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Journal Articles

Estimation method for residual sodium amount on unloaded dummy fuel assembly

Kawaguchi, Munemichi; Hirakawa, Yasushi; Sugita, Yusuke; Yamaguchi, Yutaka

Nuclear Technology, 210(1), p.55 - 71, 2024/01

This study has developed an estimation method for residual sodium film and sodium lumps on dummy fuel pins in Monju and demonstrated sodium draining behavior through gaps among the pins, experimentally. The amounts of the residual sodium on the surface of the pins were measured using the three-type test specimens: (a) single pin, (b) 7-pin assembly, and (c) 169-pin assembly. The experiments revealed that the withdrawal speed of the pins and improvement of the sodium wetting increased drastically the amounts of the residual sodium. Furthermore, the experiments using the 169-pin assembly measured the practical amounts of the residual sodium in the dummy fuel assembly of short length and demonstrated sodium draining behavior through the dummy fuel assembly. The estimation method includes four models: a viscosity flow model, Landau-Levich-Derjaguin (LLD) model, an empirical equation related to the Bretherton model, and a capillary force model in a tube. The calculation predicted comparable amounts of the residual sodium with the experiments. An uncertain of the sodium wetting effects were close to 1.8 times the estimation values of the LLD model. With this estimation method, the amounts of the residual sodium on the unloaded Monju dummy fuel assembly can be evaluated.

Journal Articles

A Study on removal mechanisms of cesium aerosol from noble gas bubble in sodium pool, 3; Measurement of decontamination factors in water simulation test

Koie, Ryusuke*; Kawaguchi, Munemichi*; Miyahara, Shinya*; Uno, Masayoshi*; Seino, Hiroshi

Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 4 Pages, 2022/08

In order to investigate removal mechanisms of cesium aerosol from noble gas bubble in sodium pool, we performed a water simulation test to measure the decontamination factors of simulant aerosols with nitrogen gas bubbles rising through the water pool. As a result, it was found that the decontamination factors increased with the increase in the aerosol diameter and the water pool depth.

Journal Articles

Phase-field mobility for crystal growth rates in undercooled silicates, SiO$$_2$$ and GeO$$_2$$ liquids

Kawaguchi, Munemichi; Uno, Masayoshi*

Journal of Crystal Growth, 585, p.126590_1 - 126590_7, 2022/05

Phase-field mobility, $$L$$, and crystal growth rates in crystallization of 11 oxides or mixed oxides in undercooled silicates, SiO$$_2$$ and GeO$$_2$$ liquids were calculated with a simple phase-field model (PFM), and material dependence of the $$L$$ was discussed. Ratios between experimental crystal growth rates and the PFM simulation with $$L=1$$ were confirmed to be proportional to a power of $$frac{TDelta T}{eta}$$ on the solid/liquid interface process during the crystal growth in a log-log plot. We determined that parameters, $$A$$ and $$B$$, of the $$L=A(frac{k_{B}TDelta T}{6pi^{2}lambda^{3}eta T_{m} })^{B}$$ were $$A=6.7times 10^{-6}$$ to $$2.6$$m$$^4$$J$$^{-1}$$s$$^{-1}$$ and $$B=0.65$$ to $$1.3$$, which were unique for the materials. It was confirmed that our PFM simulation with the determined $$L$$ reproduced quantitively the experimental crystal growth rates. The $$A$$ has a proportional relationship with the diffusion coefficient of a cation molar mass average per unit an oxygen molar mass at $$T_{m}$$ in a log-log graph. The $$B$$ depends on the sum of the cation molar mass per the oxygen molar mass, $$frac{Sigma_{i}M_{i}}{M_{O}}$$, in a compound. In $$frac{Sigma_{i}M_{i}}{M_{O}}leq 25$$, the $$B$$ decreases with the cation molar mass increasing. The assumed cause is that the B represents the degree of the temperature dependence of the $$L$$. Since the cation molar mass is proportional to an inertial resistance of the cation transfer, the $$B$$ decreases with inverse of the cation molar mass. In crystallization of the silicates of heavy cation in $$frac{Sigma_{i}M_{i}}{M_{O}}geq 25$$, the $$B$$ saturates at approximately 0.67, which leads to $$T_{p}approx 0.9T_{m}$$.

