The application of near-infrared spectroscopy for the detection of secondary uranium minerals using a fibre optic probe

Abstract

The proposed increase in usage of nuclear power implies increased nuclear waste resulting in the formation of many uranyl secondary minerals. These minerals can translocate and a method of easy identification is required. Because many of the minerals contain water and/or OH units the minerals lend themselves to NIR spectroscopy. Spectra of a range of uranyl carbonate, sulphate and silicate minerals were obtained using a fibre optic probe with an ATR cell in reflectance mode. The minerals include andersonite, liebigite, rutherfordine, uranopilite, zippeite, boltwoodite, soddyite, sklodowskite, uranophane and weeksite.
These uranyl minerals are characterised by intense bands at around 7000 cm-1 resulting from second harmonic of the normal mode of the OH groups. Uranyl silicates show intense bands in the 4200 to 5400 cm-1 region. Two sets of bands which are electronic in nature, are observed: one centred upon 10100 cm-1 and a second set around 8500 cm-1 in the high wavenumber region.