Computational simulation of thermal hydraulic processes in the core and fuel assembly in the liquid-metal fast-breader reactor in the porous medium approximation

Bidisperse porous medium (BDPM) consists of a macroporous medium whose solid phase is replaced with a microporous medium. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the microporous medium. The side walls are subjected to differential heating, while the top and bottom ones are kept adiabatic. The bidispersion effect is generated by varying the number of blocks (N2), macropore volume fraction (ϕE), and internal Darcy number (DaI) for several enclosure Rayleigh numbers (Ra). Their effect on the BDPM heat transfer (Nu) is investigated. When Ra is fixed, the Nu increases with an increase in both DaI and DaE. At low Ra values, Nu is strongly affected by both DaI and ϕE. When N2 is fixed, at high Ra values, the porous blocks in the core region have negligible effect on the Nu. A correlation is proposed to evaluate the heat transfer from the BDPM enclosure, Nu, as a function of Raϕ, DaE, DaI, and N2. It predicts the numerical results of Nu within ±15% and ±9% in two successive ranges of modified Rayleigh number, RaϕDaE.

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Effect of an electric current on the infiltration of a porous medium by liquid metal

Soviet Powder Metallurgy and Metal Ceramics ◽

10.1007/bf00793725 ◽

1982 ◽

Vol 21 (2) ◽

pp. 107-111

Author(s):

A. I. Raichenko

Keyword(s):

Porous Medium ◽

Liquid Metal ◽

Electric Current

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Main Steam Line Break Calculations Using a Coupled RELAP5/PARCS Model for the Ringhals-3 Pressurized Water Reactor

Volume 2: Fuel Cycle and High Level Waste Management; Computational Fluid Dynamics, Neutronics Methods and Coupled Codes; Student Paper Competition ◽

10.1115/icone16-48702 ◽

2008 ◽

Author(s):

Mathias Sta˚lek ◽

Jo´zsef Ba´na´ti ◽

Christophe Demazie`re

Keyword(s):

Steady State ◽

Fuel Assembly ◽

Thermal Power ◽

Steam Line ◽

Pressurized Water ◽

The Core ◽

Different Types ◽

Main Steam Line ◽

Main Steam ◽

Control Rods

A Main Steam Line Break (MSLB) is an important transient for Pressurized Water Reactors (PWR) due to the strong positive reactivity introduced by the over-cooling of the core. Since this effect is stronger when the Moderator Temperature Coefficient (MTC) has a large amplitude, a conservative result will be obtained for a high burnup of the fuel due to the more negative MTC late in the cycle. The calculations have been performed at a cycle burnup of 12.9742 GWd/tHM. The Swedish Ringhals-3 PWR is a three loop Westinghouse design, currently with a thermal power of 3000 MW. The PARCS model has 157 fuel assemblies of 8 different types. Four different types of reflector are used. The cross sections, and kinetic data were obtained from CASMO-4 calculations, using a cross section interface developed at the department. There are 24 axial nodes, and 2×2 radial nodes for each assembly. The transient option for calculating the effect of poisoning was used. The PARCS model has been validated against steady-state measurements from Ringhals-3 of the Relative Power Fraction (RPF) and of the core criticality. The RELAP5 model has 157 channels for the core which means that there is a one to one correspondence between the thermal hydraulics model and the neutronics model. There is eight axial nodes. Originally, the intention was to have 24 axial nodes but this proved not to work because of some limitation in RELAP5. There is currently no mixing between the different channels in the core. The feedwater, and turbines are modelled as boundary conditions. The stand-alone RELAP5 model has been validated against steady state measurements from Ringhals-3. A number of different cases were considered. In the first case, both the isolation of the feedwater for the broken loop, and all the control rods were assumed to work properly. For the second case one of the control rods was assumed to be stuck. The stuck rod was located in the fuel assembly with the highest power. This rod has also one of the highest rod worths. In the final case, the feedwater control valve for the broken loop was fully open. None of the cases led to any recriticality. The increase in power for each fuel assembly was also investigated. With the control rod located in the assembly with the highest power, the maximum power increase before scram turned out to be about 25% compared to the initial power.

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Optimum Natural Convection in a Porous Medium Between a Vertical Polygonal Duct and a Heated Core

Journal of Heat Transfer ◽

10.1115/1.4006101 ◽

2012 ◽

Vol 134 (8) ◽

Cited By ~ 2

Author(s):

C. Y. Wang

Keyword(s):

Porous Medium ◽

Natural Convection ◽

Free Convection ◽

Eigenfunction Expansion ◽

Energy Transport ◽

Maximum Flow ◽

Maximum Energy ◽

The Core

The natural or free convection in a polygonal duct with a heated core is solved by eigenfunction expansion and boundary collocation. The optimal sizes of the core for maximum flow or maximum energy transport are determined.

