Development of erosion test methods on underexpanded inert-gas impinging jets injected in liquid sodium

Kudo, Hideyuki*; Ota, Junki*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Hozengaku, 11(4), p.90 - 97, 2013/01

When a heat transfer tube wall in a steam generator of a sodium-cooled fast reactor fails, high-pressure steam leaks into low-pressure liquid sodium side. Then the high-temperature and highly corrosive reaction jet causes secondary failures of neighboring heat transfer tubes. The objective of the present study is to develop an experimental method to obtain data that is necessary to validate and improve a safety evaluation code on the sodium-water reaction. In the present paper, a method of sodium-droplet erosion test at the position of the local structure in underexpanded inert-gas impinging jets using the visualization method, which was developed in our previous study, was reported. The erosion phenomena observed in the sodium-droplet entrained region, where intensive erosion is expected, were found to be discussed using the existing knowledge of liquid droplet impingement (LDI) obtained in water experiments.

Void fraction distributions of inert gas jets across a single cylinder with non-wetting surface in liquid sodium

Kudo, Hideyuki*; Zhao, D.*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Journal of Nuclear Science and Technology, 49(12), p.1175 - 1185, 2012/12

https://doi.org/10.1080/00223131.2012.739019

Little work on the void fraction behaviors along structural materials with poor-wettability for liquid metals has been performed. In the present study, void fraction behaviors around a single cylinder with non-wetting surface condition were quantitatively discussed by using a gas jet-cylinder system where the impinging jet flow, the boundary layer flow, the separation flow, and the wake flow appear. The characteristics in each flow field as well as the relationship between flow fields, which have not been quantitatively discussed so far, are obtained. The local void fraction around a single cylinder with wetting condition or non-wetting condition was measured by using resistivity probes.

The Sodium oxidation reaction and suppression effect of sodium with suspended nanoparticles; Growth behavior of dendritic oxide during oxidation

Nishimura, Masahiro; Nagai, Keiichi; Onojima, Takamitsu; Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*

Journal of Nuclear Science and Technology, 49(1), p.71 - 77, 2012/01

https://doi.org/10.1080/18811248.2011.636557

Oxidation in the early stage of sodium combustion is especially important regarding the aspect of reaction continuity. The purpose of this study is to understand the sodium reaction precisely in order to apply the knowledge of the sodium reaction to promoting further safety of FRs.

Study on chemical reactivity control of sodium by suspended nanoparticles, 1

Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nagai, Masahiko*; Yoshioka, Naoki*

Journal of Nuclear Science and Technology, 47(12), p.1165 - 1170, 2010/12

https://doi.org/10.3327/jnst.47.1165

A study on the chemical reactivity control of sodium utilizing the atomic interaction of sodium with suspended nanoparticles was carried out. The atomic interaction between nanoparticles and sodium atoms were estimated by theoretical calculations and verified by fundamental physical properties measurements. Results showed the atomic bond of the sodium atom and the nanoparticle atom was significantly larger than that of the sodium atoms, when the transition metals that have the property of large electronegativity are applied as nanoparticles. From the theoretical calculation results, it was suggested that charge transfer occurs from the sodium atom to the nanoparticle atom. The fundamental physical properties of sodium with suspended nanoparticles were examined in comparison with that of sodium to verify the change of the atomic interaction. From the experimental results, it became clear that the surface tension becomes larger and the evaporation rate becomes smaller. These changes in fundamental physical properties were measured to verify the stability of the atomic interaction under the conditions of wide temperature range and the phase transformation from solid phase to liquid phase.

Growing mechanism of dendritic oxide during sodium combustion

Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*

Proceedings of 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8) (CD-ROM), 11 Pages, 2010/10

The purpose of this study is to understand oxidation behavior of sodium precisely for FR safety against sodium combustion. It was recognized that dendritic oxide took an important role for the combustion reaction such as supplying the sodium to the reaction interface. In this study, we proposed a mechanistic model of supplying liquid sodium through the dendritic oxide based on the observation result of the growing behavior of dendritic oxide during combustion. In this model we made an attention to the kinds of chemical compounds. The formation of sodium peroxides can provide the sodium supplying route in the dendritic oxide. On the other hand the formation of sodium monoxide will block sodium supplying. The kinds of chemical compounds were decided by the Gibbs's free energy of thermodynamics in the reaction field such as temperature and oxygen concentration. This mechanistic model can explain the oxidation behavior consistently with the observation results.

