Effect of Microbial Action on the Corrosion Potential of Austenitic Alloy Containers for High-Level Nuclear Waste

1995 ◽  
Vol 412 ◽  
Author(s):  
P. Angell ◽  
D. S. Dunn ◽  
G. A. Cragnolino
Keyword(s):  
Nuclear Waste ◽  
Corrosion Potential ◽  
Localized Corrosion ◽  
Minor Variation ◽  
Sulfate Reducing ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Reducing Bacteria ◽  
The Relationship ◽  
Microbial Action

AbstractThe safe disposal of high-level nuclear waste (HLW) entails the ability to ensure the integrity of waste containers for prolonged time periods. It is generally accepted that under certain conditions, microbial action may change local benign environments to those in which localized corrosion can be actively promoted. The use of repassivation potential (Erp) in relation to the value of the corrosion potential (Ecorr) has been proposed as a means of assessing the propensity of a metallic material to localized corrosion. Microbial activity is known to influence Ecorr however, the precise mechanism is unresolved. Shewanella putrefaciens, a bacteria with many of the characteristics of sulfate-reducing bacteria (SRB), are being grown under controlled conditions on 316L stainless steel (SS) surfaces to understand the relationship between Ecorr and metabolic activity. It has been observed that the growth of the bacteria under aerobic conditions, without the production of metabolic sulfide, leads to only minor variation in Ecorr. These changes possibly correlate to the periods of active bacterial growth.

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.

scholarly journals Container Materials for High-Level Nuclear Waste at the Proposed Yucca Mountain Site

1990 ◽  
Vol 212 ◽  
Author(s):  
R. Daniel McCright
Keyword(s):  
Nuclear Waste ◽  
Yucca Mountain ◽  
Localized Corrosion ◽  
Experimental Program ◽  
Degradation Rates ◽  
Design Activities ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Welding Processes

ABSTRACTCandidate container materials for high-level nuclear waste packages to be emplaced at the proposed Yucca Mountain repository site are being considered for their long-term resistance to corrosion, oxidation, embrittlement and other kinds of degradation. Selection criteria have been established, and a method has been developed for recommending a material for advanced container design activities. An extensive compilation of the degradation phenomena for six candidate materials is complete, and further studies have begun on the degradation modes affecting additional candidate materials. Phenomenological models for predicting container degradation rates are being advanced for environmental conditions applicable to Yucca Mountain. An experimental program is underway to evaluate the susceptibility of container materials to localized corrosion, stress corrosion cracking, and enhancement of corrosion and oxidation attack by gamma radiation. Initial evaluations of container fabrication and welding processes have identified some processes that appear to alleviate some long-term corrosion susceptibility concerns.

Corrosion Characteristics of Titanium Alloys in Multi-Ionic Environments

2003 ◽  
Author(s):  
Lana L. Wong ◽  
John C. Estill ◽  
David V. Fix ◽  
Rau´l B. Rebak
Keyword(s):  
Corrosion Rate ◽  
Nuclear Waste ◽  
Electrolyte Solutions ◽  
Localized Corrosion ◽  
Nuclear Waste Repository ◽  
Liquid Phases ◽  
High Level Nuclear Waste ◽  
Engineered Barriers ◽  
Titanium Grade ◽  
High Level

Yucca Mountain (Nevada) is designated as a high-level nuclear waste repository. The nuclear waste will be isolated by a series of engineered barriers. The metallic engineered barriers will consist of a double-wall container with a detached drip shield. The material for the external wall of the container is Alloy 22, a corrosion-resistant Ni-Cr-Mo alloy. Titanium grade 7 has been proposed for the drip shield. Ti alloys are highly resistant to all forms of corrosion due to the formation of a stable, protective and strongly adherent oxide film. The aim of this research was to characterize the general and localized corrosion behavior of Ti Gr 7, 16 and 12 in simulated concentrated ground waters. Welded and non-welded coupons were exposed for up to 5 years to the vapor and liquid phases of acidic and alkaline multi-ionic solutions at 60°C and 90°C. This paper describes the results obtained after approximately 2-1/2- to 5-1/2-year exposure to the testing electrolyte solutions. In general, the highest corrosion rate was obtained for Ti Gr 12; however, in all of the tested conditions, the corrosion rate was generally lower than 100 nm/yr. For all alloys, the highest corrosion rate was obtained in the concentrated alkaline solution.

Critical Conditions for Initiation of Localized Corrosion of Mild Steels in Contact with Bentonite Used in Geological Disposal Packages of Nuclear Waste

1992 ◽  
Vol 294 ◽  
Author(s):  
Guen Nakayama ◽  
Masatsune Akashi
Keyword(s):  
Mild Steel ◽  
Nuclear Waste ◽  
Localized Corrosion ◽  
Critical Conditions ◽  
Geological Disposal ◽  
Alkaline Environments ◽  
Current Design ◽  
Long Time ◽  
High Level Nuclear Waste ◽  
High Level

ABSTRACTIn the current design of geological disposal of high-level nuclear waste, the use of bentonite to stand as an artificial barrier-cum-buffer between the host rock and the packages made of mild steel is being investigated. Although mild steels commomly have been considered to be passivity in alkaline environments, under certain circumstances, they become liable to localized corrosion, e.g., pitting corrosion and crevice corrosion. Since bentonite can turn the environment alkaline to a pH of approximately 10 when it is mixed with groundwater, critical conditions for the initiation of localized corrosion of mild steel must be known to evaluate the extremely long time integrity of disposal packages serving in such an environment. This paper presents and discusses the observations and results acquired in a series of critical conditions for the initiation of localized corrosion of mild steels in various groundwater-bentonite environments at 20C, with a deaerated aqueous solution of 1 mMol/L [HCO3−] +10 ppm [CI−], simulating the natural groundwater and varying the bentonite content.

Transmutation of high-level nuclear waste by means of accelerator driven system

2013 ◽  
Vol 3 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Hamid Aït Abderrahim ◽  
Didier De Bruyn ◽  
Gert Van den Eynde ◽  
Sidney Michiels
Keyword(s):  
Nuclear Waste ◽  
Driven System ◽  
High Level Nuclear Waste ◽  
Accelerator Driven System ◽  
High Level
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