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.

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.

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.

Localized Corrosion and Stress Corrosion Cracking of Candidate Materials for High-Level Radioactive Waste Disposal Containers in U.S.: A Critical Literature Review

1988 ◽  
Vol 127 ◽  
Author(s):  
Joseph C. Farmer ◽  
R. Daniel McCright
Keyword(s):  
Radioactive Waste ◽  
The United States ◽  
Radioactive Waste Disposal ◽  
Localized Corrosion ◽  
Spent Fuel ◽  
High Level Radioactive Waste ◽  
Fuel Assemblies ◽  
Austenitic Alloys ◽  
High Level ◽  
Critical Literature

ABSTRACTThree iron-based to nickel-based austenitic alloys and three copper-based alloys are being considered in the United States of America as candidate materials for the fabrication of high-level radioactive waste containers. The austenitic alloys are Types 304L and 316L stainless steels as well as the high-nickel material Alloy 825. The copper-based alloys are CDA 102 (oxygen-free copper), CDA 613 (Cu-7A1), and CDA 715 (Cu-3ONi). Waste in the forms of spent fuel assemblies from reactors and borosilicate glass will be sent to a proposed repository at Yucca Mountain, Nevada. The decay of radionuclides will result in the generation of substantial heat and in gamma radiation.

The role of microorganisms in the bentonite barrier of high-level radioactive waste repositories

2020 ◽  
Author(s):  
Nicole Matschiavelli ◽  
Magdalena Dressler ◽  
Tom Neubert ◽  
Sindy Kluge ◽  
Ariette Schierz ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Thermophilic Bacteria ◽  
Disposal Site ◽  
Dissolution Behavior ◽  
Strictly Anaerobic ◽  
Dependent Manner ◽  
Metabolic Potential ◽  
High Level Radioactive Waste ◽  
Geochemical Parameters ◽  
High Level

<p>The global production of 12,000 metric tonnes of high-level radioactive waste (HLW) every year is a big challenge with respect to its safe long-term storage. In the favored multi-barrier system, bentonite is discussed as a geo-technical barrier in many disposal programs worldwide. The bentonite seals the space between the canister containing the HLW and the surrounding host rock, thereby fulfilling two major tasks: 1) slow down the process of corrosion when water enters the disposal site, and 2) hinder the discharge of radionuclides into the bio-geosphere in case of a leaking canister. Due to their metabolic activity, microorganisms could significantly influence the properties of the bentonite barrier. In order to investigate the metabolic potential of naturally occurring microorganisms, we conducted anaerobic bentonite-slurry experiments containing uncompacted bentonite and a synthetic Opalinus Clay pore water solution. Within one-year incubation at 30 and 60 °C, lactate- or H<sub>2</sub>-stimulated microcosms at 30 °C showed the dominance and activity of strictly anaerobic, sulfate-reducing and spore-forming microorganisms. Consequently, hydrogen sulfide gas was generated in the respective set ups, leading to the formation of fractures and iron-sulfur precipitations. Experiments that incubated at 60 °C, showed the dominance of thermophilic bacteria, independent of the presence of substrates. The respective set-ups showed/revealed no significant changes in the analyzed bio-geochemical parameters. The obtained results clearly show that indigenous microorganisms evolve in a temperature- and substrate-dependent manner. The formed metabolites can potentially affect the dissolution behavior of minerals and ions within the bentonite as well as corrosion processes and require further investigations.</p>

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.

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.

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