The yield capacity of the individual caisson units is limited to approximately 25,000 

gpm. However, the yield capacity is likely much less for most aquifers as the usual 

capacity of an individual caisson unit is 1000 to 10,000 gpm. For larger flow 

requirements, multiple caisson units are required and must connect to a common 

transmission pipe to the plant. 

IPEC is situated on a complex of Cambro-Ordovician rocks represented by the Manhattan 

Formation and Inwood Marble Formation [Ref. 6.37]. The site lies predominantly upon 

the Inwood Marble Formation which consists of relatively pure carbonate rock of 

dolomitic and/or calcic mineralogy with silica rich zones. In the bedrock present at the 
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site, groundwater occurs and migrates in open fractures or voids. These void spaces are 

termed secondary porosity with the primary porosity being the void spaces within the 

bedrock itself. Inwood Marble has a very low primary porosity, and therefore does not 

contribute to the flow or storage of significant volumes of water [Ref. 6.37]. 

IPEC is located in a crystalline rock aquifer (i.e., there is limited porosity and the majority 

of the groundwater is in the fractures). Wells installed in a crystalline rock aquifer are 

typically drilled to depths ranging between 20 ft to 600 ft, yielding between 1 and 120 

gpm; however, the well depths occasionally exceed 1000 ft and may yield more than 500 

gpm [Ref. 6.117]. Although it is possible that higher groundwater yields could be obtained 

from collector screens below and near the Riverbed, site-specific pump testing would be 

required to determine this. 

Groundwater is encountered at the site primarily in bedrock fractures and along the 

jointing or bedding planes of the various rock strata. Thus, groundwater may be 

encountered at different elevations on the site depending on the location, ground surface 

elevation, and if water-bearing fractures, joints, and bedding planes are encountered. 

Investigation performed in 2005 and 2006 indicated groundwater may be encountered in 

monitoring wells at the site between 3 feet to more than 80 ft above MSL and is generally 

encountered from 10 ft to more than 50 ft beneath the surface [Ref. 6.24]. 

Within a one mile radius of the site, there are seven United States Geological Survey 

(USGS) registered wells. As shown in Table 4.14, each well ranges in depth from 30 ft to 

500 ft below the surface and, based on available information, produces between 4 gpm to 

30 gpm [Ref. 6.117]. It should be noted that two of the registered wells are on the IPEC 

site. 

Table 4.14 Registered USGS Wells within One Mile of IPEC [Ref. 6.24] 

USGS 

Registered 

Well ID 

County 

Well Depth 

(below 

surface) 

Approximate 

Distance to 

IPEC 

Status Capacity 

(gpm) 

Primary 

Use 

WE 245 Westchester 100 ft. Onsite Unused 4 Domestic 

WE 246 Westchester 193 ft. Onsite Unused N/A N/A 

WE 244 Westchester 60 ft. 3950 ft ESE N/A 30 Unused 

WE 261 Westchester 500 ft. 500 ft. ENE N/A 25 Unused 

RO 307 Rockland 192 ft. 5280 ft E N/A N/A Domestic 

RO 313 Rockland 30 ft. 4500 ft. NW N/A N/A Domestic 

RO 314 Rockland 110 ft. 5280 ft. ENE N/A N/A Commercial 

N/A: Information not available 

As provided by Design of Water Intake Structures for Fish Protection [Ref. 6.2], the 

following guidelines should be considered for the conceptual design of radial well systems: 

 Caisson unit spacing is typically 1500 ft; however, spacing may be closer in productive 

aquifers. For example, the caisson units at the Grand Gulf Nuclear Station (near 

Vicksburg, Mississippi) have a minimum spacing of approximately 950 feet. Pump 

tests conducted in the well fields determined a minimum yield of 5600 gpm. 

 The diameter of the caisson depends on the space requirements for the pumps and on 

the clearance needed for the lateral screens. A 16 ft inner diameter is typical. 
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 Caissons depths of up to 200 feet are considered feasible; however, caisson depth is 

typically determined by the radial well vendor and is dependent on aquifer 

characteristics. 

 The diameter of the lateral screens is typically 8 to 16 inches but sizes up to 48 inches 

could be considered for a very high yield aquifer. 

 The maximum length of a lateral screen is approximately 450 feet for any diameter. 

The usual length is between 150 ft and 300 ft. The number of lateral screens and their 

lengths are typically determined by the vendor. 

 Inflow velocity through the screens typically ranges from 1 to 2 fpm and net open area 

for the lateral screens typically ranges from 18 to 22 percent. 

