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Machida, Masahiko; Iwata, Ayako; Yamada, Susumu; Otosaka, Shigeyoshi*; Kobayashi, Takuya; Funasaka, Hideyuki*; Morita, Takami*
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(1), p.12 - 24, 2023/01
We estimate inventory of tritium in two sea areas corresponding to coastal and offshore ones around Fukushima Daiichi Nuclear Power Plant (1F) based on the measurement results of sea-water tritium concentration monitored constantly from 2013 to Jan. 2021 by using Voronoi tessellation scheme. The obtained results show that the offshore area inventory and its temporal variation amount correspond to approximately 1/5 and 1/40 of that of the treated-water accumulated inside 1F, respectively. These results just suggest that the presence of tritium already included in sea-water as the background is non negligible in evaluating the environmental impact by releasing the accumulated treated-water into the sea region. We also estimate the offshore area inventory before 1F accident and find that it had exceeded over 1F stored inventory over about 30 years from 1960s to 1980s with approximately 4 times larger in the peak decade, 1960s. This fact means that we had already experienced more contaminated situation over 30 years in the past compared to the conservative case appeared by just releasing whole the present 1F inventory. Here, it should be also emphasized that the past contaminated situation was shared by the entire world. We further extend the estimation region into a wider region including an offshore area from Miyagi to Chiba prefectures and find that the area average inventory is now comparable to a half of the present 1F one. Finally, we estimate internal dose per year via ingesting fishes caught inside the area when 1F inventory is just added inside the area and kept for a year. The result indicates that it approximately corresponds to 1.0
of the dose from natural radiation sources. From these estimation results, it is found that all the tritium inventory stored inside 1F never contribute to significant dose increment even when it is instantly released into the area.
Ochi, Kotaro; Funaki, Hironori; Yoshimura, Kazuya; Iimoto, Takeshi*; Matsuda, Norihiro; Sanada, Yukihisa
Radiation and Environmental Biophysics, 61(1), p.147 - 159, 2022/03
Times Cited Count：2 Percentile：44.25(Biology)Isobe, Kanetsugu; Nakamura, Hirofumi; Kaminaga, Atsushi; Higashijima, Satoru; Nishi, Masataka; Konishi, Satoshi*; Nishikawa, Masabumi*; Tanabe, Tetsuo*
Fusion Science and Technology, 48(1), p.302 - 305, 2005/07
Times Cited Count：5 Percentile：35.66(Nuclear Science & Technology)no abstracts in English
Asai, Shiho; Sakai, Akihiro; Yoshimori, Michiro; Kihara, Shinji
JAERI-Tech 2003-071, 46 Pages, 2003/08
JAERI-Tech-2003-071.pdf:4.31MB
As part of survey concerning radioactive inventory of radwastes arising from research institutes, an analytical scheme has been studied for verifying their nuclide composition based on calculation analysis and record, in consideration of the its characteristics. In this study, radwastes are used as samples, which arise from research and testing reactors and post-irradiation examination facilities (PIE facilities). Though separation procedures are simplified and rationalized, quantifiable values could be obtained with relative errors under 10% for almost all the samples containing nuclides like 
Ni and 
U which concentrations are low, and recoveries were high on the whole. These show that the analytical scheme is useful for chemical separation of radwastes arising from research and testing reactors and PIE facilities.
TiUchida, Munenori*; Ishitsuka, Etsuo; Kawamura, Hiroshi
Journal of Nuclear Materials, 307-311(Part1), p.653 - 656, 2002/12
Times Cited Count：29 Percentile：84.85(Materials Science, Multidisciplinary)BeTi has high melting point and good chemical stability and is expected as the advanced material for the neutron multiplier of DEMO-Reactor that requires higher temperature than 600
C in a blanket. To evaluate the tritium inventory in the breeding blanket, tritium release experiment of the neutron irradiated BeTi irradiated with a total fast neutron fluence of about 4 x 10
n/cm
(E
1MeV) at 330, 400 and 500C, was carried out. It was clear that tritium could be released easier than beryllium, and the apparent diffusion coefficient of BeTi was about two orders larger than that of beryllium at 600
1100C. In addition to good tritium release property, the swelling calculated from the density change of the specimens up to 1100C in this test was smaller than that of beryllium.
