Experimental studies and empirical models for the transient self-leveling behavior in debris bed

Cheng, S.*; Tanaka, Yohei*; Gondai, Yoji*; Kai, Takayuki*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; et al.

Journal of Nuclear Science and Technology, 48(10), p.1327 - 1336, 2011/10

https://doi.org/10.3327/jnst.48.1327

To clarify this behavior, a series of experiments have been performed in which nitrogen gas has been percolated uniformly through a particle bed. In these experiments, solid particles and water contained in a rectangular tank simulate respectively fuel debris and coolant. Based on the data obtained, an empirical model was developed to describe the transient variation in the bed inclination angle during the self-leveling process. Good agreement has been obtained between calculated and experimental values. Verification of the model has been confirmed through detailed analysis of the effects of experimental parameters such as particle size, particle density, and gas flow rate. Its applicability to extended conditions was further discussed by performing modeling simulations and comparing results against experimental data obtained from a larger-scale experimental system that employed a conventional boiling method.

Experimental investigation on self-leveling behavior in debris beds

Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu

Nuclear Engineering and Design, 241(1), p.366 - 377, 2011/01

https://doi.org/10.1016/j.nucengdes.2010.11.013

Experimental study of bubble behavior in a two-dimensional particle bed with high solid holdup

Cheng, S.*; Hirahara, Daisuke*; Tanaka, Yohei*; Gondai, Yoji*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 8 Pages, 2010/05

https://doi.org/10.1115/ICONE18-29710

A series of experiments on bubble behavior in a particle bed was performed to clarify three-phase flow dynamics in debris bed, which is essential in heat-removal capability, under coolant boiling conditions. The current experiment was conducted in a 2D tank. Water was used as liquid phase, while bubbles were generated by injecting nitrogen gas from the bottom of the tank. Various experimental parameters were taken, including different particle bed height, various particle diameter, different particle type, and different nitrogen gas flow rate. By using digital image analysis method, three kinds of bubble rise behavior were observed under current experimental conditions and confirmed by the quantitative detailed analysis of bubble rise properties including bubble departure frequency and bubble departure size.

Fundamental study on flow characteristics of disrupted core pool at a low energy level (Joint research)

Morita, Koji*; Ryu, P.*; Matsumoto, Tatsuya*; Fukuda, Kenji*; Tobita, Yoshiharu; Yamano, Hidemasa; Sato, Ikken

JAEA-Research 2009-018, 52 Pages, 2009/09

JAEA-Research-2009-018.pdf:46.46MB

Dynamic behaviors of solid-particle dominant multiphase flows were investigated to model the mobility of core materials in a low-energy disrupted core of a liquid metal fast reactor. Two series of experiments were performed, that is dam-break experiments and bubble visualization experiments. Verification of fluid-dynamics models used in the fast reactor safety analysis code SIMMER-III was also conducted based on the numerical simulations of these experiments. The experimental analyses show that SIMMER-III can, to some extent, represent effects of solid particle interaction on multiphase flow behaviors by adjusting model parameters of the particle jamming model. Further improvement of SIMMER-III with more generalized models is necessary to appropriately simulate interactions between solid particles in a wider range of flow conditions.

Fundamental study on dynamic behaviors of fuel debris bed; Research report in 2007 (Joint research)

Morita, Koji*; Fukuda, Kenji*; Matsumoto, Tatsuya*; Tobita, Yoshiharu; Suzuki, Toru; Yamano, Hidemasa

JAEA-Research 2009-006, 51 Pages, 2009/05

JAEA-Research-2009-006.pdf:19.69MB

It is important to make a reasonable evaluation of coolability of debris bed with decay heat source in assessing post accident heat removal of a liquid metal cooled fast reactor. In general, the coolability of fuel debris depends on coolant convection, boiling and debris bed movement. In the present study, to understand fundamental characteristics of debris movement, self-leveling behavior caused by the coolant boiling was investigated experimentally using simulant materials. The present experiments employed depressurization boiling of water to simulate void distribution in a debris bed, which consists of solid particles of alumina. A rough estimation model of self-leveling occurrence was proposed and compared with the experimental results. Its extrapolation to reactor accident conditions was also discussed. In addition, solid-liquid flow experiments, which are relevant to debris bed movement behaviors, were analyzed to verify the validity of multiphase flow models employed in a safety analysis code. In the present verification study, basic validity of the code was demonstrated by analyzing experiments of water-column sloshing with solid particles.

