CFD modelling of particle resuspension in a toroidal geometry resulting from airflows during a loss of vacuum accident (LOVA)

Gélain, Thomas; Gensdarmes, F.; Peillon, S.; Ricciardi, Laurent

doi:10.1016/j.fusengdes.2019.111386

Cited by 12 publications

(4 citation statements)

References 28 publications

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“…The results presented in table 2 highlight that, as opposed to the béryllium particles, none of the tungsten particles is entrained away from the wall for a pressure lower than 1500 Pa. This observation can be compared with the calcu lation results presented in the recent paper [34] relative to the resuspension and transport of tungsten particles during an air ingress in a toroidal geometry. In that paper, the CFD calculation (see their Fig.…”

Section: -4-discussionsupporting

confidence: 57%

“…21 at t=1 s) reveals that a frac tion of roughly 10-4 of the initially deposited 10 ^m particles is in suspension at a pressure of 1500 Pa. This simple comparison of results of the CFD calculation with the present analytical calculations gives opposite findings, showing that the CFD simulations in [34] could overestimate the particle entrainment. The explanation is in the consideration of the near wall velocity.…”

Section: -4-discussionmentioning

confidence: 51%

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Particle behavior close to the lower wall of a tokamak type geometry during a loss of vacuum accident

Feuillebois

Gensdarmes

Gélain

2020

Fusion Engineering and Design

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The behavior of tungsten and beryllium particles close to the wall of a tokamak type geometry (i.e. a toroidal vacuum vessel) during a loss of vacuum accident (LOVA) is explored in this paper.Values of the flow field and temperature of the air surging into the torus were calculated by Computational Fluid Dynamics (CFD) simulations from an initial low pressure of 1000 Pa by Gelain et al, Fusion Engineering and Design, 100:87-99, 2015. A new CFD calculation is performed here for an initial low pressure of 500 Pa. The aerodynamic forces on particles in rarefied flow are derived from the calculated friction velocity and temperature in the lowest wall region. The focus is on spherical particles, but these values of forces are complemented for comparison with an estimate of the force on an elongated particle following Sentman (1961). Typical particles with diameters of 1, 2, 5, 10, 20 ^m are considered. The possibility for particles which are detached from the lower wall to be entrained away the wall is explored. A particle may be detached by the flow field provided it escapes the adhesion force with the wall, which occurs only for a rough wall and large particles. It is then entrained away from the lower part of the wall provided its weight is smaller than the aerodynamic force, which occurs even at low pressure for all sizes of studied beryllium particles and only for specific sizes and a pressure above 1500 Pa for tungsten particles. This key influence of particle weight on the particle dynamics in rarefied gas flow is the focus of the paper. As a result, only particles of intermediate diameters may be resuspended and transfered away from the wall during the whole pressurisation sequence of the vessel. Using the data for the initial low pressure of 500 Pa, these particle diameters are 5, 10 ^m for tungsten and 5, 10, 20 ^m for beryllium.

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Section: -4-discussionsupporting

confidence: 57%

Section: -4-discussionmentioning

confidence: 51%

Particle behavior close to the lower wall of a tokamak type geometry during a loss of vacuum accident

Feuillebois

Gensdarmes

Gélain

2020

Fusion Engineering and Design

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“…Standard gravity acceleration (m s −2 ) which relate the quantity of aerosol emitted to the initial quantity of dust involved, depending on the scenario. In order to carry out such calculations using robust numerical simulations (Gelain et al, 2020), it is necessary to first perform experimental studies to specify the physical parameters to use in the models. Among the most important parameters, the nature, size and shape of the dust must be assessed.…”

Section: Introductionmentioning

confidence: 99%

Adhesion Forces of Radioactive Particles Measured by the Aerodynamic Method - Validation with Atomic Force Microscopy and Comparison with Adhesion Models

Peillon¹,

Gélain

Payet³

et al. 2022

SSRN Journal

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“…The results showed that dust mobilization strongly depends on the relative position between the inlet air flow and the initial position of the dust. Geiain et al [6,7] used a k-w SST turbulence model to simulate the flow characteristics of air after a LOVA in ITER, which was injected into the VV through the equatorial window. They studied the effects of dust particle size, fluid density and friction velocity.…”

Section: Introductionmentioning

confidence: 99%

Highly underexpanded helium jet and its effect on dust resuspension under in-vessel loss of coolant accident of fusion reactor

Qin¹,

Zhang²,

Wang³

et al. 2022

Nucl. Fusion

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During an in-vessel loss of coolant accident (LOCA) of helium-cooled blanket in fusion reactor, the high pressure helium gas ingress into the vacuum vessel (VV) will produce highly underexpanded jet, resulting in the resuspension and migration of the radioactive dust deposited in the VV. In this study, the flow field in VV and the influence of friction velocity were simulated and analyzed by using ANSYS Fluent code. In addition, the differences between in-vessel LOCA and loss of vacuum accident (LOVA) were compared. The results showed that the pressure of the VV would reach the pressure relief limit of vacuum vessel pressure suppression system (VVPSS) rapidly after LOCA. With the development of LOCA, the Mach disk continued to move towards the equatorial break of the VV, and its shape continued to shrink, with the number of structures gradually increased. Compared with LOVA, the LOCA had a higher friction velocity, resulting in a greater probability of dust resuspension and radioactive risk.

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CFD modelling of particle resuspension in a toroidal geometry resulting from airflows during a loss of vacuum accident (LOVA)

Cited by 12 publications

References 28 publications

Particle behavior close to the lower wall of a tokamak type geometry during a loss of vacuum accident

Particle behavior close to the lower wall of a tokamak type geometry during a loss of vacuum accident

Adhesion Forces of Radioactive Particles Measured by the Aerodynamic Method - Validation with Atomic Force Microscopy and Comparison with Adhesion Models

Highly underexpanded helium jet and its effect on dust resuspension under in-vessel loss of coolant accident of fusion reactor

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