Radiation Damage Studies with the HVEM

1972 ◽  
Vol 30 ◽  
pp. 680-681
Author(s):  
J. J. Laidler ◽  
B. Mastel
Keyword(s):  
Radiation Damage ◽  
Stainless Steels ◽  
Volume Expansion ◽  
Austenitic Stainless Steels ◽  
Test Facility ◽  
Fast Breeder Reactors ◽  
Breeder Reactors ◽  
Under Construction ◽  
Development Laboratory ◽  
Insight Into

One of the major materials problems encountered in the development of fast breeder reactors for commercial power generation is the phenomenon of swelling in core structural components and fuel cladding. This volume expansion, which is due to the retention of lattice vacancies by agglomeration into large polyhedral clusters (voids), may amount to ten percent or greater at goal fluences in some austenitic stainless steels. From a design standpoint, this is an undesirable situation, and it is necessary to obtain experimental confirmation that such excessive volume expansion will not occur in materials selected for core applications in the Fast Flux Test Facility, the prototypic LMFBR now under construction at the Hanford Engineering Development Laboratory (HEDL). The HEDL JEM-1000 1 MeV electron microscope is being used to provide an insight into trends of radiation damage accumulation in stainless steels, since it is possible to produce atom displacements at an accelerated rate with 1 MeV electrons, while the specimen is under continuous observation.

Porous Body Model Based Parametric Study for Sodium to Air Heat Exchanger Used in Fast Reactors

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
S. P. Pathak ◽  
V. A. Suresh Kumar ◽  
I. B. Noushad ◽  
K. K. Rajan ◽  
K. Velusamy ◽  
...  
Keyword(s):  
Porous Body ◽  
Removal Rate ◽  
Heat Removal ◽  
Test Facility ◽  
Outlet Temperature ◽  
Finned Tubes ◽  
Decay Heat ◽  
Body Model ◽  
Fast Breeder Reactors ◽  
Breeder Reactors

Sodium to air heat exchangers (AHX) with finned tubes is used in fast breeder reactors for decay heat removal. The aim of decay heat removal is to maintain the fuel, clad, coolant, and structural temperatures within safety limits. To investigate the thermal hydraulic features of AHX, a robust porous body based computational fluid dynamics (CFD) model has been developed and validated against the experimental data obtained from a model AHX of 2 MW capacity in Steam Generator Test Facility at the Indira Gandhi Centre for Atomic Research, Kalpakkam. In the present paper, the developed porous body model is used to study the sodium and air temperature distribution and the influence of various parameters that affect the heat removal rate and sodium outlet temperature in full-size AHX used in the fast breeder reactors. The parameters include mass flow rates and inlet temperatures of sodium and air. The focus of the study has been to identify conditions that can pose the risk of sodium freezing.

scholarly journals Radiation-induced segregation in austenitic stainless steels

1991 ◽  
Vol 49 ◽  
pp. 556-557
Author(s):  
E. A. Kenik ◽  
K. Hojou
Keyword(s):  
Stainless Steels ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Test Facility ◽  
X Ray ◽  
Analytical Electron ◽  
Radiation Induced ◽  
Analysis System ◽  
Property Changes ◽  
Composition Fluctuations

Radiation-induced segregation (RIS) is driven by fluxes of point defects to sinks. RIS can induce composition fluctuations in irradiated stainless steels, which can result in microstructural and property changes, including precipitation, austenite instability, strengthening, embrittlement, and irradiation-assisted sensitization and stress corrosion cracking. Analytical electron microscopy (AEM) provides a powerful technique to study such segregation. RIS in several irradiated stainless steels has been investigated. AEM was performed in a Philips EM400T/FEG equipped with an EDAX 9100/70 analysis system. The specimens were neutron irradiated to 15 displacements per atom (dpa) at 520 ° C in the Fast Flux Test Facility (FFTF) and were only mildly radioactive (<50/μCi = 1.85 MBq), thus permitting high spatial resolution X-ray microanalysis to be employed. Typical acquisitions were performed for 100 s in the STEM mode with <2-nm-diam probes containing >0.5 nA current. Subtraction of “in-hole” spectra from the measured spectra corrected for both the normal “in-hole” counts and those associated with the radioactivity of the specimen.

scholarly journals Application of Analytical Electron Microscopy to design of creep-resistant advanced austenitic stainless steels

1987 ◽  
Vol 45 ◽  
pp. 226-227
Author(s):  
P.J. Maziasz
Keyword(s):  
Electron Microscopy ◽  
Stainless Steels ◽  
Power Plants ◽  
Fine Particles ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
High Brightness ◽  
Aisi Type ◽  
Analytical Electron ◽  
Insight Into

