Nd, Am and Cm isotopic measurement after simultaneous separation in transmutation irradiated samples

Alexandre Quemet (1) , Mathilde Angenieux (1) , Alexandre Ruas (2)

1 DMRC - Département de recherche sur les procédés pour la mine et le recyclage du combustible
2 IAEA - International Atomic Energy Agency [Vienna]

In this work, a High-Performance Liquid Chromatography (HPLC) separation followed by Thermal Ionization Mass spectrometry (TIMS) measurements was optimized to measure Am, Cm and Nd isotope ratios in irradiated samples. The method validation was performed on a natural Nd standard (JNdi-1 reference material). The literature JNdi-1 reference values are calculated using a conventional internal normalization. However, in nuclear science, such normalization is not possible as no isotope ratio can be considered as a reference. Measurements were compared to reference values using the Exponential Mass Fractionation Law, which is a powerful tool to detect drifts. The results show that the dominant bias comes from the isotope fractionation, that can be minimized using the TE method. Acquired data suggest the following absolute composition for the JNdi-1 reference standard: 142 Nd/ 144 Nd = 1.13950(47) 143 Nd/ 144 Nd = 0.51163(30), 145 Nd/ 144 Nd = 0.34876(17), 146 Nd/ 144 Nd = 0.72322(65), 148 Nd/ 144 Nd = 0.24264(46) and 150 Nd/ 144 Nd = 0.23789(68) (k = 2). These values suggest the need to revisit the agreed upon reference values when Nd absolute isotopic composition is required. The conditions of the HPLC separation were also optimized to obtain purified fractions of Nd, Am and Cm in one experiment using a cation exchange column. Separations were achieved on the LUNA SCX column and using 2-Hydroxy-MethylButyric Acid (HMB) as eluent, introduced in gradient mode. A difference below 0.03 % was observed between data obtained with separation and without separation. Compared to previous work that required three separations using two different HPLC conditions, improvements were made in terms of both duration and amount of radioactive effluents. The methodology was then successfully applied to irradiated discs coming from MARIOS and DIAMINO analytical irradiation.

Domaines: Chimie analytique

Alexandre Quemet, Mathilde Angenieux, Alexandre Ruas. Nd, Am and Cm isotopic measurement after simultaneous separation in transmutation irradiated samples. Journal of Analytical Atomic Spectrometry, 2021, 36 (8), pp.1758-1767. ⟨10.1039/D1JA00165E⟩. ⟨cea-03470782⟩