Comparable figures for the abrasion experiments were k.k percent and 

 6.3 percent, respectively. In an attempt to improve the accuracy of 

 the measurements, distilled water was used in the static outgassing and 

 abrasion experiments because Xe is more soluble in distilled water than 

 in sea water (Wood and Caputi, 1966). Because the vials were filled 

 completely with water, dead spaces were avoided and the outgassed Xe 

 remained in solution until the vials were opened for assay. About two 

 minutes elapsed from the time a vial was opened until an aliquot was in- 

 serted into the counter for radioassay. It is assumed that a negligible 

 amount of xenon was lost from the aliquot during this time because of 

 the extremely low concentration of the xenon in the solution. However, 

 in an attempt to provide an estimate of the rate of xenon escape from 

 the aliquot as well as to show that the Xe-133 detected in the aliquot 

 was the result of outgassing and not due to a fine suspension of sand in 

 the supernate, the activity of the aliquots from experiments 6S and 1A 

 was followed for 119 hours after separation, with the containers open to 

 the atmostphere continuously. These data are shown in Table A-VTII. The 

 results are given as the fraction of activity remaining in the aliquots 

 after various time lapses. In 2.5 hours about 39 percent of the dissolved 

 Xe-133 escaped from the aliquot from the static experiment and 2k percent 

 from the abrasion-experiment aliquot. In both cases the rate of escape 

 of xenon from solution is much greater than the rate of radioactive decay. 

 The results show that, although 2k to 39 percent of the xenon escapes 

 from the solution in 2.5 hours, prompt aliquoting and counting reduces 

 this loss to a reasonable figure. Further support for this conclusion 

 was obtained from another experiment in which 10 percent of the xenon 

 escaped from the IS aliquot in 30 minutes. It is estimated that the 

 error due to xenon escape from the aliquots prior to radioassay is less 

 than 1 percent of the outgassed xenon.* The results thus substantiate 

 the findings that Xenon-133 is outgassed from the xenonated sand. 



CONCLUSION 



The experimental results show that Xenon-133 is slowly released from 

 xenonated sand in the presence of water. The amount of Xe-133 lost from 

 the xenonated sand to the aqueous phase was relatively small (about 3 to 

 5 percent). There was little difference between the static-experimental 

 results and the abrasion-experimental results. Comparable results 

 obtained with sands tagged with Ba-La-lUO and Cr-51 by the NRDL water- 

 glass technique were 1 percent for the static leaching experiments and 

 k percent for the abrasion experiments (Appendix A, Part l). 



When an aliquot of the supernate from a leaching or abrasion experi- 

 ment was left open to the atmosphere, the dissolved Xe-133 gas escaped 

 into the atmosphere. This proved that the gas was dissolved in the 

 aqueous phase and was not contained in sand suspended in the water. 



The results show that the outgassing of Xe-133 from the treated sand 

 need not be of concern either as a health hazard or with respect to the 

 usefulness of Xe-133 as a tracer for the investigation of sand transport. 



* The outgassing results shown in Table I- VII tend to substantiate this 

 estimate (plateau effect at later times). 



A- 15 



