OXYGEN METAL RATIO IN U-GD OXIDE FUELS DETERMINED USING A SOLID-ELECTROLYTE GALVANIC CELL

A nondestructive method for determining the oxygen/metal (O/M) ratio i n U - Gd oxide fuels that uses a solid-electrolyte galvanic cell (SGC) is described. Calibration graphs of the cell EMF as a function of O/M are constructed for (U, Gd)O2+/-x with 4, 8, and 10 mass % Gd oxide b y using solid-state coulometric titration. Analytical expressions are found for U0.943Gd0.057O2+x, U0.886Gd0.114O2+x, and U0.858Gd0.142O2+x for O/M from 2.000 to 2.030. Factors that affect the uncertainty in th e O/M determination by the EMF method in oxide fuel are discussed. The proposed method enables O/M in U- Gd oxides to be determined with an uncertainty less than +/-0.001 O/M units.