is not fixed and raay travel into marine waters which are most restric- 

 tive from the standpoint of dispersion, exchange and biological uptcike, 

 as well as being heavily utilized by man. 



The following summarizes the conservative approximations made 

 in this evaluation, 



1. It is assumed, for coastal areas and fishing areas of the con- 

 tinental shelf, that a selected segment of the population receives all 

 its protein requirement from seafood harvested from the marine area 

 subject to waste disposal. This assumption is not overly cautious for 



a country such as Japan, but is quite conservative for the United States. 

 This restrictive assumption is relaxed when considering those areas 

 of the outer continental shelf and open sea which contribute little to the 

 fisheries harvest. 



2. In computing the distribution of activity with time resulting 

 from a given discharge, the radioactive decay was not included. 



3. In computing the effect of discharge of spent ion exchange res- 

 ins, it was assumed that all the activity was immediately released by 

 the resin to the sea water. This is a conservative assumption only if 

 the resins sink. 



4. The effect of initial mechanical dilution on the distribution of 

 activity after release to the marine environment was not included in 

 the computations. This factor would be significant only during the very 

 early stages of dispersion, since the point source solution and the fi- 

 nite source solution to the diffusion equations converge with increasing 

 time. The major importance of initial mechanical dilution would be 

 the reduction of any density difference between the effluent and the re- 

 ceiving waters. The assumption is made that no such density difference 

 exists; hence the major effect of initial mechanical dilution is in fact 

 indirectly included in the evaluation. 



5. In the computations for the outer continental shelf and for the 

 open sea, the possible transport of activity out of the surface layer by 

 settling of particulate material was not included. In inshore waters it 

 is possible that this process would be detrimentcd, since activity could 

 be concentrated onto bottoms where important shellfish and bottom 

 feeding fin fish occur. 



6. The highest measured concentration factors for the uptake of 

 a specific isotope by the biota were employed in the calculations, ex- 

 cept that where concentration in the skeleton was important, one-tenth 

 of the concentration factor from sea water to bone was used, since bone 

 makes up about one-tenth of the edible portion. 



Possible non-conservative features of our estimates include the 

 following. 



47 



