3-60 



which is about a third of the maximum tidal currents would be directed 

 down the axis of the intake channel. This effect, which is the worst 

 possible, would bo limited to the width of the intake channel and the 

 immediate vicinity of its westerly end. Further out toward the main 

 channel, the intake velocities would decrease rapidly as the volume of 

 water involved in supplying the cooling-water intake system increased. 

 In the main channel , the intake velocities would be small and their 

 effect on the tidal currents negligible. 



To quantify the velocities and temperatures in the pl\ime, a 

 physical model was constructed and various tests were conducted by the 

 Florida Engineering and Industrial Experiment Station (1972) , and sche- 

 matic representation of the behavior of the discharge plume is depicted 

 in Figure 3-15. Figure 3-16 shows the determined velocity distribution 

 along the axis of the plume. The speeds shown for the 37 to 43 m dis- 

 tances are the speeds measured in the area where the pl\jme intersects 

 the surface, the "boil area". Figure 3-16 shows these speeds to have 

 been approximately 107 cm/sec. Flow-away velocities from the boil area 

 are caused by the initial horizontal component of the momentum of the 

 discharge and, to a lesser degree, by the density-induced convection as 

 the lighter, warm water tends to spread over larger and larger areas. 

 The maximum cross-sectional area of the flow-away velocity is small and 

 is inversely proportional to the velocity (Table 3-2) . To assess the 

 magnitudes of the flow-away velocities, the scale of the model was 

 changed from the 1:20 scale used to obtain the data presented in Figure 

 3-16, to a scale of 1:40. The results of the 1 to 40 scale test show 

 that from the boil zone to the navigation channel the surface velocities 

 were of the order of 61 cm/sec, reducing gradually to about 18 cm/sec 

 near the opposite edge of the channel. The velocities of the discharge 

 plume were directed primarily across the channel even during maximum 

 flow in the channel (approximately 21 cm/sec) . The reason for the 

 cross-channel flow direction of the discharged water was that in the 

 model basin the warmer water tended to ride on top of the cooler water 

 where the main resistance to its flow was the interface friction, which 

 had a relatively small effect on the discharge velocities . In the real 



