A Probabilistic Model for Degradation of the Engineered Barriers System in the Yucca Mountain Repository

2004 ◽  
Vol 824 ◽  
Author(s):  
Z. Qin ◽  
D.W. Shoesmith
Keyword(s):  
Probabilistic Model ◽  
Crevice Corrosion ◽  
Yucca Mountain ◽  
Waste Package ◽  
Alloy 22 ◽  
Hydrogen Induced Cracking ◽  
Engineered Barriers ◽  
Engineered Barrier ◽  
Titanium Grade ◽  
Conservative Behaviour

AbstractA probabilistic model to predict the lifetimes of the engineered barrier system proposed for the Yucca Mountain repository is described. The model assumes that the titanium Grade-7 drip shield will fail by hydrogen-induced cracking and the Alloy-22 waste package by a combination of passive and crevice corrosion. The model predicts that crevice corrosion of the waste package can be completely avoided ifthe drip shield deflects seepage drips for between 2000 (realistic behaviour) and 6000 years (conservative behaviour). Sensitivity calculations on the crevice corrosion model suggest that early waste package failure is extremely unlikely providing the drip shield performs its function for a minimum of ~ 300 years.

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.

The Influence of Environmental Conditions and Passive Film Properties on the MIC of Engineered Barriers in the Yucca Mountain Repository

2004 ◽  
Vol 824 ◽  
Author(s):  
A.C. Lloyd ◽  
R.J. Schuler ◽  
J.J. Noël ◽  
D.W. Shoesmith ◽  
F. King
Keyword(s):  
Microbial Activity ◽  
Yucca Mountain ◽  
Film Properties ◽  
Waste Package ◽  
Barrier Materials ◽  
Radiation Fields ◽  
Microbially Induced Corrosion ◽  
Alloy 22 ◽  
Engineered Barriers ◽  
Package Materials

AbstractA combination of gamma radiation fields, the absence of moisture, and the high temperatures on the drip shield (DS) and waste package (WP) should combine to suspend microbial activity on the DS/WP surfaces for many tens of thousands of years. This lack of microbial activity, coupled with the corrosion resistance of the titanium Grade7 (Ti-7 drip shield) and the Alloy-22 (waste package) materials make microbially induced corrosion (MIC) of these engineered barrier materials extremely unlikely.

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.

Evolution of Chemistry and Its Effects on the Corrosion of Engineered Barrier Materials

2006 ◽  
Vol 985 ◽  
Author(s):  
Darrell Dunn ◽  
Yi-Ming Pan ◽  
Xihua He ◽  
Lietai Yang ◽  
Roberto Pabalan
Keyword(s):  
Environmental Conditions ◽  
Environmental Influence ◽  
Near Field ◽  
Yucca Mountain ◽  
High Level Waste ◽  
Seepage Water ◽  
Waste Package ◽  
Barrier Materials ◽  
Engineered Barrier ◽  
High Level

ABSTRACTThe evolution of environmental conditions within the emplacement drifts of a potential high-level waste repository at Yucca Mountain, Nevada, may be influenced by several factors, including the temperature and relative humidity within the emplacement drifts and the composition of seepage water. The performance of the waste package and the drip shield may be affected by the evolution of the environmental conditions within the emplacement drifts. In this study, tests evaluated the evolution of environmental conditions on the waste package surfaces and in the surrounding host rock. The tests were designed to (i) simulate the conditions expected within the emplacement drifts; (ii) measure the changes in near-field chemistry; and (iii) determine environmental influence on the performance of the engineered barrier materials. Results of tests conducted in this study indicate the composition of salt deposits was consistent with the initial dilute water chemistry. Salts and possibly concentrated calcium chloride brines may be more aggressive than either neutral or alkaline brines.

