Machine for testing the strength of structural materials under cyclic torsion at high temperatures

1974 ◽  
Vol 6 (6) ◽  
pp. 746-748
Author(s):  
V. N. Rudenko ◽  
A. S. Spivakov ◽  
A. F. Bezverbnyi
Keyword(s):  
High Temperatures ◽  
Structural Materials ◽  
Cyclic Torsion

Behavior of Fuel and Structural Materials in Severely Damaged Reactors

2014 ◽  
Vol 94 ◽  
pp. 93-96 ◽  
Author(s):  
Nobuaki Sato ◽  
Akira Krishima ◽  
Takayuki Sasaki
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperatures ◽  
Oxidation Behavior ◽  
Sea Water ◽  
Structural Materials ◽  
Zirconium Oxides ◽  
Solid Solution Sample ◽  
Fukushima Daiichi ◽  
Xrd Method

To study the fuel debris treatment at Fukushima Daiichi NPP, information on the behaviour of fuel and structural materials in severely damaged reactors, i.e., oxides and metals of uranium and zirconium is essential. Since sea water was introduced to the reactors, situation of fuel debris became different from that for TMI case. In this paper, phase relations of uranium and zirconium oxides were analyzed by powder XRD method at high temperatures. By the heat-treatment of the mixture of UO2 and ZrO2 (U:Zr=1:1) under 10 torr air, UO2 was oxidized to U3O8 over 800 oC, The UO2 like phase appeared again at 1350 oC which may be caused by the decomposition of U3O8. The oxidation behavior of the UO2-ZrO2 system was also investigated by using solid solution sample with different U/Zr ratios under different steam and oxygen pressures. The oxidation of the UO2-ZrO2 mixture seemed to be suppressed with decreasing U/Zr ratio. The behavior of fuel materials in the presence of seawater was also discussed as well as that for other structural materials.

Life Prediction in High-Temperature Structural Materials

1995 ◽  
Vol 117 (1) ◽  
pp. 1-6 ◽  
Author(s):  
C. E. Jaske
Keyword(s):  
High Temperatures ◽  
Life Prediction ◽  
Critical Size ◽  
Structural Materials ◽  
Prediction Methods ◽  
Engineering Systems ◽  
Degradation Mechanisms ◽  
Initial Size ◽  
Materials Used ◽  
Cycle Dependent

Life prediction methods are required to assess the performance and safety of the structural materials used in engineering systems and components that operate at high temperatures. At high temperatures, materials are subject to time-dependent creep environmental degradation, as well as cycle-dependent fatigue degradation. The life prediction methods must account for all of these degradation mechanisms and their possible interactions. The purpose of this paper is to review the methods that are used predict the creep and fatigue life of structural materials. Traditional methods that have been used to predict the life of structural materials are based on the initiation of a significant crack; whereas more recent methods employ fracture mechanics to predict life based on the growth of crack from some initial size to a critical size. Crack-growth-based life prediction methods are emphasized in this review.

In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

1991 ◽  
Vol 49 ◽  
pp. 660-661
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
High Temperatures ◽  
Image Resolution ◽  
Atomic Processes ◽  
Crystal Surfaces ◽  
Beam Radiation ◽  
Surface Areas ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

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