 The total length of the collector screens can be determined by the following formula: 

Length (ft) = 2.837 * Flow Rate (gpm) / Diameter (in) 

Based on the above design criteria, the IPEC site could conceivably support at most six 

radial well systems. Four radial wells could potentially be located north of the Unit 2 

containment building, and two radial wells could potentially be located south of the Unit 3 

containment building as shown in Attachment 2, Figure 2-19. If twelve lateral screens 

were installed in each caisson and each lateral screen was considered an individual well 

capable of producing 120 gpm, than each caisson would be capable of producing 1440 

gpm. Each lateral would be approximately 22 ft long assuming a screen diameter of 16 

inches, an inflow velocity of 1 fpm, and a percent open area of 18. Four radial wells 

servicing Unit 2 could provide up to 5760 gpm or 0.69 percent of the CW maximum 

design flow rate. Two radial wells servicing Unit 3 could provide up to 2880 gpm or 0.34 

percent of the CW maximum design flow rate required. 

Conclusions

Due to the limited sources of available groundwater and land space at IPEC, radial wells 

are not considered a technologically feasible means of significantly reducing I&E. 

4.7 Alternative Heat Rejection and Recirculation 

No method of alternative heat rejection and recirculation – including evaporative ponds, spray 

ponds, cooling canals and in-river heat exchangers – is considered as a viable alternative to 

the current screening systems at the Stations. Due to the limited sources of land area available 

at IPEC, evaporative ponds, spray ponds, and cooling canals are not considered a 

technologically feasible means of significantly reducing I&E. In-river heat exchangers would 

require a large amount of surface area to dissipate the required heat load, and would create a 

large point source heat load in the Hudson River that would have no thermal dilution. The inriver heat exchanger temperature would exceed the maximum SPDES plant discharge 

temperature permit limits, particularly during periods of slack tide. 

4.7.1 Evaporative Ponds 

Evaporative ponds, also known as cooling ponds, are not considered as viable alternatives 

to the current screening systems at the Stations, because the land area required for an 
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evaporative pond to reject the heat load of one or both Units would be much greater than 

the land area available at IPEC. 

Evaporative ponds are bodies of water that primarily use surface evaporation to reject heat 

to the atmosphere. The term ‘pond’ is relative and can be applied to small or large bodies 

of water. In areas with low land costs, artificial cooling ponds can be relatively 

inexpensive to construct and operate with small makeup water requirements. Most 

artificial cooling ponds are relatively shallow where a minimum depth of about 3.3 feet is 

normal. The warm discharge water entering the cooling pond will lose and gain heat as it 

passes through the pond by the combined mechanisms of conduction, convection, 

radiation, and evaporation. However, evaporation is the main mode of heat transfer and 

the heat loss from the cooling pond is governed by the temperature differential between the 

pond surface and the atmosphere. The main disadvantage of cooling ponds is the low heat 

transfer rate to the air requiring large evaporative surface areas for cooling large volumes 

of water [Ref. 6.70]. Cooling pond areas for power generation facilities typically range 

between 1.24 to 2.47 acres per megawatt; however, these land area requirements are not 

specific to nuclear generating facilities [Ref. 6.97]. Using this rule-of-thumb 

approximation, the Stations would require a cooling pond area of approximately 2700 to 

5300 acres to reject an appropriate amount heat from the condensers for a closed recirculating system. 

The South Texas Project (STP) nuclear power plant in Bay City, Texas utilizes a 46 acre 

essential cooling pond as the ultimate heat sink and a 7000 acre main cooling pond for 

circulating water purposes. STP currently operates two 1251 MWe units (Units 1 and 2). 

The essential and main cooling ponds were designed to support two additional 1300 MWe 

reactors (Units 3 and 4). Assuming that Units 3 and 4 are constructed as specified, the land 

area at STP used for cooling ponds will be 1.35 acres per megawatt [Ref. 6.105]. If the 

Stations could obtain the same cooling pond performance as STP, approximately 2913 

acres of evaporative surface area would be required to reject the heat loads from the 

condensers. 

Sizing of a conceptual cooling pond for the Stations was conducted using the methodology 

specified in the Advanced Air and Noise Pollution Control (AANPC) Handbook [Ref. 

6.121]. A wet bulb temperature of 33.8°F and wind speed of 4.7 mph, respectively, were 

selected by averaging meteorological data gathered from IPEC’s weather station between 

1999 through 2008. The highest wet bulb temperature reported during this time period was 

79.3°F. A design heat rejection rate of 4.65×109

 BTU/hr is specified by the condenser data 

sheets. A design surface water temperature of 93.2°F was assumed based on the maximum 

permitted average discharge water temperature allowed by the SPDES permit [Ref. 6.86]. 

