Corrosion and transport of depleted uranium in sand-rich environments

Abstract

The firing of depleted uranium (DU) weapons during conflicts and military testing has resulted in the deposition of DU in a variety of sand-rich environments. In this study, DU-amended dune sand microcosm and column experiments were carried out to investigate the corrosion of DU and the transport of corrosion products. Under field-moist conditions, DU corroded to metaschoepite ((UO 2) 8O 2(OH) 12·(H 2O) 10) at a rate of 0.10 ± 0.012 g cm −2 y −1. This loosely bound corrosion product detached easily from the coupon and became distributed heterogeneously within the sand. The corrosion of DU caused significant changes in the geochemical environment, with NO 3 - and Fe(III) reduction observed. Column experiments showed that transport of metaschoepite was mainly dependent on its dissolution and the subsequent interaction of the resulting dissolved uranyl ( UO 2 2 + ) species with sand particles. The modelling results predict that the transport of U released from metaschoepite dissolution is retarded, due to a slowly desorbing surface species (first order desorption rate constant = 5.0 (±1.0) × 10 −8 s −1). The concentrations of U eluting from the metaschoepite column were orders of magnitude higher than the World Health Organisation’s recommended maximum admissible concentration for U in drinking water of 15 μg L −1. Therefore, a relatively high level of mobile U contamination would be expected in the immediate proximity of a corroding penetrator in a sand-rich environment.