In the samples so far tested, the sand grains are slightly modified 

 by tagging. In both xenonated and gold-tagged sand a color change is 

 noticeable . 



The untagged sand, after being leached in hydrocholoric acid, was 

 medium grained (Xj> = 1.7; .31 mm), was largely quartz with accessories 

 of feldspars, metamorphic rock fragments, and heavy minerals; and was 

 light gray in color (Munsell color code 2.5 Y 7/2 or 10 YR 7/2). 



Xenonated sand was medium grained (X, = 1.6; .33 mm), color was 

 gray (7.5 YR 6/0). No noticeable change in grain morphology occurred 

 although some agglomeration was noted, and was attributed to fusion of 

 some grains in contact with the heating elements of the xenonation 

 furnace during labeling. 



The gold-tagged sand has a weak red color (2.5 YR 5/2), and although 

 after tagging it still lies in the medium grain class (X fi = 1.97; 25 mm), 

 it is shifted to the extreme fine end of the class and tne number of size 

 classes (variance) is narrowed (Figure 2) . Some agglomeration of the 

 gold-tagged sand occurred due to accidental overheating during the curing. 



Differences between size characteristics of the gold-labeled and 

 unlabeled sand are more difficult to explain than the small amount 

 of agglomeration, and size analysis of gold-tagged sediments used in 

 subsequent studies continues. Reproducibility in the size gradation 

 process is much better than the differences apparent in Figure 2, and 

 is therefore not considered as a cause for the deviations. As the size 

 characteristics of the actual gold-tagged sand were within the range 

 of characteristics of the sand at the test site, it is judged that no 

 deleterious effects were thus introduced into the experiment. No de- 

 tectable difference in specific gravity (2.65) of the sand occurred as 

 as a result of the gold tagging;none was anticipated because only a few 

 milligrams of metallic gold are used in tagging a liter (about 1,500 

 grams) of sand. 



2. Injection Devices 



As an improvement upon previously used emplacement techniques, 

 water-soluble plastic bags were utilized. Available in different thick- 

 nesses and hot-water and cold-water types, this polyvinyl alcohol mate- 

 rial has proved to be very useful. The cold-water variety is used and 

 dissolves in 20 to 30 seconds in the limited temperature range tested 

 (19-21 degrees centigrade) . The ORNL packages tagged sand which arrives 

 at the site ready for use. Prepackaging greatly facilitates field-site 

 handling, and makes safety considerations simpler. Xenonated sand is 

 packed in 1- liter quantities which are handled easily with long-handled 

 tongs . 



Gold-tagged sand, packaged in small packets of approximately 15 grams, 

 is placed in a slotted rod fitted inside a shielded cylinder (Figure 3) . 



