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Iwamoto, Chihiro*; Takamura, Masato*; Ueno, Kota*; Kataoka, Minami*; Kurihara, Ryo*; Xu, P. G.; Otake, Yoshie*
ISIJ International, 62(5), p.1013 - 1022, 2022/05
Times Cited Count：2 Percentile：32.54(Metallurgy & Metallurgical Engineering)Umeda, Ryota; Kondo, Toshiki; Kikuchi, Shin; Kurihara, Akikazu
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 9 Pages, 2021/08
In this study, in order to obtain the fundamental information on aerosol transport behavior between cells, the Multiple cells with Expandable connecting pipe Test facility (MET) was manufactured and preliminary experiments were performed. In the preliminary experiments, simulated particles were used in a test system with two cells connected horizontally or vertically, and their transport behavior was measured. As a result, it was possible to confirm the behavior of the simulated particles transporting to the horizontal or vertical cells from the results such as images and sedimentation data.
Umeda, Ryota; Shimoyama, Kazuhito; Kurihara, Akikazu
Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(4), p.234 - 244, 2020/12
Sodium-water reaction caused by failure of the steam generator tube of sodium-cooled fast reactor induce the wastage phenomenon, which has erosive and corrosive feature. In this report, the authors have performed the self-wastage experiments under high sodium temperature condition to evaluate the effect of wastage form/geometry by using two types of initial defect such as the micro fine pinhole and fatigue crack, and water leak rate on self-wastage rate. Based on the consideration of crack type influence, it was confirmed that self-wastage rate did not strongly depend on the initial defect geometry. As a mechanism of the self-plug phenomenon, it is speculated that sodium oxide intervenes and inhibits the progress of self-wastage. The dependence of initial sodium temperature on self-wastage rate was clearly observed, and new self-wastage correlation was derived considering the initial sodium temperature.
Tashiro, Koji*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Ohara, Takashi; Hanesaka, Makoto*; Yoshizawa, Yoshinori*; Yamamoto, Hiroko*; Niimura, Nobuo*; Tanaka, Ichiro*; Kurihara, Kazuo*; et al.
Macromolecules, 51(11), p.3911 - 3922, 2018/06
Times Cited Count：5 Percentile：18.18(Polymer Science)Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito; Kikuchi, Shin
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00382_1 - 17-00382_11, 2018/03
Wastage on adjacent tubes (target-wastage) arise from water/steam leak in steam generators of sodium-cooled fast reactors (sodium-water reaction). Target-wastage is likely to be caused by liquid droplet impingement erosion (LDI) and Na-Fe composite oxidation type corrosion with flow (COCF) in an environment marked by high temperature and high-alkali (reaction jet) due to sodium-water reaction. In the previous study, the authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay. In this study, the applicability of new wastage correlations was confirmed for each tube in sodium-water reaction test with straight vertical tube bundle under practical steam generator operation condition. The authors established that the new wastage correlations were applicable to each tube of tube bundle in the above test, and the time progress of wastage was qualitatively investigated for the two penetrated tubes in the period including the water and/or steam blowdown.
Umeda, Ryota; Shimoyama, Kazuhito; Kurihara, Akikazu
JAEA-Technology 2017-018, 70 Pages, 2017/08
JAEA-Technology-2017-018.pdf:9.67MB
In case of the water leak into sodium in a SG of SFRs due to tube failure, reaction jet is formed by sodium-water reaction with exothermic heat. The reaction jet forms highly alkaline environment with high temperature and high pressure, which cause local thinning of adjacent heat transfer tubes (target wastage). In this report, for the purpose of elucidation of target wastage, the authors developed the experimental apparatus and experimental technique which enable the separate evaluation of wastage influence factors, including temperature, impingement velocity, reagent ratio and so on by using high temperature sodium hydroxide as major reaction product and sodium monoxide as secondary reaction product. In addition, the impingement corrosion experiments have been conducted by using high temperature reagents (NaOH and Na
O). Based on the corrosive data, authors quantitatively evaluated the influence factors of wastage and formulated the average corrosive equations.
