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Hirayama, Hideo*; Kawasaki, Masatsugu; Matsumura, Hiroshi*; Okura, Takehisa; Namito, Yoshihito*; Sanami, Toshiya*; Taki, Mitsumasa; Oishi, Tetsuya; Yoshizawa, Michio
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.295 - 307, 2021/10
Yoshitomi, Hiroshi; Tanimura, Yoshihiko*; Tatebe, Yosuke; Tsutsumi, Masahiro; Kawasaki, Katsuya; Kowatari, Munehiko; Yoshizawa, Michio; Shimizu, Shigeru*; Kim, J.-S.*; Lee, J.-G.*; et al.
Proceedings of 4th Asian and Oceanic Congress on Radiation Protection (AOCRP-4) (CD-ROM), 4 Pages, 2015/07
Kawasaki, Michio*; Kikyo, Shogo*; Nozawa, Shigeki; Akita, Yusuke*; Hase, Yoshihiro; Narumi, Issey*
Nihon Sakumotsu Gakkai Tohoku Shibu Kaiho, (57), p.61 - 62, 2014/12
no abstracts in English
Hirayama, Hideo*; Kawasaki, Masatsugu; Matsumura, Hiroshi*; Okura, Takehisa; Namito, Yoshihito*; Sanami, Toshiya*; Taki, Mitsumasa; Oishi, Tetsuya; Yoshizawa, Michio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(3), p.119 - 126, 2014/09
A method of deducing the I-131 concentration in a radioactive plume from the time history of peak count rates determined from pulse height spectra obtained from an NaI(Tl)scintillation detector employed as a detector of a monitoring post was presented. The concentrations of I-131 in the plumes were estimated from the count rates using the calculated response of the NaI(Tl) detector with egs5 for a model of a plume uniformly containing I-131. This method was applied to the data from the monitoring posts at Nuclear Science Research Institutes of Japan Atomic Energy Agency (JAEA). The estimated time history variation of I-131 concentrations in plumes was in fair agreement with those measured directly by an air sampling method. The difference was less than a factor of 4 for plumes that arrived on March 15 and March 21, indicating relatively high I-131 concentrations among the plumes studied in this work.
Am-Be sourceKowatari, Munehiko; Onuma, Isamu; Tanimura, Yoshihiko; Kawasaki, Katsuya; Saegusa, Jun; Yoshizawa, Michio
Radioisotopes, 57(9), p.559 - 569, 2008/09
The neutron standard field using Am-Be neutron source has been widely used for the routine calibration of neutron dosemeters. The neutron fluence rate at the calibration point is one of the most essential parameters. For the precise determination of the neutron fluence rate, the effect defined as an anisotropic emission from the neutron source, F
(
), should be taken into account. For the proper calibration of the neutron dosemeters used in the Japan Atomic Energy Agency (JAEA), the anisotropic factor F(90) from an Am-Be neutron source was experimentally determined using the precision long counter. Before the determination of the anisotropic factor of the Am-Be source with the protection case, the measured angular distribution from the X3 type Am-Be source was compared with the result obtained by other researchers and with the Monte Carlo calculation using MCNP-4C, for the verification of the method the authors adopted.
O-moderated 
Cf sourceKowatari, Munehiko; Fujii, Katsutoshi; Takahashi, Masa; Yoshizawa, Michio; Shimizu, Shigeru; Kawasaki, Katsuya; Yamaguchi, Yasuhiro
Radiation Protection Dosimetry, 126(1-4), p.138 - 144, 2007/08
Times Cited Count：5 Percentile：37.19(Environmental Sciences)The facility of the Radiation Standards (FRS) of the Japan Atomic Energy Agency was equipped with the reference neutron field by using DO moderated Cf neutron source (DO-Cf), with a 30cm diameter DO sphere. In order to determine the characteristics of the reference field within the ranges of calibration distance (75 to 200 cm from the center of the source to the calibration point) in detail, the authors performed the evaluation of the neutron spectra and neutron fluence rate at various distances from the DO moderated source assembly by computations using MCNP-4C and by experimental studies using Bonner Multi-sphere neutron Spectrometer (BMS). Due to the volume neutron source, it is difficult to measure the contribution of the scattered neutron component with the desirable accuracy by shadow-cone method. In this study, the net counting rate of each counter of BMS was corrected by estimating the ratio of the counting rate of each counter in condition of the experimental and the ideal arrangement by the Monte Carlo calculation. The spectra of the direct component were unfolded by using the corrected counting rate with SAND II code. The averaged dose conversion coefficients (h
(10) and h
(10)) and neutron dose rates (H(10) and H(10)) at various distance were estimated based on the measured spectra. The effectiveness of the correction was discussed by comparing the measured and calculated values. Additionally, the suitable distance for the calibration of personal dosimeter at FRS reference field was evaluated by the results.
