A Comparison of Methods to Compute High-Temperature Gas Thermal Conductivity

Author(s):  
Grant Palmer ◽  
Michael Wright
Author(s):  
Cheng Ren ◽  
Xing-Tuan Yang ◽  
Cong-Xin Li ◽  
Zhi-Yong Liu ◽  
Sheng-Yao Jiang

High Temperature Gas-cooled Reactor (HTGR) is a typical representation of Generation IV nuclear power system for its advantages like inherent safety, high efficiency, widely application as high-temperature heat source. The first two 250-MWt high temperature reactor pebble bed modules (HTR-PM) have be installing at the Shidaowan plant in Shandong Province, China, which have the cylindrical core structure with thousands of spherical fuel elements randomly packed inside. The values of the effective thermal conductivity of the pebble bed core under different temperatures are essential parameters for the design of HTGR, which are needed to analyze the maximum fuel temperature, temperature distribution and residual heat releasing ability in reactor core. For this purpose, Tsinghua University in China has proposed a full-scale heat transfer experiment to conduct comprehensive thermal transfer tests in packed pebble bed and to determine the effective thermal conductivity through the pebble bed under vacuum condition and helium environment with temperature up to 1600°C. An essential material test equipment is built in advance to provide reliable materials and technical support for the design of the final experimental device aimed at measuring the effective thermal conductivity of pebble bed type reactor core of the high temperature gas-cooled reactor. The design of the essential material test equipment is introduced in detail, including the heat element, the insulation structure, the temperature detector, cooling water system, vacuum system, hydraulic lifting system, data acquisition system and so on. Several key technologies in design are described in detail. Test temperature in the equipment was elevated up to 1600°C, which covers the whole temperature range of the normal operation and accident condition of HTGR and could fully meet the test requirements of materials used in the reactor. The construction and commissioning of the test equipment shows that the test equipment has met the design requirements and verified the feasibility of the related materials and structures.


Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.


Author(s):  
Dmitry V. Nesterovich ◽  
Oleg G. Penyazkov ◽  
Yu. A. Stankevich ◽  
M. S. Tretyak ◽  
Vladimir V. Chuprasov ◽  
...  

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