Considerable care should be taken in any evaluation that the po- 

 tential additive effect of exposure to radiation from various sources 

 is given due consideration. The second step in the evaluation is then a 

 consideration of all sources of radiation exposure to the particular seg- 

 ment of the population which would also be potentially affected by the 

 waste disposal operations. On the basis of such consideration a portion 

 of the maximum permissible dose is assigned to sea disposal. 



The next step is the consideration of the various routes which the 

 radioactivity can take in reaching man from the marine environment. 

 Here an evaluation of the uses man maikes of the marine environment is 

 required. The possible danger of direct radiation, the harvest of sea- 

 food, possible contamination of fishing gear and of beach sand are some 

 of the items which should be considered at this stage of the study. 



The determination of the maximum permissible concentrations of 

 the various significant isotopes in those parts of the marine environ- 

 ment (seafood, bottom sediments, and shore material), which constitute 

 the routes by which radioactivity may return to man from the sea, then 

 follows as the next step in the process. From a consideration of the 

 known factors by which the biota and the sediment concentrate the var- 

 ious radioactive isotopes from the sea water, it is then possible to ar- 

 rive at the maximum permissible concentration of the various isotopes 

 in the sea water. 



The final steps involve evaluating the changes in the concentration 

 and distribution of radioactivity which may be brought about by 



(a) exchange between bottom sediment and suspended or dissolved 

 matericLL in sea water; 



(b) advection and turbulent diffusion, both within a given marine 

 environment and between adjacent environments; 



(c) initial mechanical dilution, influenced by manner of discharge; 

 and 



(d) physical and chemical form of the wastes at time of release. 



The end result is an estimate of the maxinnum rate of introduction 

 of radioactive material which will not exceed the maximum permissible 

 concentration in sea water. 



In the present problem of waste disposal from nuclear-powered 

 ships, some modification of this ideal step-wise procedure must be 

 made since we are not dealing with a fixed region of the marine or 

 coastal environment. For this reason it has been necessary for this 

 working group to take a conservative (safe) assumption at each step of 

 the evaluation. Thus, for inshore and coasted environments, when 

 considering the return route to man of radio-isotopes through seafood, 

 the assumption used here is that man receives all his protein require- 

 ment from seafood, and that the highest known concentration factor for 



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