scholarly journals Passive Corrosion Behavior of Alloy 22 in Multi-Ionic Aqueous Environments

2002 ◽  
Author(s):  
Tiangan Lian ◽  
John C. Estill ◽  
Gary A. Hust ◽  
Dave V. Fix ◽  
Raul B. Rebak
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
Yucca Mountain ◽  
Corrosion Studies ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Geological Repository ◽  
High Level Nuclear Waste ◽  
Alternative Techniques ◽  
High Level

As part of proposed geological repository at Yucca Mountain, Nevada, Alloy 22 (Ni-22Cr-13Mo-3W-3Fe) has been chosen as the candidate material for a 2-cm outer layer on the high-level nuclear waste containers. During the repository period, the container materials will be subject to corrosion due to their exposure to multi-ionic aqueous environments. Although Alloy 22 has demonstrated excellent corrosion resistance, accumulation of a small, yearly corrosion rate for 10,000 or more years can be significant. When subjected to the conventional weight loss technique for corrosion studies, Alloy 22 requires many years to demonstrate a detectible weight loss. The goal of this research is to seek alternative techniques to determine a reasonably confident corrosion rate. This paper will discuss the latest experimental results using the potentiostatic technique to determine passive dissolution rates.

scholarly journals Characterization of the Resistance of Alloy 22 to Stress Corrosion Cracking

2002 ◽  
Author(s):  
Kenneth J. King ◽  
John C. Estill ◽  
Rau´l B. Rebak
Keyword(s):  
Slow Strain Rate Test ◽  
Environmentally Assisted Cracking ◽  
Waste Container ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Current Design ◽  
Rate Test ◽  
High Level Nuclear Waste ◽  
High Level

In its current design, the high-level nuclear waste container includes an external layer of Alloy 22 (Ni-22Cr-13Mo-3W-3Fe). Since the containers may be exposed to multi-ionic aqueous environments over their lifetime, a potential degradation mode of the outer layer could be environmentally assisted cracking (EAC). The objective of the current research is to characterize the effect of applied potential and temperature on the susceptibility of Alloy 22 to EAC in simulated concentrated water (SCW) using the slow strain rate test (SSRT). Results show that Alloy 22 may suffer EAC at applied potentials approximately 400 mV more anodic than the corrosion potential (Ecorr).

Environmental Risk and the Iron Triangle: The Case of Yucca Mountain

1995 ◽  
Vol 5 (4) ◽  
pp. 753-777 ◽  
Author(s):  
Kristin S. Shrader-Frechette
Keyword(s):  
Ethical Issues ◽  
Yucca Mountain ◽  
Spent Fuel ◽  
Business Climate ◽  
The Public ◽  
Iron Triangle ◽  
Geological Repository ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Public Opposition

Abstract:Despite significant scientific uncertainties and strong public opposition, there appears to be an “iron triangle” of industry, government, and consultants/contractors promoting the siting of the world’s first permanent geological repository for high-level nuclear waste and spent fuel, proposed for Yucca Mountain, Nevada. Arguing that representatives of this iron triangle have ignored important epistemological and ethical difficulties with the proposed facility, I conclude that the business climate surrounding this triangle appears to leave little room for consideration of ethical issues related to public safety, environmental welfare, and citizen consent to risk. If my analysis of the Yucca Mountain case is correct and typical, then some of the most pressing questions of business ethics may concern how to break the iron triangle or, at least, how to expand it into a quadrilateral that includes the public.

Integrated Analysis for Long-Term Degradation of Waste Package at the Potential Yucca Mountain Repository for High-Level Nuclear Waste Disposal

2002 ◽  
Vol 713 ◽  
Author(s):  
Joon H. Lee ◽  
Kevin G. Mon ◽  
Dennis E. Longsine ◽  
Bryan E. Bullard ◽  
Ahmed M. Moniba
Keyword(s):  
Corrosion Rate ◽  
Nuclear Waste ◽  
Yucca Mountain ◽  
Integrated Analysis ◽  
Total System ◽  
General Corrosion ◽  
Waste Package ◽  
High Level Nuclear Waste ◽  
High Level

ABSTRACTThe technical basis for Site Recommendation (SR) of the potential repository for high-level nuclear waste at Yucca Mountain, Nevada has been completed. Long-term containment of the waste and subsequent slow release of radionuclides from the engineered barrier system (EBS) into the geosphere will rely on a robust waste package (WP) design, among other EBS components as well as the natural barrier system. The WP and drip shield (DS) degradation analyses for the total system performance assessment (TSPA) baseline model for the SR have shown that, based on the current corrosion models and assumptions, both the DSs and WPs do not fail within the regulatory compliance time period (10,000 years). From the perspective of initial WP failure time, the analysis results are encouraging because the upper bounds of the baseline case are likely to represent the worst case combination of key corrosion model parameters that significantly affect long-term performance of WPs in the potential repository. The estimated long life-time of the WPs in the current analysis is attributed mostly to the following two factors that delay the onset of stress corrosion cracking (SCC): (1) the stress mitigation to substantial depths from the outer surface in the dual closure-lid weld regions; and (2) the very low general-corrosion rate applied to the closure-lid weld regions to corrode the compressive stress zones. Uncertainties are associated with the current WP SCC analysis. These are stress mitigation on the closure-lid welds, characterization of manufacturing flaws applied to SCC, and general corrosion rate applied to the closurelid weld regions. These uncertainties are expected to be reduced as additional data and analyses are developed.

