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Journal Articles

Comparative methodology between actual RCCS and downscaled heat-removal test facility

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*

Annals of Nuclear Energy, 133, p.830 - 836, 2019/11

A RCCS having passive safety features through radiation and natural convection was proposed. The RCCS design consists of two continuous closed regions: an ex-reactor pressure vessel region and a cooling region with a heat-transfer surface to ambient air. The RCCS uses a novel shape to remove efficiently the heat released from the RPV through as much radiation as possible. Employing air as the working fluid and ambient air as the ultimate heat sink, the RCCS design can strongly reduce the possibility of losing the working fluid and the heat sink for decay-heat-removal. Moreover, the authors started experiment research with using a scaled-down heat-removal test facility. Therefore, this study propose a comparative methodology between an actual RCCS and a scaled-down heat-removal test facility.

Journal Articles

Improvement of heat-removal capability using heat conduction on a novel reactor cavity cooling system (RCCS) design with passive safety features through radiation and natural convection

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*

Annals of Nuclear Energy, 122, p.201 - 206, 2018/12

 Percentile:100(Nuclear Science & Technology)

A RCCS having passive safety features through radiation and natural convection was proposed. The RCCS design consists of two continuous closed regions: an ex-reactor pressure vessel region and a cooling region with a heat-transfer surface to ambient air. The RCCS uses a novel shape to remove efficiently the heat released from the RPV through as much radiation as possible. Employing air as the working fluid and ambient air as the ultimate heat sink, the RCCS design can strongly reduce the possibility of losing the working fluid and the heat sink for decay-heat-removal. This study addresses an improvement of heat-removal capability using heat conduction on the RCCS. As a result, a heat flux removed by the RCCS could be doubled; therefore, it is possible to halve the height of the RCCS or increase the thermal reactor power.

Journal Articles

Experimental study on heat removal performance of a new Reactor Cavity Cooling System (RCCS)

Hosomi, Seisuke*; Akashi, Tomoyasu*; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*; Takamatsu, Kuniyoshi

Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 7 Pages, 2018/11

A new RCCS with passive safety features consists of two continuous closed regions. One is a region surrounding RPV. The other is a cooling region with heat transferred to the ambient air. The new RCCS needs no electrical or mechanical driving devices. We started experiment research with using a scaled-down test section. Three experimental cases under different emissivity conditions were performed. We used Monte Carlo method to evaluate the contribution of radiation to the total heat released from the heater. As a result, after the heater wall was painted black, the contribution of radiation to the total heat could be increased to about 60%. A high emissivity of RPV surface is very effective to remove more heat from the reactor. A high emissivity of the cooling part wall is also effective because it not only increases the radiation emitted to the ambient air, but also may increase the temperature difference among the walls and enhance the convection heat transfer in the RCCS.

Journal Articles

Validation of three-dimensional finite-volume-particle method for simulation of liquid-liquid mixing flow behavior

Kato, Masatsugu*; Funakoshi, Kanji*; Liu, X.*; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*; Kamiyama, Kenji

Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 7 Pages, 2018/11

Journal Articles

Experimental study on debris bed characteristics for the sedimentation behavior of solid particles used as simulant debris

Shamsuzzaman, M.*; Horie, Tatsuro*; Fuke, Fusata*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Tagami, Hirotaka; Suzuki, Toru*; Tobita, Yoshiharu

Annals of Nuclear Energy, 111, p.474 - 486, 2018/01

 Times Cited Count:2 Percentile:16.17(Nuclear Science & Technology)

Journal Articles

Sedimentation behavior of mixed solid particles

Sheikh, Md. A. R.*; Son, E.*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru*

Journal of Nuclear Science and Technology, 55(6), p.623 - 633, 2018/01

 Percentile:100(Nuclear Science & Technology)

During core-disruptive accidents in sodium-cooled fast reactors, the sedimentation behavior of fragmented debris is crucial for in-vessel retention. The height of the beds formed may influence both the cooling of the bed and the neutronic characteristics. To develop an experimental database of bed formation behavior, a series of experiments using simulant materials, namely, Al$$_{2}$$O$$_{3}$$, ZrO$$_{2}$$, and stainless steel, were performed under gravity-driven discharge of solid particles from a nozzle into a quiescent cylindrical water pool. The bed height was measured for particles of different size, density, and sphericity, and an injection nozzle with varying diameter, injection velocity, and injection height. From these experiments, an empirical correlation was established to predict the bed height for both homogeneous and mixed particles for the different properties. This correlation reproduces reasonably well the experimental trend in bed height.

