NC0007064_Application_20230609

In accordance with Section 316(b) of the Federal Register (FR) (79 FR 158, 48299) 40 Code of
Federal Regulations (CFR) 5122 and 5125, Duke Energy Progress, LLC (Duke Energy) submits
the enclosed Clean Water Act (CWA) S316(b) rule for existing facilities (Rule) (USEPA 2014a)
study reports and supporting information for the Brunswick Nuclear Plant (Brunswick). Brunswick
withdraws greater than 125 million gallons per day (MGD) of raw water from a cooling water
intake structure (CWIS) and a service water intake structure (SWIS), using more than 25 percent of
the total water withdrawn for cooling purposes; therefore, it is subject to the Rule and Duke Energy
is required to submit each of the § 122.21 (r)(2)-(13) submittal requirements. This Executive
Summary provides an overview of the § 122.21 (r)(2) through (r)(13) study reports included in
Sections 2 through 13 of the main Compliance Document.
The current operating licenses for Brunswick Unit 1 and Unit 2 expire on September 8, 2036 and
December 27, 2034, respectively (USNRC 2018a, 2018b). As a result, this evaluation assumes
Unit 1 and Unit 2 will cease operations at the end of the current operating license periods (Le.
September 8, 2036 and December 27, 2034, respectively). Therefore, the year 2036 was used to
estimate the potential social costs and social benefits of candidate compliance technologies, as
detailed in Sections 10 through 12 of the compliance document and summarized in the following
sections of this Executive Summary.
Duke Energy requests determination that Brunswick currently operates as Best Technology
Available (BTA) for impingement and entrainment per the Rule as it operates a system of
technologies the following:
• Diversion structure that prevents most organisms from impingement,
• Modified traveling screens with an aquatic organism handling and return system,
• Seasonal CWIS flow reductions, and
• Long-term and continued field monitoring.
These technologies function as an advanced system to minimize impingement and entrainment
with demonstrated survival of aquatic organisms that may be impacted by the CWIS. The CWIS
protective measures at Brunswick were developed collectively by Duke Energy, U.S.
Environmental Protection Agency (USEPA), N.C. Department of Environmental Quality
(NCDEQ), and other resource agencies and are optimized to reduce potential IM and entrainment.
During development of the S316(b) Rule, Brunswick demonstrated that a facility could be compliant
with the required impingement and entrainment measures. The USEPA, in the Rule's Technical
Development Document (USEPA 2014b), cites Brunswick as one of the facilities that served as the
basis for the Impingement Mortality Standard. The USEPA (2014b) Technical Development
Document also states that the "Brunswick Power Plant in North Carolina has shown 84 percent
reduction in entrainment compared to the conventional screen systems". Several Brunswick study
documents were reviewed by the USEPA for development of the Rule.
The Cape Fear Estuary supports a complex system of life stages and trophic levels. While some
species are abundant within the estuary such as Atlantic Menhaden, Atlantic Croaker, Spot, and
anchovies, variation in species composition and dynamics over time is primarily influenced by
environmental factors such as water temperature and salinity, which are driven by freshwater input
from the Cape Fear River, rainfall events, and storms. Based on the comprehensive annual
environmental monitoring program results, the Cape Fear Estuary supports a balanced and resilient
fish and shellfish community that has not been affected by long-term operations at Brunswick.

IM compliance under IM BTA Option 6 (system of technologies) is based on the
supporting information listed below:
Diversion Structure.
# The primary purpose of the diversion structure is to limit the passage of aquatic organisms
into the intake canal, thereby reducing impingement and entrainment of aquatic organisms
at the CWIS and SWIS. The diversion structure includes bar racks with a 3-inch vertical bar
spacing placed in front of screen panels consisting of 3/8-inch by 3/4-inch mesh (Duke
Energy 2020a). Water flow through the diversion structure is restricted to the upper 18 feet
(ft) of the 46-ft-deep shipping canal and below this depth the structure is made of solid
reinforced concrete that extends to the seafloor, a design feature that helps reduce impacts
on bottom -dwelling (demersal) species like the Atlantic Sturgeon (Acipenser oxyrhynchus
oxyrhynchus), which prefer waters greater than 30 ft deep in the vicinity of the saltwater
and freshwater interface (USNRC 2006). By preventing adult, spawning -aged organisms
from entering the intake canal the diversion structure limits potential entrainment at the
CWIS. A comparison of the biomass of impinged aquatic organisms (by water volume)
before and after the construction and installation of the diversion structure demonstrated
significant impingement reduction postinstallation (USNRC 2006). The diversion structure
also includes an extension that excludes larger organisms including fish, crabs, and sea
turtles that may swim across the marsh at high tide.
Modified Traveling Water Screens with Aquatic Organism Handling and Return System
• The Brunswick CWIS and SWIS are equipped with modified fish -friendly traveling water
screens and an aquatic organism handling and return system. There are eight traveling
water screens in the CWIS and each screen has 50 panels in total, including 42 fine -mesh
screen (FMS) panels (1.0-millimeter [mm]) and eight coarse -mesh panels (3/8-inch) (Duke
Energy 2018; FMC 1981). There are four traveling water screens in the SWIS, each with
41 panels comprised of 3/8-inch coarse mesh.
# The aquatic organism return system for the CWIS utilizes a dual spray wash; a low-
pressure spray is used for the removal of aquatic organisms from the screens, followed by a
highpressure spray for debris removal. The SWIS utilizes a high-pressure spray. Aquatic
organisms removed from the screens located in the CWIS and SWIS travel to a holding
basin via a 4,000-ft-long aquatic organism return trough. The holding basin acts as an
upstream shallow -water nursery habitat, which results in a net increase in the abundance of
aquatic organisms that are returned to the source waterbody (Progress Energy 2005).
Aquatic organisms routed to the holding basin can enter Gum Log Branch and then Walden
Creek, which flows into the Cape Fear Estuary (USNRC 2006).
# The modified traveling water screen system at Brunswick has undergone extensive
modification to optimize impingement survival and entrainment reduction efficacy as
confirmed by extensive monitoring. In July 1983, 1.0-mm FMS were installed on four of
the eight traveling water screens in the CWIS, along with the introduction of the spray
wash system and aquatic organism return system. In January 1987, an upgrade was made to
install fine -mesh panels on six of the eight traveling water screens in the CWIS. In August
2003, the screens were adjusted so that four of the traveling water screens were entirely
comprised of fine mesh, while the other four were 50 percent fine mesh, alternating with
each screen panel. Finally, the current (i.e., optimized) configuration of 42 FMS panels and
eight coarse -mesh screen panels per traveling water screen was installed in January 2012 to
minimize screen and pump degradation (Duke Energy 2018).

Operational Measures I Seasonal Reductions in Withdrawals
• Brunswick has a design intake flow (DIF) of approximately 1,938 MGD based on the
design capacity of the condenser cooling water (CCW) pumps, service water pumps, and
screenwash pumps (Duke Energy 2021a, 2021b). However, the actual intake flow (AIF) at
Brunswick based on the 5-year period of record (POR) from January 1, 2016 through
December 31, 2020 was approximately 1,379 MGD, which represents a 29 percent
reduction in total water withdrawals when compared to DIF (Duke Energy 2020b). Flow
reductions have been shown to result in commensurate reductions in impingement
mortality and facilities can take credit for reductions in cooling water withdrawals at the
CWIS and SWIS.
# In addition, as discussed in Section 5.1.5, reductions in total water withdrawals at
Brunswick align with plant seasonal flow restrictions. These seasonal flow restrictions are a
condition in Brunswick's NPDES permit as daily maximum CCW pump discharge
limitations. The current seasonal daily maximum CCW pump discharge limitations are
described in the next section (Station Description).
Additionally, a comparison of recent monitoring results to data from impingement monitoring
performed at Brunswick prior to implementation of impingement reduction measures provide
evidence that IM has been substantially reduced at the Brunswick CWIS.
# Annual impingement monitoring conducted at the Brunswick CWIS since 1974 was used
to assess the effectiveness of the temporary prototype diversion structure from 1979
through 1981. Monitoring results indicated that the use of a permanent diversion structure
could reduce the total number of organisms impinged from 75-90 percent, depending on
species (CP&L 1983).
# After full implementation of the system of technologies (including seasonal flow
reductions) in 1983, the exclusion of many larger finfish by the diversion structure in
conjunction with the increased survival of those impinged organisms returned to the Cape
Fear Estuary resulted in substantial species -specific reductions in annual IM (between 88
and 99 percent) compared to baseline impingement prior to 1983, even for fragile species
such as Atlantic Menhaden (Duke Energy 2019, 2020c).
# The average 12-month mortality of organisms impinged on the traveling water screens with
this system of technologies ranged between 13.2 (2016) percent and 14.0 percent (2017)
with fragile species removed which is less than the impingement mortality standard of 24
percent.
Further, no IM reduction technology alternative is justified based on the following:
• Operations at Brunswick (detailed in Section 5) and the diversity and abundance of the fish
and shellfish community in the Cape Fear Estuary (detailed in Section 4.2) have remained
consistent since the 2016-2017 impingement study (Duke Energy 2019, 2020c), thus these
data are valid and representative of current conditions.
# The system of technologies implemented at Brunswick maximizes protection for threatened
and endangered species such as Atlantic Sturgeon, Shortnose Sturgeon (Acipenser
brevirostrum), and sea turtles.
# The estimated potential IM reduction benefit of the existing technologies at Brunswick was
estimated under IM BTA Option 6 (fish diversion structure, existing CWIS with modified

Ristroph traveling screens, aquatic organism return system, and seasonal flow reduction)
using impingement data and actual water withdrawals in 2016 and 2017. Compared to
historic impingement losses documented in 1977 and 1978, monitoring results in 2016 and
2017 indicate the reduction in total impingement losses (equivalent to organism survival)
resulting from the system of technologies implemented at Brunswick ranges from 91.0
percent to 95.6 percent. Approximately 2.3 million and 1.3 million fish and shellfish were
returned alive to the Cape Fear Estuary in 2016 and 2017, respectively.
• The social costs of designating the existing system of technologies at Brunswick as BTA
for IM reduction (see Section 6) are the foregone incremental impingement benefits ($0.08
million).
Duke Energy also requests a determination that the existing plant configuration and
operation (system of technologies) is BTA for reducing entrainment at Brunswick based on
the following:
Modified Traveling Water Screens with Aquatic Organism Handling and Return System:
• The existing intake modifications and seasonal flow reductions have reduced total
entrainment losses from historical conditions with no technology or operational measures
in place by approximately 48 (2016) to 61 percent (2017). Equivalent adult losses were
reduced by approximately 84 percent in 2016 and 63 percent in 2017. Harvest foregone
losses have been reduced by as much as 75 percent.
• Long-term monitoring results through 2018 continue to document reductions in the total
annual number of organisms entrained ranging from approximately 60 to 90 percent
depending on year with an overall annual average reduction in entrainment of 76 percent.
is Fragile forage species including anchovies, gobies, and silversides were the major
contributors to entrainment losses comparing approximately 91 to 58 percent of
entrainment losses in 2016 and 2017, respectively. Harvested species comprised
approximately 7 to 42 percent of the estimated entrainment losses in 2016 and 2017,
respectively. The dominant harvested species include with Weakfish (Cynoscion regalis),
Atlantic Croaker (Micropogonias undulatus), Spot (Leiostomus xanthurus), Commercial
Shrimp Group
(Penaeidae postlarvae), Atlantic Menhaden (Brevoortia tyrannus), and Swimming Crabs
(Portunidae megalops stage).
# Overall, egg entrainment at Brunswick represented 92.9 and 89.8 percent of total
entrainment losses in 2016 and 2017, respectively. However, the eggs of forage species
comprised the majority of egg losses in 2016 (88.5 percent) and 2017 (53.4 percent). Egg
losses for all species combined accounted for less than 1 percent of the total equivalent
adult losses for each year and approximately 5 to 7 percent of harvest foregone depending
on year. Therefore, the mesh size is appropriate for the species and life stages that could
potentially interact with the CWIS.
# Substantial numbers of the converts retained by the FMS are returned alive to the Cape
Fear Estuary based on site -specific survival studies conducted from 1984-1987 (Section 4).
Survival rates ranged from 0.7 percent for post yolk -sac larvae of fragile species such as
Bay Anchovy to 96.2 percent for juvenile swimming crabs. Survival rates of the postlarval
stage of the Commercial Shrimp Group (Penaeidae) was 95.8 percent and 87.0 percent for
swimming crab megalops. Survival rates for robust finfish post yolk -sac larvae such as