Conductivity Behavior of Salt Deposits on the Surface of Engineered Barrier Materials for the Potential High-Level Nuclear Waste Repository at Yucca Mountain, Nevada

2004 ◽  
Vol 824 ◽  
Author(s):  
Lietai Yang ◽  
Miriam R. Juckett ◽  
Roberto T. Pabalan
Keyword(s):  
Electrical Conductance ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
Conductivity Measurements ◽  
Barrier Materials ◽  
Salt Mixtures ◽  
High Level Nuclear Waste ◽  
Waste Repository ◽  
High Level ◽  
Conductivity Behavior

AbstractThe electrical conductance or conductivity of three salt mixtures, Na-K-Cl-NO3, Ca-K-Cl and Ca-Na-Cl, were measured at 25, 50 and 70°C [77, 122, and 158 °F] as a function of relative humidity (RH). Mutual deliquescence and efflorescence RH (MDRH and MERH) values were determined based on the conductivity measurements. It was found that the conductivity of the three salt mixtures started to increase at RH values that are approximately 40 % of their MDRH and increased by 1to 2 orders of magnitude just before reaching the MDRH. At the MDRH, a significant increase in conductivity was observed. The MDRH and MERH for the Ca-K-Cl and Ca-Na-Cl mixtures were found to be approximately 15 % in the temperature range of 50 to 70 °C [122 to 158 °F]. The MDRH and MERH for the Na-K-Cl-NO3system were found to be approximately 54 % at 50 °C [122 °F] and decreased significantly with an increase in temperature.

Microearthquakes at Yucca Mountain, Nevada

1992 ◽  
Vol 82 (1) ◽  
pp. 164-174
Author(s):  
James N. Brune ◽  
Walter Nicks ◽  
Arturo Aburto
Keyword(s):  
Great Basin ◽  
Narrow Band ◽  
High Gain ◽  
Yucca Mountain ◽  
Continuous Operation ◽  
Nuclear Waste Repository ◽  
High Level Nuclear Waste ◽  
Waste Repository ◽  
High Level ◽  
Approximate Magnitude

Abstract We operated a microearthquake array in the neighborhood of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The array consists of four high-gain (up to 34 million), narrow band (25 Hz) telemetered stations. Based on approximate magnitude calibration of the array we expect during quiet periods, for distances less than 15 km, complete recording of events at Yucca Mt. for M ≧ −1. We have operated the four stations for 12-hour periods overnight between August and October 1990 and intermittently afterward, until April 1991, when we began more or less continuous operation. The pattern of microearthquake activity confirms the existence of a zone of seismic quiescence in the vicinity of proposed repository. We recorded only about 10 events with S-P times of less than 3 sec (D < 24 km). Most events had S-P times between 3 and 6.5 sec, consistent with the higher seismic activity at distances between 24 and 52 km observed by Rogers et al. (1987) and Gomberg (1991). Oliver et al. (1966) found, contrary to what has been observed by us for Yucca Mountain, that in seismically active areas most of the events had S-P times of less than 3 sec. We confirmed this expectation for four microearthquake stations near Mammoth Lakes, where we observed microearthquake rates of over 100 per day, most with S-P times of less than 3 sec. Extrapolation of seismicity data from the Southern Great Basin Seismic Network confirms the low microearthquake activity in the immediate vicinity of Yucca Mountain.

Neptunium(V) Sorption Behavior on Clinoptilolite, Quartz and Montmorillonite

1995 ◽  
Vol 412 ◽  
Author(s):  
F. P. Bertetti ◽  
R. T. Pabalan ◽  
D. R. Turner ◽  
M. G. Almendarez
Keyword(s):  
Nir Spectroscopy ◽  
Electrolyte Solutions ◽  
Yucca Mountain ◽  
Sorption Behavior ◽  
Surface Loading ◽  
Wide Range ◽  
High Level Nuclear Waste ◽  
Ph Range ◽  
High Level ◽  
Carbonate Complexes

AbstractPerformance assessment models have identified 237Np as a radionuclide of concern in meeting release limits established for the geologic disposal of high-level nuclear waste at the proposed repository at Yucca Mountain, Nevada. In this study, quartz, clinoptilolite, and montmorillonite, which are minerals representative of phases that occur both in the rock matrix and as fracture coatings at Yucca Mountain, were reacted with 237Np-bearing solutions to characterize the sorption behavior of Np(V) on these minerals.Batch experiments were conducted over a wide range of conditions in which pH of solution, surface loading, sorbent surface area, initial concentration of Np(V), and partial pressure of CO2 were varied. Initial Np(V) concentrations were between 1 × 10-7 and 1- 10-6 M in electrolyte solutions of 0.1 or 0.01 M NaNO3. The oxidation state of Np in solution was verified with NIR spectroscopy and by solvent extraction. Prior to the start of experiments, minerals were pretreated to eliminate impurities, and the clinoptilolite and montmorillonite were converted to Na-form by ion exchange with NaCI solutions.Results indicate that, for all three minerals, Np(V) sorption begins at pH values coincident with the start of hydrolysis in solution (-7). For solutions undersaturated with respect to atmospheric CO2, sorption increases continuously with increasing pH. Under equilibrium with atmospheric CO2, Np(V) sorption is important in the pH range (7–9.5) where NpO2(OH)°(aq) is significant, whereas sorption is inhibited at higher pH where neptunyl carbonate complexes are the predominant species.

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