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Forced Convection in a Channel Partly Occupied by a Bidisperse Porous Medium: Symmetric Case

Journal of Heat Transfer ◽

10.1115/1.4003667 ◽

2011 ◽

Vol 133 (7) ◽

Cited By ~ 24

Author(s):

D. A. Nield ◽

A. V. Kuznetsov

Keyword(s):

Porous Medium ◽

Nusselt Number ◽

Forced Convection ◽

Analytic Solution ◽

Solid Material ◽

Symmetric Case ◽

Interface Condition ◽

Temperature Model ◽

The Core ◽

Two Temperature

An analytic solution is obtained for the problem of fully developed forced convection in a channel between parallel plane walls, partly occupied by a bidisperse porous medium (BDPM) and partly by a fluid clear of solid material, the distribution of material being symmetrical with the BDPM forming either the core or the sheath portion of the channel. The case of uniform flux boundaries is considered. For the porous medium, a two-velocity two-temperature model based on Darcy’s law is employed and the Beavers–Joseph interface condition is imposed. In each case, Nusselt number values are obtained in terms of various parameters.

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Behavior of Inert Gas Bubbles in Forced Convective Liquid Metal Circuits

Journal of Heat Transfer ◽

10.1115/1.3450470 ◽

1976 ◽

Vol 98 (1) ◽

pp. 5-11 ◽

Cited By ~ 4

Author(s):

W. J. Minkowycz ◽

D. M. France ◽

R. M. Singer

Keyword(s):

Liquid Metal ◽

Bubble Dynamics ◽

Bubble Radius ◽

Gas Bubbles ◽

Inert Gas ◽

Liquid Sodium ◽

Gas Bubble ◽

Flowing Liquid ◽

Argon Gas ◽

The Core

Conservation equations are derived for the motion of a small inert gas bubble in a large flowing liquid-gas solution subjected to large thermal gradients. Terms which are of the second order of magnitude under less severe and steady-state conditions are retained, thus resulting in an expanded form of the Rayleigh equation. The bubble dynamics is a function of opposing mechanisms tending to increase or decrease bubble volume while being transported with the solution. Diffusion of inert gas between the bubble and the solution is one of the most important of these mechanisms included in the analysis. The analytical model is applied to an argon gas bubble flowing in a weak solution of argon gas in liquid sodium. Calculations are performed for these fluids under conditions typical of normal and abnormal operation of a liquid metal fast breeder reactor (LMFBR) core and the resulting bubble radius, internal gas pressure, and mass of inert gas are presented in each case. An important result obtained indicates that inert gas bubbles reaching the core inlet of an LMFBR will always grow as they traverse the core under normal and extreme abnormal conditions and that the rate of growth is quite small in all cases.

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Measurement of Pressure Drop in a Liquid Metal Reactor Fuel Assembly

Thermal Hydraulic Problems, Sloshing Phenomena, and Extreme Loads on Structures ◽

10.1115/pvp2002-1135 ◽

2002 ◽

Cited By ~ 1

Author(s):

Seok Ki Choi ◽

Il Kon Choi ◽

Kil Yong Lee ◽

Ho Yun Nam ◽

Jong Hyeun Choi ◽

...

Keyword(s):

Experimental Data ◽

Pressure Drop ◽

Liquid Metal ◽

Fuel Assembly ◽

Diameter Ratio ◽

Pressure Drops ◽

Liquid Metal Reactor ◽

The Wire ◽

Measured Pressure ◽

Reactor Fuel Assembly

An experimental study has been carried out to measure the pressure drop in a 271-pin fuel assembly of a liquid metal reactor. The rod pitch to rod diameter ratio (P/D) of the fuel assembly is 1.2 and the wire lead length to rod diameter ratio (H/D) is 24.84. Measurements are made for five different sections in a fuel assembly; inlet orifice, fuel assembly inlet, wire-wrapped fuel assembly, fuel assembly outlet and fuel assembly upper region. A series of water experiments have been conducted changing flow rate and water temperature. It is shown that the pressure drops in the inlet orifice and in the wire-wrapped fuel assembly are much larger than those in other regions. The measured pressure drop data in a wire-wrapped fuel assembly region is compared with the existing four correlations. It is shown that the correlation proposed by Cheng and Todreas fits the best with the present experimental data among the four correlations considered.

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