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Takahara, Shogo; Iijima, Masashi*; Yoneda, Minoru*; Shimada, Yoko*
Risk Analysis, 39(1), p.212 - 224, 2019/01
Times Cited Count：5 Percentile：47.67(Public, Environmental & Occupational Health)A dose assessment model was developed based on measurements and surveys of individual doses and relevant contributors in Fukushima City for four population groups: Fukushima City Office staff, Senior Citizens' Club, Contractors' Association, and AgriculturalCooperative. In addition, probabilistic assessments were performed for these population groups by considering the spatial variability of contamination and interpopulation differencesresulting from behavior patterns. As a result of comparison with the actual measurements, the assessment results for participants from the Fukushima City Office, Senior Citizens' Club and the Agricultural Cooperative agreed with the measured values. By contrast, the measurements obtained for the participants from the Contractors' Association were not reproduced well in the present study. To assess the doses to this group, further investigations of association members' work activities and the related dose reduction effects are needed.
Takahara, Shogo; Ikegami, Maiko*; Yoneda, Minoru*; Kondo, Hitoshi*; Ishizaki, Azusa; Iijima, Masashi; Shimada, Yoko*; Matsui, Yasuto*
Risk Analysis, 37(7), p.1256 - 1267, 2017/07
Times Cited Count：6 Percentile：51.26(Public, Environmental & Occupational Health)Kurikami, Hiroshi; Malins, A.; Takeishi, Minoru; Saito, Kimiaki; Iijima, Kazuki
Journal of Environmental Radioactivity, 171, p.99 - 109, 2017/05
Times Cited Count：14 Percentile：42.77(Environmental Sciences)A modified diffusion-sorption-fixation model (mDSF) is proposed to describe the vertical migration of radiocesium in soils following fallout. The model introduces kinetics for reversible sites, meaning that the exponential-shape radiocesium distribution can be reproduced immediately following fallout. The initial relaxation mass depth of the distribution is determined by the diffusion length, which depends on the distribution coefficient, sorption rate and dispersion coefficient. The model captures the long tails of the radiocesium distribution at large depths. These tails are caused by different rates for kinetic sorption and desorption.
Favuzza, P.*; Antonelli, A.*; Furukawa, Tomohiro; Groeschel, F.*; Heidinger, R.*; Higashi, Takuma*; Hirakawa, Yasushi; Iijima, Minoru; Ito, Yuzuru; Kanemura, Takuji; et al.
Fusion Engineering and Design, 107, p.13 - 24, 2016/06
Times Cited Count：10 Percentile：67.82(Nuclear Science & Technology)Three different partners, ENEA, JAEA and University of Tokyo, have been involved during 2014 and 2015 in the Round Robin experimentation for the assessment of the soundness of the analitycal procedure for the determination of the Nitrogen impurities contained inside a solid Lithium sample. Two different kinds of Lithium samples, differing by about an order of magnitude in Nitrogen concentration (about 230 wppm, about 20-30 wppm), have been selected for this cross analysis. The agreement of the achieved results appears very good for what concerns the most concentrated Lithium and indicates each partner's procedure is appropriate and intrinsically able to lead to meaningful values, characterized by a relative uncertainty of just few %. The smaller agreement in the case of the less concentrated Lithium anyway points out that particular attention must be paid to reduce as much as possible any source of external contamination and highlights the importance of the proper blank subtraction.
Furukawa, Tomohiro; Hirakawa, Yasushi; Kato, Shoichi; Iijima, Minoru; Otaka, Masahiko; Kondo, Hiroo; Kanemura, Takuji; Wakai, Eiichi
Fusion Engineering and Design, 89(12), p.2902 - 2909, 2014/12
Times Cited Count：10 Percentile：60.52(Nuclear Science & Technology)For the irradiation test of the candidate materials for the fusion DEMO reactor, Engineering Validation and Engineering Design Activities (EVEDA) of the International Fusion Materials Irradiation Facility (IFMIF) are performed under the Broader Approach Activities. As a major Japanese activity on the target facility of the IFMIF, the engineering validation using the EVEDA Lithium Test Loop which is the largest scale liquid lithium test loop has been started in 2012. In parallel with the design and fabrication, the research on the technology establishment for the lithium safety handling was started in 2008, as one of the related technologies under the IFMIF-EVEDA. In the research, experiments of lithium chemical reaction, experiments on lithium fire, establishment of chemical analysis of impurities in lithium and experiments on advanced lithium leak detection system were carried out. This paper describes the results of these experiments.
