Wedgewire Screens Can Solve Entergy's Fish Egg Problem

Many nuclear power plants in the United States are going through feasibility studies to consider technologies to comply with an expected revision to Section 316(b) of the Clean Water Act, which sets out rules related to fish impingement and entrainment. 316(b) requires that the location, design, construction and capacity of cooling water intake reflect the best available technology for minimizing the environmental impact on fish and other aquatic life.

In the U.S. 35 of the 104 active nuclear power reactors currently use closed-cycle cooling towers while 60 use once-through cooling technology. EPA said that while their information on impact is limited, the agency claims it does know that trillions of aquatic organisms are impinged or entrained annually. EPA also said that 40 percent of all cooling water intakes are on water bodies that have threatened or engaged species.

Installation of screens at the Oak Creek Station
 on Lake Michigan. Photo courtesy WE Energies

Existing power plants do have options besides expensive and unworkable cooling tower retrofits in order to reduce impingement and entrainment. Behavioral devices intended to scare fish away from the intake system, fish collection and transfer systems, which are intended to collect and return the species to the source body of water, and exclusion devices are three alternatives for cooling water intake structures. Exclusion devices include traveling water screens manufactured by companies such as Pro-Line Water Screen Services Inc. and narrow slot wedge wire screens constructed by Intake Screens Inc., as well as many other companies, and are deployed to keep fish, fish eggs and larvae from entering the power plant cooling system.


Indian Point Energy Center

In April the New York Department of Environmental Conservation (DEC) issued a notice of denial for Entergy’s request for a water quality certificate for Indian Point. The DEC said the plant will not comply with the states water quality standards and that the plant’s water intake system and its releases of water back into the Hudson River are killing two species of fish. Indian Point must receive the water quality certificate in order for Entergy to request a 20-year license extension for Units 2 and 3, which are currently due to expire in 2013 and 2015. In late-July the DEC Administrative Law Judge held public meetings for both sides to voice their opinions. The appeals process is still ongoing.

According to Entergy conversions alone to the Indian Point plant would cost $1.1 billion for construction and would last until 2029 and being down a year without producing electricity total another $2 billion. Constructing cooling towers on site would require blasting 2 million cubic-yards of rock and granite over a period of four years in order to make space for the towers that are the size of two Yankee Stadiums.

Entergy has found technology that will provide better protection to the aquatic environment. Wedge wire screens are their solution for protecting fish eggs and larvae rather than cooling towers over the 20-year license renewal period. Installing wedge wire technology it would take three to five years and cost $200 million. (PowerGenWorldWide, Oct 1, 2010)