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Sun, G.*; Zhan, Y.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Experimental Thermal and Fluid Science, 151, p.111095_1 - 111095_15, 2024/02
Times Cited Count：1 Percentile：0.01(Thermodynamics)Uchibori, Akihiro; Doda, Norihiro; Aoyagi, Mitsuhiro; Sonehara, Masateru; Sogabe, Joji; Okano, Yasushi; Takata, Takashi*; Tanaka, Masaaki; Enuma, Yasuhiro; Wakai, Takashi; et al.
Nuclear Engineering and Design, 413, p.112492_1 - 112492_10, 2023/11
Times Cited Count：1 Percentile：72.91(Nuclear Science & Technology)The ARKAIDA has been developed to realize automatic optimization of plant design from safety evaluation for the advanced reactors represented by a sodium-cooled fast reactor. ARKADIA-Design offers functions to support design optimization both in normal operating conditions and design basis events. The multi-level simulation approach by the coupled analysis such as neutronics, core deformation, core thermal hydraulics was developed as one of the main technologies. On the other hand, ARKAIDA-Safety aims for safety evaluation considering severe accidents. As a key technology, the numerical methods for in- and ex-vessel coupled phenomena during severe accidents in sodium-cooled fast reactors were tested through a hypothetical severe accident event. Improvement of the ex-vessel model and development of the AI technology to find best design solution have been started.
Yanagisawa, Kayo; Matsueda, Makoto; Furukawa, Makoto*; Ishiniwa, Hiroko*; Wada, Toshihiro*; Hirata, Takafumi*; Takagai, Yoshitaka*
Analyst, 148(18), p.4291 - 4299, 2023/09
Times Cited Count：0 Percentile：0(Chemistry, Analytical)Quantitative imaging of trace elements was successfully performed by online isotope dilution laser ablation inductively coupled plasma mass spectrometry (online LA-ICP-IDMS). The sample aerosols produced by LA are mixed online with the mist created from an isotopically enriched spike solution via an in-house cyclonic spray chamber, which has a gas port on the top. Quantification was continuously achieved in each spot; subsequently, quantitative imaging was realized. Fe and Sr were selected as the model elements, and their spot quantifications based on online-isotope dilution. The method was applied to actual biological hard tissues, and the results were compared with electron probe microanalyzer data.
Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.
Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)Kosaka, Wataru; Uchibori, Akihiro; Okano, Yasushi; Yanagisawa, Hideki*
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1150 - 1163, 2023/08
The leakage of pressurized water from a steam generator (SG) and the progress after that are a key issue in the safety assessment or design of a SG in sodium-cooled fast reactor. The analysis code LEAP-III can evaluate a rate of water leakage during the long-term event progress, i.e., from the self-wastage initiated by an occurrence of a microscopic crack in a tube wall to the water leak detection and water/water-vapor blowdown. Since LEAP-III consists of semi-empirical formulae and one-dimensional equations of conservation, it has an advantage in short computation time. Thus, LEAP-III can facilitate the exploration of various new SG designs in the development of innovative reactors. However, there are several problems, such as an excessive conservative result in some case and the need for numerous experiments or preliminary analyses to determine tuning parameters of models in LEAP-III. Hence, we have developed a Lagrangian particle method code, which is characterized by a simpler computational principle and faster calculation. In this study, we have improved the existing particle pair search method for interparticle interaction in this code and developed an alternative model without the pair search. Through the trial analysis simulating in a tube bundle system, it was confirmed that new models reduced the computation time. In addition, it was shown that representative temperatures of the heat-transfer tubes evaluated by this particle method code, which is used to predict the tube failure in LEAP-III, were good agreement with that by SERAPHIM, which is a detailed mechanistic analysis method code.
Takagi, Hirotaka*; Takagi, Rina*; Minami, Susumu*; Nomoto, Takuya*; Oishi, Kazuki*; Suzuki, Michito*; Yanagi, Yuki*; Hirayama, Motoaki*; Khanh, N.*; Karube, Kosuke*; et al.
