Estimation of uncertainty in the determination of nitrogen and oxygen in U(Al, Si)3

Abstract

U(Al, Si)3, an inter-metallic compound, is a proposed fuel in advanced nuclear reactors. Determination of trace amounts of nitrogen and oxygen in this material is an essential requirement for quality assurance. Mass fraction of nitrogen and oxygen were determined in this compound employing inert gas fusion in conjunction with thermal conductivity and infrared detection techniques, respectively. Uncertainty in the measured data has been estimated employing bottom-up approach as per ISO guidelines. Uncertainty in the calibration of the measurement procedure employing standards with own uncertainty of the measurement was estimated following linear regression equation and uncertainty propagation laws. The relative combined uncertainty of measurement has been calculated employing law of uncertainty propagation. Finally, the expanded uncertainty of measurement (coverage factor k = 2) for the determination of nitrogen and oxygen was estimated, and they were found to be 10 and 12 %, respectively.