Fundamental study on flow characteristics of disrupted core pool at a low energy level (Joint research)

Morita, Koji*; Liu, P.*; Matsumoto, Tatsuya*; Fukuda, Kenji*; Tobita, Yoshiharu; Sato, Ikken

JAEA-Research 2007-032, 47 Pages, 2007/03

JAEA-Research-2007-032.pdf:4.04MB

Dynamic behaviors of solid particle beds in a liquid pool against pressure transients were investigated to model the mobility of core materials in a low-energy disrupted core of a liquid metal fast reactor. A series of experiments was performed with a particle bed of different heights, comprising different monotype solid particles, where variable initial pressures of the originally pressurized nitrogen gas were adopted as the pressure source. Computational simulations of the experiments were performed using SIMMER-III, a fast reactor safety analysis code. Experimental analyses using the SIMMER-III code show that physical models and methods used in the code can reasonably represent the transient behaviors of multiphase flows with rich solid phase as observed in the experiments. The validation of several key models of SIMMER-III was also discussed for treating transient behaviors of the solid-particle phase in multiphase flows.

Study on a Numerical Simulation for Thermal-Hydraulic Phenomena of Multiphase, Multicomponent Flows; Transient Vaporization/Condensation Phenomena in Multicomponent System (3)

Morita, Koji*; Matsumoto, Tatsuya*; Fukuda, Kenji*; Yamano, Hidemasa; Tobita, Yoshiharu; Sato, Ikkenn

JNC TY9400 2005-022, 119 Pages, 2005/08

JNC-TY9400-2005-022.pdf:10.85MB

It is one of important problems for more reliable reactor safety evaluation to improve numerical simulation techniques for involved thermal-hydraulic phenomena of multiphase, multicomponent flows in core disruptive accidents. In the present cooperative research, physical model development and experimental investigation were performed for transient condensation phenomena of a vapor bubble with noncondensable gas to improve applicability of a fast-reactor safety analysis code for the phase-transition phenomena in multicomponent systems. In addition, basic validity of the developed models was demonstrated through the experimental analysis, and then applicability of the fast-reactor safety analysis code was discussed for bubble condensation behaviors under rector conditions.

Study on Numerical Simulation for Thermal-Hydraulic Phenomena of Multiphase, Multicomponent Flows; Transient Vaporization/Condensation Phenomena in Multicomponent System,1

Morita, Koji*; Matsumoto, Tatsuya*; Fukuda, Kenji*; Tobita, Yoshiharu; Yamano, Hidemasa; Konishi, Kensuke; Sato, Ikkenn

JNC TY9400 2003-011, 56 Pages, 2003/04

JNC-TY9400-2003-011.pdf:2.31MB

It is one of the important problems for more reliable reactor safety evaluation to improve numerical simulation techniques for involved thermal-hydraulic phenomena of multiphase, multicomponent flows in core disruptive accidents.In the present joint research, physical model development and experimental investigation were conducted for transient condensation phenomena of a vapor bubble with noncondensable gases to improve applicability of a fast-reactor safety analysis code for the phase-transition phenomena in multicomponent systems.In this fiscal year, preliminary experiments using noncondensable gas were performed for the transient bubble condensation phenomena, and then basic data were obtained for large-scale bubble behavior without condensation.In addition, a multiple-scale flow-regime model treating large-scale bubbles was newly proposed for the fast-reactor safety analysis code and applied to the analysis of the preliminary experiments successfully.

None

Morita, Koji*; Matsumoto, Tatsuya*; *; Fukuda, Kenji*; Suzuki, Toru; Tobita, Yoshiharu; Yamano, Hidemasa

JNC TY9400 2001-016, 68 Pages, 2001/06

JNC-TY9400-2001-016.pdf:3.23MB

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*; Fukuda, Kenji*; *; *; *; *

PNC TN952 79-22, 71 Pages, 1979/09

PNC-TN952-79-22.pdf:9.22MB

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