Heat treatment for the control of marine fouling at coastal electric generating stations

The thermal tolerance of three dominant marine fouling species common to circulating water systems of coastal electric generating stations in Southern California was determined. Of the three species, the bay mussel (Mytilus edulis) was found to be the most tolerant of elevated temperatures. The barnacle (Balanus tintinnabulum) was intermediate, while the hydroid (Syncoryne eximia) exhibited the least tolerance. Although no significant difference was revealed between most Mytilus size classes, a trend toward increased thermal tolerance in larger individuals was indicated. With one exception, significant differences between temperature rise rates and Mytilus ED95's were revealed, however, the pattern was not consistent. Durations required to kill 95 percent (ED95) of the mussels, barnacles, and hydroids tested at three target temperatures were established. These results will be utilized along with additional biological data and engineering design and operating considerations to examine present operating practices and if possible derive an improved heat treatment mode for Southern California Edison Company's San Onofre Nuclear Generating Station, Units 2 and 3.