Iijima, Kazuki; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*
Radiochimica Acta, 98(9-11), p.729 - 736, 2010/11
Times Cited Count：3 Percentile：23.88(Chemistry, Inorganic & Nuclear)Distribution behavior of Cs and Am in the synthetic groundwater-bentonite colloids-granite ternary system was investigated. Radionuclide sorbed onto the bentonite colloids is desorbed by addition of granite, indicating that the sorption of Cs and Am onto the bentonite colloids are reversible. The sorption model based on cation exchange and surface complexation reaction considering high edge site density for bentonite colloids is applicable to explain the sorption behavior of Am and Cs in the ternary system.
Nakai, Satoru; Aoyama, Takafumi; Ito, Chikara; Yamamoto, Masaya; Iijima, Minoru; Nagaoki, Yoshihiro; Kobayashi, Atsuko; Onoda, Yuichi; Ohgama, Kazuya; Uwaba, Tomoyuki; et al.
Kosoku Jikkenro "Joyo" Rinkai 30-Shunen Kinen Hokokukai Oyobi Gijutsu Koenkai, 154 Pages, 2008/06
no abstracts in English
; ; ; ; Okubo, Minoru; Iijima, Tsutomu; ; ; ; ; et al.
JAERI-M 8360, 84 Pages, 1979/08
no abstracts in English
Iijima, Kazuki; Nakata, Kotaro*; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*
no journal, ,
Batch type distribution experiments of Cs and Am in the solution-bentonite colloid-granite ternary system were carried out. Considering Na concentration, distribution coefficient of Cs on bentonite colloids obtained in the ternary system is similar to the calculated value using ion selectivity coefficient evaluated in the binary system. It indicates that the method to estimate the distribution behavior in the binary system is applicable to the ternary system in this case.
Iijima, Kazuki; Kurosawa, Seiichi*; Kibe, Satoshi*; Tobita, Minoru*; Ouchi, Yuji*
no journal, ,
Diffusion behavior of humic acid and Nd in the presence of humic acid was investigated and modeled. Breakthrough of humic acid is observed in 0.1 and 1M NaCl with 1.2-1.6 Mg/m
dry density of compacted bentonite. The presence of humic acid facilitates the migration of Nd. Diffusion Parameters were evaluated from experimental results using the one dimensional diffusion model in which migration of several Nd species with different diffusion behaviors keeping equilibrium in parallel was taken into account. Obtained diffusion parameters for humic acid and Nd will be used for prediction of diffusion behavior of radionuclides in the presence of humic acid under various conditions.
Iijima, Kazuki; Kurosawa, Seiichi*; Tobita, Minoru*; Kibe, Satoshi*; Ouchi, Yuji*
no journal, ,
Diffusion behavior of humic acid in compacted bentonite was investigated by through-diffusion method. Concentration profile and molecular weight distribution of humic acid in the compacted bentonite indicate that only low molecular weight fraction of humic acid is likely to diffuses. Difference of diffusion behavior arising from difference of molecular weight is considered to be taken into account in evaluation of diffusion parameters.
Fujiwara, Kenso; Iijima, Kazuki; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*; Tits, J.*; Curti, E.*
no journal, ,
no abstracts in English
Hirakawa, Yasushi; Furukawa, Tomohiro; Iijima, Minoru; Kondo, Hiroo; Kanemura, Takuji; Wakai, Eiichi
no journal, ,
Lithium, which is used as the neutron source of the International Fusion Materials Irradiation Facility (IFMIF), reacts easily with nitrogen, oxygen and humidity in atmosphere. In this study, the R&D results on the lithium safety handling are presented in this study. The contents are (a) lithium fire extinguishing, (b) chemical reaction of lithium at elevated temperature, (c) lithium cleaning for the components and (d) impurity analysis of lithium.
Nakata, Kotaro*; Iijima, Kazuki; Tomura, Tsutomu*; Tobita, Minoru*
no journal, ,
In this study, a new experimental system has been developed to obtain the information on distribution of raidonuclide between aqueous, colloid and rock phases. Sorption, desorption and distribution experiments of Cs on smectite colloid and granite were carried out with new developed system. After confirmation of applicability of the developed system, Kd values were obtained in 3 phases coexist system. The results of desorption experiment indicated sorption of Cs on smectite colloid is reversible.
