On the radiation embrittlement of materials of support structures for WWER RPV. Part 2. Analysis of the completed studies

2019 ◽  
pp. 193-208
Author(s):  
B. Z. Margolin ◽  
E. V. Yurchenko ◽  
V. I. Kostylev ◽  
A. M. Morozov ◽  
A. Ya. Varovin ◽  
...  
Keyword(s):  
Point Defects ◽  
Neutron Fluence ◽  
Irradiation Temperature ◽  
Radiation Embrittlement ◽  
Support Structures ◽  
Dislocation Loops ◽  
Phosphorus Segregation ◽  
Metal Structures ◽  
Copper Precipitation ◽  
Low Irradiation

The features of the radiation embrittlement of materials of support structures for WWER RPV are considered. These features are connected with low irradiation temperature no exceeding 90oC and also with a use of the steels which are usually applied for building of the metal structures and have not a high resistance to the radiation embrittlement. The model for prediction of material radiation embrittlement as function of the neutron fluence and impurity of Cu and P is proposed. An irradiation temperature effect on the different mechanisms resulting in the material radiation embrittlement is considered: materials hardening due to nucleation of point defects and formation of dislocation loops, copper precipitation and materials non-hardening due to phosphorus segregation.

On the radiation embrittlement of materials of support structures for WWER RPV. Part 1. Experimental studies

2019 ◽  
pp. 175-192
Author(s):  
B. Z. Margolin ◽  
E. V. Yurchenko ◽  
V. I. Kostylev ◽  
A. M. Morozov ◽  
A. Ya. Varovin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Experimental Studies ◽  
Irradiation Temperature ◽  
Radiation Embrittlement ◽  
Support Structures ◽  
Metal Structures ◽  
Weld Metals ◽  
Sem Investigation ◽  
Low Irradiation

The features of the radiation embrittlement of materials of support structures for WWER RPV are considered. These features are connected with low irradiation temperature no exceeding90°Cand also with a use of the steels which are usually applied for building of the metal structures and have not a high resistance to the radiation embrittlement. It has been shown that support structure (SS) of WWER-440 of V-179, V-230 types may cause the operation life limit. The experimental data on the standard mechanical properties and fracture toughness are presented for different steels and weld metals in the initial and irradiation conditions. SEM investigation of fracture surface of broken specimens and atomic tomography have been performed.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Study of dislocation loops in Arsenic-Rich as-grown GaAs

1987 ◽  
Vol 45 ◽  
pp. 350-351
Author(s):  
Byung-Teak Lee
Keyword(s):  
Point Defects ◽  
Electronic Devices ◽  
Arsenic Concentration ◽  
Stoichiometric Compound ◽  
Dislocation Loops ◽  
Gaas Crystal ◽  
Ion Milling ◽  
Transmission Electron ◽  
Arsenic Source ◽  
High Arsenic

Grown-in dislocations in GaAs have been a major obstacle in utilizing this material for the potential electronic devices. Although it has been proposed in many reports that supersaturation of point defects can generate dislocation loops in growing crystals and can be a main formation mechanism of grown-in dislocations, there are very few reports on either the observation or the structural analysis of the stoichiometry-generated loops. In this work, dislocation loops in an arsenic-rich GaAs crystal have been studied by transmission electron microscopy.The single crystal with high arsenic concentration was grown using the Horizontal Bridgman method. The arsenic source temperature during the crystal growth was about 630°C whereas 617±1°C is normally believed to be optimum one to grow a stoichiometric compound. Samples with various orientations were prepared either by chemical thinning or ion milling and examined in both a JEOL JEM 200CX and a Siemens Elmiskop 102.

Contrast From Point Defects in The Infinitesimal Approximation

1980 ◽  
Vol 38 ◽  
pp. 350-351
Author(s):  
L. J. Sykes ◽  
J. J. Hren
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Broad Class ◽  
Stacking Fault ◽  
Crystalline Solids ◽  
Dislocation Loops ◽  
Analytical Expression ◽  
Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

Effect of intrinsic point defects on copper precipitation in large-diameter Czochralski silicon

2003 ◽  
Vol 83 (15) ◽  
pp. 3048-3050 ◽  
Author(s):  
Zhenqiang Xi ◽  
Deren Yang ◽  
Jin Xu ◽  
Yujie Ji ◽  
Duanlin Que ◽  
...  
Keyword(s):  
Point Defects ◽  
Large Diameter ◽  
Czochralski Silicon ◽  
Intrinsic Point Defects ◽  
Copper Precipitation

scholarly journals Irradiation temperature effects on the induced point defects in Ge-doped optical fibers.