Monte Carlo Simulations of the Degradation of the Engineered Barriers System in the Yucca Mountain Repository Using the EBSPA Code

2006 ◽  
Vol 985 ◽  
Author(s):  
Zack Qin ◽  
D. W. Shoesmith
Keyword(s):  
Monte Carlo ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
Case Scenario ◽  
Simulation Code ◽  
Worst Case ◽  
Hydrogen Induced Cracking ◽  
Waste Repository ◽  
Engineered Barriers ◽  
The Impact

AbstractBased on a probabilistic model previously proposed, a Monte Carlo simulation code (EBSPA) has been developed to predict the lifetime of the engineered barriers system within the Yucca Mountain nuclear waste repository. The degradation modes considered in the EBSPA are general passive corrosion and hydrogen-induced cracking for the drip shield; and general passive corrosion, crevice corrosion and stress corrosion cracking for the waste package. Two scenarios have been simulated using the EBSPA code: (a) a conservative scenario for the conditions thought likely to prevail in the repository, and (b) a worst-case scenario in which the impact of the degradation processes is overstated.

scholarly journals Anodic Polarization Behavior of Titanium Grade 7 in Dust Deliquescence Salt Environments

2007 ◽  
Author(s):  
Kenneth J. Evans ◽  
Raul B. Rebak
Keyword(s):  
Titanium Alloy ◽  
Crevice Corrosion ◽  
Anodic Polarization ◽  
High Strength ◽  
Yucca Mountain ◽  
Localized Corrosion ◽  
Corrosion Performance ◽  
Corrosion Resistant ◽  
Reducing Conditions ◽  
Titanium Grade

It is planned to use the highly corrosion resistant titanium grade 7 (Ti Gr 7) and a high strength titanium alloy (Ti Gr 29) to fabricate the drip shield for the Yucca Mountain repository. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance, mainly under reducing conditions. It was important to determine the corrosion behavior of Ti Gr 7 in concentrated brines at temperatures higher than 100°C, which may represent the behavior of dust deliquescence solutions. Tests were performed in concentrated NaCl + KCl solutions containing also nitrates and fluorides. Results show that Ti Gr 7 was highly resistant to general and localized corrosion. Some specimens were polarized to potentials higher than 4 volts. None of the tightly creviced specimens suffered crevice corrosion. The presence of fluoride promoted localized corrosion around the edges of the crevice former.

Efficiency of inhibitors for chloride-induced crevice corrosion of Alloy 22

2012 ◽  
Vol 1475 ◽  
Author(s):  
Mauricio Rincón Ortíz ◽  
Martín A. Rodríguez ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
High Temperatures ◽  
Crevice Corrosion ◽  
Carbonic Acid ◽  
Repassivation Potential ◽  
Alloy 22 ◽  
Engineered Barriers

ABSTRACTAlloy 22 is considered as a candidate for engineered barriers of nuclear repositories. Chloride is the only species present in groundwater that is able to promote crevice corrosion, if severe conditions such as high temperatures and a tight crevice are present. Other species present in groundwater have been shown to be inhibitors or non-detrimental species. The objective of this work was to evaluate the efficiency of different species potentially found in groundwaters as possible inhibitors of crevice corrosion of Alloy 22. The crevice corrosion repassivation potential of Alloy 22 was determined in chloride plus inhibitor solutions at 90ºC. The species tested as inhibitors were nitrate, sulfate, carbonate, bicarbonate, chromate, molybdate and tungstate. Nitrate was the most efficient among tested inhibitors. The carbonate was the only species of the carbonate / bicarbonate / carbonic acid equilibrium able to inhibit the chloride-induced crevice corrosion of Alloy 22. Sulfate, chromate and molybdate were moderately good inhibitors.

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.

Crevice Corrosion Resistance of Alloy 22 in High-Nitrate, High-Temperature Dust Deliquescence Environments

CORROSION ◽  
2008 ◽  
Vol 64 (7) ◽  
pp. 613-623 ◽  
Author(s):  
T. Lian ◽  
G. E. Gdowski ◽  
P. D. Hailey ◽  
R. B. Rebak
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Crevice Corrosion ◽  
Alloy 22
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