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JAEA Reports

Design details of bottom shape for the 3rd glass melter in TVF

Asahi, Yoshimitsu; Shimamura, Keisuke*; Kobayashi, Hidekazu; Kodaka, Akira

JAEA-Technology 2021-026, 50 Pages, 2022/03

JAEA-Technology-2021-026.pdf:6.29MB

In Tokai Reprocessing Plant, the highly active liquid waste derived from a spent fuel reprocessing is vitrified with a Liquid-Fed Ceramic Melter (LFCM) embedded in Tokai Vitrification Facility (TVF). For an LFCM, the viscosity of melted glass is increased by the deposition of oxidation products of platinum group elements (PGE) and the PGE-containing glass tends to settle to the melter's bottom basin even after draining glass out. Removal of the PGE-containing glass is needed to avoid the Joule heating current from being affected by the glass, it requires time-consuming work to remove. For the early accomplishment of vitrifying the waste, Japan Atomic Energy Agency is planning to replace the current melter with the new one in which the amount of PGE sediments would be reduced. In the past design activities for the next melter, several kinds of shapes in regard to the furnace bottom and the strainer were drawn. Among these designs, the one in which the discharge ratio of PGE-containing glass would be as much as or greater than the current melter and which be able to perform similar operational sequences done in the current melter is selected here. Firstly, an operational sequence to produce one canister of vitrified waste is simulated for three melter designs with a furnace bottom shape, using 3D thermal-hydraulic calculations. The computed temperature distribution and its changes are compared among the candidate structures. After discussions about the technical and structural feasibilities of each design, a cone shape with a 45$$^{circ}$$ slope was selected as the bottom shape of the next melter. Secondly, five strainer designs that fit the bottom shape above mentioned are drawn. For each design, the fluid drag and the discharge ratio of relatively high viscosity fluid resting near the bottom are estimated, using steady or unsteady CFD simulation. By draining silicone oil from acrylic furnace models, it was confirmed experimentally that there are no vortices

Journal Articles

Autoradiography system with phosphor powder (ZnS:Ag) for imaging radioisotope dynamics in a living plant

Kurita, Keisuke; Sakai, Takuro; Suzui, Nobuo*; Yin, Y.-G.*; Sugita, Ryohei*; Kobayashi, Natsuko*; Tanoi, Keitaro*; Kawachi, Naoki*

Japanese Journal of Applied Physics, 60(11), p.116501_1 - 116501_4, 2021/11

Radioisotope tracer imaging is useful for studying plant physiological phenomena. In this study, we developed an autoradiography system with phosphor powder (ZnS:Ag), "Live-autoradiography", for imaging radioisotope dynamics in a living plant. This system visualizes the element migration and accumulation in intact plants continuously under a light environment. An imaging test was performed on point sources of $$^{137}$$Cs, with a radioactivity of 10-100 kBq of being observed; this indicates satisfactory system linearity between the image intensity and the radioactivity of $$^{137}$$Cs. Moreover, dynamics imaging of $$^{137}$$Cs was performed on an intact soybean plant for four days. The serial images indicated $$^{137}$$Cs accumulation in the node, vein, and growing point of the plant. The developed system can be used for studying plant physiological phenomena and can be employed for quantitative measurement of radionuclides.

JAEA Reports

XAFS measurement of simulated waste glass samples prepared from borosilicate glass frit including phosphorus pentaoxide (Joint research)

Nagai, Takayuki; Kobayashi, Hidekazu; Shimamura, Keisuke; Oyama, Koichi; Sasage, Kenichi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*

JAEA-Research 2018-005, 72 Pages, 2018/09

JAEA-Research-2018-005.pdf:28.2MB

Addition of radioactive waste to a borosilicate glass frit affects the local structures of glass-forming elements and waste elements in a waste glass produced in a vitrification process. In this study, simulated waste glass samples were prepared from borosilicate glass frit including phosphorus pentaoxide, and we investigated local structures of sodium (Na), boron (B), and waste elements in these glass samples by using synchrotron XAFS measurements in soft and hard X ray region.

