Oxygen potentials of PuO 2-x were measured at temperatures of 1473 -1873 K by thermogravimetry. The oxygen potentials were determined by in situ analysis as functions of oxygen-tometal ratio and temperature. The measurement data were analyzed on the basis of defect chemistry and an approximate equation was derived to represent the relationship among temperature, oxygen partial pressure, and deviation x in PuO 2-x .
h i g h l i g h t s CEF model of the Gibbs energy for fluorite U 1Ày Ce y O 2±x and (U,Ce) 3 O 8 phases. Two sublattice ionic liquid model of the UeCeeO phase. Comparison of computed phase diagrams and calculated thermochemistry for UeCeeO and UePueO. Uranium Cerium Oxygen Compound energy formalism Calphad Oxygen potential Phase equilibria
a b s t r a c tA thermodynamic assessment of the UeCeeO system was performed by combining the existing Calphad assessments of the UeO and CeeO binaries. A compound energy formalism representation for the fluorite U 1Ày Ce y O 2±x and a partially ionic two-sublattice liquid model for UeCeeO melt were developed to describe the ternary solutions. Oxygen potentials for U 1Ày Ce y O 2±x for 0.05, 0.20, 0.30, and 0.50 Ce metal fractions were measured from thermogravimetric analysis and used, along with other thermodynamic data reported in the literature, to optimize the adjustable parameters of the models for U 1Ày Ce y O 2±x and the UeCeeO ternary liquid. In addition, the thermochemical behavior of U 1Ày Ce y O 2±x and U 1Ày Pu y O 2±x was compared in order to assess the suitability of using Ce as a surrogate for Pu in MOX fuel.
The dependence of neoclassical parallel flow calculations on the maximum order of Laguerre polynomial expansions is investigated in a magnetic configuration of the Large Helical Device ͓S. Murakami, A. Wakasa, H. Maaßberg, et al., Nucl. Fusion 42, L19 ͑2002͔͒ using the monoenergetic coefficient database obtained by an international collaboration. On the basis of a previous generalization ͑the so-called Sugama-Nishimura method ͓H. Sugama and S. Nishimura, Phys. Plasmas 15, 042502 ͑2008͔͒͒ to an arbitrary order of the expansion, the 13 M, 21 M, and 29 M approximations are compared. In a previous comparison, only the ion distribution function in the banana collisionality regime of single-ion-species plasmas in tokamak configurations was investigated. In this paper, the dependence of the problems including electrons and impurities in the general collisionality regime in an actual nonsymmetric toroidal configuration is reported. In particular, qualities of approximations for the electron distribution function are investigated in detail.
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