Transient Boiling and Cross Flow in 5×5 Rod Bundle With Rapid Heating

2018 ◽  
Author(s):  
Hiroki Takiguchi ◽  
Masahiro Furuya ◽  
Takahiro Arai ◽  
Kenetsu Shirakawa
Keyword(s):  
Fuel Assembly ◽  
Heat Generation ◽  
Cross Flow ◽  
Nuclear Safety ◽  
Wire Mesh ◽  
Coolant Temperature ◽  
Heat Output ◽  
Rod Bundle ◽  
Test Loop ◽  
The Cross

Rapid thermal elevation in nuclear reactor is an important factor for nuclear safety. It is indispensable to develop a three-dimensional nuclear thermal transient analysis code and confirm its validity in order to accurately evaluate the effectiveness of the running nuclear safety measures when heating power of reactor core rapidly rises. However, the heat transfer characteristics such as reactivity feedback characteristics due to moderator density and the technical knowledge explaining the uncertainty are insufficient. In particular, the cross propagation behavior of vapor bubble (void) in cross section of fuel assembly is not grasped. This study evaluates the cross propagation void behavior in a simulated fuel assembly at time of rapid heat generation with a thermal hydraulic test loop including a 5 × 5 rod bundle having the heat generation profile in the flow cross sectional direction. In this paper, the branching heat output condition of transient cross propagation was investigated from visualization of high speed video camera and void fraction measurement by wire mesh sensor with the inlet flow rate 0.3m/s and the inlet coolant temperature 40°C, which are based on the transient safety analysis condition. In addition, we applied the particle imaging velocimetry (PIV) technique to measure liquid-phase velocity profile of the coolant in the transient cross flow and experimentally clarified the relationship with the cross flow.

CFD Validation of Void Distribution in a Rod Bundle With Spacer

2014 ◽  
Author(s):  
Kevin Goodheart ◽  
Arto Ylönen ◽  
Victor De Cacqueray ◽  
Horst-Michael Prasser
Keyword(s):  
Nuclear Industry ◽  
Wire Mesh ◽  
Cfd Validation ◽  
Cfd Models ◽  
Rod Bundle ◽  
Void Distribution ◽  
Test Loop ◽  
Cfd Method ◽  
Stability And Accuracy ◽  
Paul Scherrer

As CFD (Computational Fluid Dynamics) continues to grow in the nuclear industry the need for validation is essential to this growth. The focus of this paper is to highlight the validation of AREVA’s 2-Phase CFD models in a rod bundle with spacer. The experimental work is based on void distribution measurements using a 64×64 wire mesh sensor at the Paul Scherrer Institute adiabatic test loop fuel rod bundle (SUBFLOW). The 2-Phase models are based on the Eulerian multiphase framework where the interaction models are further developed using user routines in a commercial CFD tool to achieve stability and accuracy in a rod bundle configuration with a spacer. The 2-Phase CFD models coincide with the SUBFLOW experiments in showing the effect of void collecting in the center of the sub-channels slightly downstream of the spacer and further downstream the smaller bubbles migrate toward the rod surfaces whereas the larger bubbles stay in the sub-channels. Good agreement is achieved between CFD and void distribution experiments. The multi-phase CFD method was used by AREVA to improve the performance of the new products GAIA and ATRIUM™ 11.

Single- and Two-Phase Diversion Cross-Flows Between Triangle Tight Lattice Rod Bundle Subchannels: Data on Flow Resistance and Interfacial Friction Coefficients for the Cross-Flow

2006 ◽  
Author(s):  
Tatsuya Higuchi ◽  
Akimaro Kawahara ◽  
Michio Sadatomi ◽  
Hiroyuki Kudo
Keyword(s):  
Friction Coefficient ◽  
Pressure Difference ◽  
Flow Resistance ◽  
Cross Flow ◽  
Resistance Coefficient ◽  
Interfacial Friction ◽  
Two Phase ◽  
Rod Bundle ◽  
The Cross ◽  
Tight Lattice

Single- and two-phase diversion cross-flows arising from the pressure difference between tight lattice subchannels are our concern in this study. In order to obtain a correlation of the diversion cross-flow, we conducted adiabatic experiments using a vertical multiple-channel with two subchannels simplifying the triangle tight lattice rod bundle for air-water flows at room temperature and atmospheric pressure. In the experiments, data were obtained on the axial variations in the pressure difference between the subchannels, the ratio of flow rate in one subchannel to the whole channel, the void fraction in each subchannel for slug-churn and annular flows in two-phase flow case. These data were analyzed by use of a lateral momentum equation based on a two-fluid model to determine both the cross-flow resistance coefficient between liquid phase and channel wall and the gas-liquid interfacial friction coefficient. The resulting coefficients have been correlated in a way similar to that developed for square lattice subchannel case by Kano et al. (2002); the cross-flow resistance coefficient data can be well correlated with a ratio of the lateral velocity due to the cross-flow to the axial one irrespective of single- and two-phase flows; the interfacial friction coefficient data were well correlated with a Reynolds number, which is based on the relative velocity between gas and liquid cross-flows as the characteristic velocity.