Journal Articles

Current status and future developments of hard X-ray photoelectron spectroscopy

Kobata, Masaaki; Okane, Tetsuo; Kobayashi, Keisuke*

Bunko Kenkyu, 67(4), p.161 - 162, 2018/08

We introduce hard X-ray photoelectron spectroscopy, which has been rapidly introduced and developed in synchrotron radiation facilities. In particular, in order to realize electronic state analysis by hard X-ray photoelectron spectroscopy of insulators, the developed charge neutralization method was described. As an example, we showed adsorption behavior of cesium to nuclear reactor structure assuming Fukushima Daiichi Nuclear Power Plant accident. Finally, future prospects of hard X-ray photoelectron spectroscopy will be described.

Journal Articles

Chemical form analysis of reaction products in Cs-adsorption on stainless steel by means of HAXPES and SEM/EDX

Kobata, Masaaki; Okane, Tetsuo; Nakajima, Kunihisa; Suzuki, Eriko; Owada, Kenji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Osaka, Masahiko

Journal of Nuclear Materials, 498, p.387 - 394, 2018/01

 Times Cited Count:9 Percentile:81.13(Materials Science, Multidisciplinary)

In this study, for the understandings of Cesium (Cs) adsorption behavior on structure materials in severe accidents at a light water nuclear reactor, the chemical state of Cs and its distribution on the surface of SUS304 stainless steel (SS) with different Si concentration were investigated by hard X-ray photoelectron spectroscopy (HAXPES) and scanning electron microscope / energy dispersive X-ray spectroscopy (SEM/EDX). As a result, it was found that Cs is selectively adsorbed at the site where Si distributes with high concentration. CsFeSiO$$_{4}$$ is a dominant Cs products in the case of low Si content, mainly formed, while Cs$$_{2}$$Si$$_{2}$$O$$_{5}$$ and Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ are formed in addition to CsFeSiO$$_{4}$$ in the case of high Si content. The chemical forms of the Cs compounds produced in the adsorption process on the SS surface has a close correlation with the concentration and chemical states of Si originally included in SS.

JAEA Reports

XAFS measurement of simulated waste borosilicate glass samples (Joint research)

Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*

JAEA-Research 2017-005, 54 Pages, 2017/06

JAEA-Research-2017-005.pdf:16.17MB

Addition of radioactive waste to a borosilicate frit affects the local structures of boron (B) and waste elements in a waste glass. Synchrotron XAFS measurement was applied to investigate the local structural changes by using simulated waste borosilicate glass samples. Following results were obtained by the B K-edge XAFS analysis. It was confirmed that B K-edge XAFS analysis enables us to discriminate sp$$^{2}$$ type boron (BO$$_{3}$$) from sp$$^{3}$$ type boron (BO$$_{4}$$). Addition of waste elements to a glass frit increases the percentage of BO$$_{3}$$ and decreases that of BO$$_{4}$$. By decreasing the SiO$$_{2}$$/Al$$_{2}$$O$$_{3}$$ ratio or increasing the (SiO$$_{2}$$+B$$_{2}$$O$$_{3}$$)/Al$$_{2}$$O$$_{3}$$ ratio in the glass composition, the BO$$_{3}$$ percentage increases and the BO$$_{4}$$ percentage decreases. Addition of P$$_{2}$$O$$_{5}$$ decreases the BO$$_{3}$$ percentage and increases the BO$$_{4}$$ percentage. Following results were obtained from XAFS measurement of the waste elements. Cerium (Ce) valence is more reduced with the increase of the B$$_{2}$$O$$_{3}$$ content. Addition of P$$_{2}$$O$$_{5}$$ has a tendency to reduce the Ce valence and to enhance deposition of Zr oxide. Deposition of ruthenium compounds separated from glass phase can not be improved by changing the B$$_{2}$$O$$_{3}$$ content. This study was performed as a part of the project, "Improvement of vitrification process of high-level radioactive liquid wastes" on the foundation business of the Agency for Natural Resources and Energy.

