RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
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Volume 56, Issue 12
Displaying 1-7 of 7 articles from this issue
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  • Application of Clear Polymethylmethacrylate Dosimeter, Radix RN-15 to Several kGy Range
    Hajime SEITOU, Tatsuya ICHIKAWA, Hiroshi WATANABE, Takuji KOJIMA
    2007 Volume 56 Issue 12 Pages 777-785
    Published: December 15, 2007
    Released on J-STAGE: March 01, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.56.777
    JOURNAL FREE ACCESS
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    Undyed and dyed polymethylmethacrylate dosimeters are widely used as routine dosimeters in radiation processing for the absorbed dose range 5-50 kGy, especially in the radiation sterilization of disposable medical products. Basic characteristics ofRadix RN15 ; a commercially available undyed polymethylmethacrylate dosimeter, was studied also in the dose range 1-10 kGy, for its wide application to radiation processing especially for the evaluation to decide sterilization dose and the quality assurance of food irradiation. The characteristics of dose response, the effect of irradiation temperature, and its stability after irradiation were examined at readout wavelength 270-320 nm. The dose response read-out at shorter wavelength is higher than that at longer wavelength. The measurable dose range of 1-10kGy is obtained at the readout wavelength of 280 nm that is shorter than conventional read-out wavelength of 320 nm. The postirradiation stability of dose response for 6 kGy is less than 4-5% for longer than 24h after irradiation. The dose response slope at 6 kGy while held at irradiation temperatures in the range -40-40°C, increases with temperature up to 20°C as the maximum, and decreases at higher temperatures. Radix RN15 has linear temperature dependence with a coefficient of +0.25%/°C, relative to the dose response at under 20°C, at irradiation temperature in the range -40-20°C.
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  • Analysis of 129I in Radioactive Wastes by Accelerator Mass Spectrometry
    Atsushi KATAYAMA, Yutaka KAMEO, Mikio NAKASHIMA
    2007 Volume 56 Issue 12 Pages 787-793
    Published: December 15, 2007
    Released on J-STAGE: March 01, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.56.787
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    Accelerator mass spectrometry (AMS) was applied to measurement of 129I/ 127I ratio to determine 129I concentration in radioactive waste. Solid phase extraction disks (Anion-SR) for chemical separation of iodine from radioactive waste samples were used to prepare AMS targets.This method made it possible to swiftly separate iodide ions from sample solutions, compared with a conventional liquid-liquid extraction method. Since the 129I concentration is calculated from an 129I/127I ratio, the amount of an 127I carrier added to a sample for chemical separation determines the measurable range of the 129I concentration. Especially in a radiation controlled area, it is important to keep the background value of the 129I/127I ratio as low as possible. The present method was successfully applied to laboratory standards and liquid waste samples arising from nuclear facilities in Japan Atomic Energy Agency.
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  • 238U-230Th Radioactive Disequilibria in the Volcanic Products from Izu Arc Volcanoes, Japan
    Yuichi KURIHARA, Masaomi TAKAHASHI, Jun SATO
    2007 Volume 56 Issue 12 Pages 795-809
    Published: December 15, 2007
    Released on J-STAGE: March 01, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.56.795
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    The timescale of magmatic processes of Izu arc volcanoes, Japan, was estimated by the 238U - 230Th disequilibria in the volcanic products from the volcanoes. The majority of the 230Th/238U activity ratios of the products were less than unity, being enriched in 238U relative to 230Th. The (230Th/232Th) - (238U/232Th) diagram for younger Fuji and Izu-Oshima volcanoes formed a whole rock isochrons, and the ages were l×104 and 2×104 years, respectively. The (230Th/232Th) - (238U/232Th) data set for younger Fuji volcano formed a cluster on the diagram, while those of Izu-Oshima formed another cluster apparently apart from each other, suggesting that the concentration of U and Th may possibly be un-uniform in the mantle beneath Izu arc.
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  • Activity Ratios of Ra and Th Isotopes Leached from Granite
    Kohta NAGAI, Masaomi TAKAHASHI, Jun SATO
    2007 Volume 56 Issue 12 Pages 811-818
    Published: December 15, 2007
    Released on J-STAGE: March 01, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.56.811
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    The activity ratios of 228Ra/226Ra in the leachates from a granite sample with HCl, NaOH and NaCl aqueous solutions were observed to be smaller than that in the granite sample. The activity ratios of 224Ra/228Ra, 230Th/232Thand 228Th/232Thincreased with an increase in pH of the HClaqueous solution. The leaching behavior of 226Raand 224Ra which are formed through 5 decay processes of 238Uand through 4 decay processes of 232Th, respectively, was different from that of 228Rawhich is formed by a single decay of 232Th. Thorium isotopes, 230Th and 228Th, decay products of 238U and 232Th, respectively, were also leached more effectively than 232Th.The leaching efficiency of Ra and Thisotopes was estimated to be dependent on the difference in the history of decay processes which have formed the nuclides. This estimation was consistent with the observations with the radioactive mineral samples reported previously.
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  • Differentiation of Endogenous and Exogenous Steroids by Monitoring Carbon Isotope Ratio as a Parameter to Indicate the Provenance
    Makoto UEKI
    2007 Volume 56 Issue 12 Pages 819-826
    Published: December 15, 2007
    Released on J-STAGE: July 21, 2010
    DOIhttps://doi.org/10.3769/radioisotopes.56.819
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  • Application of Neutron Imaging to Biological Research
    Yuji KAWABATA
    2007 Volume 56 Issue 12 Pages 827-835
    Published: December 15, 2007
    Released on J-STAGE: July 21, 2010
    DOIhttps://doi.org/10.3769/radioisotopes.56.827
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  • Applications of Neutron Imaging to Medical Field
    Kazuo KATO, Hiromi WAKAO, Kouichi OGURA, Hironobu YANAGIE, Hisao KOBAY ...
    2007 Volume 56 Issue 12 Pages 837-847
    Published: December 15, 2007
    Released on J-STAGE: July 21, 2010
    DOIhttps://doi.org/10.3769/radioisotopes.56.837
    JOURNAL FREE ACCESS
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