Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yonomoto, Taisuke; Shibamoto, Yasuteru; Satou, Akira; Okagaki, Yuria
Journal of Nuclear Science and Technology, 53(9), p.1342 - 1352, 2016/09
Times Cited Count：3 Percentile：28.09(Nuclear Science & Technology)Our previous study investigated the rewetting behavior of dryout fuel surface during transients beyond anticipated operational occurrences (AOOs) for BWRs, which indicated the rewetting velocity was significantly affected by the precursory cooling defined as cooling immediately before rewetting. The present study further investigated the previous experiments by conducting additional experimental and numerical heat conduction analyses to characterize the precursory cooling. For the characterization, the precursory cooling was firstly defined quantitatively based on evaluated heat transfer rates; the rewetting velocity was investigated as a function of the cladding temperature immediately before the onset of the precursory cooling. The results indicated that the propagation velocity appeared to be limited by the maximum heat transfer rate near the rewetting front. This limitation was consistent with results of the heat conduction analysis.
Kudo, Tamotsu; Onizawa, Kunio*; Nakamura, Takehiko
JAEA-Evaluation 2015-011, 209 Pages, 2015/11
JAEA-Evaluation-2015-011.pdf:10.36MB
Japan Atomic Energy Agency (JAEA) consulted an assessment committee, "Evaluation Committee of Research and Development (R&D) Activities for Nuclear Safety", for post- and pre-review assessment of R&D on nuclear safety research. In response to JAEA's request, the Committee assessed mainly the progress of the R&D project according to guidelines, which addressed the rationale behind the R&D project, the relevance of the project outcome and the efficiency of the project implementation during the period of the current and next plan. As a result, the Committee concluded that the progress of the R&D project is satisfactory. This report describes the results of evaluation by the Committee. In addition, the appendix of this report contains presentations used for the evaluation, and responses from JAEA on the comments from the member of the Committee.
Shibamoto, Yasuteru; Maruyama, Yu; Yonomoto, Taisuke
Journal of Nuclear Science and Technology, 50(2), p.148 - 159, 2013/02
Times Cited Count：8 Percentile：53.27(Nuclear Science & Technology)no abstracts in English
Abe, Hitoshi; Tashiro, Shinsuke; Watanabe, Koji; Uchiyama, Gunzo
JAEA-Research 2012-035, 26 Pages, 2013/01
JAEA-Research-2012-035.pdf:1.94MB
To contribute on confirmation of safety of fuel cycle facilities, an evaluation method for soundness of confinement capability of the facilities under fire accident has been investigated. Organic extraction solvents, zinc stearate, which is added into MOX powder in MOX fuel preparation process, and typical lubricating oil were considered to be examination objects as the representative combustible materials in the facilities. Combustion property data, such as mass loss rate and soot release fraction, of them and clogging property data of HEPA filter with combustion of the organic extraction solvents were measured. As the results, it was found that soot release fraction from burning 30%TBP/70%dodecane was larger than that of the other materials including dodecane and very rapid rise of differential pressure of HEPA filter, which has not been reported, would be induced in the last stage of combustion of 30%TBP/70%dodecane. Furthermore, it was confirmed that zinc stearate, of which combustibility has not been considered, burned continuously in the condition which was heated from outside.
Watanabe, Hironori; Tamai, Hidesada; Sato, Takashi; Shibata, Mitsuhiko; Mitsutake, Toru*
Flow Measurement, p.95 - 106, 2012/03
In Boiling Water Reactor (BWR), reactor power, fuel conversion ratio and reactor cooling capacity changes by the void fraction in the core. We have developed a capacitance method (C method) to measure the void fraction under the condition of high temperature and high pressure of 7MPa, simulating reactor. This C method is based on the principle that the capacitance in the two-phase flow is a function of void fraction. Using this method, we can measure void fractions in real time, at all region of void fractions, and with a small error of measurement, which was not realized by usual techniques up to now.
Shibamoto, Yasuteru; Maruyama, Yu; Yonomoto, Taisuke; Nakamura, Hideo
Journal of Nuclear Science and Technology, 48(3), p.440 - 453, 2011/03
Times Cited Count：8 Percentile：53.23(Nuclear Science & Technology)A correlation of heat transfer coefficient (HTC) in dried-out area in downstream of rewetting front is proposed based on experiments and existing correlations under conditions of anticipated operational occurrence of boiling water reactor. The effect of droplet deposition as well as vapor flow cooling were taken into account in order to apply to the wide range of wall superheat including transition boiling. The accurate HTC model in this region is crucial as boundary conditions of thermally-controlled type rewetting behavior, because the HTC distribution in the region around a rewetting front is predominant to the phenomena. The HTC correlation was well correlated by the distance from the wet front of the liquid film in the form of the exponential decay function. The present model successfully predicted the present data for wide range of the experimental conditions.
