Kaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 988, p.164900_1 - 164900_8, 2021/02
An increasing number of nuclear facilities have been decommissioned worldwide following the 2011 accident of the TEPCO' Fukushima Daiichi Nuclear Power Station. During the decommissioning, radioactive materials have to be retrieved under proper management. In this study, a small cubic CeBr spectrometer with dimensions of 5 mm 5 mm 5 mm was manufactured to perform -ray spectroscopy under intense -ray fields. Furthermore, thanks to a fast digital process unit and a customized photomultiplier, the device could perform -ray spectroscopy at dose rates of over 1 Sv/h. The energy resolution (FWHM) at 662 keV ranged from 4.4% at 22 mSv/h to 5.2% at 1407 mSv/h for a Cs radiation field. Correspondingly, at 1333 keV, it ranged from 3.1% at 26 mSv/h to 4.2% at 2221 mSv/h for a Co radiation field, which suggested to realize -ray assessment of Cs, Cs, Co, and Eu at dose rates of over 1 Sv/h.
Yamaguchi, Masaaki; Kato, Tomoko; Suzuki, Yuji*; Makino, Hitoshi
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.72 - 82, 2020/12
An efficient analytical tool to calculate temporal change of topography and repository depth due to uplift and erosion was developed for use in performance assessment of high level radioactive waste geological disposal. The tool was developed as ArcGIS model, incorporating simplified landform development simulation, to enable trial calculation of various conditions such as initial topography, uplift rate and its distributions, and repository location. This tool enables to support decision on which processes, features, and their changes should be taken into account for performance assessment, by calculating topography change and repository depth change under various conditions.
Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Sakamoto, Tomokazu*; Kawasaki, Takuro; Fukuda, Tatsuo; Sekino, Toru*; Nakayama, Tadachika*; Takeda, Masatoshi*; et al.
Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03
Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11
Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Ferroelectrics, 512(1), p.92 - 99, 2017/08
Miyabe, Masabumi; Oba, Masaki; Jung, K.; Iimura, Hideki; Akaoka, Katsuaki; Kato, Masaaki; Otobe, Haruyoshi; Khumaeni, A.*; Wakaida, Ikuo
Spectrochimica Acta, Part B, 134, p.42 - 51, 2017/08
Spectroscopic properties of atomic species of plutonium were investigated by combining laser ablation and resonance absorption techniques for the analysis of a plutonium oxide sample. For 17 transitions of Pu atoms and ions, the absorbance, isotope shift, and hyperfine splitting were determined via Voigt profile fitting of the recorded absorption spectra. Three transitions were selected as candidates for analytical use. Using these transitions, we investigated the analytical performance that was attainable and determined a correlation coefficient R2 between the absorbance and plutonium concentration of 0.9999, a limit of detection of 30-130 ppm, and a relative standard deviation of approximately 6% for an abundance of Pu of 2.4%. These results demonstrate that laser ablation absorption spectroscopy is applicable to the remote isotopic analysis of highly radioactive nuclear fuels and waste materials containing multiple actinide elements.
Yamanaka, Satoru*; Kim, J.*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Yamada, Noboru*; et al.
Advanced Sustainable Systems (Internet), 1(3-4), p.1600020_1 - 1600020_6, 2017/04
no abstracts in English
Wakasugi, Keiichiro; Yamaguchi, Masaaki; Koo, Shigeru*; Nagao, Fumiya; Kato, Tomoko; Suzuki, Yuji*; Ebashi, Takeshi; Umeki, Hiroyuki*; Niibori, Yuichi*
Nippon Genshiryoku Gakkai Wabun Rombunshi, 16(1), p.15 - 33, 2017/03
This study provides a method of safety assessment for the geological disposal of HLW to evaluate the effects of uplift and erosion which are widespread phenomena identified on regional and global scales, and are more or less difficult to avoid in Japan. This method enables to deal with different uplift rate and erosion rate, and to evaluate repository depth, the time required for a repository to reach the weathered zone and surface of the ground, and the number of waste packages eroded as a function of time by using a landform evolution model. Based on trial analysis, the result shows that the maximum dose in the Base Case (uplift rate: 0.3 mm/y) is less than the targeted criterion suggested by the international organization even if the repository reaches the ground surface. Furthermore, the diversifying effect on timing the waste packages to reach to weathered zone due to heterogeneity on altitude of bottom of weathered zone reduces one order magnitude of result of the existed dose assessment. The new method is applicable to evaluate safety of geological disposal based on realistic phenomena of uplift and erosion and to quantify a safety margin and robustness of the disposal system.
Kaburagi, Masaaki; Yamada, Hironao*; Miyakawa, Takeshi*; Morikawa, Ryota*; Takasu, Masako*; Kato, Takamitsu*; Uesaka, Mitsuru*
Polymer Journal, 48(2), p.189 - 195, 2016/02
We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between (POT1) and O5' (telomeric ssDNA) is calculated to verify the binding system for 100 ns MD. We then calculated the distance between the bases of telomeric DNA ends and the root mean square deviation and gyration radius in single and binding states. We compared the root mean square fluctuations between single and binding states and calculated the number of hydrogen bonds between POT1 and telomeric DNA. There are many hydrogen bonds between Gln94 and the first guanine of the closest TTAGGG sequence in telomeric single-stranded DNA. These Gln94 and the guanine have a large difference in root mean square fluctuation between single and binding states. We found that Gln94 and guanine are important components of the binding system, and they are related to its stability.
Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Khumaeni, A.*; Kato, Masaaki; Wakaida, Ikuo
Spectrochimica Acta, Part B, 110, p.101 - 117, 2015/08
The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5-6J/cm) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis.
Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.
Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01
The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.
Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.
Physica C, 470(Suppl.1), p.S485 - S486, 2010/12
We report the lower critical fields measurements on Fe-based oxipnictide PrFeAsO single crystals for and -planes. To avoid the difficulty of determinations due to the flux pinning, we developed a novel method using a miniature hall-sensor array which can evaluate the local magnetic induction ai each sensor position. The hall sensor which is placed on the edge of the crystal clearly resolves the first flux penetration from the Meissner state. The temperature dependence of for is well scaled by the in-plane penetration depth and is consistent with a full-gap superconducting state. The anistropy of at low temperatures is estimated to be 3, which is much smaller than of . This indicates the multiband superconductivity, in which the active bands for superconductivity are more two-dimensional.
Van der Beek, C. J.*; Rizza, G.*; Konczykowski, M.*; Fertey, P.*; Monnet, I.*; Okazaki, Ryuji*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; et al.
Physica C, 470(Suppl.1), p.S385 - S386, 2010/12
Crystalline disorder in the pnictide superconductor PrFeAsO is studied using magneto-optical visualisation of flux penetration, transmission electron microscopy, and X-ray diffraction using synchrotron radiation. Critical-state like flux distributions and the magnitude and temperature dependence of the critical current demonstrate bulk vortex pinning by oxygen vacancies at all temperatures.
Araki, Masaaki; Kato, Tomoaki; Arai, Masaji
JAEA-Technology 2010-015, 35 Pages, 2010/06
Research reactor JRR-3 is a light water moderated and cooled pool type research reactor using low enriched uranium-silicon-aluminum-dispersion-type fuel. French Competent Authority (FCA) required that the criticality safety of the JRF-90Y-950K package is maintained even if it is deformed under oblique drops onto a bar. Criticality analyses of the JRF-90Y-950K package were carried out for the transport of JRR-3, JRR-4 or JMTR fuel. The results show that criticality safety is kept even if it is deformed under oblique drops onto a bar.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06
Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.
Maekawa, Yasunari; Kato, Jun*; Katakai, Masashi*; Ishihara, Masaaki*; Enomoto, Kazuyuki; Hagiwara, Tokio*; Ishii, Tatsuhito*; Ito, Kazuo*; Koshikawa, Hiroshi; Yoshida, Masaru
Macromolecular Chemistry and Physics, 209(6), p.625 - 633, 2008/03
A polysulfonamide and copolymers consisting of sulfonamides and amides underwent Fries rearrangement and scission, forming amino groups upon EB irradiation. The EB irradiation of these films with a dose of 500 C/cm followed by the color forming reaction provided the color imaging of line/space patterns with resolution of 300 nm.
Kato, Tomoaki; Araki, Masaaki; Izumo, Hironobu; Kinase, Masami; Torii, Yoshiya; Murayama, Yoji
JAEA-Technology 2007-050, 39 Pages, 2007/08
On the conversion from aluminide fuel to silicide fuel, burnable absorbers were introduced for decreasing excess reactivity. The burnable absorbers influence reactivity during reactor operation. So, the burning of the burnable absorbers was studied and the influence on reactor operation was made cleared. Furthermore, necessary excess reactivity on beginning of operation cycle and the time limit for restart after unplanned reactor shutdown was calculated. After the conversion, the fuel exchange procedure was changed from the six-batch dispersion procedure to the fuel burn-up management procedure. The previous estimation of fuel burn-up was required for the planning of fuel exchange, so that the estimation was carried out by means of past operation data. Finally, a new fuel exchange procedure was proposed for effective use of fuel elements. The average length of fuel-staying in the core can be increased by two percent on the procedure.
Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.
JAEA-Technology 2007-038, 189 Pages, 2007/07
The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.
Kato, Yuko; Umebayashi, Eiji; Okimoto, Yutaka; Okuda, Eiichi; Takayama, Koichi; Ozawa, Takayuki; Maeda, Seiichiro; Matsuzaki, Masaaki; Yoshida, Eiichi; Maeda, Koji; et al.
JAEA-Research 2007-019, 56 Pages, 2007/03
In order to resume the System Startup Test (SST) of Monju, replacement fuel have to be loaded in exchange for some of initial fuel now loaded in the core to compensate core reactivity lost by decay of Pu-241 in them. The replacement fuel were being stored either in sodium in an ex-vessel storage tank or in air in a storage rack for about 10 years since their fabrication. The initial fuel were irradiated during the SST which was suspended in the end of 1995 and then stayed being loaded in the sodium-circulated core. As this long-term storage and loading may deteriorate mechanical integrity of the assemblies, a study has been made thoroughly on its thermal-hydraulic, structural and material effects on them that might be caused by irradiation in the core, sodium and mechanical environment. The study has shown that the mechanical integrity of them is well maintained even with this long-term storage and loading.