Spot and Atlantic Croaker were 29.4 percent and 33.7 percent, respectively. Survival of the
juvenile lifestage of Spot and Atlantic Croaker was 60.4 percent and 45.1 percent,
respectively. Based on actual water withdrawals, approximately 181.2 million and 130.9
million organisms were returned to the Cape Fear Estuary in 2016 and 2017, respectively.
Operational Measures I Seasonal Reductions in Withdrawals
# Flow reductions have reduced impingement and entrainment by approximately 24.6 percent
during 2016 and 23.9 percent during 2017. Annual estimated entrainment based on
maximum water withdrawals varied from 34.1 billion ichthyoplankton in 2016 to 17.6
billion ichthyoplankton in 2017. Actual water withdrawals, largely due to seasonal flow
reductions, resulted in ichthyoplankton entrainment reduction of 8.4 billion during 2016
(24.6 percent) and 4.2 billion during 2017 (23.9 percent).
# Prior to implementation of the technology and operational measures, entrainment losses
were 3.5 billion organisms based on estimates from 1980. With fish eggs removed (eggs
were not collected in 1980), entrainment losses were 1.8 billion orgainisms in 2016 and 1.4
billion organisms in 2017 representing reductions in entrainment losses of approximately
48 and 60 percent, respectively. The number of equivalent adult losses were reduced by
approximately 84 percent in 2016 and 63 percent in 2017 compared to the historic results
with no entrainment reduction controls in place.
As required by the Rule, three potential entrainment reduction technologies were evaluated under
§122.21(r)(10) :
• Retrofit to closed -cycle cooling through installation of mechanical draft cooling towers
(MDCTs);
• Installation and operation of 100 percent FMS with an aquatic organism return system at
the existing CWIS, and
# Use of alternate water sources (determined to be not feasible).
Using the end of the current operating license for Unit 1 (i.e., 2036), a comparison of social costs
to social benefits (Section 11) associated with each of the entrainment technologies indicated that:
# The currently installed system of technologies (including the diversion structure, existing
1.0 mm FMS, aquatic organism return system, and flow reductions based on the 5-year
POR) result in total social benefits of $109 million. The social benefits are presented in
2021 dollars and evaluated over the 53-year time period of when the previous mitigation
measures became fully operational in 1984 through the end of the plant's permitted
operation in 2036.
# Installation of MDCTs would result in social benefits of $6.44 million compared to social
costs of $870.82 million; resulting in total net benefits of -$864 38 million; and
• Installation of anew CWIS with 100 percent 1.0-mm FMS including updates to the aquatic
organism return system would result in social benefits of $3.21 million compared to social
costs of $97.56 million; resulting in total net benefits of-$94.36 million.
• Based on the evaluation of social costs and benefits of each technology, the existing or
baseline configuration at Brunswick consists of a system of technologies that meet the
definition of BTA for complying with the site -specific entrainment requirements. The cost
to install a new technology would be wholly disproportionate to the potential benefits.

Station Description
Brunswick withdraws cooling water from Cape Fear Estuary in Brunswick County near
Southport, North Carolina. Brunswick's cooling water intake system consists of an intake canal, a
diversion structure at the intake canal entrance, a CWIS, a SWIS, and an aquatic organism return
system. The plant withdraws cooling water through a CWIS and a separate nuclear -safety related
SWIS at the end of a 3-mile long intake canal that is connected to the Cape Fear Estuary and
cooling water is discharged to the Atlantic Ocean approximately 2,000 ft offshore as authorized
by NPDES Permit NC0007064.
Water from the Cape Fear Estuary flows into the intake canal through a diversion structure', which
limits passage of aquatic organisms into the intake canal, thereby reducing impingement and
entrainment of fish and shellfish at the CWIS and SWIS (Duke Energy 2018a). Water flow through
the diversion structure is restricted to the upper 18 ft of the 46-ft-deep shipping canal, a design
feature that reduces impacts on bottom -dwelling (demersal) species such as Atlantic Sturgeon
(USNRC 2006). The diversion structure consists of bar racks2 (also referred to as turtle blockers)
which help prevent large aquatic organisms and debris from entering the intake canal and fixed -
panel screens that that prevent smaller fish, shellfish, and finer debris from entering the intake
canal (NCDEQ 2018). The bar racks have a 3-inch vertical bar spacing and are in front of the fixed
screen panels consisting of 3/8-inch by 3/4-inch mesh (Duke Energy 2020a). The bar racks and
fixed screen panels are inspected and cleaned daily using a mechanical rake for the bar racks and
spray wash for the fixed screen panels (USNRC 2006). Design upgrades3 and enhanced
maintenance activities (i.e., installation of a mechanical trash rake system to remove aquatic
vegetation and debris) have been implemented to optimize fish protection as well as threatened and
endangered species protection (e.g., sea turtles, sturgeon).
The CWIS is divided into two sections (one for each generating unit) and has a total of eight intake
bays (four intake bays per unit). Each intake bay is equipped with a bar rack that prevents large debris
from entering the CWIS and a traveling water screen with an aquatic organism return system
(Progress Energy 2005). The bar racks are composed of stainless steel, have a 3-inch vertical bar
spacing, and are 15.7-ft wide (Progress Energy n.d.). Each 14-ft wide traveling water screen is
equipped with 50 total panels (42 fine -mesh panels and eight coarse -mesh panels (Duke Energy
2018a, FMC 1981). The nuclear safety related SWIS contains one large main intake bay which is
equipped with four barracks to prevent large debris from entering the SWIS and four traveling water
screens (Duke Energy 2021a). The 7.0-ft-wide bar racks have a 3-inch vertical bar spacing. The
SWIS traveling water screens are equipped with 3/8-in mesh and are 6-ft wide. The Brunswick intake
canal in the vicinity of the CWIS and SWIS has a design water elevation (El.) of 2.7 ft below mean
sea level (msl) and a design high water elevation of 5.0 ft above msl (FMC 1981; United Engineers
& Constructors Inc. 1977).
Spray wash water, withdrawn through the SWIS screens, is used to clean both the CWIS and SWIS
traveling water screens and is then routed to the aquatic organism return system. The CWIS utilizes
a dual spray wash system; a low-pressure spray is used for the removal of aquatic organisms from
the screens, followed by a high-pressure spray for debris removal. The low-pressure spray has a
minimum and maximum pressure of 7 pounds per square inch (psi) and 15 psi, respectively, and a
The diversion structure was required by the 1981 NPDES permit as part of a mitigation package to reduce
impingement and entrainment of aquatic organisms at the CWIS and SWIS and was based on the performance of a
temporary prototype structure that was in place from 1979 - 1981. The diversion structure began operations in 1982.
2 The bar racks are made of high -density composite material that is resistant to biofouling.
s The diversion structure includes an extension from each end of the diversion structure along the edge of the intake
canal marsh (just above the mean high water mark) ending where higher ground begins. The purpose of the fence is to
exclude larger organisms such as fish, crabs, and sea turtles that may swim across the marsh at high tide.

minimum and maximum flow of 280 gallons per minute (gpm) and 360 gpm, respectively (CP&L
2006). The highpressure spray has a minimum and maximum pressure of 40 psi and 90 psi,
respectively, and a minimum and maximum flow of 305 gpm and 455 gpm, respectively (CP&L
2006).
Aquatic organisms removed from the traveling screens travel to a holding basin via a 4,000-ft-long
aquatic organism return trough. The holding basin acts as an upstream shallow -water nursery habitat
which results in a net increase in the abundance of aquatic organisms that are returned to the source
waterbody (Progress Energy 2005). Aquatic organisms routed to the holding basin can enter Gum
Log Branch and then Walden Creek, which flows into the Cape Fear Estuary (USNRC 2006).
The CWIS withdraws CCW using eight CCW pumps and the nuclear safety related SWIS
withdraws service water and spray wash water using ten service water pumps and four screenwash
pumps. The CCW pumps each have a design capacity of 174,000 gpm (250.6 MGD), while the
service water pumps each have a design capacity of 5,800 gpm (8.4 MGD), and the screenwash
pumps each have a design capacity of 2,900 gpm (4.2 MGD) (Duke Energy 2021a, 2021b).
However, the CCW system is condenser -limited which restricts the capacity of the Unit 1 and Unit
2 CCW pumps to a maximum of 638,000 gpm (918.7 MGD) per unit, for a total DIF of 1,345,600
gpm (1,937.7 MGD)
(see Section 3.3). In addition, reductions in total water withdrawals at Brunswick align with plant
seasonal flow restrictions to minimize entrainment and impingement (NCDEQ 2018). These
seasonal flow restrictions are specified in Brunswick's NPDES permit as daily maximum CCW
pump discharge limitations as follow:
• Between December 1 and March 31, the daily maximum CCW pump discharge is
limited to 1,192 MGD, or approximately 65 percent of the plant CCW design capacity;
• Between April 1 and June 30, the daily maximum CCW pump discharge is limited to
1,428 MGD, or approximately 78 percent of the plant CCW design capacity;
• Between July 1 and September 30, the daily maximum CCW pump discharge is
limited to 1,509 MGD, or approximately 82 percent of the plant CCW design capacity;
• Between October 1 and November 30, the daily maximum CCW pump discharge is
limited to 1,428 MGD, or approximately 78 percent of the plant CCW design capacity;
and
• During a unit outage, the daily maximum CCW pump discharge is limited to 918
MGD, or approximately 50 percent of the plant CCW design capacity.
The AIF at Brunswick based on daily average withdrawal data from January 1, 2016 through
December 31, 2020 is presented in Section 3, Table 3-3. Brunswick's AIF during this 5-year
period was 1,379 MGD, or approximately 71 percent of the plant DIF. Average withdrawal rates
for this period were 679 MGD for Unit 1 and 700 MGD for Unit 2 (Duke Energy 2020b). See
Table 5-1 and Table 5-2 in Section 5.1.2 for number of days per year and month when the
Brunswick CCW pumps and service water pumps operated, respectively, over the 5-year period.
Regulatory Nexus
On August 15, 2014, the U.S. Environmental Protection Agency (USEPA) published in the Federal
Register the NPDES Final Regulations to Establish Requirements for Cooling Water Intake
Structures at Existing Facilities and Amend Requirements at Phase I Facilities, referred to as the
Final Rule (Rule) (USEPA 2014). The Rule establishes requirements under §316(b) of the CWA to
ensure that the location, design, construction, and capacity of a CWIS reflect the BTA for