Journal Articles

Electronic structure and correlation in $$beta$$-Ti$$_3$$O$$_5$$ and $$lambda$$-Ti$$_3$$O$$_5$$ studied by hard X-ray photoelectron spectroscopy

Kobayashi, Keisuke*; Taguchi, Munetaka*; Kobata, Masaaki; Tanaka, Kenji*; Tokoro, Hiroko*; Daimon, Hiroshi*; Okane, Tetsuo; Yamagami, Hiroshi; Ikenaga, Eiji*; Okoshi, Shinichi*

Physical Review B, 95(8), p.085133_1 - 085133_7, 2017/02

AA2017-0038.pdf:0.98MB

 Times Cited Count:6 Percentile:41.1(Materials Science, Multidisciplinary)

Journal Articles

Electronic structure of EuAl$$_4$$ studied by photoelectron spectroscopy

Kobata, Masaaki; Fujimori, Shinichi; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Nakamura, Ai*; Hedo, Masato*; Nakama, Takao*; et al.

Journal of the Physical Society of Japan, 85(9), p.094703_1 - 094703_6, 2016/09

 Times Cited Count:7 Percentile:56.08(Physics, Multidisciplinary)

Journal Articles

Hard X-ray photoelectron spectroscopy study for transport behavior of CsI in heating test simulating a BWR severe accident condition; Chemical effects of boron vapors

Okane, Tetsuo; Kobata, Masaaki; Sato, Isamu*; Kobayashi, Keisuke*; Osaka, Masahiko; Yamagami, Hiroshi

Nuclear Engineering and Design, 297, p.251 - 256, 2016/02

 Times Cited Count:1 Percentile:14.27(Nuclear Science & Technology)

Journal Articles

Evaluation of the cryogenic tensile properties for aramid fiber rod

Saito, Toru; Okubo, Toshikazu*; Izumi, Keisuke*; Okawa, Yoshinao*; Kobayashi, Norihiro*; Yamazaki, Toru; Kawano, Katsumi; Isono, Takaaki

Teion Kogaku, 50(8), p.400 - 408, 2015/08

Aramid fiber-reinforced plastic (AFRP) has been developed as a structural material that has the advantages of light weight and high strength. In this study, tensile tests were carried out to measure the tensile properties of AFRP rod on the market for reinforcement of concrete at room temperature, 77 K and 4.2 K. Especially at cryogenic temperatures, it is difficult to perform a tensile test of the bar because the specimen slips through the jig grip. To prevent the rod from slipping, tensile tests were carried out with some filling conditions. The applicable and appropriate tensile test conditions were established by modifying the jig grip, treating the surface of the rod and using cryogenic epoxy infill to grip the rod. They were more than 1100 MPa. Additionally, the AFRP rod included a temperature dependence in which the Young's modulus increased as the test temperature decreased. It was confirmed that the Young's modulus increased because aramid fiber was more dominant than epoxy.

Journal Articles

Study of oxide film with the hard X-ray photoelectron spectroscopy

Kobata, Masaaki; Kobayashi, Keisuke*

Journal of the Vacuum Society of Japan, 58(2), p.43 - 49, 2015/02

We report the applications of a hard X-ray photoelectron spectroscopy to the characterization of SiO$$_{2}$$/Si(001)systems. Large escape depth of high-energy photoelectron enables us to probe buried layers and their interfaces in multilayer structures. Estimation of SiO$$_{2}$$ overlayer thicknesses up to 25 nm by angle resolved XPS was possible in SiO$$_{2}$$/Si(001) samples. Determination of the thickness profile of a wedged shape SiO$$_{2}$$ buried layer was successfully done in Ir (8 nm)/HfO$$_{2}$$ (2.2 nm)/thickness graded-SiO$$_{2}$$ (0-10 nm) / Si (100). The Si 1s core level showed a SiO$$_{2}$$ thickness dependent shift, which was ascribed to fixed charge at the SiO$$_{2}$$-Si interface. Energy distribution of interface states at ultrathin thermal oxide/Si(100) interfaces were determined by Si 1${it s}$ core level shift by applying gate bias in metal-oxide-semiconductor (MOS) structure with 5 nm Au gate electrodes.

