Ontario Power Generation has high hopes that a fish barrier net installed at the mouth of the Pickering nuclear plant’s intake will significantly reduce the number of fish sucked in every year.

The intake draws water from the lake into the plant and the Canadian Nuclear Safety Commission (CNSC) has asked OPG to reduce the number of fish lost in the intake by 80 per cent.

A count in 2004 found about 950,000 fish were drawn into the plant, said OPG’s Tho-Dien Le, section manager for environmental support and services. Fish that swim up to the plant are caught in barriers and ultimately landfilled.

OPG has identified several different types of fish that enter the intake, including alewife, yellow perch, rainbow smelt, brown bullhead and walleye. But about 50 per cent of the fish caught are round goby, an invasive species considered undesirable in the lake.

Ms. Le said OPG considered about eight technologies before choosing to install a barrier net in October, 2009. The net is about 610 metres long with a half-inch mesh. It protrudes about 77 metres from the southern tip of the intake channel.

Divers regularly check it for tears and other damage.

“It’s very important for us to maintain the net. We do not want it to rip because it would eventually end up in our nuclear system,” said Ms. Le.

The net is removed in the winter because the icy conditions make it unsafe for the divers and it is reinstalled in the spring. Ms. Le said the bulk of the fish enter the intake channel in the summer; in the winter fish activity slows down and they’re much less likely to swim into the intake.

OPG is working on quantifying the impact of the net, but anecdotal evidence shows that it’s working.

“We’re no longer seeing the big fish,” said Ms. Le, adding there’s been a reduction in algae and zebra mussels getting into the plant as well. “That indicates to us the barrier net is working.”

The CNSC has also asked OPG to reduce the loss of fish eggs and larva due to the intake by 60 per cent. To make up for that, OPG will look at a stocking program and a fish habitat restoration program. The company is working with the local conservation authority and in the past, OPG has spent millions on habitat restoration projects across Ontario.

Ultimately, if the net doesn’t work, Ms. Le said OPG will try the next best technology, but she expects OPG will be able to meet the CNSC’s targets. The Darlington plant is newer and has a different intake design which draws water from a greater depth in the lake and does not have an issue with fish being drawn into the plant.

via durhamregion.com | OPG hopes net will stop fish from swimming into nuclear plant.