PART 2 

 XENONATED SAND: LEACHING AND ABRASION STUDIES 



INTRODUCTION 



The U. S. Army Coastal Engineering Research Center and associated 

 agencies are studying littoral transport of beach materials past coastal 

 promontories at Point Conception, California. Sand labeled with radio- 

 active nuclides is used to trace the littoral migration of the beach 

 materials. The first injection of sand labeled with radioactive Xe-133 

 occurred in June 1967- The technique for labeling sand with Xe-133 was 

 developed at Oak Ridge National Laboratory (F. N. Case and E. H. Acree, 

 Oak Ridge National Laboratory, personal communication) and is similar to 

 the familiar kryptonation technique (Carder, 1966), in which Kr-85 is 

 diffused at high temperatures and pressures into solids . The depth of 

 penetration of Kr-85 into the host solid is 103 to 105 A. Kryptonated 

 solids remain stable (no outgassing) with time at room temperature, 

 barring surface reactions such as oxidation or hydration of the host 

 solid. Although similar behavior is anticipated for xenonated solids, 

 due allowance must be made for the enhanced size of the xenon atom over 

 that of krypton, because the labeling mechanism for both techniques de- 

 pends on the entrapment of the noble gas in the interstitial spaces and 

 structural voids of the host solid. The objective of the investigations 

 reported in this paper is to determine whether outgassing of Xe-133 will 

 occur when xenonated sand is subjected to conditions prevailing at the 

 water-sand interface of a marine environment. 



Laboratory experiments were designed to determine whether outgassing 

 of Xe-133 from xenonated sand occurred. The experiments were similar to 

 those that were used to test the integrity of the Naval Radiological 

 Defense Laboratory (NRDL) water-glass technique for labeling sand with 

 radioisotopes (Appendix A, Part l). Static water tests were made to 

 determine the effect of water in causing outgassing of the xenonated 

 sand, and abrasion tests were made to determine the radioactivity loss 

 caused by the mutual abrasive action of the sand particles as would be 

 experienced in the surf zone. 



EXPERIMENTAL 



At ambient temperatures and pressures zenon is a gas with a charac- 

 teristic valence of zero. This property necessitates the use of a closed 

 system for investigation of the outgassing of Xe-133 from zenonated sand. 

 A desirable apparatus for this study would utilize all-glass construction 

 with provisions for sample agitation and for removal of outgassed Xe at 

 desired intervals. However, limitations on time and funding precluded 

 the possibility of constructing and testing such an apparatus. In place 

 of this apparatus simple experiments were prepared in 25-milliliter screw- 

 cap vials. The vials were sealed with polyethylene gaskets seated in the 

 caps. Six static experiments and six abrasion experiments were prepared 

 with these containers in the investigation of the outgassing of Xe-133 

 from the sand as a function of time. 



A-12 



