Measurement of plutonium isotope ratios in nuclear fuel samples by HPLC-MC-ICP-MS

Radioactive isotopes are traditionally quantified by means of radioactivity counting techniques (alpha, beta, gamma). However, these methods often require extensive matrix separation and sample purification before the identification of specific isotopes and their relative abundance is possible as it is necessary in the frame of post-irradiation examinations on nuclear fuel samples. The technique of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is attracting much attention because it permits the precise measurement of the isotope compositions for a wide range of elements combined with excellent limits of detection due to high ionization efficiencies. The present paper describes one of the first applications of an online high-performance liquid chromatographic separation system coupled to a MC-ICP-MS in order to overcome isobaric interferences for the determination of the plutonium isotope composition and concentrations in irradiated nuclear fuels. The described chromatographic separation is sufficient to prevent any isobaric interference between Pu-238 present at trace concentrations and U-238 present as the main component of the fuel samples. The external reproducibility of the uncorrected plutonium isotope ratios was determined to be between 0.04 and 0.2% (2 s) resulting in a precision in the parts per thousand range for the isotopic vectors of the irradiated fuel samples. (c) 2004 Elsevier B.V. All rights reserved.