-ray efficiency curves for volume samples by the combination of Monte Carlo simulations and point source calibrationSaegusa, Jun; Oishi, Tetsuya; Kawasaki, Katsuya; Yoshizawa, Michio; Yoshida, Makoto; Sawahata, Tadahiro*; Honda, Tetsutaro*
Journal of Nuclear Science and Technology, 37(12), p.1075 - 1081, 2000/12
no abstracts in English
Ichikawa, Michio; ; Kawasaki, Satoru
Journal of Nuclear Science and Technology, 26(1), p.118 - 125, 1989/01
no abstracts in English
Tanaka, Mitsugu; Yanagihara, Satoshi; Ishikawa, Michio; Kawasaki, Minoru
Proc. Int. Conf. on Decommissioning of Major Radioactive Facilities, p.25 - 31, 1988/00
no abstracts in English
Ishikawa, Michio; Kawasaki, Minoru
Enerugi Rebyu, 7(6), p.2 - 6, 1987/00
no abstracts in English
Kawasaki, Masayuki; Nagasaki, R.; Itagaki, M.*; Takemura, Michio*
Nihon Genshiryoku Gakkai-Shi, 2(3), p.136 - 146, 1960/00
U-Mo alloy is of interest as power-reactor fuel. The purpose of this work was to study the characteristic behavior of the alloy when subjected to certain heat treatments as well as to get fundamental informations concerning its general properties. The specimens were made by vacuum induction melting and were rolled at 600
and 900C. In the heat treatment tests, the phase changes by quenching from various high temperature phases, the effects of quenching rate from gamma phase range, and Ms temperature for 1.30% Mo alloy were the subjects discussed. Thermal cycling test revealed that greater improvement was obtained by gamma quenching followed by alpha annealing for the rolled rods with Mo content ranging from 0.5 to 9.0%. Oxidation test in air at 300, 400 and 500C had shown that the rate constant of oxidation decreased with increasing Mo contents in the lower Mo range, but it increased as Mo contents became higher. The same tendency was observed on the corrosion test in hot water. The minimum weight loss in 350C hot water could be obtained at 12w/o Mo.
Am-Be neutron sourceKowatari, Munehiko; Onuma, Isamu; Kawasaki, Katsuya; Tanimura, Yoshihiko; Saegusa, Jun; Yoshizawa, Michio
no journal, ,
no abstracts in English
Tatebe, Yosuke; Onuma, Isamu; Kawasaki, Katsuya; Kowatari, Munehiko; Sawahata, Tadahiro; Sato, Yasuo; Yoshizawa, Michio
no journal, ,
no abstracts in English
Am-Be neutron standard fields using new and old sourcesKowatari, Munehiko; Tatebe, Yosuke; Sato, Yasuo; Kawasaki, Katsuya; Yoshizawa, Michio
no journal, ,
For the contribution to the effective operation of Am-Be neutron standard fields, experimental studies on the comparison of the calibration factors for neutron dosemeters by old and new sources were made. Measured calibration factors for each dosemeter were compared by estimating their E
values. Results of the variation of calibration factor for neutron dosemeters were quite satisfactory and identical calibration factors were obtained at neutron calibration fields by new and old Am-Be source.
Tatebe, Yosuke; Kowatari, Munehiko; Tanimura, Yoshihiko; Kawasaki, Katsuya; Yoshizawa, Michio; Im, G. S.*; Kim, S.*; Lee, J.*; Kim, B.-H.*
no journal, ,
no abstracts in English
-ray calibration field at the FRS of JAEAKowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro; Kawasaki, Katsuya; Yoshizawa, Michio
no journal, ,
A 6-7 MeV high energy -ray field is to be established as a calibration field for radiation protection instruments at the Facility of Radiation Standards (FRS) of Japan Atomic Energy Agency (JAEA). This calibration field is essential to measure dose rates in accurate due to -rays which are observed around BWRs. The -ray field has been produced through the reaction of 
F(p,
)
O reaction using the accelerator. For establishing the calibration field, there are some difficulties to overcome which are caused by its -ray energy. In the presentation, these difficulties will be presented and discussions concerning the establishment of the high energy -ray calibration field will be made.
Kawasaki, Michio*; Takisawa, Misato*; Kanehira, Saki*; Sakio, Mika*; Honda, Kazushige*; Islam, M. N.*; Suto, Hiroki*; Nozawa, Shigeki; Akita, Yusuke*; Narumi, Issei
no journal, ,
no abstracts in English
Nishino, Sho; Tanimura, Yoshihiko; Ebata, Yoshiaki*; Yoshizawa, Michio; Yoshitomi, Hiroshi; Kawasaki, Katsuya
no journal, ,
no abstracts in English
Kawasaki, Michio*; Hatta, Yuki*; Senda, Mineo*; Suto, Hiroki*; Nozawa, Shigeki; Akita, Yusuke*; Hase, Yoshihiro; Narumi, Issey*
no journal, ,
no abstracts in English
Takahata, Eiji; Ito, Yasuhisa; Kawasaki, Takashi; Takada, Chie; Hashimoto, Makoto; Takasaki, Koji; Yoshizawa, Michio; Momose, Takumaro
no journal, ,
no abstracts in English
