Study on mixing process of two component gases in a vertical fluid layer

Takeda, Tetsuaki; Mizuno, Hiroki; Funatani, Shumpei

doi:10.1016/j.nucengdes.2013.12.012

Cited by 4 publications

(1 citation statement)

References 8 publications

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“…Mixing Process of Reverse U-Shaped Vertical Rectangular Channel 2.1. Experimental Apparatus [15] (Tanaka . Figure 1 shows the schematic drawing of an experimental apparatus of vertical rectangular channel.…”

Section: Experiments On Two-component Gasmentioning

confidence: 99%

Process of Air Ingress during a Depressurization Accident of GTHTR300

Shiga

Tanaka

Takada

2018

Science and Technology of Nuclear Installations

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A depressurization accident is the design-basis accidents of a gas turbine high temperature reactor, GTHTR300, which is JAEA’s design and one of the Very-High-Temperature Reactors (VHTR). When a primary pipe rupture accident occurs, air is expected to enter the reactor core from the breach and oxidize in-core graphite structures. Therefore, it is important to know a mixing process of different kinds of gases in the stable and unstable density stratified fluid layer. In order to predict or analyze the air ingress phenomena during the depressurization accident, we have conducted an experiment to obtain the mixing process of two component gases and the characteristics of natural circulation. The experimental apparatus consists of a storage tank and a reverse U-shaped vertical rectangular passage. One side wall of the high temperature side vertical passage is heated and the other side wall is cooled. The other experimental apparatus consists of a cylindrical double coaxial vessel and a horizontal double coaxial pipe. The outside of the double coaxial vessel is cooled and the inside is heated. The results obtained in this study are as follows. When the primary pipe is connected at the bottom of the reactor pressure vessel, onset time of natural circulation of air is affected by not only molecular diffusion but also localized natural convection. When the wall temperature difference is large, onset time of natural circulation of air is strongly affected by natural convection rather than molecular diffusion. When the primary pipe is connected at the side of the reactor pressure vessel, air will enter the bottom space in the reactor pressure vessel by counter-current flow at the coaxial double pipe break part immediately. Afterward, air will enter the reactor core by localized natural convection and molecular diffusion.

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Section: Experiments On Two-component Gasmentioning

confidence: 99%

Process of Air Ingress during a Depressurization Accident of GTHTR300

Shiga

Tanaka

Takada

2018

Science and Technology of Nuclear Installations

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R&D on commercial high temperature gas-cooled reactor

Aihara

Aoki

Fukaya

et al. 2021

High Temperature Gas-Cooled Reactors

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Experimental and Numerical Analysis of Mixing Process of Two Component Gases in a Vertical Fluid Layer in a VHTR

Takeda

2019

Journal of Nuclear Engineering and Radiation Science

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When a depressurization accident of a very-high-temperature reactor (VHTR) occurs, air is expected to enter into the reactor pressure vessel from the breach and oxidize in-core graphite structures. Therefore, in order to predict or analyze the air ingress phenomena during a depressurization accident, it is important to develop a method for the prevention of air ingress during an accident. In particular, it is also important to examine the influence of localized natural convection and molecular diffusion on the mixing process from a safety viewpoint. Experiment and numerical analysis using a three-dimensional (3D) computational fluid dynamics code have been carried out to obtain the mixing process of two-component gases and the flow characteristics of localized natural convection. The numerical model consists of a storage tank and a reverse U-shaped vertical rectangular passage. One sidewall of the high-temperature side vertical passage is heated, and the other sidewall is cooled. The low-temperature vertical passage is cooled by ambient air. The storage tank is filled with heavy gas and the reverse U-shaped vertical passage is filled with a light gas. The result obtained from the 3D numerical analysis was in agreement with the experimental result quantitatively. The two component gases were mixed via molecular diffusion and natural convection. After some time elapsed, natural circulation occurred through the reverse U-shaped vertical passage. These flow characteristics are the same as those of phenomena generated in the passage between a permanent reflector and a pressure vessel wall of the VHTR.

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Study on mixing process of two component gases in a vertical fluid layer

Cited by 4 publications

References 8 publications

Process of Air Ingress during a Depressurization Accident of GTHTR300

Process of Air Ingress during a Depressurization Accident of GTHTR300

R&D on commercial high temperature gas-cooled reactor

Experimental and Numerical Analysis of Mixing Process of Two Component Gases in a Vertical Fluid Layer in a VHTR

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