The choice of a high surface water temperature is a conservative assumption because an 

increased temperature differential between the surface water temperature and average wet 

bulb temperature provides greater heat transfer resulting in a smaller cooling pond surface 

area. The mean solar radiation coefficient was also conservatively estimated at 3795 

kilocalorie per day per square meter (kcal/d-m2

), which is an average of the lower range of 

the short-wave and long-wave solar radiation coefficients provided in the AANPC 

Handbook [Ref. 6.121]. Using these inputs, a cooling pond surface area of approximately 

320 acres would be required to reject the heat load from Unit 2 or Unit 3 and a cooling 

pond surface area of 650 acres would be required to reject the combined heat loads 
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generated by Units 2 and 3. These estimated areas are conservative because the surface 

area of actual cooling ponds would be sized to reject the required heat loads at the highest 

wet bulb temperature. At a wet bulb temperature of 79.3°F, approximately 6000 acres of 

cooling pond surface area would be required to reject the heat load from either Unit 2 or 

Unit 3, and approximately 12,100 acres of cooling pond surface area would be required to 

reject the combined heat load generated by Units 2 and 3. 

Conclusions

Although the total land area of IPEC is approximately 239 acres, only 115 acres are 

currently available for use because most of the site is already occupied [Ref 6.24]. As 

such, the land area required for a cooling pond to reject the heat load of one or both Units 

would be much greater than the land area available at IPEC, based on rule-of-thumb 

approximations, comparison to existing cooling pond systems, and theoretical design 

methods. Therefore, the use of a closed re-circulating cooling pond at IPEC is not further 

considered. 

4.7.2 Spray Ponds 

Spray ponds are not considered as viable alternatives to the current screening systems at 

the Stations, because the land area required for a spray pond to reject the heat load of one 

or both Units would be greater than the available open area at IPEC. 

Spray ponds are modified cooling ponds with spray nozzles floating on or located just 

above the pond surface. Water pumped through the spray nozzles is diffused into droplets 

increasing the surface area in contact with the ambient air, thus enhancing the rate of 

evaporative heat loss. Spray ponds also transfer heat to the atmosphere through 

evaporation from the surface of the pond similar to conventional cooling ponds. The 

required surface area of a spray pond can be 20 times less than the surface area required by 

a conventional cooling pond for an identical heat load [Ref. 6.70]. Makeup water 

requirements for a spray pond are larger than a conventional cooling pond due to the 

increased evaporation and drift, ranging from 2 to 5 percent of the water volume sprayed. 

Normally, spray pond nozzles are operated at a pressure of 7 psi with flow rates up to 50 

gpm per nozzle. For highest efficiency, spray ponds should have a rectangular shape with 

the long side oriented perpendicular to the prevailing summer wind direction [Ref. 6.106]. 

Sizing of a conceptual spray pond system for the Stations was conducted using the 

methodology specified by Spraying Systems Company [Ref. 6.106]. A design wet bulb 

temperature of 68.5°F was selected by analysis of meteorological data gathered from 

IPEC’s weather station between 1999 through 2008. Per the Spraying Systems Company 

methodology, the design wet bulb temperature is defined as the maximum wet bulb 

temperature which is exceeded in less than 5% of the summer time [Ref. 6.106]. The 

highest wet bulb temperature reported during this time period was 79.3°F. A desired spray 

pond outlet temperature of 75°F was selected and corresponds to the Unit 3 condenser 

design inlet water temperature [Ref. 6.42]. A spray pond inlet temperature of 93.2°F was 

assumed, corresponding to the maximum permitted discharge water temperature allowed 

by the SPDES permit, and a design flow rate of 1,680,000 gpm was used, corresponding to 

the maximum circulating water intake flow. Based on these inputs and the 50% 

evaporative heat transfer efficiency recommended by Spraying Systems Company [Ref. 
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6.106], the outlet temperature of water sprayed once through a spray pond would cool to a 

temperature of approximately 81°F, exceeding the desired outlet temperature of 75°F. In 

order to cool to the desired outlet temperature, the water would have to be re-sprayed 

through a second in-line spray pond. The recommended nozzle and spacing requirements 

[Ref. 6.106] determined that each of the spray ponds would need a surface area of 

approximately 60.4 acres (120.8 total acres) to reject the heat loads generated by Units 2 

and 3. Each conceptual pond would require a width of 800 ft and a length of 3290 ft, and 

would need to be oriented lengthwise from east to west due to the prevailing north-south 

summer wind direction. However, this estimated area is conservative because the surface 

area of an actual spray pond system would be sized to reject the required heat loads during 

the summer months corresponding to the highest wet bulb temperature of 79.3°F. 

