Radiation-Induced Segregation in 316 and 304 Stainless Steels Irradiated at Low Dose Rate

2000 ◽  
Vol 650 ◽  
Author(s):  
T. R. Allen ◽  
J. I. Cole ◽  
J. Ohta ◽  
K. Dohi ◽  
H. Kusanagi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Dose Rate ◽  
Stainless Steels ◽  
Low Dose ◽  
Bulk Composition ◽  
304 Stainless Steel ◽  
316 Stainless Steel ◽  
Low Dose Rate ◽  
Radiation Induced

ABSTRACTAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effects of long-term irradiation on mechanical properties and microstructure. In this work, the effect of low dose rate irradiation (10−7 to 10−8 dpa/s) on grain boundary composition in 316 and 304 stainless steels was analyzed. Samples were taken from surveillance specimens and subassemblies irradiated in the reflector region of EBR-II at temperatures from 371-390°C to maximum doses of 30 dpa. The effects of dose, dose rate, and bulk composition on radiation- induced segregation are analyzed. In 316 stainless steel, changes in grain boundary chromium and nickel concentrations occur faster than changes in iron and molybdenum concentrations. In 304 stainless steel, decreasing the dose rate increases the amount of grain boundary segregation. For a dose of 20 dpa, chromium depletion and nickel enrichment are greater in 304 stainless steel than in 316 stainless steel, the difference most likely due to dose rate. In both 304 and 316 stainless steels, the presence of a grain boundary precipitate significantly changes the composition of the adjacent grain boundary.

The Effect of Low Dose Rate Radiation on the Microchemistry of 304 Stainless Steel

1998 ◽  
Vol 540 ◽  
Author(s):  
T. R. Allen ◽  
J. I. Cole ◽  
E. A. Kenik
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Dose Rate ◽  
Low Dose ◽  
304 Stainless Steel ◽  
Pressurized Water ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Radiation Induced ◽  
Water Reactors

AbstractAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effect of long term, low dose rate irradiation. In this work, the effect of low dose rate (10 to 10−9 dpa/s) irradiation on grain boundary and void surface chemistry is analyzed. These dose rates are comparable to those in light water reactor structural components. The components were irradiated at 375-379°C, temperatures near the highest temperatures experienced in pressurized water reactors. Radiation-induced segregation (RIS) was measured on samples taken from 304 stainless steel hex ducts irradiated to doses between 10 and 12 dpa. Radiation-induced segregation is shown to vary with dose rate, with measured grain boundary chromium concentrations reaching as low as 5 at. % and nickel concentrations reaching as high as 33 at. %. For some radiation conditions, significant grain boundary precipitation occurs, possibly leaving components susceptible to environmental attack.

scholarly journals The Effect of Low Dose-Rate Irradiation on the Microstructure of 304 Stainless Steel

1998 ◽  
Vol 540 ◽  
Author(s):  
J. I. Cole ◽  
T. R. Allen
Keyword(s):  
Stainless Steel ◽  
Dose Rate ◽  
Low Dose ◽  
Rate Effect ◽  
304 Stainless Steel ◽  
Microstructural Development ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Radiation Induced ◽  
Dose Rate Effect

AbstractChanges in mechanical and corrosion properties caused by the development of radiation-induced microstructures have relevance to the aging and lifetime extension of light water reactors (LWR‘s). However, much of the current data related to microstructural development in irradiated metals are generated from studies carried out at much higher dose-rates than encountered in LWR‘s. An opportunity exists to study the influence of low dose-rate irradiation on microstructural development for a variety of structural and surveillance materials extracted from the experimental breeder reactor EBR-lI. In this study, irradiated 304 stainless steel hexagonal “hex” duct material is examined in order to compare microstructures in the dose-rate range of 10−7 - 10−9 dpa/sec. The samples, taken from the reflector locations in EBR-II, experienced a total dose between 10 and 12 dpa at a temperature of ∼375 °C. Transmission electron microscopy (TEM) analysis reveals that there is a moderate dose-rate effect on microstructural development for samples irradiated in the range of 2 × 10−8 to 4 × 10−8. dpa/sec, however a substantial dose-rate effect exists between dose-rates of 2 × 10−8 and 1 × 10−9 dpa/sec Results detail the development of the microstructure in terms of radiation-induced cavities, dislocations, and precipitates.

scholarly journals The Effect of Bulk Composition on Swelling and Radiation-Induced Segregation in Austenitic Alloys

2000 ◽  
Vol 650 ◽  
Author(s):  
T. R. Allen ◽  
J. I. Cole ◽  
N. L. Dietz ◽  
Y. Wang ◽  
G. S. Was ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Bulk Composition ◽  
High Energy ◽  
Lattice Parameter ◽  
304 Stainless Steel ◽  
Microstructural Development ◽  
Nickel Concentration ◽  
Void Swelling ◽  
Radiation Induced

