scholarly journals Characterization of the Resistance of Alloy 22 to Stress Corrosion Cracking

2002 ◽  
Author(s):  
Kenneth J. King ◽  
John C. Estill ◽  
Rau´l B. Rebak
Keyword(s):  
Slow Strain Rate Test ◽  
Environmentally Assisted Cracking ◽  
Waste Container ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Current Design ◽  
Rate Test ◽  
High Level Nuclear Waste ◽  
High Level

In its current design, the high-level nuclear waste container includes an external layer of Alloy 22 (Ni-22Cr-13Mo-3W-3Fe). Since the containers may be exposed to multi-ionic aqueous environments over their lifetime, a potential degradation mode of the outer layer could be environmentally assisted cracking (EAC). The objective of the current research is to characterize the effect of applied potential and temperature on the susceptibility of Alloy 22 to EAC in simulated concentrated water (SCW) using the slow strain rate test (SSRT). Results show that Alloy 22 may suffer EAC at applied potentials approximately 400 mV more anodic than the corrosion potential (Ecorr).

scholarly journals Passive Corrosion Behavior of Alloy 22 in Multi-Ionic Aqueous Environments

2002 ◽  
Author(s):  
Tiangan Lian ◽  
John C. Estill ◽  
Gary A. Hust ◽  
Dave V. Fix ◽  
Raul B. Rebak
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
Yucca Mountain ◽  
Corrosion Studies ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Geological Repository ◽  
High Level Nuclear Waste ◽  
Alternative Techniques ◽  
High Level

As part of proposed geological repository at Yucca Mountain, Nevada, Alloy 22 (Ni-22Cr-13Mo-3W-3Fe) has been chosen as the candidate material for a 2-cm outer layer on the high-level nuclear waste containers. During the repository period, the container materials will be subject to corrosion due to their exposure to multi-ionic aqueous environments. Although Alloy 22 has demonstrated excellent corrosion resistance, accumulation of a small, yearly corrosion rate for 10,000 or more years can be significant. When subjected to the conventional weight loss technique for corrosion studies, Alloy 22 requires many years to demonstrate a detectible weight loss. The goal of this research is to seek alternative techniques to determine a reasonably confident corrosion rate. This paper will discuss the latest experimental results using the potentiostatic technique to determine passive dissolution rates.

The Use of Repassivation Potential in Predicting The Performance of High-Level Nuclear Waste Container Materials

1994 ◽  
Vol 353 ◽  
Author(s):  
Narasi Sridhar ◽  
Darrell Dunn ◽  
Gustavo Cragnolino
Keyword(s):  
Field Tests ◽  
Localized Corrosion ◽  
High Level Waste ◽  
Repassivation Potential ◽  
Waste Container ◽  
Highly Sensitive ◽  
Plant Equipment ◽  
Robust Parameter ◽  
High Level Nuclear Waste ◽  
High Level

AbstractLocalized corrosion in aqueous environments forms an important bounding condition for the performance assessment of high-level waste (HLW) container materials. A predictive methodology using repassivation potential is examined in this paper. It is shown, based on long-term (continuing for over 11 months) testing of alloy 825, that repassivation potential of deep pits or crevices is a conservative and robust parameter for the prediction of localized corrosion. In contrast, initiation potentials measured by short-term tests are non-conservative and highly sensitive to several surface and environmental factors. Corrosion data from various field tests and plant equipment performance are analyzed in terms of the applicability of repassivation potential. The applicability of repassivation potential for predicting the occurrence of stress corrosion cracking (SCC) and intergranular corrosion in chloride containing environments is also examined.

Corrosion of Ticode-12 in A Simulated Waste Isolation Pilot Project (Wipp) Brine

1982 ◽  
Vol 15 ◽  
Author(s):  
T. M. Ahn ◽  
B. S. Lee ◽  
J. Woodward ◽  
R. L. Sabatini ◽  
P. Soo
Keyword(s):  
Corrosion Rate ◽  
Pilot Project ◽  
Intensity Level ◽  
Uniform Corrosion ◽  
Static Loads ◽  
Waste Container ◽  
Simulated Waste ◽  
High Level Nuclear Waste ◽  
Acidic Conditions ◽  
High Level

ABSTRACTThe corrosion behavior of TiCode-12 (Ti-0.3 Mo-0.8 Ni) high level nuclear waste container alloy has been studied for a simulated WIPP brine at a temperature of 150°C or below. Crevice corrosion was identified as a potentially important failure mode for this material. Within a mechanical crevice, a thick oxide film was found and shown to be the rutile form of TiO2, with a trace of lower oxide also present. Acidic conditions were found to cause a breakdown of the passive oxide layer. Solution aeration and increased acidity accelerate the corrosion rate. In hydrogen embrittlement studies, it was found that hydrogen causes a significant decrease in the apparent stress intensity level in fracture mechanics samples. Hydride formation is thought to be responsible for crack initiation. Stress corrosion cracking under static loads was not observed. Attention has also been given to methods for extrapolating short term uniform corrosion rate data to extended times.

Environmental Effects on Localized Corrosion of a High-Level Nuclear Waste Container Material

1990 ◽  
Vol 212 ◽  
Author(s):  
N. Sridhar ◽  
G. Cragnolino ◽  
W. Machowski
Keyword(s):  
Localized Corrosion ◽  
A Value ◽  
Waste Container ◽  
Electrochemical Parameters ◽  
Cyclic Potentiodynamic Polarization ◽  
High Level Nuclear Waste ◽  
Full Factorial Experimental Design ◽  
High Level ◽  
Full Factorial ◽  
High Chloride

ABSTRACTThe effect of environmental variables on the localized corrosion behavior of alloy 825 is examined in this paper. Cyclic, potentiodynamic polarization tests based on a two-level, full factorial experimental design were conducted. An index incorporating both the visual and scanning electron microscope examinations of localized corrosion and the electrochemical parameters was used for the statistical analysis. The analysis showed that chloride is the single most important promoter of localized corrosion, while nitrate was the single most important inhibitor. Fluoride was a weak inhibitor, especially at low chloride levels. Sulfate was a weak promoter, especially at high chloride levels. Temperature did not have a significant effect within the chloride levels examined. Separate experiments indicated that silicon, added as metasilicate, did not have any significant effect on localized corrosion. The adverse effect of chloride was observed at concentrations as low as 100 ppm. Addition of H2O2 increased the corrosion potential of alloy 825 to a value above the repassivation potential observed in the 300 ppm chloride solution.

Characterization of the Corrosion Behavior of Alloy 22 after Five Years Immersion in Multi-ionic Solutions

2002 ◽  
Vol 757 ◽  
Author(s):  
Lana L. Wong ◽  
David V. Fix ◽  
John C. Estill ◽  
R. Daniel McCright ◽  
Raúl B. Rebak
Keyword(s):  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Electrolyte Solutions ◽  
Underground Water ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Uniform Corrosion ◽  
Waste Container ◽  
Alloy 22

ABSTRACTAlloy 22 (N06022) is the candidate material for the corrosion resistant, outer barrier of the nuclear waste container. Two of the potential corrosion degradation modes of the container are uniform corrosion and localized corrosion. A testing program is under way at the Lawrence Livermore National Laboratory to determine the susceptibility of Alloy 22 to these two forms of corrosion using immersion tests. Metallic coupons are being exposed to several electrolyte solutions simulating concentrated underground water from pH 3 to 10 at 60°C and 90°C. This paper describes the results obtained after more than a five-year exposure of 122 specimens to the testing electrolyte solutions. Results show little general corrosion and the absence of localized corrosion. The maximum general corrosion rate was 23 nm/yr.

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