Nature Physics, 19(7), p.961 - 968, 2023/07
Times Cited Count：8 Percentile：96.03(Physics, Multidisciplinary)Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Wu, S.-Q.*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Sato, Osamu*
Physical Chemistry Chemical Physics, 25(17), p.12394 - 12400, 2023/05
Times Cited Count：1 Percentile：56.86(Chemistry, Physical)Shobuda, Yoshihiro; Harada, Hiroyuki; Saha, P. K.; Takayanagi, Tomohiro; Tamura, Fumihiko; Togashi, Tomohito; Watanabe, Yasuhiro; Yamamoto, Kazami; Yamamoto, Masanobu
Physical Review Accelerators and Beams (Internet), 26(5), p.053501_1 - 053501_45, 2023/05
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)At the Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC), theoretical predictions have indicated that the kicker-impedance would excite the beam-instability. A 1 MW beam with large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) through suppression of the beam instabilities by choosing the appropriate machine parameters. However, we require other high-intensity and high-quality smaller emittance beams (than the 1 MW beam) for the Main Ring (MR). Hence, we proposed a scheme for suppressing the kicker-impedance by using prototype diodes and resistors, thereby demonstrating the effect on the kicker impedance reduction. However, the J-PARC RCS must be operated with a repetition rate of 25 Hz, which urged us to consider special diodes that are tolerant to heating. After developments, we have demonstrated that the special diodes with resistors can suppress the beam instability by reducing the kicker impedance. Enhanced durability of the prototype diodes and resistors for the 25 Hz operation was also realized. Moreover, the new diodes and the resistors have negligible effect on the extracted beam from the RCS. From a simulation point of view, the scheme can be employed for at least 5 MW beam operation within the stipulated specifications.
Aoyagi, Mitsuhiro; Makino, Toru*; Oki, Hiroshi*; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05
Sun, G.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 8 Pages, 2023/05
When liquid sodium leaks as a liquid jet from piping in a sodium-cooled fast reactor, the jet impinges with structures to produce splashing droplets which can cause significant combustion. According to previous studies on circular nozzles, the amount of splash is affected by the state of the jet at the moment of impingement. In the present work, a nozzle with a sudden contraction in the cross-sectional area was designed to reproduce a supposed pipe leakage, and the breakup behavior of jet discharged from this nozzle was observed. The result shows that the breakup of jet was accelerated until the jet transformed into a particularly stable state when the jet velocity exceeded a certain value. Once the jet has transformed, it will not turn back unless turning down the flow rate to a very low value. The stable jet after the transformation has a longer breakup length than that before the transformation in the same flow rate.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Aoyagi, Mitsuhiro; Sonehara, Masateru; Ishida, Shinya; Uchibori, Akihiro; Kawada, Kenichi; Okano, Yasushi; Takata, Takashi
Proceedings of Technical Meeting on State-of-the-art Thermal Hydraulics of Fast Reactors (Internet), 3 Pages, 2022/09
Louie, D. L. Y.*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Takata, Takashi; Luxat, D. L.*
Proceedings of Technical Meeting on State-of-the-art Thermal Hydraulics of Fast Reactors (Internet), 6 Pages, 2022/09
Sun, G.*; Zhan, Y.*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Uchibori, Akihiro; Okano, Yasushi
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 6 Pages, 2022/08
When a liquid sodium leakage accident occurs in a sodium-cooled fast reactor, the injected sodium collides with structures to produce splashing droplets, which can result in a violent combustion. According to previous studies on circular nozzles, the amount of splash is affected by the state of the jet at the moment of impact. However, the outlet shape of damaged area is hardly to be circular; and meanwhile it influences the flow pattern of jet a lot. Considering about this, in the present work, high-speed cameras were used to observe the jet discharged from oval nozzles vertically downward to investigate the falling process of the jet. The result shows that surface wave appears on the jet and within a certain range of flow velocity it can be observed obviously, meanwhile accelerate the breakup of jet.