minimizing impingement and entrainment at the CWIS. The Rule applies to existing facilities that
withdraw more than 2 MGD from waters of the United States, use at least 25 percent of that water
exclusively for cooling purposes, and have an NPDES permit.
The Rule is applicable to Brunswick for the following reasons.
• Brunswick withdraws raw water from the Cape Fear Estuary, the source waterbody, through
a shoreline -situated CWIS and a nuclear safety related SWIS located at the end of a 3-mile-
long intake canal for use in a once -through cooling water system.
• Brunswick meets the minimum 2 MGD withdrawal rate criteria for DIF and AIF. The CCW
system is condenser -limited which restricts the capacity of the Unit 1 and Unit 2 CCW
pumps to a total DIF of 1,345,600 gpm (1,937.7 MGD). The AIF for the 5-yr period from
January 1 ,2016 through December 31, 2020 is 1,379 MGD.
• On a design basis, approximately 95 percent (1,837 MGD) of Brunswick's DIF (1 ,938
MGD) is used in the CCW system. The remaining 5 percent (101 MGD) is used for service
water and other station uses. Brunswick does not use cooling water for process units (see
Section 8.3) or contact -cooling purposes.
Although Brunswick is compliant with the impingement and entrainment provisions of the Rule,
Duke Energy has prepared technical information required under CFR 5122.21(r)(2) through (r)(13)
(see Table 1-1 of Section 1) for submittal to the Director to facilitate the determination of BTA for
Brunswick.
Under the Rule, the owner or operator of a facility must choose from one of seven compliance
options for IM reduction or an alternate exemption, as provided by the Rule. Brunswick has
installed and currently operates modified traveling screens as defined in the Rule and has
implemented other technologies and operational measures to reduce impingement.
Brunswick has installed and currently operates fine mesh screens at the CWIS and has
implemented other technologies and operational measures to reduce entrainment. The facility must
also provide results from site -specific entrainment studies and information identified at § 122.21
(r)(2) through (r)(13) and §125.98 to the permitting authority to aid in the determination of
whether site -specific controls would be required to reduce entrainment.
At § 125.98, the Rule identifies specific information that the Director Must (§ 125.98(f)(2)) consider
and information that the Director May (§ 125.98(f)(3)) consider in a site -specific entrainment BTA
determination. This Executive Summary describes the evaluation of these compliance options and
the Must and May factors for the Director to consider, as they relate to Brunswick.
Impingement Mortality Compliance
Impingement Mortality Characterization
Brunswick is compliant with the impingement mortality provisions of the Rule. Annual
impingement studies conducted at Brunswick since 1974 were used to assess the efficacy and
optimize the existing system of technologies implemented to reduce impingement mortality at the
plant. As discussed above, the optimized system of technologies includes the diversion structure,
fish -friendly traveling water screens at the CWIS and organism return system, and seasonal CCW
reductions. The diversion structure was installed in 1982 (based on a prototype installed in 1979)
followed by installation of the fish -friendly traveling water screens and organism return system in
1983. Survival studies were conducted from 1984-1987 to characterize the survival of organisms
impinged on the traveling screens and returned to the Cape Fear Estuary via the organism return

system (CP&L 1988). Seasonal flow reductions were phased in beginning in 1981 with full
implementation in 1983. After optimization, the seasonal flow reduction requirements were
implemented as described above in 1987. Details regarding the design and operation of
components for the system of technologies can be found in Sections 3, 5, and 6. Results pertaining
to the effectiveness and success of the system of technologies can be found in Sections 4, 6, 7, and
11.
Annual impingement in 1977 and 1978 (during 2-unit operation prior to installation of the
prototype diversion structure in 1979) ranged from 14.5 million to 20.3 million fish and shellfish
(CP&L 1979).
Atlantic Menhaden (Brevoortia tyrannus) was consistently the dominant species impinged
comprising approximately 53 to 59 percent of the total impingement losses during 1977 and 1978,
respectively. Higher impingement rates for Atlantic Menhaden (fragile clupeid species) were
observed during the winter months. Impingement rates for other clupeids such as Threadfin Shad
(Dorosoma petenense) are greater when water temperatures decline below 100 C (Loar et al. 1978;
EPRI 2008). The second most abundant species impinged was Bay Anchovy (Anchoa mitchilli), a
fragile species, comprising 17 percent to 15 percent of total impingement losses during 1977 and
1978, respectively (CP&L 1979).
Total annual impingement (including survival) at Brunswick was estimated using the results from
an Impingement Characterization Study performed in 2016 and 2017 and actual water withdrawals
(HDR 2021a). The total number of aquatic organisms impinged at Brunswick was estimated at 1.3
million fish and shellfish in 2016 and 0.9 million fish and shellfish in 2017. Bay Anchovy
accounted for approximately 65 percent to 75 percent of the annual impingement losses depending
on year. Note that due to the installed fish -friendly screens, impinged organisms at Brunswick have
a high survival rate. Approximately 2.3 million and 1.3 million fish and shellfish were returned
alive to the Cape Fear Estuary in 2016 and 2017, respectively.
The 12 dominant taxa impinged comprised 96.2 percent and 97.0 percent of impingement losses in
2016 and 2017, respectively. The remaining 62 taxa impinged in 2016 and 53 taxa impinged in 2017
accounted for only 3.8 percent and 3.0 percent of the total impingement losses. The dominant forage
species including Bay Anchovy, Star Drum (Stellifer lanceolatus), Threadfin Shad, Striped Anchovy
(Anchoa hepsetus), and Brief Squid (Lolliguncula brevis) comprised most of the impingement
losses during both years (74.4-78.7 percent). Star Drum was the only robust species among the
dominant forage species contributing to IM losses. The dominant harvested species contributing to
impingement losses include Brown Shrimp (Faffantepenaeus aztecus), White Shrimp (Litopenaeus
setiferus), Atlantic Croaker (Micropogonias undulatus), Spot (Leiostomus xanthurus), Pinfish
(Lagodon rhomboides), Atlantic Menhaden, and Bluefish (Pomatomus saltatrix). Atlantic
Menhaden and Bluefish were the only fragile species among the dominant harvested species
impinged. Impingement losses consisted primarily of the juvenile life stage (94.4-97.5 percent) with
age 1 individuals comprising only 2.5-5.6 percent of total impingement losses depending on year.
Mo federal or state listed threatened and endangered species were impinged during the impingement
characterization study (Section 4.5.1).
Compared to historic impingement losses documented in 1977 and 1978, monitoring results in 2016
and 2017 indicate the reduction in total impingement losses resulting from the system of
technologies implemented at Brunswick ranges from 91.0 to 95.6 percent. The reduced rate and
density of impingement documented in the 2016-2017 impingement study compared to levels
documented prior to the installation and optimization of the diversion structure, optimization of the
existing fish return system, and installation and optimization of FMS, demonstrate the effectiveness
of these technologies in reducing IM at Brunswick (Duke Energy 2019, 2020c). Prior to the

installation of the diversion structure, larger finfish, Bay Anchovy, penaeid shrimp, and portumd
crabs, comprised a substantial portion of the number and biomass impinged. The exclusion of many
larger finfish by the diversion structure, in conjunction with the increased survival of those
impinged organisms returned to the Cape Fear Estuary, has resulted in substantial species -specific
reductions in annual IM (between 88 and 99 percent) compared to baseline impimgement prior to
1983, even for fragile species such as Atlantic Menhaden (Duke Energy 2019, 2020c). The average
12-month IM for this system of technologies ranged between 13.2 (2016) percent and 14.0 percent
(2017) with fragile species removed, which is wholly compliant with the 12-month performance
standard of no more than 24 percent mortality (including latent mortality for all non -fragile species)
per the Rule at § 125.94(c). More detail is presented in Section 4.5.1.
As discussed in Section 4.11, the continued dominance of fragile forage species, such as Bay
Anchovy in impingement samples since the 1970s indicates that Bay Anchovy populations in Cape
Fear Estuary remain abundant, stable, and unaffected by impingement losses at the Brunswick
CWIS. The relative abundance of Bay Anchovy collected with trawl sampling from 2015-2017 was
the highest recorded since the marsh trawl study began in 1981 (Duke Energy 2020c). Further, long-
term monitoring data since 1974 demonstrate that the fish and shellfish communities have remained
robust during the operation of Brunswick and monitoring activities have not documented any
declines in the abundance of fish and shellfish resulting from impingement even before
implementation of the system of technologies (CP&L 1980; Duke Energy 2017, 2019, 2020c).
Details are presented in Section 4.2.
Impingement Compliance Technology Evaluation
Per § 125.98(r)(6), the owner of a facility must identify the chosen method of compliance with the
IM standard for the entire facility, or for each CWIS. Facilities may select one of seven IM BTA
Options provided in 5125.94(c) paragraphs (1) through (7) unless pursuing compliance under
paragraphs (c)(11) de minimis rate of impingement or (c)(12) low capacity utilization power
generating units (Table ES-2). The facility must also provide sufficient information and justification
to support the selected alternative compliance approach. Methods used to assess the compliance
options for addressing the requirements of Sl 22.21 (r)(6) are provided in Section 6.
Duke Energy performed a screening -level evaluation of IM reduction technologies and alternative
operational measures for the Brunswick CWIS and SWIS to identify feasible options that could be
implemented to reduce impingement at Brunswick. Alternatives that were not considered feasible
were removed from further consideration. The remaining (i.e., short-listed) options were evaluated
in greater detail and the findings, which are presented in Section 6, identify the technology or
technologies that could result in the greatest benefit while minimizing implementation,
maintenance, and operational costs.
The compliance options were evaluated using the following step -wise process:
1 . Determine if Brunswick is currently compliant with BTA for impingement under IM
Options 1 , 2, or 3, based on existing design and operational data.
2. Evaluate existing impingement data to determine if impingement rates support a de
minimis rate of impingement determination by the Director.
3. Determine if the 3-year average (based on most recent data) capacity utilization rate (CUR)
is below the Rule -defined threshold of 8 percent.