Journal Articles

Temperature control system for laser heating; Application for minute asteroidal materials

Osawa, Takahito; Kobayashi, Mikihiko*; Konno, Takeshi*; Egashira, Mitsuru*; Okazaki, Ryuji*; Miura, Yayoi*; Nagao, Keisuke*

Measurement, 50, p.229 - 235, 2014/04

 Times Cited Count:0 Percentile:0.01(Engineering, Multidisciplinary)

A temperature control system for a laser heating has been developed to extract noble gases from minute material samples recovered from the asteroid Itokawa by the Hayabusa spacecraft. An ultra-fine thermocouple was produced from 3% Re-W and 26% Re-W wires 25 $$mu$$m in diameter, and its electromotive force was calibrated. A temperature control program was originally produced using LabVIEW 2011 in which proportional-integral-derivative (PID) control was not adopted as an algorithm of the program. The program controlled the temperature of the tiny samples appropriately. The average temperature during heating was slightly lower than the setting temperature and the standard deviation and the maximum overshoot were lower than 2.5% and 6.0% of the setting temperature, respectively. The performance of the temperature control system is high enough to conduct the stepwise heating experiment for minute extraterrestrial material samples.

JAEA Reports

An Investigation for long-term storage of a spent zeolite adsorption vessel; Estimation of washing out salt component in a spent zeolite adsorption vessel, 1

Sato, Hiroyuki; Terada, Atsuhiko; Hayashida, Hitoshi; Kamiji, Yu; Kobayashi, Jun; Yamagishi, Isao; Morita, Keisuke; Kato, Chiaki

JAEA-Research 2013-042, 25 Pages, 2014/03

JAEA-Research-2013-042.pdf:5.13MB

Spent zeolite adsorption vessels in the Fukushima No.1 nuclear power plant are kept for long-term with washing out with fresh water for prevention of corrosion remaining salt component in vessel. However, corrosion result is concerned by residual concentration of salt component, washing out experiment is carried out using actual and unspent adsorption vessel (KURION). KURION adsorption vessel is filled with 1,650 ppm of sodium chloride (1,000 ppm of chloride ion) and washed out with pure water for estimating washing effect in this experiment. Pure water is streamed with volume flow rate 4.5 m$$^{3}$$/h, chloride concentration in vessel is measured with drainage sample water. 1,000 ppm of chloride concentration is decreased till 0.5 ppm and below by washing out with about double pure water volume of adsorbing material filling volume in vessel, washing out is more effective in KURION adsorption vessel.

JAEA Reports

Survey of radiation protection creiteria following the accident at the Fukushima Dai-ichi Nuclear Power Plant

Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.

JAEA-Review 2013-033, 51 Pages, 2013/12

JAEA-Review-2013-033.pdf:2.73MB

After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.

Journal Articles

The Possible interplanetary transfer of microbes; Assessing the viability of ${it Deinococcus}$ spp. under the ISS environmental conditions for performing exposure experiments of microbes in the Tanpopo mission

Kawaguchi, Yuko*; Yang, Y.*; Kawashiri, Narutoshi*; Shiraishi, Keisuke*; Takasu, Masako*; Narumi, Issey*; Sato, Katsuya; Hashimoto, Hirofumi*; Nakagawa, Kazumichi*; Tanigawa, Yoshiaki*; et al.

Origins of Life and Evolution of Biospheres, 43(4-5), p.411 - 428, 2013/10

 Times Cited Count:29 Percentile:78.06(Biology)

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ (x =0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

Journal Articles

Uniaxial-pressure control of magnetic phase transitions in a frustrated magnet CuFe$$_{1-x}$$Ga$$_{x}$$O$$_{2}$$ ($$x$$ = 0, 0.018)

Nakajima, Taro*; Mitsuda, Setsuo*; Takahashi, Keiichiro*; Yoshitomi, Keisuke*; Masuda, Kazuya*; Kaneko, Chikafumi*; Homma, Yuki*; Kobayashi, Satoru*; Kitazawa, Hideaki*; Kosaka, Masashi*; et al.