Deguchi, Yoshihiro*; Muranaka, Ryota*; Kamimoto, Takahiro*; Takagi, Taku*; Kikuchi, Shin; Kurihara, Akikazu
Applied Thermal Engineering, 114, p.1319 - 1324, 2017/03
Times Cited Count：2 Percentile：12.87(Thermodynamics)The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products quantitatively. The counter-flow diffusion experiment device was employed to analyze the reaction path and reaction products using laser diagnostics. The main product of sodium-water reaction was determined to be NaOH and the sodium oxide was not notably measured compared with NaOH.
Umeda, Ryota; Kurihara, Akikazu; Shimoyama, Kazuhito
JAEA-Technology 2016-030, 50 Pages, 2016/12
JAEA-Technology-2016-030.pdf:5.22MB
In case of tube failure of a steam generator in sodium-cooled fast reactors, the reaction jet with high temperature and high velocity under highly alkaline environment is formed by cited exothermic reaction (sodium-water reaction). When the high temperature reaction jet covers the adjacent tubes, the material strength of tube decreases in the high temperature condition, and the adjacent tube may be swollen and failed by inner pressure (overheating tube rupture). For evaluation of the overheating tube rupture, tube failure is judged by comparison the hoop stress loaded by inner pressure with stress strength standard defined as creep strength depending on tube temperature. Thus, it is important to confirm the validation of this failure criterion based on the findings obtained in the simulated experiment of overheating tube rupture. In this report, for consideration on the validation of the failure criteria and elucidation on the failure mode and strength characteristics of failure, the authors carried out the rapid heating rupture experiment for the thin single and double-walled 9Cr steel tubes at high temperature up to 1500 K by using TRUST-2 rig in the Japan Atomic Energy Agency.
Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.
Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00
no abstracts in English
Kurihara, Akikazu; Umeda, Ryota; Kikuchi, Shin; Shimoyama, Kazuhito; Ohshima, Hiroyuki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(4), p.235 - 248, 2015/11
Sodium-water reaction would take place due to a breach of heat transfer tube in steam generator (SG) of sodium-cooled fast reactor (SFR), and the reaction jet may cause wear to the neighboring tubes by thermal and chemical effects, which is so-called target-wastage. Accordingly, failure propagation caused by target-wastage may potentially detract the secondary cooling system integrity. In previous study, a great number of target-wastage experiments have been carried out for candidate materials under practical SG operation conditions. Target-wastage rate was derived from macroscopic boundary factors of reaction jet. However, this mock-up approach is not versatile, and does not befit for large-scale SG design. Therefore, target-wastage should be focused for safety assessment of the various SG design. In this study, experiment apparatus and technique on composite oxidation type corrosion with flow (COCF), which is integral part of target-wastage, were constructed to figure out the separation effect of local wastage factors under the high temperature sodium hydroxide (NaOH) and sodium monoxide (NaO) environment mainly generated by SWR. The authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and diffusion coefficient of Mod.9Cr-1Mo steel into NaOH-NaO. Besides, it was revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay.
Takechi, Manabu; Matsunaga, Go; Sakurai, Shinji; Sasajima, Tadayuki; Yagyu, Junichi; Hoshi, Ryo*; Kawamata, Yoichi; Kurihara, Kenichi; JT-60SA Team; Nishikawa, T.*; et al.
Fusion Engineering and Design, 96-97, p.985 - 988, 2015/10
Times Cited Count：10 Percentile：64.63(Nuclear Science & Technology)Deguchi, Yoshihiro*; Muranaka, Ryota*; Kamimoto, Takahiro*; Takagi, Taku*; Kikuchi, Shin; Kurihara, Akikazu
Proceedings of 3rd International Workshop on Heat Transfer Advances for Energy Conservation and Pollution Control (IWHT 2015) (CD-ROM), 6 Pages, 2015/10
The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products quantitatively. The counter-flow diffusion experiment device was employed to analyze the reaction path and reaction products using laser diagnostics. The main product of sodium-water reaction was determined to be NaOH and the sodium oxide was not notably measured compared with NaOH.
