X-ray absorption spectra measurement and analysis with the first principles calculation for Americium oxide (AmO2)

Minor actinides (MA:Np, Am, Cm), which are long-lived radionuclides, are accumulated in the spent nuclear fuels from nuclear power plants, so that disoposal of these MAs is impotant problems for nuclear energy uses. In prticular, the valecy change of Am with strong radiotoxicity has a strong influence on oxygen potential and thermal properties of Am-mixed oxide (MOX) fuel, so that it is important to clarify the electronic state around Am atoms in Am-MOX fuel. XANES involves important infomaton to clarify the electronic state around the specific atom in the bulk specimen, but XANES analysis has not been repoted with repect to Am oxides such as AmO2 and Am2O3 as well as Am-MOX. We evaluated the electronic state around Am atom by XANES measurement in transmission mode with radiation light and XANES analysis with the first principles calculation. (Fig .1) We are going to perform XNAES meassurement and analysis for Am2O3 or (U, Am)O2-x with various compositions as simulants of Am-MOX fuel.

Fig. 1 Experimental and calculated spectra of Am LIII XANES of AmO2

References
[1] T.Nishi et al., "EXAFS and XANES study of americium dioxide with fluorite structure", J. Nucl. Mater, 374, pp.339-343 (2008).
[2] C. Suzuki et al., "XANES and the electronic strucuture of Actinide oxide", 7th International Workshop on Materials Models and Simulations for Nuclear Fuels, (2008)
[3] C. Suzuki, T. Nishi, M. Nakada, M. Akabori, M. Hirata, Y. Kaji, "Calculation of the electronic structure of AmO2 and Pr6O11 for XANES analysis with redox property", Int. J. Quam. Chem. 109 (2009) 2744-2752.
[4] C. Suzuki et al, "XANES and the electronic state of Am oxide", 8th International Workshop on Materials Models and Simulations for Nuclear Fuels, (2009).