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Site Visit Report

Brunswick Steam Electric Plant

Highway 87 North

Southport, NC 27562

January 28, 2008

1.0 Background and Objectives

The Environmental Protection Agency (EPA) is in the process of revising the 

316(b) Phase II regulation. As part of this process, EPA staff is visiting several 

electric generators to better understand the cooling water intake structure (CWIS) 

technologies in use at typical facilities, including the site-specific characteristics 

of each facility and how these affect the selection and performance of CWIS 

technologies. Brunswick Steam Electric Plant (Brunswick) was selected for a site 

visit due to its use of fine mesh traveling screens with a fish return and its 

relatively large intake flows.

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2.0 Facility Description

Brunswick is a two unit nuclear facility in North Carolina 40 miles south of 

Wilmington. Unit 1 is a 938 MWe General Electric Type 4 boiling water reactor 

that began operations in September 1976. Unit 2 is a 937 MWe General Electric 

Type 4 boiling water reactor that began operations in December 1974. The source 

waterbody for cooling is tidal water (salinity typically 15 to 30 parts per 

thousand) obtained from Walden Creek near the Cape Fear River estuary. The 

owner Carolina Power & Light (Progress Energy) employs about 900 employees.

Brunswick permit number is NC0007064, expired as of November 30, 2006.

3.0 Electricity Generation and Transmission

Total generating capacity is approximately 1580 MW of nuclear fueled power for 

baseload electricity with a capacity utilization rating of 94.7 percent. Scheduled 

outages that include refueling occur every year alternating between units 1 and 2. 

Outages are usually for 20 to 30 days. 

4.0 Cooling Water Intake Structure

The Cape Fear River Estuary is an elongated shallow bay with a narrow dredged 

deep ship’s channel. Above the narrow constriction at Sunny Point, the estuary is 

highly stratified with salt water intrusion along the bottom and freshwater flow 

out along the surface. Below Sunny Point the estuary is well mixed and 

characterized by a large ocean exchange rate of about 80 percent of the water over 

a 12-h period. Brunswick obtains cooling water from the lower reach, with 

approximately 0.74 percent of the tidal excursion withdrawn by the intake canal.

 

1 EPA was unable to provide a copy of this report to the facility for review prior to publication.
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Brunswick has vertical turtle bars (bar racks) at the canal entrance. Additional fish 

diversion structure with 3/8 inch (9.4 mm) screens installed in 1982. The 

diversion structure is located near the confluence of the intake canal and Walden 

Creek. Copper-nickel screen panels are set between reinforced concrete pilings. 

Mechanical grass rakes keep debris out of the canal. The canal is dredged 18 feet 

deep with frequency dictated by annual storm events. Design intake flow is 1.9 

billion gallons daily, with the actual intake (3-year average) reported as 1.427 

billion gallons daily with an intake velocity of 0.98 feet per second. 

A fine mesh and a fish return handling system was installed in 1983. After the 2.7 

mile long intake canal, water flows to each generating unit’s cooling system 

consisting of four intake bays and pumps. Originally, vertical traveling screens 

installed in each bay were fitted with 9.4 mm mesh screens. Eight fine mesh FMC 

screens were retrofit on the traveling screens to reduce entrainment of larvae2. 

The third fine-mesh screen per unit was installed in 1987. As of a 2000 study, 

three of the four traveling screens for each unit were fitted with 1 mm fine-mesh 

screens. Currently, an alternative configuration is being studied where 1 mm fine 

mesh overlay is installed on 2 of 4 screens creating a 50/50 panel on the two bays.

The other two bays have fine mesh screens on all panels. The traveling screens 

have two operating speeds, where the higher speed is triggered by a pressure drop 

across the screens. The screens are visually inspected twice daily. Impinged 

organisms are washed off the screens into a 1.4-km fiberglass fish return. The 

organisms are transported to a constructed holding pond that is open to a tributary

of Walden Creek, allowing impinged organisms a full return route to the 

sourcewater. 

December through March flow reduction management is utilized for further 

protection of larval fin fish. Cooling water flow is reduced from 31.1 cm/unit to 

26.1 cm/unit. Normally, all flow is through traveling screens fitted with fine 

mesh. The cooling water flow for one unit only is allowed to be increased to 

34.8 cm during July, August, and September by using a forth intake pump fitted 

with 9.4-mm mesh screens.

Seasonal algae has been observed to foul the intake. Biocontrol is conducted by

addition of hypochlorite and brome into the service water bays every other hour, 

and to the salt water pumps twice a day. A silicone coating on the main cooling 

water system further reduces biofouling. 

The return canal is a 5 mile open canal that is eventually piped under the IntraCoastal Waterway and remains submerged into the Atlantic Ocean. The returned 

warm water is dispersed 200 feet offshore the Oak Island area. Water is returned 

less than 4 degrees F higher at the ocean. Permit conditions allow for a 2 acre 

mixing zone, with a 2,000 acre grid monitored for compliance.

 

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Prior to installation of fine-mesh screens, all entrained larvae were returned to the ocean rather than back 

to the estuary, therefore they were considered 100 percent mortality.
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5.0 Impingement and Entrainment Information

Brunswick has conducted a representative species approach to population level 

effects as part of the demonstration to the state that there is no adverse 

environmental impact; population modeling is not required by the state. 

Brunswick has conducted some form of monitoring for more than 30 years. 

Brunswick staff indicated their data shows that the species composition, 

seasonality, and abundance of organisms has not changed as a result of operation 

of the plant.

As early as 1968, baseline studies were designed to collect preliminary biological 

and environment data prior to simultaneous operation of both units. Initial studies 

were conducted when plant operations commenced in the 70’s. Detailed I&E 

studies were conducted weekly in the mid-80s. Sampling was conducted 3/day

and 3/night over a 24 hour period, with data stratified by the tide conditions. Two 

nets in the discharge canal are used to collect organisms to show comparative 

density of entrainment. Overall abundance was generally found to be lower in the 

fall. Brunswick performance data showed 84 percent reductions in entrainment

with the fine mesh over regular mesh (9.4 mm). Impingement mortality 

reductions ranging from 40 to 92 percent were observed depending on species and 

mesh configuration. Currently monitored species of interest include Atlantic 

menhaden, spot, blue crab, and shrimp. Other previously monitored species 

include croaker, flounder, mullet, bay anchovy, and sea trout. Potential impacts to

threatened and endangered (T&E) species include short-nosed sturgeon and 

turtles. 

6.0 Additional Information

The base for a natural draft wet cooling was built, but the tower was not 

completed due to projected adverse impacts to air. 

List of attendees: Charles Nelson, Thomas Thompson

Attachments:

Please see DCN 10-6559A through Q accompanying this document for photos from the 

site visit.