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Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 12 Pages, 2022/03
An unstructured mesh-based analysis method has been integrated into the sodium-water reaction analysis code, SERAPHIM, in our recent studies. In this study, numerical analysis of an experiment on sodium-water reaction in a tube bundle domain was performed to investigate the effect of the unstructured mesh. The unrealistic behavior appeared in the coarse structured mesh was improved by the unstructured mesh. The numerical result in the case of the unstructured mesh reproduced the peak value of the temperature in the reacting flow.
Sugimoto, Taro*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Kurihara, Akikazu; Takata, Takashi; Ohshima, Hiroyuki
Nuclear Engineering and Design, 380, p.111306_1 - 111306_11, 2021/08
Times Cited Count：3 Percentile：45.99(Nuclear Science & Technology)Liquid droplet entrainment by a high-speed gas jet is a key phenomenon for evaluation of sodium-water reaction. In this study, a visualization experiment for liquid droplet entrainment by an air jet in a water pool by using frame-straddling method was carried for development of an entrainment model in a sodium-water reaction analysis code. This experiment successfully provided clear images that captured generation and movement of droplets. Droplet diameter and moving speed were obtained at different locations and gas jet velocities from image processing. The measured data contributes phenomena elucidation and model development.
Saito, Masafumi*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Kurihara, Akikazu; Takata, Takashi*; Ohshima, Hiroyuki
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 7 Pages, 2021/08
In order to provide the data for validation and improvement of the sodium-water reaction analysis code, a visualization experiment on liquid droplet entrainment in a high-pressure air jet submerged in a water pool was conducted. Diameter and velocity of entrained liquid droplets were successfully measured. The effect of a nozzle shape was elucidated.
Uchibori, Akihiro; Yanagisawa, Hideki*; Takata, Takashi; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 86(883), p.19-00353_1 - 19-00353_6, 2020/03
Evaluation of occurrence possibility of tube failure propagation under sodium-water reaction accident is an important issue. In this study, a numerical analysis method to predict occurrence of failure propagation by overheating rupture was constructed to expand application range of an existing computer code. Applicability of the method was constructed through the numerical analysis of the experiment on water vapor discharging in liquid sodium.
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.
Shimoyama, Kazuhito; Kurihara, Akikazu; Kikuchi, Shin; Umeda, Ryota
no journal, ,
Self-wastage comes from water/steam leak through the penetrating crack caused in the steam generator tube of sodium-cooled fast reactor. When the self-wastage proceeds to inside wall of tube, breach area and water leak rate will be larger, then, it will be likely to spread the affected area caused by sodium-water reaction. It is very important to clarify the self-wastage behavior for locally affected region and detection of the water leak in real plant. In the 1st report, the authors have performed the self-wastage experiments for the pinhole type micro crack. In this report, fatigue crack type self-wastage experiments were carried out to evaluate the effect of wastage form/geometry and water leak rate, it was confirmed that initial defect geometry, such as pinhole and fatigue crack, does not strongly influence to self-wastage rate.
Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
no journal, ,
For assessment of the wastage environment under tube failure accident in a steam generator of sodium-cooled fast reactors, a mechanistic computer code called SERAPHIM calculating compressible multicomponent multiphase flow with sodium-water chemical reaction has been developed. The original SERAPHIM code is based on the finite difference method. In this study, unstructured mesh-based numerical method was developed and introduced into the SERAPHIM code to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Validity of the unstructured mesh-based SERAPHIM code was investigated through the analysis of an underexpanded jet experiment. The calculated pressure profile showed good agreement with the experimental data. Numerical analysis of water vapor discharging into liquid sodium was also performed. It was demonstrated that the proposed numerical method could be applicable to evaluation of the sodium-water reaction phenomenon.
Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito
no journal, ,
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 material strength standard which is one of the major influencing factor. In this report, rapid heating tube rupture experiments were conducted on the double-walled tube (Mod.9Cr-1Mo steel) under the same experimental conditions as those in the single-walled tube experiments, and evaluated quantitatively failure hoop stress and failure time. The authors confirmed the validity of the existing stress strength standard under the conditions that the double-walled tubes were uniformly heated.
Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi
no journal, ,
A computational fluid dynamics code SERAPHIM for a sodium-water reaction phenomenon has been developed. An unstructured mesh-based analysis method has been integrated into this code for evaluation in a complex-shaped domain including multiple heat transfer tubes. In this study, a numerical analysis of an experiment on sodium-water reaction in a tube bundle domain was performed to investigate applicability of the unstructured mesh-based SERAPHIM code. The formulated high-temperature region and its temperature level agreed with an experimental result.
Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi*
no journal, ,
A computational fluid dynamics code, SERAPHIM, for sodium-water reaction has been developed. An unstructured mesh-based analysis method was integrated into this code for a complex-shaped domain including multiple heat transfer tubes. In this study, both structured- and unstructured-mesh analyses of the experiment on sodium-water reaction in a tube bundle domain was performed to investigate. The analyses showed that non-physical flow behavior in the case of the coarse structured mesh was improved by the unstructured mesh.
Saito, Masafumi*; Kaneko, Akiko*; Uchibori, Akihiro; Kurihara, Akikazu; Takata, Takashi*; Ohshima, Hiroyuki
no journal, ,
In order to provide the data for validation and improvement of the sodium-water reaction analysis code, a visualization experiment on liquid droplet entrainment in a high-pressure air jet submerged in a water pool was conducted. Diameter and velocity of entrained liquid droplets were successfully measured. The effects of a nozzle shape and a liquid level were elucidated.
Saito, Masafumi*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Kurihara, Akikazu; Ohshima, Hiroyuki
no journal, ,
In order to provide the experimental data for validation and improvement of the sodium-water reaction analysis code, a visualization experiment on liquid droplet entrainment in a high-pressure air jet submerged in a water pool was carried out. Diameter and velocity of the entrained liquid droplets were successfully measured at different locations in the jet. This experiment indicated the possibility that the fluctuation of the jet boundary affects diameter, velocity, and generation rate of the liquid droplets.
Uchibori, Akihiro; Shiina, Yoshimi*; Kurihara, Akikazu; Okano, Yasushi; Saito, Masafumi*; Kaneko, Akiko*; Abe, Yutaka*
no journal, ,
In order to establish a safety evaluation method of a steam generator of sodium-cooled fast reactors, a computer program called SERAPHIM has been developed to calculate compressible multicomponent multiphase flow with sodium-water chemical reaction under tube failure accident. In this study, a numerical model for liquid droplet entrainment from an interface of the gaseous jet and its transport was validated through the analysis of experiment on vertical discharging of high-pressure air in a water pool. This model considers the mass, momentum, and energy conservation equations including the correlation of liquid droplet entrainment velocity. The numerical result showed the entrained liquid droplet phase was accelerated by the air jet. The calculated velocity of the liquid droplet falls within the dispersion of the measured data.
Togasaki, Shun*; Jang, S.*; Kawaguchi, Munemichi*; Sawa, Kazuhiro*; Kosaka, Wataru; Uchibori, Akihiro; Okano, Yasushi
no journal, ,
no abstracts in English
