Analytical Sciences

Automated Gravimetric Sample Pretreatment Using an Industrial Robot for the High-Precision Determination of Plutonium by Isotope Dilution Mass Spectrometry

Naoki SURUGAYA, Toshiaki HIYAMA, and Masaru WATAHIKI

Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai, Naka, Ibaraki 319-1194, Japan

A robotized sample-preparation method for the determination of Pu, which is recovered by extraction reprocessing of spent nuclear fuel, by isotope dilution mass spectrometry (IDMS) is described. The automated system uses a six-axis industrial robot, whose motility is very fast, accurate, and flexible, installed in a glove box. The automation of the weighing and dilution steps enables operator-unattended sample pretreatment for the high-precision analysis of Pu in aqueous solutions. Using the developed system, the Pu concentration in a HNO₃ medium was successfully determined using a set of subsequent mass spectrometric measurements. The relative uncertainty in determining the Pu concentration by IDMS using this system was estimated to be less than 0.1% (k = 2), which is equal to that expected of a talented analyst. The operation time required was the same as that for a skilled operator.

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