On the Incorrect Derivation and Use of In-situ Retardation Factors from Natural Isotope Profiles By I.

Abstract

The characterization of the retardation of radionuclides during their transport by deep groundwaters is complex, time-consuming and, in many cases, inherently limited by technical problems. The stated goal of many natural analogue studies is thus the direct quantification of solute retardation in-situ in relevant geological environments. This paper reviews the claims for a methodology for determining in-situ retardation factors from a mathematical deconvolution of multiple radioisotope measurements of natural decay series elements. It is concluded that the assumptions involved in development of the mathematical approach are geochemically inconsistent and inapplicable to most geological systems of interest. Misapplications of this model are identified and the dangers of accepting its nonsensical output are discussed.

The Behavior of U- and Th-series Nuclides in Groundwater

“…The role of these studies in radionuclide containment performance assessments has been discussed by Ivanovich et al (1992a) and Smellie et al (1997). Reservations have been put forward about the applicability of the information obtained from natural radionuclide modeling studies to anthropogenic nuclides that may be released at higher concentrations and in waters that have distinctive characteristics (McKinley and Alexander 1996). It is indeed clear that such studies cannot fully examine all the important characteristics at sites to support concrete predictions about pollutant migration.…”