Chapter 6 



PRECIPITATION OF FISSION PRODUCT ELEMENTS ON THE OCEAN 

 BOTTOM BY PHYSICAL, CHEMICAL, AND BIOLOGICAL PROCESSES 



Dayton E. Carritt, The Johns Hopkins University 



and 

 John H. Harley, Health and Safety Laboratory, U. S. Atomic Energy Commission 



Introduction 



It has been suggested that naturally occurring 

 processes will remove radioactive waste mate- 

 rials from solution or suspension in the oceans, 

 carrying them to the ocean floor where they will 

 be kept out of the human environment until 

 natural radioactive decay destroys them. 



In this section we will attempt to define the 

 processes by which materials may be carried to 

 the bottom, to note the conditions under which 

 these several processes can be expected to op- 

 erate, and to assess the extent to which these 

 processes have been responsible for the removal 

 of activity to the bottom in cases where bottom 

 accumulation has been measured. 



It should be noted that the deposition of fis- 

 sion products on the bottom has not been stud- 

 ied in such a way as to permit an evaluation of 

 the mechanisms responsible for the deposition 

 and retention of the activities. Measurements 

 of bottom-held activities have been made pri- 

 marily to estimate the total activity. We will 

 discuss later the kind of information that might 

 be obtained in connection with weapons tests 

 and large-scale tracer experiments, and which 

 is needed for a better evaluation of the extent 

 to which deposition processes remove fission 

 product elements from the ocean. 



Sources of Fission Products 



The oceans may receive fission products from 

 two sources, materials from each of which have 

 unique properties important to deposition. The 

 two sources are: 



(1) Radioactivities resulting from bomb bursts, 

 either in weapons testing or military use of 

 bombs in war time. Partial controls can be 

 put on the location and time of weapons tests 



to take advantage of desirable dispersal or con- 

 centrating properties of the oceans. 

 (2) Radioactivity obtained from nuclear power 

 production plants and released to the oceans for 

 containment or dispersal. The time and location 

 of introduction of wastes of this type can be 

 controlled to obtain optimum oceanic charac- 

 teristics, and the character of the wastes might 

 be altered by the removal of one or more un- 

 desirable active or inactive constituents. 



In both cases it can be expected that the 

 fission products will partition into a soluble and 

 an insouble fraction. An estimate of the ele- 

 ments that will appear in each fraction is given 

 in another part of this report. 



This division into soluble and insoluble frac- 

 tions presents essentially two different systems 

 so far as deposition or dispersal processes are 

 concerned. 



Deposition and Retention Processes 



Deposition and retention of fission product 

 waste on the ocean floor will occur when the 

 waste is sufficiently denser than sea water to 

 permit it to settle to the bottom, and when the 

 stability of a waste-bottom component complex 

 is sufficiently greater than the stability of soluble 

 complexes that might form to prevent its re- 

 dissolving. 



Solid formation 



The "denser-than-sea-water" requirement can 

 be met when one of two processes occur: (1) 

 the formation of insoluble substances by inter- 

 action of the radioactive components of the 

 wastes with a sea water component, and (2) 

 sorption of the radioactive components of the 



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