Journal of the Physical Society of Japan, 81(9), p.094710_1 - 094710_8, 2012/09

 Times Cited Count:12 Percentile:62.78(Physics, Multidisciplinary)

Journal Articles

Role of cerium oxide in the enhancement of activity for the oxygen reduction reaction at Pt-CeO$$_{x}$$ nanocomposite electrocatalyst; An in situ electrochemical X-ray absorption fine structure study

Masuda, Takuya*; Fukumitsu, Hitoshi*; Fugane, Keisuke*; Togasaki, Hirotaka*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Yoshikawa, Hideki*; Kobayashi, Keisuke*; Mori, Toshiyuki*; et al.

Journal of Physical Chemistry C, 116(18), p.10098 - 10102, 2012/05

 Times Cited Count:103 Percentile:94.24(Chemistry, Physical)

In situ electrochemical X-ray absorption fine structure (XAFS) measurements were performed at the Pt L$$_{3}$$ and Ce L$$_{3}$$ edges of the Pt-CeO$$_{x}$$/C catalyst, which was prepared by a combined process of precipitation and coimpregnation methods, as well as at the Pt L$$_{3}$$ edge of the conventional Pt/C catalyst in oxygen-saturated H$$_{2}$$SO$$_{4}$$ solution to clarify the role of CeO$$_{x}$$ in the reduction of the overpotential for the oxygen reduction reaction (ORR) at the Pt-CeO$$_{x}$$ nanocomposite compared with the conventional Pt/C catalyst. XAFS measurements clearly show that the enhancement of ORR activity is attributed to the inhibition of Pt oxide formation by the CeO$$_{x}$$ layer, of which Ce$$^{3+}$$ was oxidized to Ce$$^{4+}$$ instead of Pt at the Pt oxide formation potential.

Journal Articles

Role of residual transition-metal atoms in oxygen reduction reaction in cobalt phthalocyanine-based carbon cathode catalysts for polymer electrolyte fuel cell

Kobayashi, Masaki*; Niwa, Hideharu*; Harada, Yoshihisa*; Horiba, Koji*; Oshima, Masaharu*; Ofuchi, Hironori*; Terakura, Kiyoyuki*; Ikeda, Takashi; Koshigoe, Yuka*; Ozaki, Junichi*; et al.

Journal of Power Sources, 196(20), p.8346 - 8351, 2011/10

 Times Cited Count:32 Percentile:70.76(Chemistry, Physical)

The electronic structure of Co atoms in CoPc-based carbon catalysts, which were prepared by pyrolyzing a mixture of CoPc and phenol resin polymer up to 1000$$^circ$$C, has been investigated using XAFS analysis and HXPES. The Co K XAFS spectra show that most of the Co atoms are in the metallic state and small quantities of oxidized Co components are present in the samples even after acid washing to remove Co atoms. Based on the difference in probing depth between XAFS and HXPES, it was found that after acid washing, the surface region with the aggregated Co clusters is primarily composed of metallic Co. Since the electrochemical properties remain almost unchanged even after the acid washing process, the residual metallic and oxidized Co atoms themselves will hardly contribute to the ORR activity of the CoPc-based carbon cathode catalysts, implying that the active sites of the CoPc-based catalysts primarily consist of light elements such as C and N.

Journal Articles

Conduction-band electronic states of YbInCu$$_4$$ studied by photoemission and soft X-ray absorption spectroscopies

Utsumi, Yuki*; Sato, Hitoshi*; Kurihara, Hidenao*; Maso, Hiroyuki*; Hiraoka, Koichi*; Kojima, Kenichi*; Tobimatsu, Komei*; Okochi, Takuo*; Fujimori, Shinichi; Takeda, Yukiharu; et al.

Physical Review B, 84(11), p.115143_1 - 115143_7, 2011/09

 Times Cited Count:7 Percentile:31.79(Materials Science, Multidisciplinary)

We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu$$_4$$ by means of temperature-dependent hard X-ray photoemission spectroscopy (HX-PES), soft X-ray absorption spectroscopy (XAS), and soft X-ray photoemission spectroscopy (SX-PES) of the valence band. We have described the valence transition in YbInCu$$_4$$ in terms of the charge transfer from the CB to Yb 4$$f$$ states.

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