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Kim, M.; Malins, A.*; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(4), p.156 - 169, 2023/11
Dose reduction factor of a Japanese house is important information in the external exposure estimation of returning residents. In 2019, a total of 19 wooden houses were surveyed in Iitate Village and Namie Town using a gamma plotter that can continuously measure the air dose rate. In addition, the characteristics of the reduction factor were investigated from the measured air dose rate. In the vicinity of houses, uncontaminated areas exist underneath houses and, the ratio of paved surfaces such as asphalt roads is relatively high; furthermore, the pavement has a tendency for the radiation source to decay quickly. Therefore, the air dose rate near the house showed a relatively low value in common at all sites. Air dose rates above unpaved surfaces showed higher values and larger variations than those above paved surfaces within a radius of 50 m form the center of a house. The reduction factor was widely distributed even for one house, if the ratio of every air dose rate observed inside and outside the house is considered. It is suggested that a realistic reduction factor may not be obtained when the reduction factor is obtained based on the measured values at a small number of points that do not have the representativeness of the radiation field to be measured.
Saito, Kimiaki; Kurihara, Osamu*; Matsuda, Norihiro; Takahara, Shogo; Sato, Tetsuro*
Radioisotopes, 65(2), p.93 - 112, 2016/02
Late information is introduced on dose evaluation due to external exposures which employ an important role in the exposures due to the Fukushima accident. First, merits and demerits of the currently used two methods, that is the estimation based air dose rates and the measurements using personal dosimeters, are discussed indicating some basic data after a fundamental concept of external dose evaluation is provided. Next, main activities are summarized on external dose measurements and evaluations after the accident. Finally, a new trial on dose evaluation in introduced.
Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Tachibana, Yukio; Yamaji, Masatoshi*; Iyoku, Tatsuo; Hoshiya, Taiji*
Materials Science Research International, 9(3), p.235 - 241, 2003/09
2D-C/C composite is one of the promising materials as a next-generation core material in gas-cooled reactors. Effect of air-oxidation on the thermal diffusivity up to 1673K of the 2D-C/C composite was investigated. The C/C composite specimens for measurement of thermal diffusivity were oxidized from 1 to 11 percent weight loss in air at 823K. Thermal diffusivity at room temperature declined 10
20 percent for parallel to lamina direction and 59 percent for that of perpendicular within 11 percent weight loss by oxidation. Thermal diffusivity tended to decrease gradually as the increase of oxidation loss in parallel to lamina, however, it decreased in the beginning of oxidation pretty much and not so changed by further oxidation loss in perpendicular to lamina. Change in thermal conductivity under oxidation condition was also estimated.
Takeda, Takeshi; Tachibana, Yukio
Nuclear Engineering and Design, 223(1), p.25 - 40, 2003/07
Times Cited Count：2 Percentile：18.9(Nuclear Science & Technology)no abstracts in English
Morita, Kenji*; Suzuki, Hironori*; Soda, Kazuo*; Iwahara, Hiroiku*; Nakamura, Hirofumi; Hayashi, Takumi; Nishi, Masataka
Journal of Nuclear Materials, 307-311(2), p.1461 - 1465, 2002/12
Times Cited Count：2 Percentile：16.96(Materials Science, Multidisciplinary)no abstracts in English
; ; Takasaki, Koichi*; ;
JAERI-Review 98-005, 203 Pages, 1998/03
JAERI-Review-98-005.pdf:8.96MB
no abstracts in English
Takeda, Takeshi; Kunitomi, Kazuhiko; Okubo, Minoru; *
Nucl. Eng. Des., 185(2-3), p.229 - 240, 1998/00
Times Cited Count：12 Percentile：68.65(Nuclear Science & Technology)no abstracts in English
Hibiki, Takashi*; Mishima, Kaichiro*; Yoneda, Kenji*; Fujine, Shigenori*; Tsuruno, Akira; Matsubayashi, Masahito
Nuclear Instruments and Methods in Physics Research A, 351, p.423 - 436, 1994/00
Times Cited Count：36 Percentile：92.83(Instruments & Instrumentation)no abstracts in English
Suzuki, Tomoo*; ; Tanaka, Shunichi;
JAERI-M 93-143, 82 Pages, 1993/07
no abstracts in English
; ; Onodera, Junichi; ; Ikezawa, Yoshio
Proc. of the Int. Conf. on Radiation Effects and Protection, p.434 - 439, 1992/00
no abstracts in English
Ikezawa, Yoshio
Kuki Seijo, 28(3), p.630 - 647, 1990/08
no abstracts in English
;
Genshiryoku Kogyo, 32(9), p.70 - 74, 1986/09
no abstracts in English
; ; *;
JAERI-M 84-177, 20 Pages, 1984/10
no abstracts in English
; ;
Nihon Genshiryoku Gakkai-Shi, 16(9), p.478 - 485, 1974/09
no abstracts in English
; ; ;
Proc.1st Intern.Cong.of Radiation Protection,Rome, p.1153 - 1166, 1966/09
no abstracts in English
Uesawa, Shinichiro; Ono, Ayako; Yamashita, Susumu; Yoshida, Hiroyuki
no journal, ,
To evaluate the thermal behavior of fuel debris of porous media in PCVs of TEPCO's Fukushima Daiichi Nuclear Power Station for air cooling, JAEA has developed a numerical simulation method with JUPITER. In this presentation, we report the numerical simulation results of the thermal behavior in the PCV considering three effective thermal conductivity models for fuel debris. The results showed the temperature and the velocity distributions and the heat removal amount from the fuel debris were different for each model. It is important to understand the internal structure of the fuel debris and choose the appropriate effective thermal conductivity model for the analysis of the thermal behavior because the model affects the simulation results.
