EVALUATION OF AN INTERLABORATORY COMPARISON INVOLVING PYROCARBON- AND SILICON CARBIDE-COATED URANIUM-THORIUM CARBIDE BEADS - PHASEⅡ

摘要

Six chemistry laboratories and one nondestructive assay laboratory participated in the second phase of an interlaboratory comparison program, involving pyrocarbon- and silicon carbide-coated, uranium-thorium carbide beads. Accuracy and precision of measurements were estimated by supplying known quantities of mixtures of four different ratios of thorium oxide (Th02) to uranium oxide (U02). The ratios for the oxide mixtures were nominally 0, 10, 16, 25:1 of Th02 to U02.nThe range of the chemical determination of uranium content in the oxide mixtures was less than 0.3％ of the assigned value and the within-laboratory precision ranged from 0.07 to 0.33 (％ standard deviation of relative difference). The determination of thorium in the mixtures exhibited a generally much lesser degree of refinement in the state-of-the art compared to the uranium analyses.