Oxidation behavior of liquid sodium droplet before combustion; Dependency of initial temperature and oxygen fraction

Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*

Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 12 Pages, 2008/10

Liquid sodium is used as the coolant of the fast reactor (FR), because of its high thermal conductivity and wide temperature range of liquid phase. It is superior as thermal medium, however the chemical reactivity with water and oxygen is very high. Hence FR plants have been taking safety measures for these reactions. After the "Monju" sodium leak accident, it is desired that more physical and chemical understanding of reaction phenomena and more mechanistic analysis for the sodium fire from the view point of public acceptance. The purpose of this study is to understand oxidation behavior of a liquid sodium droplet precisely, which is a fundamental reaction of spray fire and is easy to observe the reaction interface. This study is also useful for the establishment of safety criterion to handle the remained non-burning sodium after the accident. The oxidation of a liquid sodium droplet was visualized by using a simple experimental setup and a high speed video camera. A sodium single droplet of ca. 50 mg was made at the tip of a nozzle in a combustion chamber. The oxidation was started by supply of oxygen and nitrogen mixture gas. The initial temperature of sodium droplet and the oxygen fraction in the atmosphere were selected as experimental parameters. It was shown that columnar oxides grew longer as initial temperature of sodium droplet was lower and oxygen fraction was lower. In addition, it was observed that sodium combustion with an orange light emission started from the tip of columnar oxides grown out from the droplet surface. These observations suggest the existence of mechanism that liquid sodium is drawn up from droplet to reaction interface by the capillary force caused in the porous oxides which are formed on the droplet surface.

Mixing behavior of argon jet with liquid sodium around a single rod; A Basic study on sodium-water reaction

Tsuruoka, Hokuto*; Tamura, Takeshi*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki

Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM), 6 Pages, 2008/05

The occurrence of secondary heat transfer tube failure due to overheating by sodium-water reaction in LMFBR steam generators has been concerned from the viewpoint of public acceptance. To evaluate the phenomena, a sophisticated computer code SERAPHIM has been developed by JAEA. For the purpose of obtaining fundamental data for the validation of the code, a sodium experiment was carried out, where the void fraction around a single rod set in a sodium pool without sodium-water reaction was measured. The void fraction was observed to somewhat increase with increasing the gas jet velocity. The increase rate was clearly smaller compared with that in the water experiment. The void fraction also showed more monotonous distribution from the stagnation point to the rear point than that in water pool. These results reflect the difference of surface tension between water and sodium. It is concluded that the entrainment of ambient sodium is easily caused and this leads monotonous distribution of void fraction in the sodium pool.

Entrainment of water around a single rod immersed in water pool with gas jet impingement, 2

Tamura, Takeshi*; Soga, Kazuo*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Suda, Kazunori

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04

To evaluate the phenomena for the secondary heat transfer tube failure due to overheating by sodium-water reaction in steam generator of liquid sodium cooled fast breeder reactor, a sophisticated computer code SERAPHIM has been developed by JAEA. As the first step to verify the adequacy of SERAPHIM code, a visualization experiment of Ar gas jet impinging a single rod with 20mm in diameter immersed in a water pool was performed in our previous study. In this paper, we measured the void fraction around a single rod in the water pool as a basic experiment using the apparatus capable of doing sodium pool experiment to investigate the flow pattern and the water entrainment around a single rod. The result of the void fraction reflected the result of the heat transfer experiment that had been reported before was obtained, and a certain prospect of the measurement of the void fraction in sodium pool was obtained.

Research on the fundamental process of thermal-hydraulic behaviors in severe accident; Breakup and cooling of molten material jets, JAERI's nuclear research promotion program, H10-027-2 (Contract research)

Sugiyama, Kenichiro*; Iguchi, Kentaro*

JAERI-Tech 2002-010, 67 Pages, 2002/03

JAERI-Tech-2002-010.pdf:4.4MB

no abstracts in English

Heat transfer characteristics around a single heated rod immersed in sodium pool with Ar gas jet impingement and behavior of injected gas jet

Niikura, Hideto*; Soga, Kazuo*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki

no journal, , 

no abstracts in English