Journal Articles

Numerical simulation of solid-particle sedimentation behavior using a multi-fluid model coupled with DEM

Kawata, Ryo*; Ohara, Yohei*; Sheikh, Md. A. R.*; Liu, X.*; Matsumoto, Tatsuya*; Morita, Koji*; Guo, L.*; Kamiyama, Kenji; Suzuki, Toru

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09

Journal Articles

Experimental database for bed formation behaviors of solid particles

Sheikh, M. A. R.*; Son, E.*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 10 Pages, 2016/11

During the material relocation phase of core disruptive accidents in sodium-cooled fast reactors, the sedimentation behavior of fragmented debris leading to the formation of debris beds is crucial for in-vessel retention by debris bed cooling. In this study, a series of experiments using simulant materials was performed to develop an experimental database of bed formation behavior by gravity driven discharge of solid particles from a nozzle into a quiescent cylindrical water pool. The bed height as well as the bed shape was measured. Three types of spherical and non-spherical particles, namely Al$$_{2}$$O$$_{3}$$, ZrO$$_{2}$$ and stainless steel with different size were employed to study the effect of key experimental parameter on debris bed mound shape. Based on the experimental results, an empirical correlation as experimental database was proposed to predict the particle bed height. The proposed correlation reasonably reproduces the experimental trend of the bed height variation on the crucial factors. This result demonstrates a wide applicability of the proposed empirical model to predict the bed height in terms of all crucial factors with reasonable accuracy.

Journal Articles

New reactor cavity cooling system (RCCS) with passive safety features; A Comparative methodology between a real RCCS and a scaled-down heat-removal test facility

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Morita, Koji*

Annals of Nuclear Energy, 96, p.137 - 147, 2016/10

 Times Cited Count:1 Percentile:76.09(Nuclear Science & Technology)

After Fukushima Daiichi nuclear disaster by TEPCO, a cooling system to prevent core damage became more important from the perspective of defense in depth. Therefore, a new, highly efficient RCCS with passive safety features without a requirement for electricity and mechanical drive is proposed. Employing the air as the working fluid and the ambient air as the ultimate heat sink, the new RCCS design strongly reduces the possibility of losing the heat sink for decay heat removal. The RCCS can always stably and passively remove a part of the released heat at the rated operation and the decay heat after reactor shutdown. Specifically, emergency power generators are not necessary and the decay heat can be passively removed for a long time, even forever if the heat removal capacity of the RCCS is sufficient. We can also define the experimental conditions on radiation and natural convection for the scale-down heat removal test facility.

Journal Articles

Experimental investigation on characteristics of mixed particle debris in sedimentation and bed formation behavior

Sheikh, M. A. R.*; Son, E.*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru

Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-11) (USB Flash Drive), 12 Pages, 2016/10

This paper reports an experimental evaluation on debris bed formation characteristics in core-disruptive accidents cogitating the heterogeneous mixture of particles. In the present study, to appraise the characteristics, a series of experiments was accomplished by gravity driven discharge of solid binary mixtures of particles as simulant debris from a nozzle into a quiescent water pool in isothermal condition at room temperature. Currently, two types of spherical particles, namely Alumina and stainless steel with different diameter are employed to study the effect of key experimental parameters on bed mound shape. In experimental investigation both convex and concave mound shapes were perceived based on the effect of particle size and nozzle diameter. The present outcomes could be useful to validate numerical models and simulation codes of particulate debris sedimentation.

