Microstructure Enhanced Heat Exchanger for Pressurized Water Reactor

2007 ◽  
Author(s):  
Kun Lian ◽  
Min Zhang ◽  
Guoqiang Li ◽  
Su-Seng Pang ◽  
Zhong-Geng Ling ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Power Input ◽  
Heating Element ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Heat Transfer Efficiency ◽  
Boiling Process ◽  
Vapor Nucleation

The goal of this research is to enhance the heat exchanger efficiency of pressurized water reactor (PWR) by using LIGA or LIGA-like technique made microstructures. The heat transfer inside the boiler is a complex combination of different physical phenomena, which, besides the traditional convection, conduction, and radiation, includes liquid to vapor phase change, vapor nucleation and evolution, surface tension between the liquid and heating element, and so on. This paper presents the updated total heat transfer enhancement results of the boiling process by adding microstructures on the surface of the heating elements. Different types of microstructure configurations were tested. The power input, temperature of the heating element, and boiling phenomena were recorded. The behavior of increase in power versus rise in temperature of testing coupon is used to evaluate the heat transfer efficiency of the heating element. The steam generating efficiency at fixed input power and fixed temperature have been used to assess the performance of heating elements with different microstructure configurations. The preliminary results show that by simply adding micro-sized poles on the surface of the heating element, the power input can be increased almost 100% higher than that without poles on the surface at 360°C. The current results suggest that the main factors leading to the enhanced boiling process are the surface morphology and configuration of the microstructures. These provide enhanced vapor nucleation sites at heating surface, which result in a better vapor evolution processes, and yield a low superheat temperature. It ultimately results in a higher boiling heat transfer efficiency.

Estimation of Pressure Loads During Ex-Vessel Steam Explosion

2008 ◽  
Author(s):  
Matjazˇ Leskovar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Phase 1 ◽  
Interaction Process ◽  
Radioactive Material ◽  
Primary System ◽  
Pressurized Water Reactor ◽  
Reactor Accident ◽  
Pressurized Water ◽  
Water Reactor

An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In the paper, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which is being developed for the simulation of fuel-coolant interactions. A comprehensive parametric study was performed varying the location of the melt release (central and side melt pours), the cavity water sub-cooling, the primary system overpressure at vessel failure and the triggering time for explosion calculations. The main purpose of the study was to determine the most challenging ex-vessel steam explosion cases in a typical pressurized water reactor and to estimate the expected pressure loadings on the cavity walls. Special attention was given to melt droplets freezing, which may significantly influence the outcome of the fuel-coolant interaction process. The performed analysis shows that for some ex-vessel steam explosion scenarios much higher pressure loads are predicted than obtained in the OECD program SERENA Phase 1.

Heat Transfer in Pressurized Water Reactor Components Most Often Subject to Thermal Shock

1980 ◽  
Vol 47 (1) ◽  
pp. 125-152 ◽  
Author(s):  
F. Parras ◽  
M. Bosser ◽  
D. Milan ◽  
G. Berthollon
Keyword(s):  
Heat Transfer ◽  
Thermal Shock ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

Pressure Load Estimation During Ex-Vessel Steam Explosion

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Matjaž Leskovar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Phase 1 ◽  
Interaction Process ◽  
Radioactive Material ◽  
Primary System ◽  
Pressurized Water Reactor ◽  
Reactor Accident ◽  
Pressurized Water ◽  
Water Reactor

An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor pressure vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel-coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In the article, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which is being developed for the simulation of fuel-coolant interactions. A comprehensive parametric study was performed by varying the location of the melt release (central and side melt pours), the cavity water subcooling, the primary system overpressure at vessel failure, and the triggering time for explosion calculations. The main purpose of the study was to determine the most challenging ex-vessel steam explosion cases in a typical pressurized water reactor and to estimate the expected pressure loadings on the cavity walls. Special attention was given to melt droplet freezing, which may significantly influence the outcome of the fuel-coolant interaction process. The performed analysis shows that for some ex-vessel steam explosion scenarios much higher pressure loads are predicted than obtained in the OECD program SERENA Phase 1.

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