4. Assess the potential efficacy, technical feasibility, and relative costs of IM reduction
technologies and operational measures applicable to open -cycle cooling systems (IM
Options 4, 5, and 6).
5. Evaluate the potential efficacy, technical feasibility, and relative costs of ceasing
operations.
Results of the screening -level evaluation of IM reduction technologies and operational measures
that could be implemented at Brunswick to comply with the IM reduction requirements of the Rule
are discussed below.
Brunswick utilizes a once -through cooling system and withdraws more than 125 MGD of raw
water for cooling purposes. The existing design and operation of the CWIS and SWIS results in
TSV estimates of greater than 0.5 fps; therefore, the plant does not comply with IM BTA Options
1, 2, or 3. Additionally, Brunswick does not currently comply with IM BTA Option 4 (existing
offshore velocity cap). Brunswick does comply with IM BTA Options 5 and 6 as the plant
operates a system of technologies including a diversion structure, modified traveling water screens
with an aquatic organism return system, and seasonal CCW flow reductions. The system of
technologies is also compliant with IM BTA Option 7 since average 12-month IM is less than the
impingement mortality standard of 24 percent. Brunswick does not meet the low capacity
utilization rate (CUR) option, as the current 24-month capacity utilization is greater than 8
percent.
The use of the diversion structure, along with the location of the CWIS (at the end of the intake
canal and downstream of the diversion structure) provides substanitial IM reduction benefits and is
fully compliant with the Rule IM provisions. At the design water elevation and design flow, a
conservative impingement AOI for the CWIS is represented as the area defined by an arc extending
approximately 132 ft into the intake canal from the center of the CWIS. Although the impingement
AOI extends into the intake canal, Brunswick has an aquatic organism return system that removes
impinged organisms from the traveling water screens located in the CWIS and SWIS and returns
them to the source waterbody. This system helps to reduce the mortality of impinged organisms.
Additionally, the AIF withdrawn at the CWIS for the POR (from January 1, 2016 through
December 31, 2020) represents a 29 percent reduction in total water withdrawals when compared
to DIF, which results in additional IM reduction benefits.
Summary of Selected Impingement Mortality Compliance Options
Based on the information presented above, estimated annual impingement losses at Brunswick based
on actual water withdrawals from 2016 and 2017 was 1,312,624 and 942,559 fish and shellfish,
respectively. However, the number of impinged fish and shellfish returned alive to the estuary ranged
from 2,321,224 in 2016 to 1,281,915 in 2017. Bay Anchovy, a fragile forage species, was the
dominant species impinged accounting for approximately 65 to 75 percent of impingement mortality
depending on year. With fragile species removed, the average 12-month IM for this system of
technologies ranged between 13.2 (2016) percent and 14.0 percent (2017) which is less than the
impingement mortality standard of 24 percent. Implementation and optimization of the system of
technologies at Brunswick has resulted in substantial species -specific reductions in annual IM
(between 88 and 99 percent) compared to baseline impingement prior to 1983, even for fragile
species such as Atlantic Menhaden.

Brunswick implements multiple IM reduction measures including operation of an existing diversion
structure at the entrance of the intake canal, modified traveling screens with an aquatic organism
handling and return system, and operational measures (such as seasonal flow reductions) that reduce
both IM and entrainment. Additionally, the current U.S. Nuclear Regulatory Commission (USNRC)
operating license for both generating units at Brunswick will expire by 2036, which would not be
enough time to yield measurable benefits following a potential retrofit of additional technology or
operational measures for this compliant facility. Based on the results of this analysis, Duke Energy
is requesting that the current design and operation of the cooling water system at Brunswick be
designated as BTA for IM compliance per IM BTA Option 6. Given the existing level of IM reduction
benefits, and results of the social cost and social benefit evaluation discussed in Sections 10-12 of
the compliance document, installation of additional IM reduction technologies at Brunswick is not
practical or warranted.
Analyses Performed in Support of an Entrainment BTA
Determination
Brunswick has substantially reduced entrainment with the currently installed technologies and
operational measures. This section summarizes the analyses required by the Rule for submission to
the Director in support of a site -specific best professional judgment (BPJ) review and entrainment
BTA determination. Although information presented under the requirements of § 122.21 (r)(2)
through (r)(8) of the Rule (i.e., Sections28 of the compliance document) provides useful
perspective on the location, design, and operation of the existing facility, this section focuses on
reports prepared under § 122.2 1 (r)(9) through (r)(12) of the Rule (i.e., Sections 9-13), which offer
perspective on entrainment BTA for this compliant facility. The process and results for evaluating the
social costs, social benefits, and other environmental impacts related to entrainment BTA, as
prepared under § 122.2 1 (r)(9) through (r)(12), are outlined along with a description of and results
from the peer review process in §122.21(r)(13).
Entrainment Characterization Study § 122.21(r)(9)
Annual entrainment studies were performed at Brunswick from 1974-1978 in conjunction with a
broad range of estuarine fish and shellfish community studies to address the potential for adverse
environmental impact on the estuary (CP&L 1980). Results from entrainment studies indicated no
detectable effects of entrainment at the Brunswick CWIS on estuarine fish and shellfish
communities, and that annual variation in fish and shellfish populations in the Cape Fear Estuary
were driven by environmental variables including freshwater discharge to the estuary, salinity, and
water temperature (Copeland et al. 1979; CP&L 1980).
While the data collected for the 1974-1978 annual entrainment studies did not identify impacts to the
estuarine fish and shellfish communities, a mitigation package in the form of engineering
modifications and operational measures (system of technologies) was implemented to reduce
entrainment at Brunswick. The existing configuration was determined through an iterative
installation and testing process that included consultation and collaboration with State resource and
regulatory agencies as documented in the 1980 Interpretive Report (CP&L 1980). The 1.0-mm FMS
panels currently in use at the facility were selected based on the dominant commercially and
recreationally important species at Brunswick which are spawned offshore, and most entrained life
stages are of sufficient size that they are effectively retained on the 1.0-mm FMS currently in use at
Brunswick. The remaining species and life stages entrained with the 1.0-mm FMS consist primarily
of smaller -bodied, estuarine resident spawners such as Bay Anchovy, which are fragile, forage fish
that often exhibit high mortality on smaller mesh screens. As such, there would be no substantial
incremental entrainment reduction benefit of installing a smaller size FMS at Brunswick. See Section
7 for details regarding the optimization studies.

Site -specific data from a 2-year Entrainment Characterization Study (Study) (see Section 9 and
Appendix 9-A) coupled with a larval impingement study to assess entrainment converts (see
Sections 4 and 7) were conducted at Brunswick in 2016 and 2017. A total of 84,463 ichthyoplankton
representing 42 distinct taxa from 27 families were collected with entrainment samples during the
two-year Study.
Ichthyoplankton entrained through the condensers were dominated by species in the Engraulidae
family (i.e. anchovies), which includes Bay Anchovy and Anchoa spp., and the Sciacmdae family,
which includes Weakfish, Silver Perch (Bairdiella chrysoura), Atlantic Croaker, Spot, Kingfish
(Menticirrhus sp.), and drum species. Shellfish belonging to the Commercial Shrimp Group (Penaeidae
postlarvae) dominate shellfish entrainment but contributed less than 1 percent to total entrainment. A
small number of eggs (< 0.05 percent) were collected during 2016 comprising the Herring Group
(Blueback Herring/Alewife) are designated a Species of Concern by the National Oceanic and
Atmospheric Administration.
Samples collected in 2016 predominantly consisted of eggs (93.8 percent), followed by post yolk -sac
larvae (5.5 percent). Yolk -sac larvae and juveniles account for less than one percent of the sample.
The 2017 entrainment samples were also dominated by eggs, which accounted for over 89 percent of
entrained organisms, followed by post yolk -sac larvae (8.1 percent). Yolk -sac larvae and juveniles
accounted for 2 percent of the 2017 samples. The dominance of eggs entrained during both years was
due to the 1.0-mm FMS which are designed to reduce the numbers of larvae and juveniles entrained.
A total of 17,147,369 organisms (entrainment converts) were collected with larval impingement
sampling during 2016 (47 taxa) and 2017 (36 taxa). Four taxa including Atlantic Croaker (post yolk -
sac larvae/juveniles), Spot (post yolk -sac larvae/juveniles), Commercial Shrimp Group, and
Swimming Crabs (megalops) comprised approximately 88 to 81 percent of the converts collected in
2016 and 2017, respectively. No eggs were collected with larval impingement sampling. Survival
rates ranged from 0.7 for fragile species such as anchovies to 90 percent for penaeid shrimp
postlarvae. With fragile species removed, the estimated total mortality without applying survival
estimates was 536.1 million compared to total mortality of 225.0 million with survival rates applied
representing a reduction in total mortality of 58.0 percent. This means that for all fish and shellfish
combined, approximately 5 8. 0 percent (311.1 million) of the entrainable converts were returned alive
back to the Cape Fear Estuary during 2016 and 2017 combined.
Comprehensive Technical Feasibility and Cost Evaluation Study-
§ 122.21(r)(10)
Brunswick should be considered BTA for entrainment based on the use of installed technologies
and operational measures. However, Duke Energy has conducted an evaluation of feasibility and
costs for additional entrainment control measures to support an entrainment BTA determination by
the Director. This includes quantification of the potential social costs of alternative entrainment
control measures and comparison to potential social benefits. Due to the diversity in organism
biology, habitat requirements, and different body sizes of entrainable organisms, the available
additional technologies and measures expected to be reasonably effective at reducing entrainment
are relatively limited. An evaluation of potential entrainment reduction technologies for Brunswick
was performed to identify those that are feasible and practical to address requirements listed at
§ 122.21(r)(10).
• As required by the Rule, an evaluation of the technical feasibility and costs of potential
types of entrainment reduction technologies, including but not limited to:

1. A closed -cycle cooling system retrofit;
2. Installation and operation of FMS with an aquatic organism return system
(includes fine -mesh traveling water screens or fine -slot wedgewire screens); and
3. Use of alternate cooling water sources to supplement or replace the withdrawals
used in the existing cooling system.
• An evaluation of potential entrainment reduction technology installation locations to
identify options that would pose minimal impacts on plant operations and the
surrounding community;
• An assessment of potential entrainment reduction technology operational concerns (e.g.
no negative impacts to plant intake velocities or flows, does not exceed pressure
specifications of condensers);
• An evaluation of potential impacts to station reliability due to entrainment reduction
technology installation; and
• An evaluation of facility -level capital and operation and maintenance (O&M) costs
associated with each entrainment reduction technology.
Technology Feasibility of Potential Entrainment Reduction Technologies
An assessment of multiple additional entrainment reduction compliance technologies was performed
to evaluate potential feasibility at Brunswick. This included analyses of a closed -cycle cooling system
retrofits (i.e., MDCTs, natural draft cooling towers (NDCTs), hybrid/multi-cell/plume-abated cooling
towers, and dry cooling systems), a 1.0-mm FMS retrofit in the existing CWIS (including upgrades
to the existing aquatic organism return system), installation of 1.0-mm FMS in a new structure
(including upgrades to the existing aquatic return system), installation of 1.0-mm fine -slot wedgewire
screens, and water reuse or alternate sources of cooling water.
The evaluation determined that existing water reuse strategies and alternate cooling water sources
are unavailable or would be unable to provide the amount of water needed to replace the volume of
cooling water required by Brunswick. Therefore, these were excluded from further consideration.
Results of the assessment indicated that all but two of the evaluated compliance technologies were
infeasible and/or impractical at Brunswick; therefore, they were excluded from further consideration.
The two entrainment reduction technologies determined to be technically feasible for potential
implementation at Brunswick were 1) installation of closed -cycle MDCTs and 2) installation of 1.0-
mm fine -mesh screens in a new fine -mesh screen structure and upgrades to existing aquatic
organism return system. These two technologies were retained for further evaluation.
For the two potentially feasible technologies, a conceptual design, including location of
infrastructure, capital costs associated with technology implementation, project scheduling,
permitting requirements, and O&M costs were developed through the end of the current USNRC
operating license in 2036. The net present value (NPV) of the social costs of each technology was
then developed based on the estimated start of operations for each technology and extending through
2036.
Installation of closed -cycle MDCTs is considered technically feasible but impractical due to the
significant construction and requirements for plant redesign, lengthy construction outages that would

