Localized Corrosion Susceptibility of Alloy 22 as a Waste Package Container Material

2002 ◽  
Vol 713 ◽  
Author(s):  
Gustavo A. Cragnolino ◽  
Darrell S. Dunn ◽  
Yi-Ming Pan
Keyword(s):  
Chloride Concentration ◽  
Department Of Energy ◽  
Localized Corrosion ◽  
Waste Package ◽  
Alloy 22 ◽  
Microstructural Effects ◽  
Anionic Species ◽  
Corrosion Susceptibility ◽  
High Level ◽  
Increasing Temperature

ABSTRACTAlloy 22 is the material preferred by the U.S. Department of Energy for the waste package outer container for geological disposal of high-level radioactive waste at the proposed repository site in Yucca Mountain, Nevada. The susceptibility of Alloy 22 to localized corrosion is an important consideration in the evaluation of the waste package behavior and the assessment of the overall performance of the proposed repository. The effects of the environment chemical composition and temperature on localized corrosion susceptibility were examined by measuring the repassivation potential for crevice corrosion in chloride-containing solutions at temperatures ranging from 80 to 150°C. The effect of potentially inhibiting anionic species, such as nitrate, was also determined. In addition to the mill annealed material, tests were conducted on both welded and thermally aged material to evaluate microstructural effects related to container fabrication processes. The resistance of Alloy 22 to localized corrosion decreased with increasing temperature and chloride concentration. Welding and thermal aging also decreased the localized corrosion resistance of the alloy.

Effect of Inhibiting Oxyanions on the Localized Corrosion Susceptibility of Waste Package Container Materials

2004 ◽  
Vol 824 ◽  
Author(s):  
D.S. Dunn ◽  
L. Yang ◽  
C. Wu ◽  
G.A. Cragnolino
Keyword(s):  
Radioactive Waste ◽  
Crevice Corrosion ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Waste Package ◽  
High Level Radioactive Waste ◽  
License Application ◽  
Alloy 22 ◽  
Corrosion Susceptibility ◽  
High Level

AbstractThe DOE is currently preparing a license application for the permanent disposal of high level radioactive waste at Yucca Mountain, Nevada. The proposed design of waste packages for the disposal of high level radioactive waste consists of an outer container made of Alloy 22, a corrosionresistant Ni-Cr-Mo-W alloy, surrounding an inner container made of Type 316 nuclear grade stainless steel. Under conditions where passivity is maintained, the uniform corrosion rate of Alloy 22 is slow and long waste package lifetimes are projected. However, the initiation of localized corrosion such as pitting or crevice corrosion may decrease waste package lifetimes. In this study the crevice corrosion susceptibility of Alloy22 was determined in chloride solutions with additions of oxyanions that are present in the groundwater at the potential repository site. When present in sufficient concentrations relative to chloride, nitrate, carbonate, bicarbonate, and sulfate inhibited pitting and crevice corrosion of Alloy 22.

Evaluation of Corrosion Processes Affecting the Performance of Alloy 22 as a Proposed Waste Package Material

2003 ◽  
Vol 807 ◽  
Author(s):  
Gustavo A. Cragnolino ◽  
Darrell S. Dunn ◽  
Yi-Ming Pan
Keyword(s):  
Stress Corrosion ◽  
Compact Tension ◽  
Department Of Energy ◽  
Localized Corrosion ◽  
Chloride Solutions ◽  
Waste Package ◽  
Alloy 22 ◽  
High Level ◽  
Long Term Performance ◽  
Term Performance

ABSTRACTThis paper presents recent work on evaluating localized corrosion and stress corrosion cracking, two corrosion processes that are important to the long-term performance of Alloy 22 (58Ni-22Cr-13Mo-3W-4Fe). This alloy is the material preferred by the U.S. Department of Energy (DOE) for the outer container of the waste package to be used in the proposed high-level radioactive waste repository at Yucca Mountain, Nevada. It was found that both welded and thermally aged materials are more susceptible to localized corrosion in chloride solutions at temperatures above 60 EC than the mill-annealed material. This observation suggests that welding and certain post-welding operations may decrease the estimated life of the waste packages. However, no stress corrosion crack growth was observed in concentrated chloride solutions and simulated, concentrated groundwater at 95 EC when precracked compact tension specimens were tested under both constant and cycling loading.

