28. 



steady state the rate at which activity becomes available for diffusion 

 is equal to the rate of disposal (no containment), and within certain re- 

 strictions as to the relative dimensions of the disposal area, water 

 depth, and distance from the disposal area for which the theory is 

 valid, a relationship is presented that permits calculation of the max- 

 imum concentration that will be found at various distances downstream 

 from the disposal area. A specific case is cited in which the rate of 



supply is 100 curies per year, the water depth 30 meters, the diffusivity 



2 , 

 1 cm /sec, and the current velocity 5 n. mi. /day. The maximum con- 

 centrations at 1, 10, and 100 km downstream from the source will be 



-7 -7 -7 



2. 1 X 10" , 0. 7 X 10" , and 0.2 x lO' uc/ml respectively. These con- 

 centrations are approaching the MPC values for drinking water, and as 

 will be shown later, also the maximum permissible concentrations in 

 sea water. However, it should be emphasized that these figures are 

 most certainly on the conservative side. No allowance has been made 

 for "cooling" in the disposal container, which would modify the assump- 

 tion that diffusion rate is equal to disposal rate; and it is assumed that 

 no removal takes place by processes such as association with bottom 

 deposits and suspended sediments, or through the marine biota. 



Diffusion from individual sources. The analogues of the theoretical 

 model are the disposal containers. Two cases are considered. In the 

 first, the waste is available for diffusion upon contact with the bottom; 