Journal Articles

New reactor cavity cooling system with a novel shape and passive safety features

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Morita, Koji*

Proceedings of 2016 International Congress on Advances in Nuclear Power Plants (ICAPP 2016) (CD-ROM), p.1250 - 1257, 2016/04

After Fukushima Daiichi nuclear disaster by TEPCO, a cooling system to prevent core damage became more important from the perspective of defense in depth. Therefore, a new, highly efficient RCCS with passive safety features without a requirement for electricity and mechanical drive is proposed. Employing the air as the working fluid and the ambient air as the ultimate heat sink, the new RCCS design strongly reduces the possibility of losing the heat sink for decay heat removal. The RCCS can always stably and passively remove a part of the released heat at the rated operation and the decay heat after reactor shutdown. Specifically, emergency power generators are not necessary and the decay heat can be passively removed for a long time, even forever if the heat removal capacity of the RCCS is sufficient. We can also define the experimental conditions on radiation and natural convection for the scale-down heat removal test facility.

Journal Articles

An Investigation on debris bed self-leveling behavior with non-spherical particles

Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Takeda, Shohei*; Nishi, Shimpei*; Nishikido, Tatsuya*; Zhang, B.*; Matsumoto, Tatsuya*; et al.

Journal of Nuclear Science and Technology, 51(9), p.1096 - 1106, 2014/09

AA2013-0303.pdf:1.68MB

 Times Cited Count:13 Percentile:12.31(Nuclear Science & Technology)

Journal Articles

Experimental study and empirical model development for self-leveling behavior of debris bed using gas-injection

Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Takeda, Shohei*; Nishi, Shimpei*; Zhang, B.*; Matsumoto, Tatsuya*; et al.

Mechanical Engineering Journal (Internet), 1(4), p.TEP0022_1 - TEP0022_16, 2014/08

Journal Articles

Evaluation of debris bed self-leveling behavior; A Simple empirical approach and its validations

Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Annals of Nuclear Energy, 63, p.188 - 198, 2014/01

 Times Cited Count:21 Percentile:4.37(Nuclear Science & Technology)

Journal Articles

A Methodological study extending an empirical model to predict self-leveling behavior of debris beds with non-spherical particles

Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Proceedings of International Conference on Power Engineering 2013 (ICOPE 2013) (USB Flash Drive), 6 Pages, 2013/10

Journal Articles

An Experimental investigation on self-leveling behavior of debris beds using gas-injection

Cheng, S.; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Gondai, Yoji*; Nakamura, Yuya*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Experimental Thermal and Fluid Science, 48, p.110 - 121, 2013/07

 Times Cited Count:13 Percentile:29.21(Thermodynamics)

Journal Articles

Recent knowledge from an experimental investigation on self-leveling behavior of debris bed

Cheng, S.; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Takeda, Shohei*; Nishi, Shimpei*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Proceedings of 21st International Conference on Nuclear Engineering (ICONE-21) (DVD-ROM), 8 Pages, 2013/07

Journal Articles

Characteristics of self-leveling behavior of debris beds in a series of experiments

Cheng, S.; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Nuclear Engineering and Technology, 45(3), p.323 - 334, 2013/06

 Times Cited Count:22 Percentile:5.42(Nuclear Science & Technology)

Journal Articles

Empirical correlations for predicting the self-leveling behavior of debris bed

Cheng, S.; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*

Nuclear Science and Techniques, 24(1), p.010602_1 - 010602_10, 2013/02

Journal Articles

Experimental investigation of debris sedimentation behaviour on bed formation characteristics

Shamsuzzaman, M.*; Horie, Tatsuro*; Fuke, Fusata*; Kai, Takayuki*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*; Tagami, Hirotaka; Suzuki, Toru; Tobita, Yoshiharu

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 10 Pages, 2012/12

Investigation on sedimentation behavior of debris is important to evaluate the sequence of core disruptive accident in SFR. To clarify this behavior, a series of experiments was performed by gravity driven discharge of solid debris from a nozzle into a water pool. The discharged debris accumulates on the collector plate at the bottom, forming either a Gaussian-type convex or ring-type concave mound depending on the experiment parameters. Three types of spherical debris with three diameters are employed to study the effect of experiment parameters on mound height of debris bed. During the experiment, mound height becomes decreasing with nozzle diameter and increasing with debris volume, which exhibits descending tendency in asymmetrical fashion with density variation and an unalike variation in mound height was observed with debris diameter. An empirical model was developed applying dimensional analysis to predict the variation in mound height of debris bed during sedimentation process.

74 (Records 1-20 displayed on this page)