Journal Articles

Analytical study on removal mechanisms of cesium aerosol from a noble gas bubble rising through liquid sodium pool, 2; Effects of particle size distribution and agglomeration in aerosols

Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi; Atsumi, Takuto*; Uno, Masayoshi*

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coolant as bubbles have an influence on the removal of cesium aerosol by the sodium pool in a period of bubble rising to the pool surface. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion from a noble gas bubble rising through liquid sodium pool was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption considering the effects of particle size distribution and agglomeration in aerosols. In the analysis, initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration in the bubble were changed as parameter, and the results for the sensitivities of these parameters on decontamination factor (DF) of cesium aerosol were compared with the results of the previous study in which the effects of particle size distribution and agglomeration in aerosols were not considered. From the results, it was concluded that the sensitivities of initial bubble diameter, the aerosol particle diameter and density to the DF became significant due to the inertial deposition of agglomerated aerosols. To validate these analysis results, the simulation experiments have been conducted using a simulant particles of cesium aerosol under the condition of room temperature in water pool and air bubble systems. The experimental results were compared with the analysis results calculated under the same condition.

Journal Articles

Kinetic and Fourier transform infrared studies on the thermal decomposition of sodium hydride

Kawaguchi, Munemichi

Journal of Physical Chemistry C, 125(22), p.11813 - 11819, 2021/06

 Times Cited Count:1 Percentile:14.68(Chemistry, Physical)

Isothermal and constant heating thermogravimetry-differential thermal analysis (TG-DTA) and Fourier transform infrared spectrometer (FTIR) measurements have been performed for pre- and post-fired sodium hydride (NaH) in the temperature range of 500-700 K, respectively. Temperature dependence of NaH thermal decomposition rates obtained by the isothermal TGs showed an inflection point at around 620 K, which was caused by two kinds of hydrogen states (rapid diffusing and immobile hydrogen). In the FTIR spectra for the NaH and sodium (Na), the specific signals were observed at around 873.4, 1010.4, 1049.5 and 1125.7 cm$$^{-1}$$, and the integrated values of FTIR signals for post-fired NaH at below 550K and at above 698 K were comparable to those for pre-fired NaH and Na, respectively. Those for post-fired NaH at 602-667 K were the intermediate values of the pre-fired NaH and Na, which denoted that the Na-Na bonds haven't grown sufficiently and the hydrogen coexisted in metallic Na. In order to predict the practical kinetics of NaH thermal decomposition reaction, we suggested the simple kinetics model which assumed two kinds of rapidly diffusing and immobile hydrogen states. The simulation results revealed the inflection point in temperature dependence of the thermal decomposition rates accordingly because the transition from immobile hydrogen to rapid diffusing hydrogen crosses over at around 620 K.

Journal Articles

Phase-field model for crystallization in alkali disilicate glasses; Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$

Kawaguchi, Munemichi; Uno, Masayoshi*

Journal of the Ceramic Society of Japan, 128(10), p.832 - 838, 2020/10

 Times Cited Count:2 Percentile:17.37(Materials Science, Ceramics)

This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient ($$L$$). The crystal growth rates ($$v_0$$) obtained by the PFM calculation with the constant $$L$$ were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the $$L$$ was determined from the experimental crystal growth rates and the $$v_0$$. Using the determined $$L$$, the crystal growth rates ($$v$$) in alkali disilicate glasses, Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$ were simulated. The temperature dependence of the $$v$$ was qualitatively and quantitatively so similar that the PFM calculation results demonstrated the validity of the $$L$$. Especially, the $$v$$ obtained by the PFM calculation appeared the rapid increase just below the thermodynamic melting point ($$T_{rm m}$$) and the steep peak at around $$T_{rm m}$$-100 K. Additionally, as the temperature decreased, the $$v$$ apparently approached zero ms$$^-1$$, which is limited by the $$L$$ representing the interface jump process. Furthermore, we implemented the PFM calculation for the variation of the parameter $$B$$ in the $$L$$. As the $$B$$ increased from zero to two, the peak of the $$v$$ became steeper and the peak temperature of the $$v$$ shifted to the high temperature side. The parameters $$A$$ and $$B$$ in the $$L$$ increased exponentially and decreased linearly as the atomic number of the alkali metal increased due to the ionic potential, respectively. This calculation revealed that the $$A$$ and $$B$$ in the $$L$$ were close and reasonable for each other.