Based on the methodology specified by Spraying Systems Company, the outlet 

temperature of a spray pond system cannot be less than the design wet bulb temperature. 

Thus, a spray pond system designed to the highest web bulb temperature (79.3°F) could 

not reject the heat required to provide condenser inlet water at a temperature of 75°F. Inlet 

water at a temperature of 93.2°F and flow rate of 1,680,000 gpm would need to be 

circulated through nine spray ponds to be cooled to a temperature of 79.3°F, requiring a 

spray pond surface area of approximately 544 acres. 

Conclusions

As discussed in Section 4.7.1, only 115 acres are currently available for use at IPEC 

because most of the site is already occupied. As such, the required surface area of a spray 

pond system would be greater than the available open area at IPEC. Therefore, the use of 

closed, re-circulating spray ponds at IPEC is not further considered. 

4.7.3 Cooling Canals 

Cooling canals are not considered as viable alternatives to the current screening systems at 

the Stations, because the land area required for a cooling canal to reject the heat load of 

one or both Units would be much greater than the land area available at IPEC. 

Cooling canals are long, narrow artificial bodies of water that primarily use surface 

evaporation to reject heat to the atmosphere. Open cooling canal systems function as 

thermal buffers by reducing the temperature of heated effluent prior to discharging into an 

ocean, River, or estuary. Re-circulating cooling canal systems operate like radiators: 

heated water is discharged into one end of the system, the heat is released to the 

environment as the water travels through the canals, and cooled water is withdrawn from 

the opposite end of the system. Most cooling canals are relatively shallow with depths 

typically ranging from 1 ft to 3 ft. Similar to evaporative cooling ponds, the main 

disadvantages of cooling canals are the low heat transfer rate to the air and the large 

surface areas required for cooling large volumes of water [Ref. 6.70]. 

Turkey Point Nuclear Plant (Turkey Point) in Miami-Dade County, Florida utilizes a 6700-

acre re-circulating cooling canal system for cooling of its two 693 MWe nuclear reactor 

units (Units 3 and 4) and two 400 MWe fossil units (Units 1 and 2). As shown in Figure 

4.27, the cooling canal system consists of 32 parallel canals that carry warm water from the 

condenser and eight parallel canals that return cooled water to the condenser inlets. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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Figure 4.27 Cooling Canal System at Turkey Point [Ref. 6.36] 

The cooling canals at Turkey Point are approximately 200 ft wide and are separated by 90 

ft wide berms. The cumulative length of the canals is about 168 miles with an effective 

surface area of 3860 acres. Flow to the canals from Units 3 and 4 is approximately 

1,300,000 gpm [Ref. 6.36]. The residence time in the canals is about 40 hours, during 

which time the water temperature drops to within 3 to 4°F of the adjoining Biscayne Bay’s 

ambient temperature [Ref. 6.75]. A cooling canal system at IPEC would require less 

surface area than the cooling canal system at Turkey Point due to the significant difference 

in ambient conditions at the two sites. 

The heat removal performance of a cooling canal system at IPEC is expected to be similar 

to a cooling pond system because each system utilizes surface evaporation as the primary 

mode of heat removal. Based on the heat removal performance of cooling pond systems as 

described in Section 4.7.1, a minimum of 320 acres of evaporative surface area would be 

required for the heat rejection loads of a single Unit and approximately 650 acres would be 

required for the heat rejection loads of Units 2 and 3 combined. The total land area 

necessary for a cooling canal system would likely be larger than the calculated surface area 

because a cooling canal system would require a system of parallel canals similar to that of 

Turkey Point. Applying the ratio of total land area compared to the evaporative surface 
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area at Turkey Point (1.74) to the calculated evaporative surface areas required at IPEC 

indicates that approximately 560 acres (Unit 2 or Unit 3) or 1120 acres (Units 2 and 3 

combined) of land area would be required for a cooling canal system at IPEC. 

Conclusions

As discussed in Section 4.7.2, only 115 acres are currently available for use at IPEC 

because most of the site is already occupied. As such, the land area required for a closed 

re-circulating cooling canal system would be much greater than the land area available at 

IPEC. Therefore, the use of closed re-circulating cooling canals at IPEC is not further 

considered. 

4.7.4 In-River Heat Exchangers 

In-river heat exchangers are not considered as viable alternatives to the current screening 

systems at the Stations, because the use of in-river heat exchangers would be expected to 

present significant thermal biological issues. 