Corrosion Processes Affecting the Performance of Alloy 22 as a High-Level Radioactive Waste Container Material

2000 ◽  
Vol 663 ◽  
Author(s):  
G.A. Cragnolino ◽  
D.S. Dunn ◽  
Y.-M. Pan ◽  
O. Pensado
Keyword(s):  
Radioactive Waste ◽  
Electrochemical Techniques ◽  
Department Of Energy ◽  
Localized Corrosion ◽  
Dissolution Behavior ◽  
Uniform Corrosion ◽  
High Level Radioactive Waste ◽  
Waste Container ◽  
Alloy 22 ◽  
High Level

ABSTRACTAlloy 22 is the material preferred by the U.S. Department of Energy for the waste package outer container for geological disposal of high-level radioactive waste at the proposed site in Yucca Mountain, Nevada. Alloy 22 is considered to be extremely resistant to various modes of aqueous corrosion over broad ranges of temperature, pH, and concentration of anionic and oxidizing species. Uniform corrosion under passive dissolution conditions, localized corrosion in the form of crevice corrosion, and stress corrosion cracking are discussed on the basis of experimental results obtained with mill annealed, thermally treated, and welded specimens using electrochemical techniques. The approach developed for long-term performance prediction, including the use of empirically derived parameters for assessing localized corrosion and the modeling of the passive dissolution behavior, is described.

Determination of Crevice Corrosion Susceptibility of Alloy 22 Using Different Electrochemical Techniques

2010 ◽  
Vol 1265 ◽  
Author(s):  
Mauricio Rincon Ortiz ◽  
Martín A. Rodríguez ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Electrochemical Techniques ◽  
Localized Corrosion ◽  
Repassivation Potential ◽  
Alloy 22 ◽  
Cyclic Potentiodynamic Polarization ◽  
Corrosion Susceptibility ◽  
High Level Nuclear Waste ◽  
High Level

AbstractAlloy 22 belongs to the Ni-Cr-Mo family and it is highly resistant to general and localized corrosion. It may suffer crevice corrosion in aggressive environmental conditions. This alloy has been considered as a corrosion-resistant barrier for high-level nuclear waste containers. It is assumed that localized corrosion may occurs when the corrosion potential (ECORR) is equal or higher than the crevice corrosion repassivation potential (ER,CREV). The latter is measured by means of different electrochemical techniques using artificially creviced specimens. These techniques include cyclic potentiodynamic polarization (CPP) curves, Tsujikawa-Hisamatsu electrochemical (THE) method or other non-standard methods, such as the PD-GS-PD technique.The aim of the present work was to determine reliable critical or protection potentials for crevice corrosion of Alloy 22 in pure chloride solutions at 90°C. Conservative methodologies (which include extended potentiostatic steps) were applied for determining protection potentials below which crevice corrosion cannot initiate and propagate. Results from PD-GS-PD technique were compared with those from these methodologies in order to assess their reliability. Results from the CPP and the THE methods were also considered for comparison. The repassivation potential resulting from the PD-GS-PD technique was conservative and reproducible, and it did not depend on the amount of previous crevice corrosion propagation.

Modeling Corrosion Processes for Alloy 22 Waste Packages

2006 ◽  
Vol 932 ◽  
Author(s):  
D.S. Dunn ◽  
O. Pensado ◽  
Y.-M. Pan ◽  
L.T. Yang ◽  
X. He
Keyword(s):  
Localized Corrosion ◽  
Anodic Current Density ◽  
Uniform Corrosion ◽  
Aqueous Corrosion ◽  
Package Design ◽  
Waste Package ◽  
Low Concentrations ◽  
Alloy 22 ◽  
Maximum Penetration ◽  
High Level

ABSTRACTThe proposed waste package design for the disposal of high-level radioactive waste at the potential repository at Yucca Mountain, Nevada, consists of an outer container made of Alloy 22, a corrosion resistant Ni-Cr-Mo-W alloy, surrounding an inner container made of Type 316 nuclear grade stainless steel. Models to assess the influence of waste package degradation modes on the overall system performanceconsider uniform and localized corrosion processes. Based on measurements of passive anodic current density, the uniform aqueous corrosion rate of Alloy 22 is estimated to be slow, and long waste package lifetimes are projected in the absence of conditions that promote accelerated degradation processes. The initiation of localized corrosion is possible in chloride-containing waters with low concentrations of inhibiting oxyanions such as nitrate. Although propagation rates for localized corrosion are typically orders of magnitude greater than the passive uniform corrosion rates, the maximum penetration depth of localized attack may be limited to depths significantly less than the container thickness as a result of stifling andarrest of localized corrosion.

Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions: Part 1—Mill-Annealed Condition

CORROSION ◽  
2005 ◽  
Vol 61 (11) ◽  
pp. 1078-1085 ◽  
Author(s):  
D. S. Dunn ◽  
Y-M. Pan ◽  
L. Yang ◽  
G. A. Cragnolino
Keyword(s):  
Localized Corrosion ◽  
Annealed Condition ◽  
Chloride Solutions ◽  
Alloy 22 ◽  
Corrosion Susceptibility

scholarly journals Development of Integrated Mechanistically-Based Degradation-Mode Models for Performance Assessment of High-Level Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
J. C. Farmer ◽  
R. D. Mccright ◽  
J. C. Estill ◽  
S. R. Gordon
Keyword(s):  
Stainless Steel ◽  
Crevice Corrosion ◽  
Chloride Concentration ◽  
Yucca Mountain ◽  
304 Stainless Steel ◽  
High Level Waste ◽  
Mechanistic Models ◽  
Alloy 22 ◽  
High Level ◽  
Impurity Elements

AbstractAlloy 22 [UNS N06022] is now being considered for construction of high level waste containers to be emplaced at Yucca Mountain and elsewhere. In essence, this alloy is 20.0–22.5% Cr, 12.5–14.5% Mo, 2.0–6.0% Fe, 2.5–3.5% W, with the balance being Ni. Other impurity elements include P, Si, S, Mn, Co and V. Cobalt may be present at a maximum concentration of 2.5%. Detailed mechanistic models have been developed to account for the corrosion of Alloy 22 surfaces in crevices that will inevitably form. Such occluded areas experience substantial decreases in pH, with corresponding elevations in chloride concentration. Experimental work has been undertaken to validate the crevice corrosion model, including parallel studies with 304 stainless steel.

Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions: Part 2—Effect of Fabrication Processes

CORROSION ◽  
2006 ◽  
Vol 62 (1) ◽  
pp. 3-12 ◽  
Author(s):  
D. S. Dunn ◽  
Y-M. Pan ◽  
L. Yang ◽  
G. A. Cragnolino
Keyword(s):  
Localized Corrosion ◽  
Chloride Solutions ◽  
Alloy 22 ◽  
Corrosion Susceptibility

Evaluation of The Long-Term Stability of Passive Corrosion On The Drip Shield and Waste Package Under Yucca Mountain Conditions

2002 ◽  
Vol 713 ◽  
Author(s):  
D.W. Shoesmith
Keyword(s):  
Environmental Conditions ◽  
Yucca Mountain ◽  
Localized Corrosion ◽  
Waste Package ◽  
Long Term Stability ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Engineered Barriers ◽  
Titanium Grade

ABSTRACTPossible long term corrosion scenarios for the engineered barriers proposed for the Yucca Mountain (Nevada, USA) repository are reviewed.Introduction:The materials proposed for the engineered barriers in the Yucca Mountain repository (Nevada, USA), Alloy-22 for the waste packages (WP) and titanium Grade-7 (Ti-7) for the drip shield (DS), appear unlikely to suffer localized corrosion (LC) and have very low passive corrosion (PC) rates (1–3). Since environmental conditions will become more benign as temperatures decline and aqueous environments become more dilute (4), this leads to the prediction of exceedingly long waste package lifetimes. In this review, possible corrosion scenarios are discussed in the context of the anticipated evolution in the repository environment.

Methodologies for Predicting the Performance of Ni-Cr-Mo Alloys Proposed for High Level Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
D. S. Dunn ◽  
G. A. Cragnolino ◽  
N. Sridhar
Keyword(s):  
Nuclear Waste ◽  
Current Density ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Aqueous Corrosion ◽  
Wide Range ◽  
Anionic Species ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Passive Current

AbstractFor the geologic disposal of the high level nuclear waste (HLW), aqueous corrosion is considered to be the most important factor in the long-term performance of containers, which are the main components of the engineered barrier subsystem. Container life, in turn, is important to the overall performance of the repository system. The proposed container designs and materials have evolved to include multiple barriers and highly corrosion resistant Ni-Cr-Mo alloys, such as Alloys 625 and C-22. Calculations of container life require knowledge of the initiation time and growth rate of localized corrosion. In the absence of localized corrosion, the rate of general or uniform dissolution, given by the passive current density of these materials, is needed. The onset of localized corrosion may be predicted by using the repassivation and corrosion potentials of the candidate container materials in the range of expected repository environments. In initial corrosion tests, chloride was identified as the most detrimental anionic species to the performance of Ni-Cr-Mo alloys. Repassivation potential measurements for Alloys 825, 625, and C-22, conducted over a wide range of chloride concentrations and temperatures, are reported. In addition, steady state passive current density, which will determine the container lifetime in the absence of localized corrosion, was measured for Alloy C-22 under various environmental conditions.

Sign in / Sign up

Export Citation Format

Share Document