Journal Articles

Measurement of thermal decomposition temperature and rate of sodium hydride

Kawaguchi, Munemichi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

In decommissioning sodium-cooled fast reactors, the operators can be exposed to radiation during dismantling of the cold trap equipment (C/T). The C/T has higher dose equipment because the C/T trapped the tritium of the fission product during the operation to purify the sodium coolant. In this research, the thermal decomposition temperature and rate of sodium hydride were measured as the fundamental research for improvement of the thermorlysis method prior to the dismantling. We measured the thermal decomposition temperature and rate using sodium hydride powder (95.3%, Sigma-Aldrich) in Al$$_2$$O$$_3$$ crucible with TG-DTA (STA2500, NETASCH Japan). The heating rates were set to $$beta$$ = 2.0, 5.0, 10.0, 20.0 K/min, and the weight decrease was measured. The thermal decomposition temperature and rate were obtained from the temperature of the onset of the weigh decrease and the Kissinger plot, respectively. Furthermore, we set to the thermal decomposition temperature of around 600 K, and the weight decreasing rates were measured. The change of the chemical composition of the sodium hydride with heating (from NaH to Na) was measured with X-Ray Diffraction (XRD) analysis. As a result, the thermal decomposition occurred at around 600 K, and the almost all hydrogen in the sodium hydride released within 1 h. The thermal decomposition rate strongly depended on the heating temperature.

Journal Articles

Analytical study on removal mechanisms of cesium aerosol from a noble gas bubble rising through liquid sodium pool

Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released as an aerosol such as cesium iodide and/or oxide together with xenon and/or krypton. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption. Initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration were changed as parameter. From the results, it was concluded that the initial bubble diameter was most sensitive parameter to the decontamination factor (DF). It was found that the sodium pool depth, the aerosol particle diameter and density have also important effect on the DF, but the sodium temperature has a marginal effect. To meet these results, the experiments are under planning to validate the results.

Journal Articles

Study on optical properties of metallic sodium by vacuum ultra violet in UVSOR, 2

Kawaguchi, Munemichi; Saito, Junichi; Daido, Hiroyuki*; Suemoto, Toru*

UVSOR-47, P. 85, 2020/08

To elucidate theoretically the transparent metallic sodium in the vacuum ultraviolet (VUV) spectral range, the aim of this research is to obtain the accurate spectrum using UVSOR. We confirmed the validity for the transmittance measurement in UVSOR by the measurement of transmittance of CaF$$_2$$ windows. However, the transparency phenomenon of VUV in the metallic sodium has never been confirmed by our group. In the future, we will improve the sodium sample and conduct the measurement again.

Journal Articles

A Study on sodium-concrete reaction in presence of internal heating

Kawaguchi, Munemichi; Miyahara, Shinya*; Uno, Masayoshi*

Journal of Nuclear Engineering and Radiation Science, 6(2), p.021305_1 - 021305_9, 2020/04

Sodium-concrete reaction (SCR) is one of the important phenomena during severe accidents in sodium-cooled fast reactors (SFRs) owing to the generation of large sources of hydrogen and aerosols in the containment vessel. In this study, SCR experiments with an internal heater were performed to investigate the chemical reaction beneath the internal heater (800$$^{circ}$$C), which was used to simulate the obstacle and heating effect on SCR. Furthermore, the effects of the internal heater on the self-termination mechanism were discussed. The internal heater on the concrete hindered the transport of Na into the concrete. Therefore, Na could start to react with the concrete at the periphery of the internal heater, and the concrete ablation depth at the periphery was larger than under the internal heater. The high Na pool temperature of 800$$^{circ}$$C increased largely the Na aerosol release rate, which was explained by Na evaporation and hydrogen bubbling, and formed the porous reaction product layer, whose porosity was 0.54-0.59 from the mass balance of Si and image analyzing EPMA mapping. They had good agreement with each other. The porous reaction products decreased the amount of Na transport into the reaction front. The Na concentration around the reaction front became about 30wt.% despite the position of the internal heater. It was found that the Na concentration condition was one of the dominant parameters for the self-termination of SCR, even in the presence of the internal heater.

