halflives and energy (Table I), while not yet used in the program, have 

 potential application in multiple isotope studies, or at other places 

 where their particular characteristics might be desirable. 



TABLE I 

 Isotopes Considered for Use in the Study, Showing Halflives and Energy 







Energy 









(million elec- 





Element 



Halflife 

 6U . 8 hours 



tron volts ) 



Abundance 



Gold -198 



.1+1 



96% 



Barium-l^O 



12.8 days 



-5** 



25% 



Lant h anum- 1 k 



U0.2 hours 



1.6 



95% 



Xenon-133 



5.27 days 



.081 



25% 



Krypton-85 



.IO.76 years 



• 52 



o.k% 



Chromium- 51 



27.8 days 



.32 



9% 



The NRDL studies (see Appendix A) indicated that loss by leaching 

 and abrasion of barium-ll+O, lanthanum-ll+O , and chromium-51 from sand 

 labeled with the NRDL water-glass technique is of small magnitude (l to 

 k percent). Some modifications in the size of particles are indicated 

 by the NRDL data but the differences are minor and are probably within 

 the limits of experimental error. Results of tests in the CERC labora- 

 tory, using samples supplied by NRDL, lead to the same conclusion, 

 although there is more spread in the data than with xenonated sand. 



NRDL also conducted experiments on loss of xenon from xenonated sand 

 due to leaching and abrasion. Results of that study indicated approxi- 

 mately 3 to 5 percent of xenon was lost. Recent tests carried out by 

 ORNL personnel indicate loss of xenon is negligible; possibly reflecting 

 the improvement in labeling since the NRDL experiments. 



2. Injection Devices 



An apparatus capable of placing sand on the bottom in deep water, or 

 in the relatively shallow water of the breaker zone, was required. Systems 

 used in previous studies were designed primarily for point source injec- 

 tions and were unsatisfactory for working in a surf zone or for placing 

 labeled sand in a line source. A suitably designed apparatus should be 

 able to make injections in the surf zone and deeper water, inject line 

 sources and point sources, and also provide radiation shielding. 



The initial device used in the RIST study was a cylindrical hopper 

 with pump and hoses (Figure 5) designed to emplace a slurry of labeled 

 sand on the marine bottom, either as a point source or line source. Tests 

 of the apparatus at ORNL and at the April 1967 Cape Kennedy field tests 

 were successful. However, during the first injection of the June 1967 

 test at Surf, California, the sand bridged above the orifice and would 

 not discharge. The device required that sand in the hopper remain dry, 