carry significant financial impacts, significant capital and annual O&M costs, and extensive
permitting requirements. In addition, during the warmest times of the year, the cooling tower cold
water temperatures may not be low enough to maintain acceptable turbine backpressures, which may
result in reduced electrical generation. There would be significant additional energy consumption at
the plant, and turbine operation and generation efficiencies would be impacted due to increased
backpressure caused by warmer CCW compared to existing operations.
Installing new 1.0-mm FMS in a new FMS structure and upgrading the existing aquatic organism
return system are considered to be technically feasible but impractical due to extensive construction,
civil work, in -water work, significant disturbance to the existing intake canal, and significant capital
and annual O&M costs. Upgrades to the existing aquatic organism return system and connection to
the new FMS structure would require in -water work and construction near the 100-year floodplain
and critical plant infrastructure. Increased total system headloss due to the hypothetical new FMS
structure could impact the performance of the existing CCW pumps, which could then potentially
impact plant reliability, nuclear safety, and entrainment reduction efficacy. Annual energy
consumption at the plant would increase due to the new equipment, continuous screen rotation, and
the impacts of increased headloss on the existing CCW pumps. The likelihood of screen clogging or
biofouling would increase which could impact plant reliability, nuclear safety, and availability of
CCW flow. The complete process and results of the evaluations are provided in Section 10.
Social Costs of Entrainment Reduction Compliance Technologies
Social costs were used to determine whether the potential additional entrainment reduction
technology costs would result in the station becoming economically infeasible to operate. Since a
premature shutdown of Brunswick would result in social costs (i.e., lost jobs, income, and tax base;
increased generation costs as power plants lower in the dispatch order would be called upon to
make up the lost generation; and increased pollutant air emissions of replacement generation),
installing additional entrainment reducing technologies at Brunswick to comply with the Rule
represents additional operational costs that would most likely be passed onto Duke Energy's electric
customers in the form of higher rates. Thus, the social costs were determined assuming that Duke
Energy would incur these additional costs and pass them on to electric customers.

The engineering costs of installing entrainment reduction technologies are estimated by determining
the total capital and annual O&M costs, including permitting costs borne by the station for each of
the evaluated technologies. The social costs associated with each entrainment reduction technology
are estimated by determining the electricity price increases resulting from compliance (i.e.,
technology installation) and power systems costs, externality costs, and government regulatory costs.
Following the requirements of the Rule, Table ES-4 provides engineering and social costs (in 2020
dollars) under two discount rates: 3 and 7 percent (79 FR 158, 48428). As the first column of Table
ES-4 shows, the top half of the table presents the present value of social costs discounted at 3
percent, and the bottom half presents the social costs discounted at 7 percent. The next column of the
table presents each of the potentially feasible entrainment reduction technologies evaluated at
Brunswick. The third and fourth columns present the compliance costs estimated for each of these
technologies, including capital and annual O&M costs.
The analysis discounts the future stream of each of these social costs at the relevant discount rate and
sums them over the years they are specified to occur to develop the total social cost estimate
presented in the next to last column in the table, annual social costs for each technology are
presented in the last column.

-o 'C-(0
Benefits Valuation Study - § 122.21(r)(1 1)
The goal of the Benefits Valuation Study is to demonstrate the estimated social benefits that would
result from impingement and entrainment reductions based on implementation of one or more
additional technologies at Brunswick.
Losses from Entrainment and Impingement Mortality under Technology Scenarios
Impingement and entrainment losses under actual withdrawal volumes for each Reduced -
Entrainment scenario (i.e., Post-IM BTA [for impingement], FMS, and MDCT) were converted to
net benefits, defined as the potential reduction in entrainment or impingement from the baseline or
With -Entrainment scenario. For comparison purposes, an additional scenario (Without -Entrainment)
was added to represent the total benefit that would occur to the fishery with the complete elimination
of entrainment at Brunswick and assumes a 100 percent elimination of baseline entrainment losses
estimated under actual water withdrawal volumes recorded at Brunswick over the 2-year Study.
Reductions in entrainment and impingement were estimated with the following assumptions:
• Baseline scenario - In addition to the existing diversion structure includes losses based
on existing conditions (optimized to include 84 percent or 42 of 50 screen panels using
1.Omm fine mesh and seasonal flow reductions) at Brunswick under actual water
withdrawal volumes from 2016 and 2017 and the existing organism return system;
• MDCT scenario - Based on estimated reduction in percent water withdrawal anticipated
under the preliminary design assumptions (Section 10) including the existing diversion
structure,
• FMS scenario - In addition to the existing fish diversion structure, includes a new FMS
structure equipped with 100 percent 1.0-mm FMS for both units and upgrades to the
existing aquatic return system. This scenario is based on installation of exclusion
efficacy of 1.0-mm FMS (Section 10), on -screen survival (Appendix 11-A), and
assumes a 100 percent effective organism return system. Impingement losses under the
FMS scenario are the same as for the baseline condition since the additional
impingement mortalities potentially resulting from the additional FMS panels would be
the result of on -screen mortality of entrainment converts, which are included in the
entrainment loss estimates.
The detailed methodology for developing species and life -stage specific estimates of the potential
incremental reductions in entrainment and impingement among compliance technology scenarios is
detailed in Section 11. The entrainment and impingement loss reductions estimated for each
technology are provided in Appendix 11-A.

Historic Losses Comparison
The baseline scenario at Brunswick includes a system of technologies and operational measures that
provide substantial entrainment reduction benefits compared to historic losses prior to
implementation of these technologies (i.e., diversion structure, modified traveling screens with an
aquatic organism handling and return system, seasonal CWIS flow reductions, long-term and
continued field monitoring). Fish eggs were not targeted or collected during the 1980 entrainment
sampling efforts since most of the dominant harvested species spawned offshore and entered the
estuary as larvae. Therefore, to facilitate a direct comparison to the 2016 and 2017 study results, eggs
were removed from the 2016 and 2017 entrainment data. Total entrainment loss estimated in 1980
was approximately 3.5 billion organisms compared to 1.8 billion in 2016 and 1.4 billion in 2017. The
number of equivalent adult losses was reduced by approximately 84 percent in 2016 and 63 percent
in 2017 compared to the historic results with no entrainment reduction controls in place. Equivalent
adult biomass and harvest foregone estimates for 2016 were reduced by approximately 64 and 75
percent, respectively. The increase in harvest foregone losses in 2017 was driven by entrainment of a
large number of juvenile Weakfish due to higher than normal river flows during the spawning season.
Comparing historical data to results from 2016 only, which represents a typical year at Brunswick
with respect to spring and summer freshwater flow events, the existing system of technologies has
reduced total entrainment losses by approximately 48 percent, which results in a 75 percent reduction
in harvest foregone and translates to a substantial benefit to the fish community of the Cape Fear
Estuary. The remainder of the discussion in this section focuses on the benefits of the additional
technologies to reduce entrainment based on data in 2016 and 2017.
Regardless of the interannual variability in species composition and abundance of entrainment at
Brunswick, this comparison demonstrates that the existing system of technologies and operational
measures employed at Brunswick have reduced entrainment losses substantially when compared to
historic conditions. Specific information regarding the historic loss comparisons is provided in
Appendix 11-G.
Estimated Changes in Stock Size or Harvest Levels
The potential benefits to the fishery, due to changes in stock size or harvest levels, of the estimated
entrainment reductions were estimated using commonly applied population and harvest models (EPRI
2004, 2012) that use numeric- and mass -based data in the Production Foregone, Equivalent Adult,
and Equivalent Yield models. These three models were used to determine the potential entrainment
reduction benefits (for both "use" and "nonuse" scenarios) on recreational harvest (as harvest
foregone), as well as the effects of loss of forage associated with the entrainment of other finfish (as
production foregone). Parameters used in population modeling were derived from the literature (EPRI
2004; IJSEPA 2006) and also reflect site -specific information on the Cape Fear Estuary fishery (when
available) and data specific to the recreational uses of the fishery.
The models estimate a maximum benefit of 132,986 to equivalent adults with a biomass between
18,659 and 686,787 lbs and a maximum 786,413 lbs of recreational yield that would be returned to
the fishery under the baseline or Without -Entrainment scenario. The degree of interannual variation
in equivalent adults, production foregone, and harvest foregone estimates demonstrate the potential
annual variation in benefits that can be anticipated for fishery stocks in the Cape Fear Estuary near
the Brunswick CWIS under an entrainment reduction technology. Furthermore, it is important to
consider how variable ecological factors (e.g., year class strength, annual precipitation and flow
changes, annual temperature patterns and fluctuations) can influence fishery stocks and annual
entrainment estimates. Therefore, annual entrainment estimates and potential entrainment reduction

benefits are intended to be generally representative of potential conditions at Brunswick and are not
intended to represent minimum or maximum scenarios.
Uncertainty is an inherent aspect of model -based estimation techniques (i.e., equivalent adult and
production foregone models) due to the complexities of economics and natural biological systems.
The equivalent adult (recreational species) and production foregone (forage or non -game species)
estimates for Brunswick were used to determine the benefits achievable under each candidate
entrainment reduction technology scenario. Although unlikely to substantially change the results of
the benefits analysis performed for Brunswick, the BPJ decisions and assumptions made in the
development of equivalent adult and production foregone models cumulatively have the potential to
affect the monetization of benefits. Therefore, a qualitative evaluation was performed on the primary
sources of uncertainty associated with this analysis (Appendix 11-F). While efforts were made to
control uncertainty to the maximum extent practicable, the models used are "ecologically simplistic
and ignore important ecological processes that affect the growth and survival of fish" (EPRI 2004).
For example, the equivalent adult and production foregone models do not incorporate density -
dependence, nor do they assume that entrained and impinged fish are returned to the waterbody
(which is often the case, where they can support future primary and secondary production).
However, as a means to present the maximum benefits possible with entrainment or
impingementreducing technologies, input parameters used in the Benefits Valuation Study were
based on the most conservative data from literature, and therefore overestimate the potential benefits
that would likely occur in the fishery of Cape Fear Estuary.
Monetization of Benefits
The benefits of reductions in entrainment and impingement losses of early life stage fish are best
evaluated by translating losses to an ecological or human -use context and assessing differences in
total losses among compliance technology scenarios discussed in Section 10. The estimation of social
benefits was based on use benefits derived from potential changes in recreational fish stocks (e.g.,
equivalent adults, forage production foregone, and equivalent yield) and their associated economic
effects annualized over the remaining useful plant life.
Another benefit category, nonuse benefits, results from changes in values that people may hold for a
resource, independent of their use of the resource. Given the precepts of nonuse values and
consideration of estimated entrainment reduction costs and benefits, and the absence of federal or
state listed species in entrainment (Section 9), impingement (Section 4 and Section 6), and source
waterbody assessments (Section 4), and with entrainment reduction costs that are disproportionate to
benefits, correctly measured nonuse benefits would not influence a BTA determination that considers
benefits and costs based on historically applied criteria. A detailed discussion of the typical methods
used to evaluate nonuse benefits and the justification for not applying those at Brunswick is provided
in Appendix 11-E.

