REDUCTION OF MEASUREMENT UNCERTAINTY IN THE SPECTROSCOPIC DETERMINATION OF URANIUM

Optical absorbance spectroscopy techniques show significant promise for the rapid determination of uranium concentrations in process streams for the recycling of nuclear fuel. However, the measurement of uranium absorption is highly dependent on the nitrate concentration in the process stream due to changes in speciation. Current procedures which rely on calibrations at expected process concentrations insert an additional systemic bias due to the variation of nitrate concentrations from the matrix used to calibrate the system. To reduce this systemic bias, a technique has been developed to simultaneously determine the nitrate and uranium concentrations in the process stream. By correcting the measured uranium concentration to account for the difference in speciation due to the nitrate concentration, the overall measurement uncertainty for uranium in the process stream is reduced. The systemic bias introduced by the changing nitrate concentration in the process stream is also effectively removed from the measurement.