In-river heat exchangers are a form of closed-loop cooling, whereby heat is rejected 

directly to the source water body without drawing an intake flow. As shown in Figure 

4.28, an in-river heat exchanger works in three stages. First, the circulating water pump 

draws cold water across the condenser, condensing the main steam and increasing the 

temperature of the closed-loop flow. The hot recirculating water is then pumped from the 

condenser through a series of heat exchangers submerged in the source waterbody (i.e., inriver heat exchanger). The in-river heat exchanger allows heat to pass directly from the 

closed-loop cooling water to the flow of the river, and thus cool the closed-loop flow. 

After the circulating water has been cooled, it is drawn back to the condenser to close the 

cooling loop. 

Figure 4.28 Conceptual Diagram of In-River Heat Exchanger System 

At the Stations, in-river heat exchangers would encounter several site specific design 

challenges which would need to be addressed prior to determining feasibility. First, 

because the Hudson River is an estuary, the flow ebbs and floods and thus would not 

provide a constant cooling capacity, which would affect the operation of each Unit. 

During the transition periods between ebb and flood river flow (slack tide), the cooling 

capability of the in-river heat exchanger would be greatly reduced. Second, the in-river 

heat exchanger would need to be constructed of a material that would not corrode in the 

brackish Hudson River water. Materials suitable for use in brackish water typically are 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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more expensive and have a lower thermal conductivity than materials used in freshwater 

sources. Third, the in-river heat exchanger temperature would exceed the maximum 

SPDES plant discharge temperature permit limits [Ref. 6.86], particularly during slack 

tide. 

Traditional cost-effective shell-and-tube heat exchangers seldom have temperature 

approaches less than 10°F [Ref. 6.77]. Because in-river heat exchangers at the Stations 

would not have a constant River cross flow rate and would be subject to corrosion and 

fouling performance limitations, it is assumed that in-river heat exchangers at the Stations 

would do no better than an approach of 10°F. However, this approach would be very 

optimistic based on to the size required, operational considerations, and the variable flow 

conditions at the Stations. Complex heat exchanger configurations exist that could 

increase heat exchanger performance; however, the use of such configurations at IPEC 

would be limited by significant operational issues, including excessive fouling and 

pumping requirements. Lack of sufficient flow across the in-river heat exchangers could 

also lead to increased condenser back pressures and potential unplanned reactor 

shutdowns. 

Based on historical river data collected at the Stations from 2001-2008, the maximum 

measured daily average circulating water inlet temperature is 83.8°F. At the maximum 

river temperature, the assumed 10°F temperature approach would result in a 93.8°F 

condenser inlet temperature. Similar to current once-through operation, the in-river heat 

exchanger system would be designed with a 17°F temperature rise over the condenser, 

based on the condenser BTU rejection requirements and 840,000 gpm flow rate. For 

context, at the maximum river temperature the condenser outlet temperature would be 

110.8°F, exceeding the Stations’ SPDES permit allowable discharge limit of 110°F [Ref. 

6.86]. The in-river heat exchanger temperature would also exceed the SPDES permit limit 

of 93.2°F19 between April 15 and June 30 for more than 15 days every year between 2001 

and 2008, except 2003. Concurrently, the yearly average between 2001 and 2008 would 

exceed 10 days with an in-river heat exchanger temperature over 93.2°F. 

Conclusions

In comparison with the current once-through cooling design, an in-river heat exchanger 

system would inherently raise the condenser cooling water inlet and discharge 

temperatures. It is important to note that the in-river heat exchanger would require a large 

amount of surface area to dissipate the required heat load, and would create a large point 

source heat load in the Hudson River that would have no thermal dilution although heat 

dissipation through the Hudson River would occur. For context, the in-river heat 

exchanger temperature would exceed the maximum SPDES plant discharge temperature 

permit limits, particularly during periods of slack tide. In addition, operational issues 

associated with fouling and corrosion could present significant challenges. For these 

reasons, in-river heat exchanger closed-loop cooling systems would be expected to present 

 

19 Between April 15 and June 30, the maximum discharge temperature is limited by the SPDES permit to 93.2°F for 

an average of no more than ten days per year; provided that the daily average discharge temperature over this period 

does not exceed 93.2°F on more than 15 days in any year [Ref. 6.86]. 
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significant thermal biological issues and are not further considered as alternatives to the 

current CWIS technologies. 
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5 Conclusions 

Based on the feasibility and engineering evaluations documented in Section 4, Table 5.1 

summarizes the various technologies and operational measures that were evaluated for biological 

compliance required by the NYSDEC in a draft modified SPDES permit. 

