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.

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.

scholarly journals The Proposed Yucca Mountain Repository from a Corrosion Perspective

2006 ◽  
Vol 932 ◽  
Author(s):  
Joe H. Payer
Keyword(s):  
Corrosion Resistance ◽  
Nuclear Waste ◽  
Yucca Mountain ◽  
Department Of Energy ◽  
Process Models ◽  
Localized Corrosion ◽  
Waste Package ◽  
Advanced Technologies ◽  
The U.S

ABSTRACTIn this paper, the proposed Yucca Mountain Repository is viewed from a corrosion perspective. A major component of the long-term strategy for safe disposal of nuclear waste at the Yucca Mountain Repository is first to completely isolate the radionuclides in the waste packages for long times and to greatly retard the egress and transport of radionuclides from penetrated packages. Therefore, long-lived waste packages are important. The corrosion resistance of the waste package outer canister is reviewed, and a framework for the analysis of localized corrosion processes is presented. An overview is presented of the Materials Performance targeted thrust of the U.S. Department of Energy/Office of Civilian Radioactive Waste Management's Office of Science and Technology and International. The thrust program strives for increased scientific understanding, enhanced process models and advanced technologies for corrosion control.

scholarly journals Long-Term Immersion Testing of Alloy 22 and Titanium Grade 7 Double U-Bend Specimens

2007 ◽  
Author(s):  
Kenneth J. Evans ◽  
Marshall L. Stuart ◽  
Phillip D. Hailey ◽  
Raul B. Rebak
Keyword(s):  
Residual Stress ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Saturated Water ◽  
Environmentally Assisted Cracking ◽  
Alloy 22 ◽  
Immersion Testing ◽  
Titanium Grade ◽  
Scanning Electron

Double U-bend specimens of Alloy 22 (N06022) and Titanium Grade 7 (R52400) were exposed to a naturally aerated concentrated Basic Saturated Water (BSW) electrolyte at 105°C for over six years. Different type of discoloration of the Ti Gr 7 and Alloy 22 specimens was observed. General Corrosion was minimal and not distinguishable under a scanning electron microscope. None of the tested specimens suffered environmentally assisted cracking (EAC) or localized corrosion under the tested conditions. The specimens retained their residual stress after the long environmental exposure.

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 Evaluation of the Corrosivity of Dust Deposited on Waste Packages at Yucca Mountain, Nevada

2006 ◽  
Vol 932 ◽  
Author(s):  
Charles Bryan ◽  
Russell Jarek ◽  
Thomas Wolery ◽  
David Shields ◽  
Mark Sutton ◽  
...  
Keyword(s):  
Corrosion Product ◽  
Experimental Studies ◽  
Yucca Mountain ◽  
Localized Corrosion ◽  
Small Droplet ◽  
Waste Package ◽  
Physical Isolation ◽  
Salt Minerals ◽  
Dry Out ◽  
Diffusive Gradients

ABSTRACTPotentially corrosive brines can form during post-closure by deliquescence of salt minerals in dust deposited on the surface of waste packages at Yucca Mountain during operations and the pre-closure ventilation period. Although thermodynamic modeling and experimental studies of brine deliquescence indicates that brines are likely to form, they will be nitrate-rich and noncorrosive. Processes that modify the brines following deliquescence are beneficial with respect to inhibition of corrosion. For example, acid degassing (HCl, HNO3) could dry out brines, but kinetic limitations are likely to limit the effect to increasing their passivity by raising the pH and increasing the NO3/Cl ratio.Predicted dust quantities and maximum brine volumes on the waste package surface are small, and physical isolation of salt minerals in the dust may inhibit formation of eutectic brines and decrease brine volumes. If brines do contact the WP surface, small droplet volumes and layer thicknesses do not support development of diffusive gradients necessary for formation on separate anodic-cathodic zones required for localized corrosion. Finally, should localized corrosion initiate, corrosion product buildup will stifle corrosion, by limiting oxygen access to the metal surface, by capillary retention of brine in corrosion product porosity, or by consumption of brine components (Cl−).

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.

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