Uchibori, Akihiro; Sonehara, Masateru; Aoyagi, Mitsuhiro; Takata, Takashi*; Ohshima, Hiroyuki
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 9 Pages, 2022/04
A new computational code, SPECTRA, has been developed for integrated analysis of in- and ex-vessel phenomena during severe accidents in sodium-cooled fast reactors. The in-vessel thermal hydraulics module includes coupled analytical models for multidimensional multifluid model considering compressibility and relocation of a molten core. A lumped mass model is employed for computing behavior of ex-vessel compressible multicomponent gas including aerosols. This model is coupled with the models for ex-vessel phenomena such as sodium fire. Loss of reactor level event starting from leakage of sodium coolant was computed. Basic capability to evaluate severe accident progress was demonstrated through this analysis.
Aoyagi, Mitsuhiro; Uchibori, Akihiro; Takata, Takashi
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 13 Pages, 2022/03
Kosaka, Wataru; Uchibori, Akihiro; Takata, Takashi; Yanagisawa, Hideki*; Watanabe, Akira*; Jang, S.*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 11 Pages, 2022/03
For the safety assessment of a steam generator (SG) in a sodium-cooled fast reactor, the analysis code LEAP-III can evaluate the water leak rate during the long-term event progress including the tube failure propagation triggered by an occurrence of a small water leak in a failed heat transfer tube in SG. The LEAP-III has the advantage in completing the calculation with low computational cost since it consists of semi-empirical formulae and one-dimensional equations of conservation. However, an evaluation model of temperature distribution by the reacting jet provides wider high temperature region than the experimental data. As a result, LEAP-III shows excessive conservativeness in some case. A Lagrangian particle method code based on engineering approaches has been developed in order to improve this model to get more realistic temperature distribution. In this method, the jet behavior and chemical reaction are simulated using Newton's equation of motion with several engineering approximations instead of solving multi-dimension multiphase thermal hydraulic equations with sodium-water reaction. In this study, interparticle interaction force model was added, and also the chemical reaction and gas-liquid heat transfer evaluation models were improved. We conducted a test analysis, and compared the results by this particle method with the ones by SERAPHIM, that is a mechanistic analysis code for multi-dimensional multiphase flow considering compressibility and sodium-water reaction. Through this test analysis, it confirmed that this particle method has the basic capability to get a realistic temperature distribution with low computational cost, and also to predict tube failure occurrence by coupled with LEAP-III.
Kosaka, Wataru; Uchibori, Akihiro; Yanagisawa, Hideki*; Takata, Takashi; Jang, S.*
Nihon Kikai Gakkai Rombunshu (Internet), 88(905), p.21-00310_1 - 21-00310_9, 2022/01
If a pressurized water/water-vapor leaks from a heat transfer tube in a steam generator (SG) in a sodium-cooled fast reactor (SFR), sodium-water reaction forms high-velocity, high-temperature, and corrosive jet. It would damage the other tubes and might propagate the tube failure in the SG. Thus, it is important to evaluate the effect of the tube failure propagation for safety assessment of SFR. The computational code LEAP-III can evaluate water leak rate during the tube failure propagation with short calculation time, since it consists of empirical formulae and one-dimensional equations of conservation. One of the empirical models, temperature distribution evaluation model, evaluates the temperature distribution in SG as circular arc isolines determined by experiments and preliminary analyses instead of complicated real distribution. In order to improve this model to get more realistic temperature distribution, we have developed the Lagrangian particle method based on engineering approaches. In this study, we have focused on evaluating gas flow in a tube bundle system, and constructed new models for the gas-particles behavior around a tube to evaluate void fraction distribution near the tube. Through the test analysis simulating one target tube system, we confirmed the capability of the models and next topic to improve the models.
Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometryKoarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.
Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08
Times Cited Count：5 Percentile：55.72(Chemistry, Analytical)Rapid analysis of Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of Sr in small bone and tooth samples derived from terrestrial animals.
Chen, Y.*; Sato, Masahiro*; Tang, Y.*; Shiomi, Yuki*; Oyanagi, Koichi*; Masuda, Takatsugu*; Nambu, Yusuke*; Fujita, Masaki*; Saito, Eiji
Nature Communications (Internet), 12, p.5199_1 - 5199_7, 2021/08
Times Cited Count：8 Percentile：61.37(Multidisciplinary Sciences)