During recent investigations into the properties of spent nuclear fuel (SNF), substantial phase alterations of UO2 have been observed.1 The moist, oxidising environment of fuel repositories has been found to encourage the formation of uranyl containing minerals such as schoepite and studtite.2, 3 These complex transitions affect the chemical and physical properties of SNF - studtite has been seen to affect the mobility of radionuclides in SNF - and have massive ramifications for the stability of the fuel in long-term storage.4This presentation details the examination of ten uranyl minerals via photochemical and cyclic voltammetric techniques to compare the effects of varying interstitial cations (Na+, K+ or Ca2+); bridging anions (O22-, OH-, CO32- or PO43-) and structural motifs (1D chain or 2D layer) on the redox chemistry of the mineral, leading to a better understanding of the mechanism of leaching of radionuclides from SNF. HR-XANES and EXAFS were also used to better understand the differences between studtite and its dehydrated form metastudtite.1. B. D. Hanson, B. McNamara, E. C. Buck, J. I. Friese, E. Jenson, K. Krupka and B. W. Arey, Radiochim. Acta, 2005, 93 , 159-168.2. D. J. Wronkiewicz, J. K. Bates, S. F. Wolf and E. C. Buck, J. Nucl. Mater., 1996, 238 , 78.3. R. J. Finch and R. C. Ewing, J. Nucl. Mater., 1992, 190 , 133.4. P. C. Burns, K. M. Deely and S. Skanthakumar, Radiochim. Acta, 2004, 92 , 151-160.

Uranyl minerals and their relation to spent nuclear fuel

246th National Meeting (2013)

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