Journal Articles

Study on optical properties of metallic sodium by vacuum ultra violet in UVSOR

Kawaguchi, Munemichi; Saito, Junichi; Daido, Hiroyuki*; Suemoto, Toru*

UVSOR-46, P. 89, 2019/08

To elucidate theoretically the transparent metallic sodium in the vacuum ultraviolet spectral range, the aim of this research is to obtain the accurate spectrum using UVSOR. The sodium sample maintained metallic luster by designing the special cells to prevent from oxidizing. The results of UVSOR measurement showed the possibility to occur the intransparent layer for vacuum ultraviolet light on the MgF$$_2$$ windows. In the near future, we will improve the sodium sample to solve the problems and conduct the measurement again

Journal Articles

Melting behavior and thermal conductivity of solid sodium-concrete reaction product

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Journal of Nuclear Science and Technology, 56(6), p.513 - 520, 2019/06

 Times Cited Count:2 Percentile:21.95(Nuclear Science & Technology)

This study revealed melting points and thermal conductivities of four samples generated by sodium-concrete reaction (SCR). We prepared the samples using two methods such as firing mixtures of sodium and grinded concrete powder, and sampling depositions after the SCR experiments. In the former, the mixing ratios were determined from the past experiment. The latter simulated the more realistic conditions such as the temperature history and the distribution of Na and concrete. The thermogravimetry-differential thermal analyzer (TG-DTA) measurement showed the melting points were 865-942$$^{circ}$$C, but those of the samples containing metallic Na couldn't be clarified. In the two more realistic samples, the compression moldings in a furnace were observed. The observation revealed the softening temperature was 800-840$$^{circ}$$C and the melting point was 840-850$$^{circ}$$C, which was 10-20$$^{circ}$$C lower than the TG-DTA results. The thermodynamics calculation of FactSage 7.2 revealed the temperature of the onset of melting was caused by melting of the some components such as Na$$_{2}$$SiO$$_{3}$$ and/or Na$$_{4}$$SiO$$_{4}$$. Moreover, the thermal conductivity was $$lambda$$=1-3W/m-K, which was comparable to xNa$$_{2}$$O-1-xSiO$$_{2}$$ (x=0.5, 0.33, 0.25), and those at 700$$^{circ}$$C were explained by the equation of $$NBO/T$$.

Journal Articles

A Study on self-terminating behavior of sodium-concrete reaction, 2

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Journal of Nuclear Science and Technology, 55(8), p.874 - 884, 2018/08

 Times Cited Count:4 Percentile:39.03(Nuclear Science & Technology)

As parts of severe accident studies in sodium-cooled fast reactor, experiments were performed to investigate the termination mechanism of sodium-concrete reaction (SCR). In the experiment, the reaction time was controlled to investigate the distribution change of sodium (Na) and the reaction products in the pool and around the reaction front. In the results, the Na around the reaction front decreased from the enough amount with the reaction time. The concentrations were 18-24 wt.% for Na, and 22-18 wt.% for Si after the termination. From the thermodynamics calculations, the stable materials around the reaction front comprised more than 90 wt.% solid products such as Na$$_{2}$$SiO$$_{3}$$, and no Na. Further, the distribution of Na and reaction products could be explained by a steady-state sedimentation-diffusion model. At the early stage of SCR, the reaction products were suspended as particles in the Na pool because of the high H$$_{2}$$-generation rate. As the concrete ablation proceeds, they start settling down due to the decreased H$$_{2}$$-generation rate, thereby allowing SCR termination. It was concluded that SCR termination was caused by the sediment of the reaction products and the lack of Na around the reaction front.