Investigation of Mixing Flow Process Using PIV and PLIF Techniques

2013 ◽  
Vol 816-817 ◽  
pp. 1054-1058
Author(s):  
Ezddin Hutli ◽  
Dániel Tar ◽  
Valer Gottlasz ◽  
Gyorgy Ezsol
Keyword(s):  
Temperature Distribution ◽  
Fuel Assembly ◽  
Cross Section ◽  
Temperature Difference ◽  
Power Distribution ◽  
Coolant Temperature ◽  
Mixing Process ◽  
Flow Process ◽  
Flow Rates ◽  
Rod Bundle

A coolant mixing investigation in a head of a half-size model of VVER-440 fuel assembly (simulator) has been performed at KFKI. The PIV and PLIF measurements have been done under a selected list of power distribution options, flow rates and powers. The experiments were focused on obtaining a data for investigating the trends in temperature difference between the value registered by a thermocouple and that obtained using PLIF technique. The coolant temperature distribution has been measured in many positions along the coolant trajectory and where coolant flow leaves the rod bundle and in the cross section location of thermocouple, thus the dynamics of effect of mixing process is also declared. PIV and LPIF results show their ability to verify the primary results of CFD calculations.

MHD free convective mass transfer flow of radiative uniform heat generation (absorption) fluid through a wavy permeable channel in the presence of Soret and Dufour effects

2017 ◽  
Vol 95 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Sanjib Sengupta ◽  
Nazibuddin Ahmed
Keyword(s):  
Mass Transfer ◽  
Thermal Radiation ◽  
Heat Generation ◽  
Wall Temperature ◽  
Fluid Model ◽  
Cross Flow ◽  
Soret And Dufour Effects ◽  
The Cross ◽  
Primary Velocity ◽  
Transfer Flow

The paper aims to present analytically the parametric effect of thermo-diffusion (Soret) and diffusion-thermo (Dufour) effects on a two-dimensional steady magnetohydrodynamic (MHD) free convective heat and mass transfer flow of a reasonably viscous incompressible electrically conducting fluid in the presence of thermal radiation and zeroth-order heat generation (absorption) effects. The governing system of partial differential equations with favorable boundary conditions is first non-dimensionalized and then solved by splitting the solution into a mean part and a perturbed part. Ostrach’s static fluid model is used to solve the mean part of the solution, while long wave approximations are employed to deal with the perturbed part of the solution. It is observed that an increase in parametric values of Soret and Dufour numbers as well as wall temperature and wall concentration parameters increase the primary velocity, while the cross flow velocity is found to be decreasing because of the increase in values of Soret and Dufour numbers. The primary and the cross flow velocities are both found to be increasing because of the increase in the thermal radiation parameter. The Nusselt number at the plates decreases because of the increase in the wall temperature parameter. It is also interesting to observe that the temperature and concentration of fluid particles near a plate are regulated by the influence of wall temperature and wall concentration parameters.

Effect of operational modes on the removal of a synthetic organic chemical by powdered activated carbon during ultrafiltration

2001 ◽  
Vol 1 (5-6) ◽  
pp. 39-47
Author(s):  
Y. Matsui ◽  
A. Yuasa ◽  
F. Colas
Keyword(s):  
Activated Carbon ◽  
Cross Flow ◽  
Powdered Activated Carbon ◽  
Organic Chemical ◽  
Filtration Cycle ◽  
Dead End ◽  
Synthetic Organic Chemical ◽  
The Cross ◽  
Short Time ◽  
Operational Modes

The effects of operational modes on the removal of a synthetic organic chemical (SOC) in natural water by powdered activated carbon (PAC) during ultrafiltration (UF) were studied, through model simulations and experiments. The removal percentage of the trace SOC was independent of its influent concentration for a given PAC dose. The minimum PAC dosage required to achieve a desired effluent concentration could quickly be optimized from the C/C0 plot as a function of the PAC dosage. The cross-flow operation was not advantageous over the dead-end regarding the SOC removal. Added PAC was re-circulated as a suspension in the UF loop for only a short time even under the cross-flow velocity of gt; 1.0 m/s. The cross-flow condition did not contribute much to the suspending of PAC. The pulse PAC addition at the beginning of a filtration cycle resulted in somewhat better SOC removal than the continuous PAC addition. The increased NOM loading on PAC which was dosed in a pulse and stayed longer in the UF loop could possibly further decrease the adsorption rate.

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