Determination of 107 Pd in Pd purified by selective precipitation from spent nuclear fuel by laser ablation ICP-MS

Abstract

Determination of radiopalladium ¹⁰⁷Pd is required to ensure radiation safety of the Pd extracted from spent nuclear fuel for recycling or disposal. We employed nanosecond laser ablation inductively coupled plasma quadrupole mass spectrometry (ns-LA-ICP-QMS) to simplify the analytical procedure of ¹⁰⁷Pd. Pd was separated through a selective Pd precipitation reaction induced by pulsed laser irradiation that reduces Pd(II) ions to metal Pd(0). Laser ablation facilitates direct measurement of the Pd precipitates, skipping the dissolution and dilution procedure with aqua regia and HCl, which causes serious corrosion damage to the introduction system of the ICP. In the present study, ¹⁰²Pd in natural Pd standard solution was used as an internal standard owing to its absence in spent nuclear fuel. Pd precipitates with diameters ranging from 0.2 to 0.5 μm, obtained by pulsed laser irradiation, were embedded uniformly on the surface of the centrifugal filter to form a microscopically thin and flat Pd surface. The resulting homogeneous Pd layer is suitable for obtaining a stable signal ratio of ¹⁰⁷Pd/¹⁰²Pd (< 4%, 2RSD). The mass bias-corrected ratio of ¹⁰⁷Pd/¹⁰²Pd and the amount of ¹⁰⁷Pd were 0.163 ± 0.004 and 17.8 ± 0.6 ng, respectively, which correspond to the values obtained by solution nebulization measurement after the dissolution of identical Pd precipitates.

Graphical abstract

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