Direct determination of the 237Np/238U ratio in nuclear fuel samples by multicollection inductively coupled plasma mass spectrometry (MC-ICP-MS)

Abstract

AbstractA new method for the direct measurement of 237Np/238U ratio in irradiated UO2 pellets by multicollection inductively coupled plasma mass spectrometry (MC-ICP-MS) is proposed. It allows the determination of ratios down to 10 × 10–6 mol·mol−1 using ion counter and Faraday cup. This approach was validated by intercomparison with the usual two-step-method (Quadrupole ICP-MS for 237Np determination and isotope dilution mass spectrometry (IDMS) for 238U). For ratios between 10 × 10–6 and 100 × 10–6 mol·mol−1, expanded uncertainties (k = 2) varied from 2.75% to 0.81%, twice lower than the uncertainties determined by the usual method.