Given the estimated change in losses and resulting benefits modeled under baseline
conditions in 2016 and 2017, it is important to note that significant time and costs have
been expended to date to implement and optimize the existing system of technologies at
Brunswick, which has already substantially reduced entrainment losses compared to
historic, pre-1984 losses documented at Brunswick. The potential entrainment reduction
benefits under each of the scenarios presented in Table ES-IO validate the efficacy of the
existing installed system of technologies. Regardless of technology, year of estimated loss,
or discount rate assumptions, the present value of reductions in entrainment due to
technology implementation were estimated to range between $464, 184 (FMS with 2016
entrainment data, 7 percent discount) and $3,986,906 (MDCT with 2017 entrainment data,
7 percent discount). The total annual benefit value was estimated to range between
$51,576 (FMS with 2016 entrainment data, 7 percent discount) and $707,055 (MDCT
with 2017 entrainment data, 3 percent discount).
Barnthouse (2013) notes that the available peer -reviewed literature does not support a
conclusion that entrainment reductions will produce measurable improvements in
recreational or commercial fish populations. Further, the substantial social costs of the
evaluated technologies are orders of magnitude larger than the estimated benefits, even
when factoring potential impacts of interannual variability in the fish community or from
model uncertainty (see Section 11.7).
Other Benefits
Other benefits from reducing entrainment can include ecosystem effects such as
population resilience and support, nutrient cycling, natural species assemblages, and
ecosystem health and integrity (79 FR 158, 48371). The fisheries benefits study
(summarized in Section 11) does not quantify other effects on the fish community, such
as density -dependent influences including increased competition, predation, or increased
abundance of introduced or non-native species populations. Further, non-use values or
effects which many occur in the absence of entrainment or impingement were
demonstrated to be minimal ranging from $3,470 to $ 10,458 depending on year and
discount rate. Regardless, source water monitoring data demonstrate that a balanced and
indigenous fish community continues to exist in the Cape Fear Estuary in the vicinity of
Brunswick. The reduction or elimination of warm water discharges with the installation
of an MDCT at Brunswick could potentially lead to certain social costs and/or benefits.
Heated water discharged into the Atlantic Ocean from the plant potentially enhances the
localized food web that in turn transfers to increased concentrations of fish and other
aquatic organisms (see Section 11.8).
Non -water Quality Environmental and Other Impacts Study § 122.21(r)(12)
The Rule at § 122.21(r)(12) requires an assessment of other non -water quality
environmental impacts, including estimates of the level of impact, for each technology or
operational measure considered under §122.21(r)(10). It also requires a discussion of
reasonable efforts to mitigate the impacts; this information is presented in Section 12.
The evaluation must address, if relevant to the alternative technology being assessed, the
following items:
s Estimates of changes to energy consumption, including but not limited to, auxiliary
power consumption and turbine backpressure energy penalty;
s Estimates of increases in air pollutant emissions;
s Estimates of changes in noise generation;

• A discussion of potential impacts to safety;
• A discussion of facility reliability;
• Estimation of changes in water consumption; and
* Discussion of efforts to mitigate these adverse impacts.
The conceptual approach to each potential entrainment reduction technology (e.g., location
and design of cooling towers) defined in §122.21(r)(10) has an important effect on the level
of impacts determined under §122.21(r)(12). The quantitative engineering and cost analyses
developed under §122.21(r)(10) includes an evaluation of potential impacts and
incorporates reasonable estimates of impact mitigation and associated costs. Impact
information presented in Section 12 of the compliance document are summarized and
discussed below in the sections addressing the "Must" and "May" factors.
Peer Review - § 122.21(r)(13)
As required by the Rule at §122.21(r)(13), the reports prepared under §122.21(r)(10)-
(r)(12) were subjected to external peer review by subject matter experts. Four expert peer
reviewers were selected in fields relevant to the material presented in the submittal
package (i.e., power plant engineering, aquatic biology, and resource economics). Section
13 of this document provides a summary of the peer reviewer qualifications (Appendix
13-A), a log of written/electronic/phone communication with peer reviewers (Appendix
13-8), documentation of formal peer review comments and responses to those comments
(Appendix 13-C and 13-D), and includes confirmation from reviewers of their satisfaction
with responses to comments and recommended revisions.
Entrainment BTA Factors that Must Be Considered
The Rule requires that the Director consider several factors in the written explanation
of the proposed entrainment BTA determination. The following Must factors to be
considered for entrainment BTA (§ 125.98(f)(2)). are:
• Numbers and types of organisms entrained, including federally listed, threatened and
endangered species, and designated critical habitat (e.g., prey base, glochidial host
species);
• Impact of changes in particulate emissions or other pollutants associated with
entrainment technologies;
• Land availability as it relates to the feasibility of entrainment technology;
• Remaining useful plant life; and
• Quantitative and qualitative social benefits and costs of available entrainment
technologies.
While each of the Must factors is considered separately in Section 10 for the potential
technologies considered (i.e., MDCT and FMS with an aquatic organism return), a brief
summary of findings for each factor is presented below along with references to the
relevant section(s) of the report.
Numbers and Types of Organisms Entrained

Baseline entrainment losses under existing conditions (optimized to include 84 percent or 42
of 50 screen panels using 1.0-mm fine mesh and seasonal flow reductions) at Brunswick were
calculated as the sum of the total losses estimated from entrainment and larval impingement
studies (converts). Sections 9, 7, and 11 present the number and types of organisms entrained
based on the 2-year Study at Brunswick (HDR 2021b); these data were annualized and
adjusted for actual intake flow (AIF) to estimate total annual entrainment losses (Appendix
11-A; Tables 11-A3 and 11-A4). The annual estimates are presented separately for 2016 and
2017 based on the rates of entrainment documented during the 2016-2017 Study in
conjunction with the larval impingement study and demonstrate the range of interannual
variation in entrainment losses that can occur at the Brunswick CWIS.
In 2016, entrainment mortality was estimated at 25.7 billion ichthyoplankton. Forage species
were the major contributors to entrainment losses during 2016 (91.4 percent) with anchovies,
gobies, and silversides dominating the forage species losses. Harvested species only
represented 8.6 percent of the estimated 2016 total entrainment losses with Weakfish, Atlantic
Croaker, Spot, Commercial Shrimp Group, Atlantic Menhaden, and swimming crabs
(megalops stage). In 2017, entrainment mortality was estimated at 13.4 billion
ichthyoplankton. Forage species accounted for 58.4 percent of total entrainment losses during
2017 with anchovies and gobies comprising the majority of forage species losses. Notably,
silverside mortalities (all life stages combined) were approximately 89 percent lower in 2017
compared to 2016 declining from 106 million to 11 million. Harvested species entrained in
2017 accounted for 41.6 percent of total losses, and consisted primarily of Weakfish, Atlantic
Croaker, Spot, and the Commercial Shrimp.
Prior to implementation of the current technologies and operational measures at Brunswick, annual
entrainment of larvae was estimated to be 3,490,151,060. This is approximately 91 to 154 percent
greater than the current entrainment in 2016 and 2017, respectively.
Annual estimated entrainment based on maximum water withdrawals varied from 34.1 billion
ichthyoplankton in 2016 to 17.6 billion ichthyoplankton in 2017. Annual entrainment estimates
based on actual water withdrawals varied from 25.7 billion ichthyoplankton in 2016 to 13.4 billion
ichthyoplankton in 2017, a reduction in estimated entrainment losses of approximately 24.6 percent
in 2016 and 24.0 percent in 2017. In addition to reductions in losses associated with reduced water
withdrawal, substantial numbers of entrainment converts were returned alive to the estuary. Based
on actual water withdrawals, approximately 181.2 million and 130.9 million organisms were
returned to the Cape Fear Estuary in 2016 and 2017, respectively.
Overall, egg entrainment at Brunswick represented 92.9 and 89.8 percent of total entrainment losses
in 2016 and 2017, respectively. However, the eggs of forage species comprised the majority of egg
losses in 2016 (88.5 percent) and 2017 (53.4 percent). Egg losses for all species combined
accounted for less than 1 percent of the total equivalent adult losses for each year and
approximately 5 to 7 percent of harvest foregone depending on year. The current mesh size (1.0
mm) was selected to reduce impacts to recreational and commercial fish; therefore use of a smaller
mesh screen would provide little incremental benefit.
Although entrainment occurs year-round at Brunswick, the primary period of entrainment occurred
between April and August of 2016 and May and July 2017 and was composed largely of
Engraulidae and Sciaenidae eggs (primarily Weakfish and Silver Perch). The dominance of eggs is
influenced by the intake modifications, specifically the 1.0-mm FMS, designed to reduce the
entrainment of larvae and juveniles. Results of the Study are consistent with long-term monitoring
results at Brunswick which indicate (1) that the species composition of entrained organisms and

populations of fish and shellfish in the Cape Fear Estuary have remained consistent over time and
(2) that fish and shellfish populations in the Cape Fear Estuary have also remained stable and there
is no evidence that cooling water withdrawal has limited the recruitment of estuarine dependent
species to the nursery habitats (Duke Energy 2017, 2019, 2020c). Thus, results of the Study
combined with long-term monitoring data indicate no measurable effect on the waterbody from
entrainment at the Brunswick CWIS, and that documented variability in the fish and shellfish
communities (i.e., organism distribution and abundance) is related to environmental variables such
as freshwater discharge rather than ongoing operations at Brunswick (Duke Energy 2017, 2019,
2020c).
Long-term annual monitoring results through 2018 document reductions in the total annual number
of organisms entrained ranging from approximately 60 to 90 percent depending on year with an
overall average of 76 percent (See Section 7.1.3). Similar reductions in the average annual number
entrained for the dominant taxa were observed for anchovies (all Anchoa spp. combined) (79
percent), Atlantic Menhaden (57 percent), Spot (60 percent), Atlantic Croaker (63 percent), seatrout
(Cynoscion spp.) (64 percent), mullet (Mugil spp.) (89 percent), flounder (91 percent), gobies
(Gobiosoma spp.) (80 percent), Commercial Shrimp Group postlarvae (83 percent), and Swimming
Crab megalops (95 percent) (Duke Energy 2020c)
It is important to place the rates of entrainment at Brunswick into the context of the trends
documented for Cape Fear Estuary, the source waterbody (see Section 4):
• Duke Energy periodically monitors the Cape Fear Estuary fish community, with results
that continue to demonstrate a stable and balanced, self-sustaining population with a
robust forage fish base supportive of predatory species (Section 4).
• Based on the annual environmental monitoring program results, the Cape Fear Estuary
supports a balanced fish and shellfish community that has not been affected by long-
term operations at Brunswick. The Cape Fear Estuary supports a complex system of life
stages and trophic levels. While some species are frequently abundant within the estuary,
such as Atlantic Menhaden, Atlantic Croaker, Spot, and anchovies, variation in species
composition and dynamics over time is primarily influenced by environmental factors
such as water temperature and salinity, which are driven by freshwater input from the
Cape Fear River, rainfall events, and storms.
• The direct and indirect effects of the loss of organisms at Brunswick, as demonstrated
through modeling (specifically designed to overestimate effects), does not result in a
negative impact to the recreational fishery (see Section 11).
These findings are interrelated and driven by the same factors: (1) Brunswick entrainment consisted
of early life stages of highly fecund species, many of which exhibit high natural mortality, and (2)
entrainment losses represent a small portion of the available Cape Fear Estuary resources. Given
that harvest foregone losses have been reduced by as much as 75 percent compared to historical loss
estimates without existing technologies and operational measures in place, the losses resulting from
entrainment are not expected to impact the Cape Fear Estuary fish community. Results of extensive
long-term monitoring support this conclusion.
The incremental reductions in estimated entrainment losses, and their effect on the fishery as
represented by production foregone, equivalent adults, and harvest foregone, were modeled for
each of the potential compliance scenarios described in Section 11 of the compliance document.
Although the additional modeled technologies provide incremental reductions in entrainment, the
existing system of technologies (Baseline Condition) has already reduced total entrainment
losses by approximately 48 to 61 percent, which results in reductions of up to 84 percent for