ABSTRACTChanges in bulk composition are known to affect both radiation-induced segregation and microstructural development, including void swelling in austenitic stainless steel. In this work, three alloys (designations corresponding to wt%) have been studied: Fe-18Cr-8Ni alloy (bulk composition corresponding to 304 stainless steel), Fe-18Cr-40Ni (bulk composition corresponding to 330 stainless steel), and Fe-16Cr-13Ni (bulk composition corresponding to 316 stainless steel). Following irradiation with high-energy protons, the change in hardness and microstructure (void size distribution and grain boundary composition) due to irradiation was investigated. Increasing the bulk nickel concentration decreases void swelling, increases matrix hardening, and increases grain boundary chromium depletion and nickel enrichment. The analysis shows that decreases in lattice parameter and shear modulus due to radiation- induced segregation (RIS) correlate with decreased void swelling and a decreased susceptibility to irradiation assisted stress corrosion cracking (IASCC). Traditional thinking on IASCC assumed RIS was a contributing factor to cracking. It may, however, be that properly controlled RIS can be used to mitigating cracking.

scholarly journals Mechanical Properties of 20% Cold-Worked 316 Stainless Steel Irradiated at Low Dose Rate

2002 ◽  
Author(s):  
Todd R. Allen ◽  
Hanchung Tsai ◽  
James I. Cole ◽  
Joji Ohta ◽  
Kenji Dohi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Dose Rate ◽  
Work Hardening ◽  
Low Dose ◽  
Dose Range ◽  
Total Elongation ◽  
316 Stainless Steel ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Cold Worked

To assess the effects of long-term, low-dose-rate neutron exposure on mechanical strength and ductility, tensile properties were measured on irradiated 20% cold-worked Type 316 stainless steel. Samples were prepared from reactor core components retrieved from the EBR-II reactor following final shutdown. Sample locations were chosen to cover a dose range of 1–47 dpa at temperatures from 371–385°C and dose rates from 0.8–2.8 × 10−7 dpa/s. These dose rates are about one order of magnitude lower than those of typical EBR-II in-core experiments. Irradiation cuased hardening, with the yield strength (YS) following approximately the same trend as the ultimate tensile strength (UTS). At higher dose, the difference between the UTS and YS decreases, suggesting the work-hardening capability of the material is decreasing with increasing dose. Both the uniform elongation and total elongation decrease up to the largest dose. Unlike the strength data, the ductility reduction showed no signs of saturating at 20 dpa. While the material retained respectable ductility at 20 dpa, the uniform and total elongation decreased to <1 and <3%, respectively, at 47 dpa. Fracture in the 30 dpa specimen is mainly ductile but with local regions of mixed-mode failure consisting of dimples and microvoids. The fracture surface of the higher-exposure 47 dpa specimen displays significantly more brittle features. The fracture consists of maily small facets and slip bands that suggest channel fracture. The hardening in these low-dose-rate components differs from that measured in test samples irradiated in EBR-II at higher-dose-rate. The material irradiated at higher dose rate loses work hardening capactiy faster than the lower dose rate material, although this effect could be due to compositional differences.

scholarly journals Properties of 20% Cold-Worked 316 Stainless Steel Irradiated at Low Dose Rate

2004 ◽  
Vol 1 (9) ◽  
pp. 11252 ◽  
Author(s):  
TR Allen ◽  
H Tsai ◽  
JI Cole ◽  
J Ohta ◽  
K Dohi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Dose Rate ◽  
Low Dose ◽  
316 Stainless Steel ◽  
Low Dose Rate ◽  
Cold Worked

scholarly journals Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
K. A. Habib ◽  
M. S. Damra ◽  
J. J. Saura ◽  
I. Cervera ◽  
J. Bellés
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Breakdown Point ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Protective Oxide ◽  
Aisi 304 ◽  
316 Stainless Steel ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3scale totally disappeared and exclusively Fe2O3was formed, in AISI 316 stainless steel some Cr2O3persisted and Fe3O4was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.

The Progress of ICRP New Recommendations

2010 ◽  
Author(s):  
Aiguo Shang ◽  
Changjie Lu ◽  
Jin Qin
Keyword(s):  
Comparative Analysis ◽  
Dose Rate ◽  
Low Dose ◽  
System Analysis ◽  
Weighting Factor ◽  
Radiological Protection ◽  
Stochastic Effects ◽  
Risk Coefficient ◽  
Low Dose Rate ◽  
Radiation Induced

In order to probe into the usage of the Recommendations of the ICRP, through comparative analysis of low-dose-rate radiation-induced stochastic effects of a nominal risk coefficient, radiation weighting factor, tissue weighting factor as well as the the implementation of changes on the radiological protection system, analysis of the international on Radiological Protection fundamental recommendations of the Committee on the latest changes in radiological protection and development, and that these changes can not affect the existing radiation protection of China’s basic policy and standards.

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