Journal Articles

Discussion about sodium-concrete reaction in presence of internal heater

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07

Sodium-concrete reaction (SCR) is one of the important phenomena during severe accidents in sodium-cooled fast reactors (SFRs) owing to the presence of large sources of hydrogen and aerosols in the containment vessel. In this study, SCR experiments with an internal heater (800$$^{circ}$$C) were performed to investigate the chemical reaction under the internal heater. Furthermore, the effects of the internal heater on the self-termination mechanism were discussed. Because the internal heater hindered the transport of Na, the moisture in the concrete, and reaction products, Na could permeate and react with the surface concrete at the periphery of the internal heater. As the SCR proceeded, the reaction products accumulated under the internal heater and disturbed the Na diffusion. Therefore, the Na concentration under the internal heater decreased relatively lower, and the concrete ablation depth under the internal heater decreased compared to that under the periphery of the internal heater. However, the Na concentration around the reaction front was about 30 wt.% despite the position of the internal heater. The Na concentration was similar to that of Na$$_2$$SiO$$_3$$, which was almost same as that in our past study. It was found that the Na concentration condition was one of the dominant parameters for the self-termination of SCR, even in the presence of the internal heater.

Journal Articles

Thermophysical properties of sodium-concrete reaction products

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Netsu Sokutei, 45(1), p.2 - 8, 2018/01

Liquid sodium (Na) has been used as the coolant of fast reactors for the various merits, such as the high thermal conductivity. On the other hand, it is postulated that a steel liner may fail and lead to a sodium-concrete reaction (SCR) during the Na-leak accident. Because of concrete ablation and release of hydrogen gas due to the chemical reactions between Na and concrete components, the SCR is one of the important phenomena in the Na-leak accident. In the study, fundamental experiments related to the SCR were performed using Na and concrete powder. Here, the used concrete powder is milled siliceous concrete which is usually used as the structural concrete in Japanese nuclear power plants. The obvious temperature changes at 3 temperature regions were observed for the reaction process such as Na-melt, NaOH-SiO$$_{2}$$ and Na-H$$_{2}$$O-SiO$$_{2}$$ reaction, which occurred around 100, 300 and 500$$^{circ}$$C, respectively. Especially, the violent reaction around 500$$^{circ}$$C caused the temperature peak to $$836 sim 853^{circ}$$C, and the reaction heat of $$0.15 sim 0.23$$ kW/g was estimated under the Na-concrete mixing ratio such as $$gammaapprox 0.32$$. The main components of the reaction products was identified as Na$$_{2}$$SiO$$_{3}$$ with X-ray diffraction technique. Moreover, the measured thermophysical properties such as melting point, density, specific heat, thermal conductivity and viscosity were similar to those of $$x$$Na$$_{2}$$O-$$(1-x)$$SiO$$_{2}$$ ($$xleq 0.5$$).

Journal Articles

A Study on self-terminating behavior of sodium-concrete reaction

Kawaguchi, Munemichi; Doi, Daisuke; Seino, Hiroshi; Miyahara, Shinya

Journal of Nuclear Science and Technology, 53(12), p.2098 - 2107, 2016/12

 Times Cited Count:6 Percentile:49.65(Nuclear Science & Technology)

A sodium concrete reaction (SCR) is one of the important phenomena to cause the structural concrete ablation and the release of H$$_2$$ gas in the case of sever accident of sodium cooled fast reactors. In this study, the long-time SCR test had been carried out to investigate the self-termination mechanism. The results showed the SCR terminated even if the enough amount of Na remained on the concrete. The quantitative data were collected on the SCR terminating such as temperature and H$$_2$$ generation. The reaction products, which became the small solids in liquid Na were transferred with slurry state by generated H$$_2$$ bubbles. Though the Na transfers actively and ablated the concrete surface with the high H$$_2$$ generation rate, the mass exchange coefficient defined as $$E_p$$ decreased and the reaction products settled gradually with decreasing the H$$_2$$ generation rate. Therefore, the Na concentration decreased at the reaction front and resulted in the SCR terminating naturally.

