Molecular Approach to Sodium Vapour Condensation, Rewetting and Vaporization in LMFBR Bundle under Hypothetical Accident Conditions

Bottoni, M.

doi:10.3327/jnst.41.579

Cited by 3 publications

(2 citation statements)

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“…The simulation of the rarefied gas flow through circular tube of finite length in the transitional regime at both low Knudsen number and high Knudsen number is done by using the DSMC method by Shinagawa et al [5]. More recently, Bottoni [6] used the molecular approach based upon a MonteCarlo simulation for sodium vapor flow of monoatomic molecules in liquid metal fast breeder reactor bundle. Simulation of flows like recirculation flow problems or near continuum flows is still expensive due to the particular nature of the DSMC method [7].…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of a binary gas flow inside a rotating cylinder

Ganjaei

Nourazar

2009

J Mech Sci Technol

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A new approach to calculate the axially symmetric binary gas flow is proposed. Dalton's law for partial pressures contributed by each species of a binary gas mixture (argon and helium) is incorporated into numerical simulation of rarefied axially symmetric flow inside a rotating cylinder by using the time relaxed Monte-Carlo (TRMC) scheme and the direct simulation Monte-Carlo (DSMC) method. The results of flow simulations are compared with the analytical solution and results obtained by Bird [1]. The results of the flow simulations show better agreement than the results obtained by Bird [1] in comparison with the analytical solutions. However, the results of the flow simulations using the TRMC scheme show better agreement than those obtained using the DSMC method in comparison with the analytical solutions.

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Section: Introductionmentioning

confidence: 99%

Numerical simulation of a binary gas flow inside a rotating cylinder

Ganjaei

Nourazar

2009

J Mech Sci Technol

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“…1). The computer code THEMIS, 2) first developed as a two dimensional program at the O-Arai Engineering Center, Japan Nuclear Cycle Development Institute (JNC), Ibaraki-ken, Japan, was applied to a mock up of a reactor bundle consisting of an equivalent annular domain between two co-axial cylindrical surfaces.…”

Section: Introductionmentioning

confidence: 99%

Molecular Approach to Sodium Vapour Condensation, Rewetting and Vaporization in LMFBR Bundle under Hypothetical Accident Conditions

Bottoni¹

2004

Journal of Nuclear Science and Technology

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In the frame of safety analysis of Liquid Metal Fast Breeder Reactors (LMFBRs) under hypothetical Unprotected Loss-of-Flow (ULOF) conditions, two phase flow of sodium is simulated in a reactor core. Traditional approaches used in safety analysis codes to simulate sodium vapour condensation and vaporization rely upon application of macroscopic semi-empirical correlations for heat transfer and vapour condensation or evaporation rates. As an alternative to this macroscopic approach, we developed a microscopic methodology based upon the application of the basic laws of the kinetic theory for the determination of the evaporation and condensation rates of vapour in a reactor bundle. This microscopic approach is based upon a Monte Carlo simulation of the molecular trajectories, collision rates between vapour molecules and of the molecules with the surfaces of the claddings of the pins of a reactor bundle. The pins surfaces are treated in the Monte Carlo simulation as diffusely reflecting surfaces. Scattering of sodium particles is simulated with the ''hard sphere'' collision model. The ''step splitting'' technique is applied, which consists in separating the collisions dynamic calculation from collisionsless paths of the molecules. Vapour particles are assumed to condense on the surfaces of the pins when, after diffuse reflection, their velocity would be less than one third of the most probable velocity corresponding to the wall temperature. Rewetting of dried out regions of the cladding surfaces is simulated with a dynamic film model which computes the velocity distribution of the liquid across the film thickness and then the mean liquid film velocity. Evaporation of sodium molecules from the film yields a source of molecules which re-enter into the Monte Carlo calculation of the molecular dynamic approach. The coupling of the micro-and macroscopic models has been applied to the numerical simulation of an out-of pile sodium boiling experiment run at

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