NSWC/WOL/TR 75-3 5 



cobalt chloride, were incorporated in an explosive charge of TNT. 5 

 The amount of tracer in the water samples was analyzed chemically. 



Radioactive tracers were employed in the HYDRA-IIA series 

 sponsored by the Naval Radiological Defense Laboratory during the 

 early 60' s. The radioactive tracers used on HYDRA-IIA were 

 Lutetium-177 and Xenon-133, which provided excellent results in 

 following the history of the explosion products, because extremely 

 low concentrations of radioactive materials are detectable. The 

 disadvantages of using radioactive tracers are (1) difficulty in 

 handling due to high level of radiation, (2) a source of pollution 

 affecting the marine environment, and (3) relatively expensive. 



Fluorescent dyes are used frequently by oceanographers for the 

 study of diffusion processes and as tracers for sewage and other 

 pollutants. They do not have the undesirable features of radioactive 

 tracers. A container of fluorescein dye, mixed with water, can be 

 attached to the supporting cable directly above the charge. A 

 ratio of one lb of dye to 100 lb of explosive should provide 

 visibility for at least one-half hour. 3 



With the help of the tracers, sampling can be done by locating 

 the pool and traversing it with a small boat. If the approximate 

 location of the pool can be predicted beforehand, an array of fixed 

 sampling stations can also be set up before the explosion. Samples 

 can then be collected at a time sequence and at various depths. 



Dye concentration can be measured in-situ or in sampling bottles 

 with a fluorometer. Dye concentration can also be determined from 

 an aerial photographic negative with a photodensitometer . This 

 method has the advantage of providing data for the entire surface 

 pool at selected times. 



Young, G. A., op cit, pg 9 



5 Young, G. A., "Effects of the Explosion of 45 Tons of TNT Under 

 Water at a Depth Scaled to Test Baker", Naval Ordnance Laboratory, 

 NAVORD Report 2891, 1953. 



6 Ichiye, T. and Plutchak, N. B., "Photodensitometric Measurement of 

 Dye Concentration in the Ocean", Limnology and Oceanography, l±, 

 No. 3, 364 (1966) . 



16 