Journal Articles

Development of fast reactor containment safety analysis code, CONTAIN-LMR, 3; Improvement of sodium-concrete reaction model

Kawaguchi, Munemichi; Doi, Daisuke; Seino, Hiroshi; Miyahara, Shinya

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

CONTAIN-LMR code is an integrated analysis tool to predict the consequence of severe accident in a liquid metal fast reactor. A sodium-concrete reaction is one of the most important phenomena, and Sodium-Limestone Concrete Ablation Model (SLAM) has been installed into the original CONTAIN code. The SLAM treats chemical reaction kinetics between the sodium and the concrete compositions mechanistically, the application is limited to the limestone concrete. In order to apply SLAM to the siliceous concrete which is an ordinary structural concrete in Japan, the chemical reaction kinetics model has been improved. The improved model was validated to analyze a series of sodium-concrete experiments which were conducted in Japan Atomic Energy Agency. It has been found that relatively good agreement between calculation and experimental results is obtained and the CONTAIN-LMR code has been validated with regard to the sodium-concrete reaction phenomena.

Journal Articles

Development of fast reactor containment safety analysis code, CONTAIN-LMR, 5; Improvement of debris-concrete interaction model

Seino, Hiroshi; Kawaguchi, Munemichi; Izumi, Keitaro*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

As a part of development of CONTAIN-LMR, CORCON and VANESA models for calculating the debris-concrete interaction (MCCI) have been improved taking into account the influence of soudium-pool existence. In this study, the following LMFR specific models in the code have been developed and improved: (1) chemical reaction in sodium pool, (2) aerosol decontamination in sodium pool, and (3) heat conduction in concrete. These models have been also confirmed and validated with experimental results. As a result, improved CORCON and VANESA can represent the MCCI behavior reasonably well. Further improvement and validation of CONTAIN-LMR will be continued in order to apply to the ex-vessel accident progression of LMFRs.

Journal Articles

Reactive wetting by liquid sodium on thin Au plating

Kawaguchi, Munemichi; Hamada, Hirotsugu

Journal of Nuclear Science and Technology, 51(2), p.201 - 207, 2014/02

 Times Cited Count:3 Percentile:24.02(Nuclear Science & Technology)

The behavior of sodium wetting is investigated for the practical use of the under sodium viewer (USV), in which the modeling of the reactive and non-reactive wetting for the metallic-plated steels by liquid sodium are performed to simulate the behavior of sodium wetting. Simulation results of the non-reactive wetting showed a good agreement with the Tanner's law. For the simulation of reactive wetting, the model of fluid flow induced by the interfacial reaction was incorporated into that of the non-reactive wetting. The simulation results of the reactive wetting, such as the behavior of precursor liquid film and the central droplet, showed a good agreement with the sodium wetting experiments using thin Au plating at 250$$^{circ}$$C. In reactive wetting simulation, it is important that the gradient of reaction energy at the interface appeared on the new interface around the triple junction, and that the fluid flow was induced.

Journal Articles

Reactive wetting of metallic plated steels by liquid sodium

Kawaguchi, Munemichi; Tagawa, Akihiro; Miyahara, Shinya

Journal of Nuclear Science and Technology, 48(4), p.499 - 503, 2011/04

The sodium wetting experiments were performed to investigate the reactive wetting of metallic plating materials by liquid sodium at 250 $$^{circ}$$C for the ultrasonic sensor of the under-sodium viewer. SUS304 stainless steel specimens were electrolytically plated with four metallic materials (Nickel, Palladium, Gold and Indium) which have different solubility in sodium, and the spreading velocity of sodium droplets on the metallic plated specimens was measured. It was confirmed that the spreading velocity increased as the solubility increased, and the constant $$alpha$$ on the spreading velocity on the plated specimens was unique for the plating materials and was proportional to the logarithm of the solubility of the plating materials. Furthermore, it is considered possible to select plating materials based on solubility from the result of this study.

43 (Records 1-20 displayed on this page)