Analytical electron microscopy (AEM) has been used for the last ten years to study precipitation produced in reactor-irradiated austenitic stainless steels, such as AISI type 316. These studies have provided the insight to design irradiation resistant steels based on control of precipitiation. More recently, similar insight into precipitation effects in steels allowed the design of advanced austenitics that also exhibit outstanding thermal creep resistance at 700°C. These steels have direct application for superheater/ reheater tubing materials that will withstand higher temperatures and stresses in advanced steam cycle fossil power plants.Fine particles (<10 nm in diam) on extraction replicas have been studied by AEM using a high brightness electron source to provide sufficient probe currents for reliable analyses. These studies allowed alloy compositional modifications to be selected that produced stable, fine precipitates for creep strength.

scholarly journals Hydrogen Embrittlement Mechanism in Fatigue Behaviour of Austenitic and Martensitic Stainless Steels

2018 ◽  
Vol 165 ◽  
pp. 22002
Author(s):  
Sven Brück ◽  
Volker Schippl ◽  
Hans-Jürgen Christ ◽  
Claus-Peter Fritzen
Keyword(s):  
Fatigue Crack ◽  
Hydrogen Embrittlement ◽  
Crack Growth ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Short Fatigue Crack ◽  
Crack Morphology ◽  
Insight Into

In the present study, the influence of hydrogen on the fatigue behaviour of the high strength martensitic stainless steel X3CrNiMo13-4 and the metastable austenitic stainless steels X2Crni19-11 with various nickel contents was examined in the low and high cycle fatigue regime. The focus of the investigations was the changes in the mechanisms of short crack propagation. The aim of the ongoing investigation is to determine and quantitatively describe the predominant processes of hydrogen embrittlement and their influence on the short fatigue crack morphology and crack growth rate. In addition, simulations were carried out on the short fatigue crack growth, in order to develop a detailed insight into the hydrogen embrittlement mechanisms relevant for cyclic loading conditions.

HVEM Radiation Damage Studies: Past, Present and Future

1980 ◽  
Vol 38 ◽  
pp. 22-25
Author(s):  
T.E. Mitchell ◽  
L.W. Hobbs
Keyword(s):  
Radiation Damage ◽  
Scientific Method ◽  
Defect Formation ◽  
Technological Problem ◽  
Extreme Caution ◽  
Secondary Defect ◽  
Damage Process ◽  
Fast Breeder Reactors ◽  
Breeder Reactors ◽  
Damage Processes

First let it be said that this article is not intended to be a comprehensive review of HVEM radiation damage studies. The reader will do much better to peruse the writings of Urban, Kiritani, Cosslett and others, or to scan the various HVEM symposium reports. Nor is this article intended to justify the use of HVEM to develop suitable materials for fast-breeder reactors, fusion reactors, ion implantation devices, nuclear waste disposal or any other technological problem where radiation damage is important. Rather, this article seeks to assess the role that HVEM has, can, and will display in understanding the fundamental aspects of radiation damage processes. The point to be made is that HVEM provides an excellent scientific method of investigating the primary displacement process, and, especially, secondary defect formation. However, although the electron damage process is much simpler than neutron or ion damage, HVEM damage observations still must be evaluated with extreme caution.

Strain-induced martensite effects on transgranular carbide precipitation in type 304 stainless steels

1991 ◽  
Vol 49 ◽  
pp. 604-605
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D. Matlock
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Deformation Twin ◽  
Austenitic Stainless Steels ◽  
Carbide Precipitation ◽  
Strain Induced Martensite ◽  
Type 304

Thermomechanically induced strain is a key variable producing accelerated carbide precipitation, sensitization and stress corrosion cracking in austenitic stainless steels (SS). Recent work has indicated that higher levels of strain (above 20%) also produce transgranular (TG) carbide precipitation and corrosion simultaneous with the grain boundary phenomenon in 316 SS. Transgranular precipitates were noted to form primarily on deformation twin-fault planes and their intersections in 316 SS.Briant has indicated that TG precipitation in 316 SS is significantly different from 304 SS due to the formation of strain-induced martensite on 304 SS, though an understanding of the role of martensite on the process has not been developed. This study is concerned with evaluating the effects of strain and strain-induced martensite on TG carbide precipitation in 304 SS. The study was performed on samples of a 0.051%C-304 SS deformed to 33% followed by heat treatment at 670°C for 1 h.

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