Water resources research program. Thermal plumes from submerged discharges at Zion Nuclear Power Station: prototype measurements and comparisons with model predictions

Several field surveys of thermal plumes from the two submerged discharges at the Zion plant were carried out during 1975. The survey results are presented in the form of horizontal isotherm maps at vertical intervals of 0.5 m from the surface to a depth of 3.0 m. Selected vertical cross sections are also presented. It was found that the direction of the ambient lake current, with respect to the initial discharge direction, can have a significant effect on initial dilution as well as subsequent plume size. The plumes from the two outfalls were found to interact significantly, resulting in the double-discharge plume being more than ten times as large as the sum of two separate single-discharge plumes. The results of the field measurements are compared with several analytical model predictions and with the results of preoperational physical-model studies. The surface isotherm areas are also compared with data collected at several surface-discharge sites. Compared with the surface discharges, the submerged discharge at the Zion plant produces larger initial surface dilutions and much smaller high-temperature isotherm areas. The differences, however, become less striking after the excess temperature has dropped to about 20 percent of its initial value