Prior to quantifying ⁹⁰Sr using inductively coupled plasma-mass spectrometry (ICP-MS), its stable isobar, ⁹⁰Zr, should be removed from analytical samples. To resolve this issue, a facile method was developed to selectively adsorb and extrude Zr from samples containing both Sr and Zr using a relatively inexpensive γ-cyclodextrin polymers. The saturated adsorption capacities of γ-cyclodextrin for Sr and Zr, calculated using the Langmuir adsorption isotherm model, are 0.0818±0.0025 and 7.41±0.13 mg/g, respectively, which indicates the feasibility of the selective removal of Zr from Sr/Zr mixtures. The observed difference in the adsorption capacity can be attributed to the diameter of γ-cyclodextrin being larger than that of the hydrated Zr ion but smaller than that of the hydrated Sr ion. As γ-cyclodextrin polymers are insoluble granules, they can be easily separated from the solid-liquid phase and then immersed in ethanol for extruding Zr from γ-cyclodextrin. Ethanol can then be evaporated, leaving less volume of the Zr residue. This strategy could reduce the preprocessing time for Sr quantification by ICP-MS and thus the radiation exposure of workers during the decommissioning work of a nuclear reactor.

 Radioactivity concentrations of short-lived nuclides of ¹¹C, ¹³N, ¹⁵O and ⁴¹Ar with half-lives of about 2 to 110 min, produced by air activation under the spallation neutron environment at the Materials and Life Science Experimental Facility in J-PARC, were measured using a scintillation gas monitor. Since these radionuclides decay with β⁺ without emitting γ-rays except for ⁴¹Ar, the contribution of each radionuclide was separated by fitting a multi-component function depending on the half-lives of the products to the time variation of measured counting rates. Concentration conversion factors to convert count rates to radioactivity concentrations were determined by taking account of the result of Monte Carlo calculations. Using this method, the radioactivity concentrations of these nuclides were obtained with an accuracy of about 10-25%.