Shibamoto, Yasuteru; Maruyama, Yu; Nakamura, Hideo
Journal of Engineering for Gas Turbines and Power, 132(10), p.102909_1 - 102909_8, 2010/10
Times Cited Count：3 Percentile：23.46(Engineering, Mechanical)A series of experiments was performed for rewetting phenomena on dried-out fuel rod surfaces under post-BT (Boiling Transition) conditions with high-pressure and high-water flow rate simulating anticipated operational occurrences of a BWR. An analytical model for rewetting velocity, defined by a propagation velocity of a quench front, has been developed on the basis of the experimental results. The rewetting for the post-BT condition is characterized by the faster propagation of the quench front than that for reflood phase conditions during a postulated large-break loss-of-coolant accident. In order to provide an explanation of this characteristic, the present analytical model took an effect of a precursory cooling into account by modifying the existing correlation by Sun-Dix-Tien which is based on a one-dimensional analysis in a flow direction during the reflood phase. The present model demonstrates that the precursory cooling can significantly increase the rewetting velocity by more than an order of magnitude. Applying the experimental correlation developed in the separately conducted experiment into the heat transfer coefficient in the present model at a wet and a dry region with precursory cooling, our data of the rewetting velocity as well as the wall temperature profiles for the variable flow rates are successfully predicted.
Watanabe, Hironori; Mitsutake, Toru*; Shibata, Mitsuhiko; Takase, Kazuyuki
Nihon Kikai Gakkai Rombunshu, B, 76(769), p.1379 - 1385, 2010/09
The electro void fraction meter (Capacitance type meter) was applied to high temperature and high pressure condition measurement with various shapes of flow conduits such as rod bundle and pipe geometries. The principle of the meter is that the electrical capacitance of a gas liquid two phase flow changes with the void fraction. High frequency power supply enables to measure the electrical capacitance of the ion exchanged water with even though conductivity of pure water. It was confirmed by steam water boiling two phase flow experiments that void fraction can be obtained in real time way. Void fraction ranging from 0 to 0.9 at maximum was successfully measured under steam water boiling two phase flow conditions of 2 MPa through 18 MPa pressure.
Shibamoto, Yasuteru; Maruyama, Yu; Nakamura, Hideo
Proceedings of 17th International Conference on Nuclear Engineering (ICONE-17) (CD-ROM), 10 Pages, 2009/07
A series of experiments was performed for rewetting phenomena on dried-out heated surfaces under post-BT (Boiling Transition) conditions with high-pressure and high-water flow rate simulating anticipated operational occurrences of a BWR. An analytical model for rewetting velocity, defined by the propagation velocity of quench front, has been developed on the basis of the experimental results. The experiment was conducted within the ranges of the flow rate and the pressures covering an actual BWR plant conditions. The rewetting for the post-BT conditions is characterized by faster propagation of the quench front than that for reflood phase conditions during a postulated large-break loss-of-coolant accident. In order to provide an explanation of this characteristic, the present analytical model took the effect of precursory cooling into account by modifying the existing correlation of Sun-Dix-Tien (1975) which is based on the one-dimensional analysis in a flow direction during the reflood phase. The present model demonstrates that the precursory cooling can significantly increase the rewetting velocity by more than an order of magnitude. Appling the experimental correlation developed in the separately conducted experiment into the heat transfer coefficient in the present model at a wet and a dry region with precursory cooling, our experimental data of the rewetting velocity as well as the wall temperature profiles for the variable flow rates are successfully predicted. It is found that the effect of precursory cooling is indispensable to explain the considerably high rewetting velocity under the large flow rate condition due probably to the significant droplets cooling contribution.
