Radiation Safety Management
Online ISSN : 1884-9520
Print ISSN : 1347-1511
ISSN-L : 1347-1511
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  • Shogo HIGAKI
    2024 Volume 23 Pages 1-6
    Published: 2024
    Released on J-STAGE: February 05, 2025
    JOURNAL FREE ACCESS

     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.

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  • Koichi SAKASHITA, Yuto ARAKAWA, Koichi MASUYAMA, Koichi SATO, Kazunari ...
    2024 Volume 23 Pages 7-15
    Published: 2024
    Released on J-STAGE: March 31, 2025
    JOURNAL FREE ACCESS

     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%.

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