Transient Simulation on Reactor Core Melt and Lower Support Plate Ablation in In-Vessel Retention

To precisely understand the accident process of reactor core melt in In-vessel retention (IVR) condition, 3-dimensional transient thermal conduction analysis with moving boundary is performed on quarter reactor core model. The decline of decay power and water level in reactor pressure vessel (RPV), and the radial distribution of assemblies of different material is considered. Convective heat transfer on rod surface and coolant interface is computed with empirical correlation of natural convection of saturated steam vapor / water. Radiation heat transfer with 16 neighboring rod is considered. Also, a dynamic ablation model is developed to simulate the ablation of lower support plate (LSP) caused by continuously accumulation of molten corium. The impingement heat transfer of the falling corium and the molten pool formed in LSP ablation cavity is taken into account. The simulation gives the ablation process on the surface of LSP as well as temperature history and molten proportion of the reactor core, which shows agreement with reference. Simulation shows: the melt process of reactor core accelerated in the accident process of 2600s, when coolant in RPV dry up. 65% of the core mass has molten at 8000 second. LSP is completely penetrated in 6000s, the ablation of LSP is mainly focused on an annular region of radius 700mm.

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Josef Stefan and His Contributions to Heat Transfer

Heat Transfer: Volume 3 ◽

10.1115/ht2008-56073 ◽

2008 ◽

Author(s):

John Crepeau

Keyword(s):

Heat Transfer ◽

Moving Boundary ◽

Radiation Heat Transfer ◽

The Arctic ◽

Arctic Seas ◽

James Clerk Maxwell ◽

Josef Stefan ◽

The University ◽

Solid Liquid ◽

Boltzmann Law

Josef Stefan was a professor of physics at the University of Vienna between 1863 and 1893. During his time in Vienna he was a fruitful researcher in many scientific fields, but he is best known for his work in heat transfer. He was a gifted experimentalist and theoretician who made contributions to conduction, convection and radiation heat transfer. Stefan was the first to accurately measure the thermal conductivity of gases, using a device he invented called the diathermometer. He also determined the diffusion of two gases into each other, a process now known as Maxwell-Stefan diffusion. His work provided experimental verification of the newly formulated kinetic theory of gases published by the great Scottish physicist James Clerk Maxwell. Stefan also experimentally studied the motion of gases induced by evaporation along a liquid surface, a phenomenon known as Stefan flow. In addition, Stefan received data from various expeditions on ice formation in the arctic seas. From that solid/liquid phase change data, he formulated solutions to the moving boundary problem, now called the Stefan problem. The work for which he is most famous is the T4 radiation law which he deduced from the experimental work of a number of investigators. However, his theory was not widely accepted until his former student, Ludwig Boltzmann, derived the same relation from first principles. In their honor, the T4 radiation equation is called the Stefan-Boltzmann law. Despite his varied contributions, little is known about Stefan the man. This paper gives some details on his life and describes the seminal work he performed in broad areas of heat transfer.

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Numerical Analysis of a Two-Dimensional Jet Impinging on an Oscillated Heat Transfer Surface

Journal of Heat Transfer ◽

10.1115/1.3139188 ◽

2009 ◽

Vol 131 (9) ◽

Cited By ~ 4

Author(s):

Koichi Ichimiya ◽

Shuichi Watanabe

Keyword(s):

Heat Transfer ◽

Moving Boundary ◽

Low Frequency ◽

Local Heat Transfer ◽

Reynolds Numbers ◽

Local Heat ◽

Two Dimensional ◽

Oscillation Effect ◽

Impingement Heat Transfer ◽

Impingement Surface

Numerical analyses were performed to determine the oscillation effect of an impingement surface on the impingement heat transfer and flow with a confined wall. As a moving boundary problem, two-dimensional governing equations were solved for the Reynolds numbers Re=200 and 500, the Prandtl number Pr=0.71, the dimensionless space between the nozzle and impingement surface H=1.0, and the Strouhal number Sf=0–1.0. Oscillation induced both the enhancement and depression of the local heat transfer. The local heat transfer was improved at a comparatively low frequency due to the flow fluctuation. On the other hand, at a high frequency, it was depressed due to the flow in an upper direction near the impingement surface. The oscillation effect spatially appeared downstream after the impingement.

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