2017 ◽  
Vol 169 ◽  
pp. 012008
Author(s):  
A. Alessi ◽  
I. Reghioua ◽  
S. Girard ◽  
S. Agnello ◽  
D. Di Francesca ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Point Defects ◽  
Temperature Effects ◽  
Irradiation Temperature

Effect of Self-Interstitial Diffusion Anisotropy in Electron-Irradiated Zirconium. A Cluster Dynamics Modeling

2005 ◽  
Vol 237-240 ◽  
pp. 659-664
Author(s):  
Frédéric Christien ◽  
Alain Barbu
Keyword(s):  
Point Defects ◽  
Thin Foil ◽  
Elastic Interaction ◽  
Dislocation Loops ◽  
Considerable Influence ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Diffusion Anisotropy ◽  
Vacancy Loops ◽  
Transmission Electron

Irradiation of metals leads to the formation of point-defects (vacancies and selfinterstitials) that usually agglomerate in the form of dislocation loops. Due to the elastic interaction between SIA (self-interstitial atoms) and dislocations, the loops absorb in most cases more SIA than vacancies. That is why the loops observed by transmission electron microscopy are almost always interstitial in nature. Nevertheless, vacancy loops have been observed in zirconium following electron or neutron irradiation (see for example [1]). Some authors proposed that this unexpected behavior could be accounted for by SIA diffusion anisotropy [2]. Following the approach proposed by Woo [2], the cluster dynamics model presented in [3] that describes point defect agglomeration was extended to the case where SIA diffusion is anisotropic. The model was then applied to the loop microstructure evolution of a zirconium thin foil irradiated with electrons in a high-voltage microscope. The main result is that, due to anisotropic SIA diffusion, the crystallographic orientation of the foil has considerable influence on the nature (vacancy or interstitial) of the loops that form during irradiation.

scholarly journals Hardening in AlN Induced by Point Defects

1991 ◽  
Vol 235 ◽  
Author(s):  
H. Suematsu ◽  
T. E. Mitchell ◽  
T. Iseki ◽  
T. Yano
Keyword(s):  
Point Defects ◽  
Defect Density ◽  
Single Point ◽  
Length Change ◽  
Dislocation Loops ◽  
Three Samples ◽  
Different Temperatures ◽  
Hardness Change ◽  
Isolated Point ◽  
Small Clusters

ABSTRACTPressureless-sintered AlN was neutron irradiated and the hardness change was examined by Vickers indentation. The hardness was increased by irradiation. When the samples were annealed at high temperature, the hardness gradually decreased. Length was also found to increase and to change in the same way as the hardness. A considerable density of dislocation loops still remained, even after the hardness completely recovered to the value of the unirradiated sample. Thus, it is concluded that the hardening in AlN is caused by isolated point defects and small clusters of point defects, rather than by dislocation loops.Hardness was found to increase in proportion to the length change. If the length change is assumed to be proportional to the point defect density, then the curve could be fitted qualitatively to that predicted by models of solution hardening in metals. Furthermore, the curves for three samples irradiated at different temperatures and fluences are identical. There should be different kinds of defect clusters in samples irradiated at different conditions, e.g, the fraction of single point defects is the highest in the sample irradiated at the lowest temperature. Thus, hardening is insensitive to the kind of defects remaining in the sample and is influenced only by those which contribute to length change.

Coupled irradiation-temperature effects on induced point defects in germanosilicate optical fibers

2017 ◽  
Vol 52 (18) ◽  
pp. 10697-10708 ◽  
Author(s):  
A. Alessi ◽  
S. Agnello ◽  
S. Girard ◽  
D. Di Francesca ◽  
I. Reghioua ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Point Defects ◽  
Temperature Effects ◽  
Irradiation Temperature
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