Intake Technologies Used at the Brunswick 

Steam Electric Plant to Achieve a Reduction 

in Impingement Mortality to a Level Similar 

to Closed Cycle Cooling

By

Tom Thompson

September 5, 2011
Atlantic 

Ocean Ocean 

Discharge 

Area

Plant Site

NORTH CAROLINA

BrunswickSteam 

Electric Plant

N

Kilometers

Miles

0 2 4

0 2

*

Brunswick Steam Electric Plant 

•2-Unit Nuclear Station

•Cape Fear River Estuary

•Once-through Cooling

•AIF 1,192- 1,509 MGD

•Extensive Environmental 

Studies, 1970-1980

•Long-term Monitoring 1981-

1993 (Fish & Shellfish 

Populations, I, E)

•Impingement & Entrainment 

Monitoring, 1994-Present 
Intake structure

Fish return system

Intake canal

Nancy's Creek

Gum Log Branch Access road

Diversion

structure

Walden Creek

Cape Fear River

Return basin

N

0

0 1000 2000 3000

500 1000

meters 

feet 

Plant area

Brunswick Steam Electric Plant 

Intake Canal
Fish Diversion Structure
Intake Structure and Fish Return Flume
Mean Percent Survival

Fish Return System (1984-1987)

Blue crab 96

Shrimp 92

Striped mullet 92

Blackcheek tonguefish 83

Flounder spp. 71

Spot 60

Croaker 45

Weakfish 35

Atlantic menhaden 16

Bay anchovy 5

96-hour survival studies 
Annual Number and Percent Reduction of Atlantic Menhaden Impinged 

at the Brunswick Steam Electric Plant, 1977-2009

Prototype fish diversion structure

effective during 1979

Fish diversion structure

Completed Nov 1982

Number impinged Baseline Impingement

Percent Reduction Fish Diversion Structure

X Percent Reduction Fish Diversion Structure & Return System
Annual Number and Percent Reduction of Spot Impinged 

at the Brunswick Steam Electric Plant, 1977-2009

Fish diversion structure

Completed Nov 1982

Number impinged Baseline Impingement

Percent Reduction Fish Diversion Structure

X Percent Reduction Fish Diversion Structure & Return System
Annual Number and Percent Reduction of Atlantic Croaker Impinged 

at the Brunswick Steam Electric Plant, 1977-2009

Fish diversion structure

Completed Nov 1982

Number impinged Baseline Impingement

Percent Reduction Fish Diversion Structure

X Percent Reduction Fish Diversion Structure & Return System
Annual Number and Percent Reduction of Blue Crab Impinged 

at the Brunswick Steam Electric Plant, 1977-2009

Fish diversion structure

Completed Nov 1982

Number impinged Baseline Impingement

Percent Reduction Fish Diversion Structure

X Percent Reduction Fish Diversion Structure & Return System
Annual Number and Percent Reduction of Penaeid Shrimp Impinged 

at the Brunswick Steam Electric Plant, 1977-2009

Fish diversion structure

Completed Nov 1982

Number impinged Baseline Impingement

Percent Reduction Fish Diversion Structure

X Percent Reduction Fish Diversion Structure & Return System
Summary and Conclusions

● Variation in the effectiveness of the technologies was 

species specific.

▪ Menhaden can be characterized by poor survival in the fish 

return system but is effectively excluded from the intake 

canal by the diversion structure.

▪ Blue crab and penaeid shrimp are less effectively excluded 

by the diversion structure but are characterized by high 

survival in the return system.

▪ Spot and croaker represent species that are intermediate 

regarding the effectiveness of the diversion structure and 

return system in reducing impingement mortality. The 

combination of the technologies was necessary to achieve 

overall reductions in IM of 90-99%.
Summary and Conclusions

● The combination of the fish diversion structure, 

modified traveling screens, and return system 

reduced impingement mortality for representative 

species to a level approaching that of closed cycle 

cooling.

▪ Annual reductions in IM ranged from 90-99%.