the distxibution of concentration steady. 



Since the source area is actually a collection of discrete small sources , 

 the question of micro- scale distribution of concentration arises. In this case 

 the Individual packages are treated as small but finite box sources of knovm 

 volume and surface area. We consider two different problems in order to es- 

 tablish certain limits of activity concentration : (a) If the complete contents 

 of the box are suddenly allowed to disperse into the environment we have the 

 case of an instantaneous source and the resulting distribution of concentration 

 in the environment is time dependent, (b) If the radioactive material is sub- 

 ject to a uniform rate of leaching througji the walls of the box we have the case 

 of a continuous source \\^ere a steady state of distribution of concentration is 

 attained in the vicinity of the source. In both cases our interest focuses on the 

 maximum concentration which may result at different distances from the source. 

 For case (a) we are also interested in evaluating the time for which the activity 

 concentration is above a prescribed value . 



I. SUSTAINED GROSS SOURCE 

 We consider a source area on the sea bed with horizontal dimensions L x L 

 in a depth of water D . Furthermore, we consider a uniform current of speed 

 U parallel to shore . For large distances from the center of the source area , 

 particularly if D <Ji L , the source is essentially equivalent to a vertical line 

 source contained between two parallel planes. If Q. represents the rate of 

 supply of radioactivity of a given isotope to the source region (and also the rate 

 of dispersal as well) , then the concentration of radioactivity, C. , due to 



