Uranium assay determination using Davies and Gray titration: An overview and implementation of GUM for uncertainty evaluation

International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) represents a standardized way of evaluating and expressing uncertainty in measurements. The implementation of GUM to modified Davies and Gray titration, an analytical method routinely used for uranium assay in accountability measurements, will be discussed. The modified Davies and Gray titration method developed at New Brunswick Laboratory (NBL) is widely used for uranium content measurements (i.e. assay) of uranium-bearing materials and solutions in the nuclear fuel cycle. The dominant components of the combined uncertainty for NBL Davies and Gray method will be discussed.