Features

SAN CLEMENTE — Lights, loud underwater noises and a curtain of air bubbles haven’t stopped fish from getting caught in the San Onofre nuclear power plant’s ocean water cooling system, according to a coastal commission report. 

Over the past 10 years, the power plant, operated by Southern California Edison Co., has been testing various methods that would reduce the number of fish killed by the generator cooling system that sucks in sea water at a rate of 2 feet per second. 

The alternate methods tested either failed to deter fish, were too expensive to install and maintain, or were harmful to other marine life, the report said. 

The California Coastal Commission, which ordered the study, was scheduled to discuss the report at its meeting Thursday in Oceanside but the commission does not have to take action. 

The report recommends that the power plant be allowed to stop researching other fish deterrence methods and be allowed to continue current methods as long as fish deaths don’t increase. 

“Nobody can come up with any techniques that work better than what’s working now,” said Susan Hansch, director of the commission’s Energy, Ocean Resources and Water Quality Department. “This is one place where (Edison employees) have really tried.” 

The San Onofre Nuclear Generating Station, located along the southern tip of the Orange County coast, currently diverts larger fish from intake pipes with guiding vanes that lead fish to an elevator, which returns them to the ocean. 

The intakes for San Onofre’s Units 2 and 3 reactors kill about 20 tons of adult fish a year, according to the commission’s Marine Review Committee. The current fish protection measures save about 4.3 tons of fish a year and meet commission requirements. 

The tests to further reduce fish deaths included using strobe lights, mercury vapor lights and varying intensities of light. Researchers also tested air bubble curtains, pneumatic guns and electrified nets. 

“The results were very mixed. Some fish were attracted, some were sent in other directions, depending on the species,” said David Kay, manager of Edison’s marine mitigation program. 

The power plant also cleans its intake system with warm water, which dissuades fish from entering the pipes. 

The intake is heated about seven times a year by reversing the flow of water through the system. Workers increase the water temperature gradually to drive fish from the system before the temperature reaches lethal levels.