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Oshima, Masumi*; Goto, Jun*; Haraga, Tomoko; Kin, Tadahiro*; Ikebe, Yurie*; Seto, Hirofumi*; Bamba, Shigeru*; Shinohara, Hirofumi*; Morimoto, Takao*; Isogai, Keisuke*
Journal of Nuclear Science and Technology, 57(6), p.663 - 670, 2020/06
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Gamma-gamma coincidence measurement utilized in -ray spectroscopy experiments is well known to be effective for the improvement of signal-to-noise ratio in a -ray spectrum. We study its applicability to determination of long-lived radioactive nuclides in environmental samples. The -ray simulation code Geant 4.10.2 was used. We took up 35 nuclides which need to be determined for the evaluation of fission product leakage at the nuclear accident in the Fukushima nuclear power plants. Among them five nuclides of Co, Nb, Cs, Eu and Eu can be the objectives of the multiple -ray detection method. The simulation results indicate that the signal-to-noise ratio can be improved by a factor between 9.8 and 283, and the detection limit by a factor between 2.7 and 8.5 relative to the singles measurement, implying that the method can be well applied to the determination of the long-lived radioactive nuclides.
Suzuki, Takashi; Bamba, Shigeru*; Kitamura, Toshikatsu; Kabuto, Shoji*; Isogai, Keisuke*; Amano, Hikaru
Nuclear Instruments and Methods in Physics Research B, 259(1), p.370 - 373, 2007/06
Times Cited Count:14 Percentile:67.69(Instruments & Instrumentation)no abstracts in English
Suzuki, Takashi; Kitamura, Toshikatsu; Kabuto, Shoji; Isogai, Keisuke*; Bamba, Shigeru*; Katayama, Atsushi; Kameo, Yutaka; Kuwabara, Jun; Sakamoto, Shinya*; Togawa, Orihiko; et al.
no journal, ,
no abstracts in English
Terada, Hiroaki; Nagai, Haruyasu; Isogai, Keisuke*; Nitta, Wataru*
no journal, ,
We have been verifying and improving SPEEDI-MP which is a comprehensive prediction system of migration of radionuclides in the atmosphere, ocean, and terrestrial region. In this study, we conducted atmospheric dispersion simulations of radioactive noble gas Kr released from the Rokkasho reprocessing plant for the whole Japan area by using an atmospheric model in SPEEDI-MP, and analyzed significant increases of atmospheric Kr concentration above its background level measured by Japan Chemical Analysis Center. Meteorological fields such as wind field and turbulence were predicted by an atmospheric dynamic model MM5, and atmospheric dispersion of Kr was calculated by a Lagrangian particle dispersion model GEARN. The calculation results agreed well with the measurements of atmospheric Kr concentration at Dazaifu in April 2008 and at Sapporo in September 2008 to confirm the high prediction performance of the model.
Konno, Yuta*; Maeyama, Takeshi*; Saegusa, Jun; Shinohara, Hirofumi*; Ota, Hiroshi*; Isogai, Keisuke*
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no abstracts in English
Ishimori, Kenichiro; Oki, Keiichi; Kameo, Yutaka; Takaizumi, Hirohide; Nakashima, Mikio; Oki, Yoshiyuki*; Isogai, Keisuke*
no journal, ,
no abstracts in English
Kameo, Yutaka; Katayama, Atsushi; Nakashima, Mikio; Oki, Yoshiyuki*; Isogai, Keisuke*
no journal, ,
no abstracts in English