Table 5.1 Summary of Alternatives 

Technology or 

Operational 

Measure 

Comments 

Existing CWIS Technologies and Operational Measures (Section 3) 

Current 

Configuration 

Includes modified Ristroph-type traveling water screens, fish handling and return 

systems, low pressure screenwash systems, flow reductions due to dual/variable speed 

pump operation, flow reductions due to maintenance outages, and maintenance outage 

schedule considerations. 

Current reductions from Regulatory Baseline (Attachment 6): 

 EA1 Entrainment - approximately 33.8% 

 EA1 Impingement - approximately 80.2%

Fish Handling and Return Systems (Section 4.1) 

Upgraded Fish 

Handling and Return 

System 

The existing fish return systems are considered to be state-of-the-art with respect to 

impingement losses and Siemens Water Technologies would not recommend any 

upgrades to the current fish return systems that would improve survivability rates. 

Traveling Water Screens (Section 4.2) 

Alternative Ristroph 

Screens (i.e., 

Ristroph screens 

with different mesh 

opening sizes than 

the mesh opening 

size of the existing 

Ristroph-type 

TWSs) 

Potential Reductions from Regulatory Baseline (Attachment 6): 

 EA1 Entrainment - up to 34.9% 

 EA1 Impingement - approximately 80.2% 

Potential Costs (2.0 mm mesh size): 

 Initial Costs - approximately $373 million capital costs and approximately 3.9 

million to 6.3 million MW-hrs per Unit of lost generation due to the required 

construction outages 

 Annual Costs - At a minimum, maintenance costs required would be at least 4 

times the costs required to maintain the existing coarse mesh TWSs 

None of the mesh sizes evaluated would be expected to significantly reduce EA1 

entrainment or EA1 impingement over the current screening systems. 
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Table 5.1 Summary of Alternatives 

Technology or 

Operational 

Measure 

Comments 

Dual Flow Traveling 

Water Screens 

Potential Reductions from Regulatory Baseline (Attachment 6): 

 EA1 Entrainment - up to 34.9% 

 EA1 Impingement - approximately 80.2% 

Potential Costs (2.0 mm mesh size): 

 Initial Costs – approximately $350 million capital costs and approximately 

4.7 million to 6.3 million MW-hrs per Unit of lost generation due to the 

required construction outages 

 Annual Costs - At a minimum, maintenance costs required would be at least 3 

times the costs required to maintain the existing coarse mesh TWSs 

None of the mesh sizes evaluated would be expected to significantly reduce EA1 

entrainment or EA1 impingement over the current screening systems. 

Angled Traveling 

Screens / Modular 

Inclined Screens 

Potential Reductions from Regulatory Baseline: 

 Similar to dual flow screens or Ristroph screens 

Potential Costs (2.0 mm mesh size): 

 Initial Costs - would be significantly higher than the costs associated with 

dual flow screens or Ristroph screens 

 Annual Costs - At a minimum, maintenance costs required would be 4 to 5 

times the costs required to maintain the existing coarse mesh TWSs 

None of the mesh sizes evaluated would be expected to significantly reduce EA1 

entrainment or EA1 impingement over the current screening systems. 

WIP Screens 

Potential Reductions from Regulatory Baseline: 

 Similar to dual flow screens or Ristroph screens 

Potential Costs (2.0 mm mesh size): 

 Initial Costs - would be significantly higher than the costs associated with 

dual flow screens or Ristroph screens 

 Annual Costs - At a minimum, maintenance costs required would be 

approximately 10 times the costs required to maintain the existing coarse 

mesh TWSs 

None of the mesh sizes evaluated would be expected to significantly reduce EA1 

entrainment or EA1 impingement over the current screening systems. 

MultiDisc® Screens 

Potential Reductions from Regulatory Baseline: 

 Similar to dual flow screens or Ristroph screens 

Potential Costs (2.0 mm mesh size): 

 Initial Costs - would be significantly higher than the costs associated with 

dual flow screens or Ristroph screens 

 Annual Costs - At a minimum, maintenance costs required would be 

approximately 6 times the costs required to maintain the existing coarse mesh 

TWSs 

None of the mesh sizes evaluated would be expected to significantly reduce EA1 

entrainment or EA1 impingement over the current screening systems. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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115 

Table 5.1 Summary of Alternatives 

Technology or 

Operational 

Measure 

Comments 

Passive Intake Systems (Section 4.3) 

Cylindrical 

Wedgewire Screens

Potential Reductions from Regulatory Baseline (Through-Slot Velocity of 0.5 fps) 

