원전 취수구 스크린 막힘 현상 규명을 위한 동해 연안 표층에서의 Salpa fusirormis의 분포

Abstract

Euphausiids and jellies have been reported to be the main organisms to clog the drum screen in the cooling water supply system of the nuclear power plant at Uljin, eastern coast of Korea. However, a large amount of gelatinous plankton was also sucked into the seawater intake and clog the screen at 18 Jun 2003. The animals were mainly identified later as Salpa fusiformis, while other various gelatinous plankters of small size were also included. Korea Hydro & Nuclear Co. estimated presumptively the whole amount of the clogged animals at 295 ton and the malfunction by the animal clogging caused 38% of decrease in generation capability of the power plant. We examined distributional patterns of zooplankton near the nuclear power plant using a ecosounder with 200kHz transducer and sets of multiple towing nets during the day and at night from 5 to 6 Jun 2003. Shallow DSL by gelatinous plankton was observed in broad area. Correspondent net samples included various gelatinous zooplankton known to be warm water current species of salps, Salpa and Doliolum, and siphonophores, Diphyes and Muggiaea. The larger speices, Salpa fusiformis occupied 25.4% in individual density among the gelatinous plankton and showed surface distribution in the depth shallower than thermocline, but did not perform diel vertical migration. TS and satellite data showed warm current predominated over the southern region from the power plant in Jun. The results suggested that warm surface current developed near the coast may cause clogging power plant intakes at Uljin by gelatinous plankton.