equivalent adults, 46 percent for production foregone, and 75 percent for harvest foregone. This
translates to a substantial benefit to the fish community of the Cape Fear Estuary. Entrainment
not already managed by the existing technologies and operational measures was estimated to be
reduced by 92.4 percent under a closed -cycle cooling (MCDT) retrofit, based on the anticipated
water withdrawal volumes. The potential percent reductions estimated under the 1.0-mm FMS
retrofit scenario (i.e., the product of the rate of exclusion and post -exclusion on -screen survival)
were between than 72.6 and 76.1 percent for equivalent adults. Equivalent adult biomass
reductions would be 28.2 and 34.9 percent in 2016 and 2017, respectively. Reductions in losses
of production foregone would vary between 13.3 and 28.9 percent. Reductions in losses to the
fishery under the FMS scenario varied between 36.5 and 39.7 percent. The entrainment losses at
Brunswick in 2016 and 2017 were dominated by fragile forage species (primarily from family
Engraulidae) and recreational species in the family Sciacmdae.
The organisms entrained at Brunswick are highly fecund species that spawn over large geographic
areas including estuarine, nearshore and offshore ocean with protracted spawning seasons. No
protected species were entrained at Brunswick. Based on these findings, the number and types of
organisms entrained do not provide a compelling basis under the Rule to evaluate additional
entrainment measures. The entrainment rates at Brunswick do not negatively affect the Cape Fear
Estuary fish community, which continues to reflect a dynamic and resilient community.
Air Pollutant Emissions Impacts
The evaluation of potential entrainment reduction technologies considers increases in air
pollutant emissions due to technology implementation under § 122.2 1 (r)(1 3). The increase in air
pollutant emissions would be associated with two factors: (1) particulate matter (PM) emitted as
drift from the hypothetical MDCTs due to the concentration of total dissolved solids (TDS) and
total suspended solids (TSS) in the cooling water, and (2) off -site combustion emissions
produced to replace lost Brunswick generation during the MDCT operational period due to
increased energy consumption from the auxiliary energy requirements and backpressure energy
penalty.
Emissions associated with the replacement of lost generation at Brunswick would include minor
increases in carbon dioxide, sulfur dioxide, and nitrogen oxides. These increased emissions are
based on assumptions and results of Duke Energy's Power System Simulation Model (PROSYM).
No attempt was made to monetize the social costs of the increased emissions.
Land Availability Related to Technology Retrofit Options
Land availability for infrastructure associated with the retrofit of potential entrainment
technologies was considered in the assessment of entrainment BTA for Brunswick. While land is
technically available at Brunswick to facilitate a closed -cycle cooling tower retrofit, there are
substantial site constraints that would impact the placement, required infrastructure, and
associated costs.
Two on -site locations were evaluated for the hypothetical MDCT retrofit at Brunswick (Location A
and
Location B. For costing purposes, it is assumed that Location A would be utilized for the
hypothetical MDCT retrofit at Brunswick. The conceptual design for hypothetical cooling tower
Location A includes placing two linear back-to-back MDCTs, one for each unit, to the southeast
of the main plant on a cleared and undeveloped area. This hypothetical location would limit
demolition of existing plant infrastructure but would pose construction constraints including

construction in close proximity to existing plant infrastructure, the 100-year floodplain
associated with the Cape Fear Estuary, and overhead electric lines.
The conceptual design for hypothetical cooling tower Location B includes placing two linear back-
toback MDCTs, one for each unit, to the southwest of the main plant on undeveloped forest area.
This hypothetical location would avoid steep slopes at the plant but would pose construction
constraints including relocation of on -site overhead electric lines, demolition of existing plant
infrastructure, and construction in close proximity to the 100-year floodplain associated with the
Cape Fear Estuary. Additionally, Location B would require significant tree clearing prior to
construction. Cooling tower Location B is farther from the existing intake canal and would require
demolition of existing plant infrastructure for the construction of the cold water channel.
Additionally, Location B would require the relocation of on -site overhead electric lines and
significant tree clearing. For these reasons, Location B is less suitable than Location A for the
construction and operation of hypothetical closed -cycle cooling towers at Brunswick, and a
conceptual cooling tower design at this location is not evaluated further.
Remaining Useful Plant Life
The remaining life of a generating unit and each potentially feasible entrainment reduction
technology impacts annual O&M costs, potential future technology replacement costs (if the life of
a generating unit is longer than the anticipated life of a technology), and the associated social
benefits. The current operating licenses for Brunswick IJnit 1 and Unit 2 expire on September 8,
2036 and December 27, 2034, respectively (USNRC 2018a, 2018b). Duke Energy intends to apply
for renewed operating licenses from the USNRC prior to expiration of the existing operating
licenses. As a result, this evaluation assumes Unit 1 and Unit 2 will cease operations at the end of
the current operating license periods on September 8, 2036 and December 27, 2034, respectively. If
a hypothetical entrainment reduction technology were to be in good operating order at the time of
license expiration, it is assumed that the technology would be retired (no salvage value has been
included). This evaluation will be reviewed with each subsequent NPDES renewal application as
prescribed by the 316(b) Rule.
Quantitative & Qualitative Social Benefits and Costs of Available Entrainment
Technologies
The social costs and social benefits for each additional compliance technology option evaluated for
Brunswick are summarized in Section 10 which provides the present value estimates discounted at 3
and 7 percent based on the estimated annual losses for entrainment and impingement for 2016 and
2017. The social benefits include both the impingement and entrainment benefits estimated for each
compliance option. The methodology and results for estimating the entrainment benefits are
presented in the Entrainment Reduction Benefits Study (Appendix 11-E). The methods and results
for estimating the social costs are presented in the Social Costs of Purchasing and Installing
Entrainment Reduction Technologies Study (Appendix 10-G).
Quantitative Cost to Benefit Comparison
The social costs and benefits of the entrainment compliance options for Brunswick are presented
as present values discounted at 3 percent in Figure ES -I . The figure also illustrates social costs
and benefits of the IM compliance option identified in Section 6. Including the impingement
technology provides

context for determining the entrainment BTA under the Rule's site -specific entrainment evaluation.
Specifically, the Rule has two separate regulatory components:
• a command and control component in which the facility must implement one of seven
impingement compliance alternatives (§ 125.94(c)) if not currently installed, or
demonstrate that its rate of impingement is de minimis (§125.94(c)(11)), and
• a site -specific best technology available evaluation to determine the maximum
entrainment reduction warranted based, in part, on the social costs and social benefits of
each technology.
By comparing the entrainment reduction options to the impingement option, the evaluation provides
context for what is warranted for entrainment versus what is required for impingement.
The total social costs are greater than the social benefits for each of the entrainment compliance
options and the System of Technologies for the impingement compliance option (the continued
operation of Flow Minimization with Fine Mesh Screens and Fish Diversion System at Brunswick).
The social costs of the System of Technologies are the forgone incremental impingement benefits of
the next, leastcost impingement compliance alternative, which is Modified Ristroph Screens in a
new FMS structure.
The impingement compliance option of System of Technologies has net benefits of -$0.08 million.
By comparison, the entrainment compliance options of FMS in a new FMS structure and mechanical
draft cooling towers (MDCT) have net benefits of-$94.36 million and-$864.38 million, respectively.
Entrainment BTA determinations require consideration of both benefits and costs. Under the
criterion that governs benefit -cost -based determinations, only technologies that have social benefits
that exceed their social costs are justified (Boardman et al. 2018; Freeman et al. 2014). As noted in
the Rule, "[i]f all technologies considered have social costs not justified by the social benefits... the
Director may determine that no additional control requirements are necessary beyond what the
facility is already doing. The Director may reject an otherwise available technology as a BTA
standard for entrainment if the social costs are not justified by the social benefits (§ 125.98(f)(4))."
Given that Brunswick is compliant with the Rule, the net benefits are negative for each of the
additional alternatives, and the social costs are not justified by the potential social benefits.
Therefore, neither the FMS nor MDCT entrainment compliance option is justified as the BTA under
the Rule's site -specific entrainment compliance requirements, and no additional entrainment control
requirements are necessary beyond Brunswick's current configuration. Additionally, the 2016-2017
entrainment monitoring data clearly demonstrate that the existing system of technologies (diversion
structure, fish -friendly traveling screens fitted with 84 percent 1.0-mm FMS, organism return
system, and seasonal flow reduction) substantially reduce entrainment at the CWIS compared to
historical losses with no technology or operational measures in place.
Brunswick's CWIS has undergone several modifications since 1981. A permanent diversion
structure was installed at the entrance to the intake canal in 1982, and the plant implemented flow
reductions to decrease the rate of impingement and entrainment. From 1983 through 2012, each
traveling water screen has been updated with 42 1.0-mm fine mesh and 8 coarse mesh panels along
with a continuous spray wash and aquatic organism return system.

Figure ES -I. Comparison of Social Benefits and Costs at Brunswick Nuclear Plant
(Assumes generation will cease in 2036) (Source: Veritas 2022)
Qualitative Cost to Benefit Comparison
The qualitative costs and benefits of additional reduced entrainment and IM are difficult to evaluate
and quantify and therefore are not included in the benefits valuation presented in Section 11.
Monitoring at Brunswick continues to demonstrate the existence of a healthy aquatic community.
The determined qualitative effects could potentially result in ecosystem benefits such as increased
population resilience and support, nutrient cycling, and overall health and integrity of the ecosystem
(79 FR 158, 48371). The reduction in entrainment losses could also result in qualitative costs to the
fish community due to density -dependent influences such as increased competition, predation, or
increased populations of introduced species.
The elimination of warm water discharges at Brunswick is a potential outcome under the MDCT
scenario (see Section 1 1), which could lead to social costs or social benefits. The Brunswick
discharge is routed to the Atlantic Ocean rather than back into the estuary. This configuration was
determined after consultation with the agencies during permitting activities prior to construction
(CP&L 1980). Routing the discharge in this fashion eliminates potential thermal impacts to the
valuable estuarine nursery areas. Therefore, elimination of the thermal discharge would not be
expected to benefit localized fish and shellfish communities within the estuary. However, the fish
species composition found in the vicinity of the discharge may also change in response to reduced
warm water discharges. Depending on the species, this may be seen as either a cost or a benefit.
Elimination of the thermal discharge may adversely affect angling opportunities and subsequent
catch rates. Facility personnel routinely observe anglers fishing in the thermal plume or using the
area to enhance their ability to capture live bait (clupeid species) frequenting the area (see Section 1
1.8). Forage species may use the thermal plume as a foraging area, as a thermal refuge or refuge
from predators since the discharge water is more turbid relative to the ocean and may contain a
greater abundance of forage for higher trophic level organisms. Research conducted on the discharge
from the Calvert Cliffs Nuclear facility suggested that the thermal discharge enhanced the localized
food web that in turn transferred to increased concentrations of diving ducks in the vicinity (Swarth
and Llanso 2012). Similarly, other species of fish and seabirds may be attracted to the thermal plume
as has been observed for Brunswick.
Entrainment BTA Factors that May Be Considered
The May factors to be considered for entrainment BTA (§ 125.98(f)(3))are:
a Entrainment impacts on the waterbody;
Thermal discharge impacts;
Credit for reductions in flow associated with the retirement of units occurring within the
ten years preceding October 14, 2014;
• Impacts on the reliability of energy delivery within the immediate area;
• Impacts on water consumption; and
• Availability of process water, grey water, wastewater, reclaimed water, or other waters
of appropriate quantity and quality for reuse as cooling water.
The information from this list is included or addressed in detail in the study reports and
supporting documentation provided in Sections 2 through 12 of the compliance submittal
document. The findings of the entrainment BTA assessment relative to the factors that
SCDHEC may consider are provided below.

