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This report was prepared as an account of work sponsored bv the Umtrd States Government. Neiner Ihf United Sutes nor the United Sutrs Deputmrnt of Encriv. nor tnv of iheir lh"ir employees, makes any warranty, express or implied, or assumes any le^Kl liability or responsibility i*or the accuracy, completenesi. or usefulness of any tn:irm»tion. apparatus, product, or process disclosed, or represents that iU use would not infringe privately owned rights. SORPTION-DESORPTIOr STUDIES OF NEVADA TEST SITE ALLUVIUM AND LEACHING STUDIES OF NUCLEAR

This article describes a field experiment studying the migration in alluvium of radioactive elements away from an underground nuclear explosion at the Nevada Test Site in the United States. Nuclides detected in the pumped water are tritium and chlorine-36 -both at levels below the maximum permissible concentration for drinking water in controlled areas. The chlorine-36 elution curve precedes that of tritium and is due to an anion exclusion process. A conventional two-dimensional convection-diffusion equation does not fully describe the elution curves for tritium and chlorine-36; the tailing of the curves is longer than predicted. Successful modeling of this experiment will be important for validating codes and models to be used in the high-level nuclear waste program.

We have developed a method to determine >10* atoms of **Tc or *7Tc and 5 X 10* atoms of **Tc by negative thermal ionization mass spectrometry. Interferences from Isobaric Impurities or hydrocarbons are equivalent to 5 X 10* atoms of technetium or less. Lanthanum oxide Ion enhancers In conjunction with Ca(N03)2 are added to single, zone-refined rhenium filaments to achieve Ionization efficiencies that are >2% for the formation of Tc04~.