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Sanada, Yukihisa; Tokiyoshi, Masanori*; Nishiyama, Kyohei*; Sato, Rina; Yoshimura, Kazuya; Funaki, Hironori; Abe, Tomohisa; Ishida, Mutsushi*; Nagamine, Haruo*; Fujisaka, Motoyuki*
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(2), p.87 - 96, 2023/04
Since the accident at the Fukushima Daiichi Nuclear Power Plant, many decontamination works have been carried out, but it is difficult to say that much data on workers' exposure has necessarily been analyzed in detail. In this paper, based on the GPS location information carried by the workers together with their personal dosimeters, the air dose rate in the work area and the characteristics of each type of work were analyzed. The results showed that more than 50% of the measured actual doses were more than twice the median planned dose calculated from the air dose rate and actual working hours. Furthermore, as a result of the analysis by work type, it was found that the exposure doses of demolition workers tended to be high, and that this was due to the fact that most of the work was carried out before the work was carried out to reduce the dose at the work site. In addition, when the conversion from air dose to effective dose was taken into account, there were many cases of underestimation where the planned values were lower than the measured values, and it is considered important for management to set appropriate working factor.
Lee, T.-G.*; Nishiyama, Kazuya*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
JPS Conference Proceedings (Internet), 14, p.020808_1 - 020808_3, 2017/02
Times Cited Count：0 Percentile：0.03(Astronomy & Astrophysics)Nishiyama, Jun*; Ohgama, Kazuya; Sakamoto, Tatsujiro*; Watanabe, Rin*
Nihon Genshiryoku Gakkai-Shi ATOMO
, 57(2), p.123 - 125, 2015/02
no abstracts in English
Onizawa, Kunio; Masaki, Koichi; Osakabe, Kazuya*; Nishikawa, Hiroyuki*; Katsuyama, Jinya; Nishiyama, Yutaka
Nihon Hozen Gakkai Dai-9-Kai Gakujutsu Koenkai Yoshishu, p.374 - 379, 2012/07
To assure the structural integrity of a reactor pressure vessel (RPV) is known as one of the critical issues to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment methods for RPV integrity, stipulated in the codes and standards, have been endorsed by the regulatory body. Authors have initiated extensive research on the improvement of structural integrity assessment methods of RPVs. In this paper, we describe some research results obtained from the first-year activity. These include the study on revisiting the technical background of the methods, such as loading conditions, postulated crack definition, the other evaluation methods. In addition, studies on probabilistic methods for the applicability to the current rules and the standardization of the probabilistic analysis methods have been presented.
Ca
Cu
O
superconductorTokiwa, Kazuyasu*; Mikusu, Satoshi*; Higemoto, Wataru; Nishiyama, Kusuo*; Iyo, Akira*; Tanaka, Yasumoto*; Kotegawa, Hisashi*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Watanabe, Tsuneo*
Physica C, 460-462(2), p.892 - 895, 2007/09
Times Cited Count：3 Percentile：17.87(Physics, Applied)Zero- and longitudinal-field muon-spin rotation (ZF-
SR and LF-SR) measurements were carried out on a multi-layered HgBaCaCuO (Hg-1245) superconductor with 
of 108 K. With decreasing temperature, the observed ZF-SR function changed from a Gaussian-type to an exponential-type below 60 K and zero field muon precession was also observed below 45 K. These SR signals are attributed to the development of the antiferromagnetic ordering in inner CuOplanes with a low carrier concentration. These results seem to indicate clear evidence that antiferromagnetism microscopically coexists with superconductivity in the Hg-1245 superconductor below 60 K.
Katsumata, Genshichiro; Masaki, Koichi*; Osakabe, Kazuya*; Nishikawa, Hiroyuki*; Katsuyama, Jinya; Nishiyama, Yutaka; Onizawa, Kunio
no journal, ,
To assure the structural integrity of a reactor pressure vessel (RPV) is known as one of the critical issues to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment methods for RPV integrity, stipulated in the codes and standards, have been endorsed by the regulatory body. Authors have initiated extensive research on the improvement of structural integrity assessment methods of RPVs. In this paper, we describe some research results obtained from the second-year activity. These include the study on revisiting the technical background of the methods, such as loading conditions, postulated crack definition, the other evaluation methods. In addition, studies on probabilistic methods for the applicability to the current rules and the standardization of the probabilistic analysis methods have been presented.
Lee, T.-G.*; Yasutake, Nobutoshi*; Nishiyama, Kazuya*; Maruyama, Toshiki; Tatsumi, Toshitaka*
no journal, ,
no abstracts in English
Abe, Tomohisa; Sanada, Yukihisa; Tokiyoshi, Masanori*; Nishiyama, Kyohei*; Sato, Rina*; Yoshimura, Kazuya; Funaki, Hironori; Ishida, Mutsushi*; Nagamine, Haruo*; Fujisaka, Motoyuki*
no journal, ,
We attempted to analyze in detail the actual external exposure doses of workers involved in decontamination work, which had been difficult to analyze in detail until now, by recording location information and exposure doses using GPS. As a result, it was found that more than 50% of the planned exposure dose calculated from the air dose rate and the number of actual working hours were more than twice the median the measured exposure doses. Furthermore, analysis by work type showed that the exposure doses of demolition workers tended to be higher. This information on the external exposure dose of workers linked to location information is useful for detailed analysis of external exposure factors and will contribute to the optimization of future radiation protection programs for workers.
