Massive cooling water dispersion behavior in a shallow macro-tidal coastal zone in Korea

The Hanbit Nuclear Power Plant is located on a macro-tidal coastline in mid-western Korea; it generates 5900 MW of electricity through 6 units. It discharges 354.6 m(3) s(-1) of cooling water, with excess temperature of Delta T = 7.6 degrees C, into the shallow coastal water. The mean depth around the Hanbit NPP is similar to 10 m, in which strong tidal currents of >1.0 m s(-1) occur during spring tides. This study examines the complex thermal dispersion in a shallow sea environment. To accurately delineate the dispersion characteristics, 15 sets of seasonal field observations for wave, tide, tidal currents, and water temperature were conducted over 3 years from 2002 to 2004. Water temperature at 30 stations around the power plant was measured simultaneously over a 15-day period to investigate seasonal changes in the tidal hydrodynamics. Spectral analysis was employed to understand the dominant semidiurnal forcing upon thermal plume movement. The results revealed that wide thermal plumes were spreading beyond the regional tidal excursion. Numerical models based on two-dimensional hydrodynamic advanced circulation (ADCIRC) and fine-grid Eulerian-Lagrangian transport models were also developed, which reproduced the results of the field observations with satisfaction.