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka
Fusion Technology, 39(2-Part2), p.1078 - 1082, 2001/03
no abstracts in English
Sakai, Akihiro
KURRI-KR-56, p.58 - 79, 2001/03
no abstracts in English
Konishi, Satoshi; Asaoka, Yoshiyuki*; Hiwatari, Ryoji*; Okano, Kunihiko*
Purazuma, Kaku Yugo Gakkai-Shi, 76(12), p.1309 - 1312, 2000/12
no abstracts in English
*
JNC TN1440 2000-007, 115 Pages, 2000/08
JNC-TN1440-2000-007.pdf:4.45MB
no abstracts in English
; ; ; ;
JNC TN9400 2000-066, 52 Pages, 2000/06
JNC-TN9400-2000-066.pdf:1.82MB
Phase I of feasibility studies on commercialized fast reactor system is being peformed for two years from Japanese Fiscal Year 1999. In this report, results of the study on fluid fuel reactors (especialiy a molten salt fast breeder reactor concept) are described from the viewpoint of technical and economical concerns of the plant system design. ln JFY1999, we have started to investigate the fluid fuel reactors as alternative concepts of sodium cooled FBR systems with MOX fuel, and selected the unique concept of a molten chloride fast, breeder reactor, whose U-Pu fuel cycle can be related to both light water reactors and fast breeder reactors on the basis of present technical data and design experiences. We selected a preliminary composition of molten fuel and conceptual plant design through evaluation of technical and economical issues essential for the molten salt reactors and then compared them with reference design concepts of sodium cooled FBR systems under limited information on the molten chloride fast breeder reactors. The following results were obtained. (1)The molten chloride fast breeder reactors have inherent safety features in the core and plant performances, ad the fluid fuel is quite promising for cost reduction of the fuel fabrication and reprocessing. (2)On the other hand, the inventory of the molten chloride fuel becomes high and thermal conductivity of the coolant is inferior compared to those of sodium cooled FBR systems, then, the size of main components such as lHX's becomes larger and the amount of construction materials is seems to be increased. (3)Furthermore economical vessel and piping materials which contact with the molten chloride salts are required to be developed. From the results, it is concluded that further steps to investigate the molten chloride fast breeder reactor concepts are too early to be conducted.
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka
JAERI-Tech 2000-002, p.37 - 0, 2000/02
JAERI-Tech-2000-002.pdf:1.49MB
no abstracts in English
Nishikawa, Masabumi*; *; Kawamura, Yoshinori; Nishi, Masataka
JAERI-Conf 98-006, p.170 - 182, 1998/03
no abstracts in English
Yoshida, Hiroshi; O.Kveton*; J.Koonce*; D.Holland*; Haange, R.*
Fusion Engineering and Design, 39-40, p.875 - 882, 1998/00
Times Cited Count：25 Percentile：85.88(Nuclear Science & Technology)no abstracts in English
Yamanishi, Toshihiko; Nishikawa, Masabumi*; *
Purazuma, Kaku Yugo Gakkai-Shi, 73(12), p.1326 - 1332, 1997/12
no abstracts in English
Baba, Atsushi*; Nishikawa, Masabumi*; Kawamura, Yoshinori; Okuno, Kenji
Journal of Nuclear Materials, 248, p.106 - 110, 1997/09
Times Cited Count：4 Percentile：37.09(Materials Science, Multidisciplinary)no abstracts in English
Iwai, Yasunori; Yamanishi, Toshihiko; Okuno, Kenji
JAERI-Tech 96-043, 31 Pages, 1996/11
no abstracts in English
Kawamura, Yoshinori; Okuno, Kenji; Nishikawa, Masabumi*
Proceedings of 4th International Workshop on Ceramic Breeder Blanket Interface (CBBI-4), p.235 - 248, 1995/10
no abstracts in English
Konishi, Satoshi; Yamanishi, Toshihiko; Enoeda, Mikio; Hayashi, Takumi; Ohira, Shigeru; Yamada, Masayuki; Suzuki, Takumi; Okuno, Kenji; Sherman, R. H.*; Willms, R. S.*; et al.
Fusion Engineering and Design, 28, p.258 - 264, 1995/00
Times Cited Count：4 Percentile：43.46(Nuclear Science & Technology)no abstracts in English
OTakeshita, Hidefumi; *
Journal of Nuclear Materials, 208, p.186 - 190, 1994/00
Times Cited Count：2 Percentile：47.65(Materials Science, Multidisciplinary)no abstracts in English
Konishi, Satoshi; Ohira, Shigeru; Inoue, Masahiko*; Watanabe, Tetsuo*; Naruse, Yuji; Okuno, Kenji; Barnes, J. W.*; Sherman, R. H.*; Bartlit, J. R.*; Anderson, J. L.*
JAERI-M 93-085, 40 Pages, 1993/03
no abstracts in English
