A numerical model of the effects of reactor cooling water on fjord circulation. Part 2, figures

In the search for possible sites for new nuclear power plants in Sweden a site on Braaviken, a narrow fjord, is being considered. A numerical hydrodynamic model has been developed to predict the probable effects of the waste heat disharged into the estuary on the natural estuarine flow. The model employs the basic equations of motion and conservation of salt and heat with appropriate approximations to make predictions. The primary approximation in the model consists of considering the estuary as a channel in which cross channel effects do not explicitly appear. The along channel motion is thus primary determined by the along channel density gradients. With the construction of a bottom intake located at the depth of about 40 meters there will be little noticable effect on the circulation, temperature or salinity fields in the estuary in the summer. However in the winter the bottom intake offers only a partial improvement over a surface intake. During the winter the heated water would cause changes of as much as 50 % in the natural state. The surface intake would cause changes which sometimes are almost twice as big. The problem arises because the 10 deg C heated water creates sizable horizontal density gradients which are sufficient to counteract the weak natural flow