Ontario Power Generation (OPG) recently reinstalled fish nets near the water inlet used by the 3,100 MW Pickering Nuclear Generating Station for cooling the plant, the Canadian Nuclear Safety Commission (CNSC) said. CNSC said the measure is aimed at substantially reducing the impact of the plant’s activities on aquatic life.

“We’re starting our third full year of operation and our research shows we’ve significantly reduced the volume of fish entering our water intake channel,” said Glenn Jager, senior vice president, Pickering A.

In 2008, the CNSC raised the problem of fish mortality due to impingement and entrainment as a major issue for OPG to resolve. Impingement affects fish, which die when they are pulled into the screens of the intakes. Entrainment affects eggs, larvae and very small fish that are able to pass through the screens into the cooling system where the water is too warm and pressurized for them. As a result, OPG installed barrier nets in front of water intakes during the spring, summer and fall of 2010.

During 2010, the first year of testing, the net reduced mortality by close to 80 percent. Areas for improvements were identified, however, in response to events involving algae influx and unusually strong lake currents. New design improvements to the barrier nets were implemented by July 2011. The net is about 610 meters long with a half-inch mesh. It’s anchored to the lake bottom and has 19 lighted buoys to warn boaters. It sits about 80 meters from the southern tip of the intake channel.

OPG will continue to monitor year-round screen house fish counts and seasonal net performance in 2012 to determine if the new design is adequate.

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