Demonstration study on diffusion of warm discharge in sea

The diffusion of warm water discharge from nuclear and thermal power stations is difficult to presume because topography, sea condition, weather and the state of discharge are related complicatedly. In Japan, the method of analyzing the result of long term observation of sea condition at a concerned area, determining the input data, and carefully predicting by mathematical simulation analysis and hydraulic model experiment has been standardized. This procedure has been proved to be adequate by comparing with the actual measurement, but it takes long time. It was found that many physical items were deeply related to the area of diffusion, by the multiple regression analysis of the measured data of warm water discharge. By factor analysis, several main factors controlling the diffusion, which should be regarded as important, were shown. The form of lowering water temperature due to distance changed according to the design of discharge ports, and in the diffusion in high temperature region, the movement induced by jet played as important role. The diffusion equation, to which the above mentioned results of observation were reflected as far as possible, was derived, and it was confirmed by the comparison with the measurement that it was practically usable. (Kako, I.)