Entrainment Impacts on the Waterbody
Brunswick employs multiple entrainment reduction technologies and operational measures,
including modified FMS, a diversion structure, and seasonal reductions in flow. These
technologies and measures reduce the potential for entrainment at the CWIS. Since 1983, the
percentage of aquatic organisms entrained at Brunswick has been significantly reduced in
comparison to pre -diversion structure and pre -fine -mesh panel installation (Duke Energy 2017,
2019, 2020c). Based on historical and ongoing biological monitoring data and results of the
2016-2017 entrainment study presented in Sections 9, 7, and 11, the Cape Fear Estuary supports a
diverse, balanced, and resilient fish and shellfish community in the presence of ongoing
operations at Brunswick. No decline in the abundance of fragile species such as Bay Anchovy or
the dominant harvested species entrained and impinged have been documented. Interannual
variability in the distribution and abundance of fish and shellfish is a function of environmental
variation, primarily changes in the timing and magnitude of freshwater flow events to the estuary
(Copeland et al. 1979; CP&L 1980; Duke Energy 2017, 2019, 2020c).
The degree of susceptibility of aquatic organisms to entrainment can be quite variable depending
on their size, swimming ability, wind speed and direction, bathymetry of the estuary and intake
canal, and the rate and variability of flows withdrawn at the Brunswick CWIS. Due to the
variability associated with these factors, an entrainment AOI at Brunswick was not quantified, but
is discussed qualitatively. Most entrainable-sized organisms are unable to swim and, thus float
within the water column or at the water surface where they are subject to ambient flows and
currents within Cape Fear Estuary and the Brunswick intake canal.
Based on the information presented above and in the compliance document, entrainment at
Brunswick does not result in substantial or adverse impacts to the fish community of Cape Fear
Estuary. This position is further supported by the results of the quantitative modeling of the effects
of entrainment, using recent monitoring data collected at Brunswick in 2016 and 2017 (Section
9), including direct losses of recreational species as well as indirect losses from trophic transfer
of forage species to consumers or predators (see Section 11).
Credit for Flow Reductions
As discussed in Section 3.3, Brunswick has a DIF of approximately 1 ,938 MGD based on the
design capacity of the CCW pumps, service water pumps, and screenwash pumps (Duke Energy
2021 a, 2021 b). However, the AIF at Brunswick based on the 5-year period of record (January
1 , 2016 through December 31, 2020) was approximately 1 ,379 MGD, which represents a 29
percent reduction in total withdrawals when compared to DIF (Duke Energy 2020).
In addition, as discussed in Section 5.1.5, reductions in total water withdrawals at Brunswick
align with plant seasonal flow restrictions. These seasonal flow restrictions are a condition in
Brunswick's NPDES permit as daily maximum CCW pump discharge limitations. The current
seasonal daily maximum CCW pump discharge limitations are as follows (NCDEQ 2018):
0 Between December 1 and March 31 , the daily maximum CCW pump discharge is
limited to 1,192 MGD, or approximately 65 percent of the plant CCW design
capacity;

e Between April 1 and June 30, the daily maximum CCW pump discharge is limited to
1,428 MGD, or approximately 78 percent of the plant CCW design capacity;
e Between July I and September 30, the daily maximum CCW pump discharge is
limited to 1 ,509 MGD, or approximately 82 percent of the plant CCW design
capacity;
s Between October 1 and November 30, the daily maximum CCW pump discharge is
limited to 1,428 MGD, or approximately 78 percent of the plant CCW design
capacity; and
s During a unit outage, the daily maximum CCW pump discharge is limited to 918
MGD, or approximately 50 percent of the plant CCW design capacity.
Flow reductions result in commensurate reductions in impingement (and associated mortality) at
the CWIS and SWIS, and facilities can take credit for these reductions in total withdrawals.
Impacts on the Reliability of Energy Delivery
Brunswick is a large nuclear carbon -free generating asset that supports the reliable supply of
electricity to Duke Energy's customers. Maintaining safe and reliable energy delivery is
imperative to Duke Energy, their customers, and their shareholders, and has been considered in
this entrainment BTA assessment in the following manner:
s During the conceptual design phase for potential additional entrainment
reduction technologies, consideration was given to the location, configuration,
operational requirements, and other design specifics for each potential
technology to improve generation reliability. This information was incorporated
into capital and social costs estimated for each potential technology
implementation option.
• System modeling (i.e., PROSYM) was performed by Duke Energy to evaluate
the extent and impact (system -wide) of loss of generation capacity associated
with potential technology implementation options to ensure reliable energy
delivery and to estimate the social costs of securing it.
Under the MDCT retrofit scenario, the plant would potentially be required to operate at reduced
power during the warmest and most humid periods of a typical year due to the inability of the
cooling towers to provide an acceptable cold water discharge temperature during these periods.
The power reduction is anticipated to result in reliability impacts due to increased condenser
and turbine backpressures. Additionally, during periods of peak demand in winter, there would
be the potential for icing on Brunswick's transmission lines due to cooling tower plume
formation, which could impact nuclear safety and plant reliability.
Under the full 1.0-mm FMS implementation scenario, there would be overall increases to TSV
and headloss across the screens, especially during high debris loading (i.e., clogging) events,
which could impact the performance of the existing CCW pumps, plant reliability, nuclear
safety, and availability of CCW flow.

Availability of Alternate Water Sources for Use as Cooling Water
Alternate water sources, such as groundwater and grey water sources, were evaluated for
potential use to supplement the cooling water needs at Brunswick. These sources were evaluated
by first comparing the distance and available flow of the potential alternate water source to the
location of the plant, and then by determining its practicability as a source of cooling water for
the station. Due to permitting challenges such as stream and wetlands crossings, numerous
rights -of -way required over private properties, and prohibitive construction costs, alternate water
sources greater than a distance of 5 miles from the plant are not considered feasible. The
potential flow available from off -site grey and potable water sources is less than one percent of
the total CCW design flow at Brunswick. Additionally, the total yield of all reporting
groundwater wells within five miles of the plant is less than one percent of the total CCW design
flow. Reuse of existing on -site water sources is considered infeasible.
Conclusions
Based on the existing optimized system of technologies and operational measures employed at
Brunswick, the substantial reductions documented for entrainment and IM losses, a determination
that the existing configuration is BTA for impingement is requested as the IM Option for the
Brunswick CWIS. The data presented in Section 6 and summarized in this Executive Summary
demonstrate that the current design and operations of the system of technologies at Brunswick result
in substantially reduced IM ranging up to 88-99 percent and that the social costs of implementing
additional impingement -reduction technologies at Brunswick do not justify the potential social
benefits.
As outlined in the Rule, the requirements of the NPDES Director include the following (40 CFR
§ 125.98(f)), Site -specific Entrainment Requirements):
(4) If all technologies considered have social costs not justified by the social benefits, or
have unacceptable adverse impacts that cannot be mitigated, the Director may determine
that no additional control requirements are necessary beyond what the facility is already
doing. The Director may reject an otherwise available technology as a BTA standard for
entrainment if the social costs are not ustified by the social benefits.
Model -based estimates of the direct and indirect effects of the loss of organisms at Brunswick,
based on conservative assumptions and BPJ decisions, indicate that losses do not have a negative
impact on the recreational fishery of Cape Fear Estuary. Brunswick incorporates existing
entrainment reduction technologies and operational reductions (29 percent) of water withdrawals
from the DIF, based on the most recent 5-year POR. Long-term monitoring results through 2018
document reductions in the total annual number of organisms entrained ranging from approximately
60 to 90 percent depending on year with an overall average annual reduction of 76 percent since
1984.
The model -based estimates of entrainment losses were used to assess the social costs and social
benefits of potential additional entrainment reduction technologies, including: (1) installation of
MDCT and (2) the installation of a new CWIS with 100 percent 1-mm FMS and updated organism
return system. Monetized social costs and social benefits were estimated for both technologies to

provide a common basis for comparison, which is consistent with the goals and requirements of the
Rule. The estimates were based on conservative assumptions and include evaluations of uncertainty
at multiple stages of the development process. The social cost to social benefit comparison indicated
substantial net -negative benefits for the modeled entrainment reduction technologies, and
unavoidable adverse effects were identified for both evaluated technologies. A potential MDCT
retrofit would result in nuclear safety concerns, increased air emissions, increased noise, and
potential impacts to station reliability.
Based on historical and ongoing biological monitoring data and results of the 2016-2017
entrainment Study presented in Sections 9, 7, and 11, the Cape Fear Estuary supports a diverse,
balanced, and resilient fish and shellfish community in the presence of ongoing operations at
Brunswick with the currently installed protective technologies and operational measures. No
protected species were collected in the recent impingement and entrainment studies. These data,
combined with the evaluations described in Sections 10 through 12, demonstrate that additional
entrainment reduction technologies identified as feasible in Section 10 (MDCT and FMS) are not
justified as BTA for entrainment at Brunswick. The estimated social costs would be wholly
disproportionate compared to the potential social benefits.
The NPDES Director must consider the social costs and benefits of each evaluated entrainment
compliance option when determining the maximum entrainment reduction warranted; however,
from a practical standpoint, any modifications to the existing intake structure or station operations
would provide minimal biological benefits. Based on the evaluation of social costs and benefits of
each technology, the existing (i.e., baseline) configuration at Brunswick represents BTA for meeting
the entrainment requirements of the Rule.
Furthermore, per § 122.2 1 (r)(6), the owner of a facility must identify the chosen method of
compliance with the IM standard for the entire facility and provide sufficient information and
justification to support the selected alternative compliance approach. Based on the current IM
reduction benefits at the station (i.e., installed 316(b) Rule compliant traveling screens, an organism
return system, diversion structure, seasonal flow reductions) and the results of the social cost and
social benefit evaluation, installation of additional IM reduction technologies at Brunswick is not
practical or warranted.