Tomoyori, Katsuaki; Kurihara, Kazuo; Tamada, Taro; Kuroki, Ryota
JPS Conference Proceedings (Internet), 8, p.036004_1 - 036004_6, 2015/09
We aim to build a high-resolution neutron time-of-flight diffractometer for biomacromolecules at the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC) that allows the collection of neutron diffraction data from crystals with unit cells of 
250 
;. Considering both the flux and pulse width necessary to realize data collection covering a minimum d-spacing of 2.0 ; and with a unit cell constant of 250 ; we chose a decoupled moderator (DM) as the appropriate source for this high-resolution diffractometer. We considered a simple instrumentation model that includes a moderator, neutron guide, sample size, and neutron detector; we then investigated its spot separation performance and estimated the instrumental parameters for the design of a new diffractometer for protein crystals with large unit cells at J-PARC/MLF. It is preferable to extend the total flight path to resolve Bragg reflections for protein crystals with large unit cells as the scattering angle increases. Meanwhile, to ensure resolvable detection capacity at the middle scattering angle region (2
90
), it is necessary to restrict the angular divergence. In the case of 
0.2, scattering angles from around 290 to higher backscattering angles are more efficient for protein crystals with large unit cells (
250 ) with a resolution of 2.0 .
Tashiro, Koji*; Hanesaka, Makoto*; Yamamoto, Hiroko*; Wasanasuk, K.*; Jayaratri, P.*; Yoshizawa, Yoshinori*; Tanaka, Ichiro*; Niimura, Nobuo*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; et al.
Kobunshi Rombunshu, 71(11), p.508 - 526, 2014/11
Times Cited Count：6 Percentile：22.37(Polymer Science)The crystal structure analysis of various polymer substances has been reviewed on the basis of wide-angle high-energy X-ray and neutron diffraction data. The progress in structural analytical techniques of polymer crystals have been reviewed at first. The structural models proposed so far were reinvestigated and new models have been proposed for various kinds of polymer crystals including polyethylene, poly(vinyl alcohol), poly(lactic acid) and its stereocomplex etc. The hydrogen atomic positions were also clarified by the quantitative analysis of wide-angle neutron diffraction data, from which the physical properties of polymer crystals have been evaluated theoretically. The bonded electron density distribution has been estimated for a polydiacetylene single crystal on the basis of the so-called X-N method or by the combination of structural information derived from X-ray and neutron diffraction data analysis. Some comments have been added about future developments in the field of structure-property relationship determination.
; Assignment of bound diatomic molecules as OMurakawa, Takeshi*; Hayashi, Hideyuki*; Sunami, Tomoko; Kurihara, Kazuo; Tamada, Taro; Kuroki, Ryota; Suzuki, Mamoru*; Tanizawa, Katsuyuki*; Okajima, Toshihide*
Acta Crystallographica Section D, 69(12), p.2483 - 2494, 2013/12
Times Cited Count：14 Percentile：68.77(Biochemical Research Methods)The crystal structure of a Cu amine oxidase from was determined at 1.08 resolution with the use of low-molecular-weight polyethylene glycol (LMW PEG; average molecular weight 
200) as a cryoprotectant. The final crystallographic 
-factor and 
value are 13.0% and 15.0%, respectively. Several molecules of LMW PEG were found to occupy cavities in the protein interior including the active site, which resulted in the marked reduction of the overall 
factor and consequently led to a sub-atomic resolution structure for a relatively large protein with a monomer molecular weight of 70,000. About 40% of all the presumed hydrogen atoms were observed as clear electron densities in the 
- 
difference map. Multiple minor conformers were also identified for many residues. Anisotropic displacement fluctuations were evaluated in the active site that contains a post-translationally derived quinone cofactor and a Cu atom. Furthermore, diatomic molecules, most likely molecular oxygen, are bound to the protein, one of which is located in the region that has been previously proposed as an entry route for the substrate dioxygen from the central cavity of the dimer interface to the active site.
Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito; Abe, Yuta; Kikuchi, Shin; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu, B, 79(808), p.2640 - 2644, 2013/12
Overheating tube rupture of adjacent tubes arises from water/steam leak in steam generators of sodium-cooled fast reactors. It is very important to predict the tube wall stress (tube wall temperature) with a high degree of accuracy on evaluation of overheating tube rupture, and is crucial to estimate quantitatively the heat transfer coefficient between reaction jet and adjacent tubes which is one of the major influencing factor. The authors carried out the sodium-water reaction test (SWAT-1R) under the simulated operation condition of a real plant, and measured the correlation between heat transfer coefficient and void fraction around an adjacent tube. The authors confirmed that thermal environment around an adjacent tube was inferable from measured data, and heat transfer correlation equation proposed by Hamada et al. was applicable to the operation condition at elevated pressure and temperature.
Tamura, Kenta*; Deguchi, Yoshihiro*; Muranaka, Ryota*; Kusano, Koji*; Takata, Takashi*; Kikuchi, Shin; Kurihara, Akikazu
Proceedings of 24th International Symposium on Transport Phenomena (ISTP-24) (USB Flash Drive), 5 Pages, 2013/11
The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products. The counter-flow diffusion experiment device is in the form of introducing the argon-based water vapor from the top of depressurized reaction chamber to the liquid sodium pool. Na, Na, HO, and reaction products in the counter-flow sodium-water reaction field were measured using laser diagnostics. The temperature controlled device was also improved to reduce the condensation of Na in the reaction zone for the better measurement performance. The main product in the sodium-water reaction was determined to be NaOH from the experimental results and its reaction path was discussed using Na-HO elementary reaction analysis.
Deguchi, Yoshihiro*; Tamura, Kenta*; Muranaka, Ryota*; Kusano, Koji*; Kikuchi, Shin; Kurihara, Akikazu
Reza Kenkyu, 41(11), p.927 - 931, 2013/11
In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes. Therefore the study on sodium-water chemical reactions is of paramount importance for security reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. The measurement results show that the sodium-water reaction proceeds mainly by the reaction Na + HO = NaOH + H and the main product is NaOH from this reaction.
-thrombin-bivalirubin complex at pD 5.0; Protonation states and hydration structure of the enzyme-product complexYamada, Taro*; Kurihara, Kazuo; Onishi, Yuki*; Tamada, Taro; Tomoyori, Katsuaki; Masumi, Kenji*; Tanaka, Ichiro*; Kuroki, Ryota; Niimura, Nobuo*
Biochimica et Biophysica Acta; Proteins and Proteomics, 1834(8), p.1532 - 1538, 2013/08
Times Cited Count：17 Percentile：48.69(Biochemistry & Molecular Biology)The protonation states and hydration structures of the -thrombin-bivalirubin complex were studied by joint XN refinement of the single crystal X-ray and neutron diffraction data at resolutions of 1.6 and 2.8 , respectively. The atomic distances were estimated by carrying out X-ray crystallographic analysis at 1.25 resolution. The complex represents a model of the enzyme-product (EP) complex of -thrombin. The neutron scattering length maps around the active site suggest that the side chain of H57/H was deuterated. The joint XN refinement showed that occupancies for D
1 and D
2 of H57/H were 1.0 and 0.7, respectively. However, no significant neutron scattering length density was observed around the hydroxyl oxygen O
of S195/H, which was close to the carboxylic carbon atom of dFPR-COOH. These observations suggest that the O atom of S195/H is deprotonated and maintains its nucleophilicity in the EP complex. In addition to the active site, the hydration structures of the S1 subsite and the Exosite I, which are involved in the recognition of bivalirudin, are presented.
Saegusa, Jun; Kurikami, Hiroshi; Yasuda, Ryo; Kurihara, Kazuo; Arai, Shigeki; Kuroki, Ryota; Matsuhashi, Shimpei; Ozawa, Takashi; Goto, Hiroaki; Takano, Takao; et al.
Health Physics, 104(3), p.243 - 250, 2013/03
Times Cited Count：3 Percentile：25.73(Environmental Sciences)After the Nuclear accident on March 2011, water discharge from many outdoor swimming pools in the Fukushima prefecture was suspended out of concern that radiocesium in the pool water would flow into farmlands. We have reviewed the existing flocculation method for decontaminating pool water and established a practical decontamination method by demonstrating the process at several pools in the Fukushima prefecture.