(Attachment 6): 

 EA1 Entrainment - up to 89.8% 

 EA1 Impingement - approximately 99.9% 

Potential Costs: 

 Initial Costs 

 approximately $41.7 million for 2.0 mm screens, and approximately 

$36.5 million for 9.0 mm CWW screens for a through-slot velocity of 0.5 

fps 

 approximately $63.3 million for 2.0 mm screens, and approximately 

$52.0 million for 9.0 mm CWW screens for a through-slot velocity of 

0.25 fps 

 resolution of unknown factors associated with the conceptual CWW 

system design would be required during the detailed design phase; these 

factors could, increase the total cost of implementing CWW screen 

systems to more than $100 million 

 approximately 33,000 to 46,000 MW-hrs of lost generation due to the 

CW pump pit excavation and construction 

 Annual Costs - At a minimum, maintenance costs would include the costs 

required to maintain the existing coarse mesh TWSs, the new airburst 

systems, and the new stop log systems, as well as the additional cost of divers 

as needed to clean/maintain the CWW screens 

In order to determine the optimal slot size for the Stations, a site-specific study would 

be required. A three-year site-specific engineering and biological effectiveness study 

would also be required to determine the optimum slot width for reducing EA1 

entrainment losses at which fouling would not be a concern. 

Perforated Pipe 

Inlets 

Perforated pipe intakes are obsolete and are have more engineering and operational 

difficulties than cylindrical wedgewire screens. 

Porous Dikes / 

Leaky Dams

Porous dikes/leaky dams are not considered as viable alternatives to the current 

screening systems at the Stations due to nuclear safety concerns associated with 

possible clogging and reduced flow to safety-related SW pumps and the unproven 

nature of the technology at nuclear generating facilities. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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116 

Table 5.1 Summary of Alternatives 

Technology or 

Operational 

Measure 

Comments 

Barrier Technologies (Section 4.4)

Aquatic Filter 

Barriers 

Potential Reductions from Regulatory Baseline (Attachment 6): 

 EA1 Entrainment - approximately 90.2% 

 EA1 Impingement - approximately 90.4% 

Potential Costs: 

 Initial Costs - approximately $67.4 million capital costs 

 Annual Costs - At a minimum, annual costs required would be approximately 

$3 million for the O&M and seasonal deployment, removal, and repair, not 

including the costs required to maintain the existing coarse mesh TWSs 

Aquatic filter barriers are not considered as the primary alternatives to the current 

intake screening system due to nuclear safety challenges associated with possible 

entanglement and reduced flow to safety-related SW pumps. 

Fish Barrier Nets 

Fish barrier nets are not considered as viable alternatives to the current screening 

systems due to nuclear safety challenges associated with possible entanglement and 

reduced flow to safety-related SW pumps and the lack of comparable reductions to 

closed-loop cooling or other alternative technologies. 

Behavioral Barriers 

(Light Guidance System, 

Acoustic Deterrents, Air 

Bubble Curtains, 

Electrical Barriers)

Behavioral barriers are potentially technologically feasible, but additional study would 

be required because previous studies of behavioral barriers performed at the Stations 

and other sites have been inconclusive or have shown no significant reduction in 

impingement or entrainment. A site-specific study would be required to provide the 

optimal type, location, and configuration of any behavioral barriers. 

Louver System 

Louver systems are potentially technologically feasible, but additional study would be 

required to produce an optimized design for the Stations and determine the biological 

benefits. However, based on previous studied a louver system would not be expected 

to provide any appreciable reductions to entrainment or impingement. 

Alternate Intake Location (Section 4.5) 

Alternate Intake 

Location 

Retrofit to an alternative intake location is potentially technologically feasible, but 

additional study would be required because IPEC site-specific biological information 

does not provide the optimal location or depth for an offshore intake.

Flow Reduction (Section 4.6) 

Dual / Variable 

Speed Pumps 

The maximum available reductions from baseline in EA1 entrainment and 

impingement associated with reductions in the design flow rates would be 

approximately 49.9% and 85.0%, respectively. These reductions would not be 

comparable to those potentially achievable by conversion to closed-loop cooling, and a 

significant cost would be associated with the active power reductions resulting from 

the flow reductions. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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117 

Table 5.1 Summary of Alternatives 

Technology or 

Operational 

Measure 

Comments 

Use of Recycled 

Wastewater as 

Cooling Water 

Use of recycled wastewater is technologically infeasible due to limited sources of grey 

water in the vicinity of IPEC. 