Watanabe, Hironori; Mitsutake, Toru*; Kakizaki, Sadayuki*; Takase, Kazuyuki
Nihon Kikai Gakkai Rombunshu, B, 75(751), p.155 - 157, 2009/03
Capacitance type electro-void fraction meters with various shapes of electrodes were developed for two-phase flow measurement in tubes of 1mm in the smallest diameter. Ring and wire- type electrodes were applied to measure void fraction. The principle of the meter is that the electrical capacitance of a gas-liquid two-phase flow changes with void fraction. A high-frequency power supply enables to measure the low electrical capacitance of the water including pure water. It was confirmed by the air-water two-phase flow experiments that void fraction can be obtained in real time way every 50 millisecond. Void fraction in the experiment ranged from 0 to higher than 0.9. The void fraction was correlated with the electric capacitance by a linear function for the ring-electrode and hyperbolic function for the opposite wires-electrode under the atmospheric condition.
Watanabe, Hironori; Mitsutake, Toru*; Kakizaki, Sadayuki*; Takase, Kazuyuki
Nihon Kikai Gakkai Rombunshu, B, 74(742), p.1257 - 1262, 2008/06
Liu, W.; Kureta, Masatoshi
Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM), 9 Pages, 2008/05
R&D project to investigate thermal-hydraulic performance in the tight-lattice rod bundles for Innovative Water Reactor for Flexible Fuel Cycle (FLWR) has been progressed at Japan Atomic Energy Agency (JAEA). The basic thermal-hydraulic characteristics about the critical power and the pressure drop, under both steady and transient conditions, have been ascertained with using 37-rod tight lattice bundle. The effect of the spacer on the critical power has also been ascertained. However, as to the axial power distribution, the severest one - which is called as the basic heating case in this research - is selected in these experiments, with no considering to the change of the axial power distribution with the proceeding of the burnup. Therefore, an experimental research on the effect of the axial power distribution on the critical power is necessary. In this paper, an experimental research on the effect of the axial power distribution on the critical power is performed under the atmospheric pressure with using a circular tube, which is axially divided into 3 insulated levels and is heated separately by 3 DC power supplies. The test section is capable to simulate the power distribution in the double-humped core. Axial uniform heating condition, the upper 3 layers simulation and the center 3-layers simulation of the basic heating case are selected as the cases for the detailed evaluation. The effects of relative power ratio on the critical power, critical quality and critical boiling length under different heating conditions are ascertained for the detailed evaluation cases. With using the experimental data, existed correlating methods for the boiling transition are evaluated. As the result, a combination of the critical quality - boiling length method and the critical heat flux - critical quality method is found a good correlating to the present data with a changed axial power distribution.
Watanabe, Hironori; Mitsutake, Toru*; Kakizaki, Sadayuki*; Takase, Kazuyuki
no journal, ,
The electro-void fraction meter (Capacitance Type meter) is practical for high void fraction measurement. It can be used with various shapes of flow conduits such as round, rectangular and rod-bundle geometries. The principle of the meter is that the electrical capacitance of a gas-liquid two-phase flow changes with respect to the void fraction. High-frequency power supply enables to measure the void fraction of the pure water. It was confirmed by an air-water two-phase flow experiment that void fraction can be obtained in real time by measuring the capacitance of the two-phase flow. Void fraction ranging from 0 to more than 0.9 in a 37-rod bundle was successfully measured under 7MPa pressure conditions.
Maruyama, Yu; Otsu, Iwao; Suzuki, Mitsuhiro; Nakamura, Hideo
no journal, ,
no abstracts in English
Shibamoto, Yasuteru; Maruyama, Yu; Omiya, Toshihito
no journal, ,
no abstracts in English
Watanabe, Hironori; Mitsutake, Toru*; Kakizaki, Sadayuki*; Sekine, Katsunori*; Takase, Kazuyuki
no journal, ,
no abstracts in English
Shibamoto, Yasuteru; Maruyama, Yu; Nakamura, Hideo
no journal, ,
no abstracts in English
Shibamoto, Yasuteru; Maruyama, Yu; Nakamura, Hideo
no journal, ,
no abstracts in English
Watanabe, Hironori
no journal, ,
The electro void fraction meter was applied to void fraction measurement with various shapes of flow conduits such as rod bundle geometries. The principle of the meter is that the electrical capacitance of as liquid two phase flow changes with void fraction. High frequency power supply enables to measure the electrical capacitance of two phase flow of public water and even pure water. It was confirmed that void fraction can be obtained in real time way under air water and steam water conditions. In the steam water boiling experiments, void fraction was successfully measured from 0 to 0.9 at maximum under pressure conditions of 2MPa through 18MPa pressure. Moreover the electrical void fraction meters of capacitance type were developed for measurement in mini channel.
Shibamoto, Yasuteru; Yonomoto, Taisuke; Maruyama, Yu
no journal, ,
no abstracts in English
