Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements. 1998 annual progress report

'This research develops techniques for measuring globally distributed radionuclides occurring today in extremely low abundances (fallout from the era of atmospheric nuclear testing), and then applies these techniques to better understand the mechanisms by which radionuclides migrate. The techniques employ accelerator mass spectrometry (AMS), a relatively new analytical tool that permits this work to be conducted for the first time. Because the nuclides addressed in this project originated from thermonuclear events, they are generally those of most concern when assessing the extent of and risk from actual or potential radioactive contamination. The advantages of the authors approach include: (1) the ability to conduct migration studies in locations most like those of concern to public health, e.g., a far-field environment; (2) sites of multiple contamination, e.g., by VOCs, can be avoided; (3) it becomes unnecessary to collect research samples that are themselves radioactive waste and are therefore difficult to handle and dispose of in the laboratory; and (4) since the nuclides are globally distributed, migration research can be conducted in any chosen environment. This report summarizes the research progress through the first 16 months of a 3-year project. It discusses the work completed and in progress on the development of AMS techniques for {sup 99}Tc, {sup 129}I, {sup 36}Cl, and the development of a demonstration field site chosen for this project in arid unsaturated soils.