Outage Timing 

The maximum incremental reduction in EA1 entrainment (2.6%) and EA1 

impingement (1.2%) would result from a shift in scheduled outage timing to 

September. As such, a change in the current schedule outage timing is not further 

considered as an alternative to the current technologies and operational measures. 

Radial Wells Use of radial wells is technologically infeasible due to limited sources of available 

groundwater and land space at IPEC. 

Alternative Heat Rejection and Recirculation (Section 4.7) 

Evaporation Ponds Use of evaporative ponds is technologically infeasible due to limited land space at 

IPEC. 

Spray Ponds Use of spray ponds is technologically infeasible due to limited land space at IPEC. 

Cooling Canals Use of cooling canals is technologically infeasible due to limited land space at IPEC. 

In-River Heat 

Exchangers 

In-river heat exchanger closed-loop cooling systems would be expected to present 

significant thermal biological issues. For context, in-river heat exchanger 

temperatures would exceed the maximum SPDES plant discharge temperature permit 

limits, particularly during periods of slack tide. 

As shown in Table 5.1, CWW screens have the potential to achieve reductions in I&E at the 

Stations comparable to the NYSDEC Proposed Project and are considered to be the primary 

alternative. As discussed in Section 4.3.1, cylindrical wedgewire screens have been 

implemented at a facility with a total intake flow rate comparable to the total intake flow rate at 

the Stations.20

Several conceptual cylindrical wedgewire screening array designs, each fitting within the 

Stations’ exclusionary zone, were created. Although EPA typically recommends cylindrical 

wedgewire through-slot velocities at or below 0.5 feet per second (fps), NYSDEC has indicated 

interest in through-slot velocities at or below 0.25 fps. As such, separate conceptual cylindrical 

wedgewire screen systems were designed to provide a maximum through-slot velocity of at or 

below both 0.5 fps and 0.25 fps. The estimated capital costs associated with the installation of 

the conceptual CWW screen designs discussed in Section 4.3.1 would be: 

 Approximately $41.7 million for 2.0 mm screens, and approximately $36.5 million for 

9.0 mm CWW screens for a through-slot velocity of 0.5 fps. 

 

20 Oak Creek Power Plant in Milwaukee, Wisconsin operates the largest installation of cylindrical wedgewire 

screens, which includes an offshore intake system that filters a flow rate of 1,560,000 gpm. The cylindrical 

wedgewire screen system at Oak Creek became operational in January 2009 and is designed to operate year round. 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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118 

 Approximately $63.3 million for 2.0 mm screens, and approximately $52.0 million for 

9.0 mm CWW screens for a through-slot velocity of 0.25 fps. 

As described in Section 4.3.1, several unknown factors associated with the conceptual CWW 

system design developed in this Report would require resolution during the detailed design 

phase. These factors could more than double the costs, increasing the total cost of implementing 

CWW screen systems to more than $100 million. There would also be potentially 33,000 to 

46,000 MW-hrs of lost generation due to the required CW pump pit excavation and construction 

for both Units. Each of the slot sizes evaluated would be expected to achieve comparable 

reductions in EA1 I&E to the NYSDEC Proposed Project. Specifically, operation of cylindrical 

wedgewire screens with a mesh size of 2.0 mm and through-slot velocity at or below 0.5 fps has 

the potential to reduce EA1 I&E from the regulatory baseline by as much as approximately 

99.9% and 89.8%, respectively. In addition, according to Attachment 6, the estimated 

cumulative total reduction in EA1 I&E for CWW screens (98% and 87% for EA1 impingement 

and entrainment losses, respectively) would be greater than the estimated cumulative total 

reduction in EA1 I&E for the NYSDEC Proposed Project (86% and 50% for EA1 impingement 

and entrainment losses, respectively).21 Because CWW screens with smaller slot sizes would 

create significant opportunity for fouling, slot sizes ranging from 2.0 mm to 9.0 mm were 

selected for initial evaluation in an attempt to minimize both entrainment and fouling. Before 

cylindrical wedgewire screens can be implemented at the Stations, a site-specific study would be 

required to determine the optimal slot width for reducing entrainment at which fouling would not 

be a concern. 

 

21 For the cumulative benefits analysis, the installation schedule for CWW screens is consistent with a proposal 

based on studies of the technology, as discussed in Attachment 6. The installation schedule for the NYSDEC 

Proposed Project was derived by ENERCON [Ref. 6.22] with input from counsel to Entergy and Spectra Energy 

Transmission (owner of the gas pipeline that would have to be re-located in order to construct the NYSDEC 

Proposed Project). 
 ALTERNATIVE INTAKE TECHNOLOGIES 

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119 

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