Environmental effects on corrosion properties of Alloy 22

Subtask 1: Experimental Determination of Parameters for the General Corrosion Model Subtask 2: Corrosion Under Dust Deposits Containing Hygroscopic Salts Subtask 3: Heated Electrode Approach for the Study of Corrosion Under Aggressive Conditions Subtask 4: Effect of Hydrogen Permeation on the Stability of the Passive Film of Alloy 2

Environmental Effects on Corrosion Properties of Alloy 22

During the regulatory life of the Yucca Mountain High Level Nuclear Waste (HLNW) repository the primary engineered barrier that is to prevent release of radioactive material into the environment is proposed to be a Corrosion-Resistant Material (CRM) outer shell covering the Waste Package (WP) container. The current selection for the CRM is Alloy 22 (UNS N06022), a Ni-Cr-Mo-W-Fe alloy. Alloy 22 forms a defective chromic oxide passive film which results in excellent corrosion resistance; the presence of molybdenum in Alloy 22 offers corrosion resistance in reducing environments as well as oxidizing environments

Continue stress corrosion cracking/ electrochemical testing and model support

The work reported here is focused on measuring values for various model parameters for the General Corrosion Model (GCM). The objective of the UNR work is to obtain the parameter values under Quality Assurance protocols, so that the data can be incorporated into models that might be used to address licensing issues, for example. The derived kinetic parameters may be used in models for predicting the accumulation of general and localized corrosion damage to Alloy-22 canisters over the 10,000-year lifetime of the YM repository. The work focuses on obtaining data of the highest possible accuracy to derive kinetic parameters for the dominant processes in the growth and breakdown of passive films on Alloy-22. This work also forms the basis of Mr. Glen McMillion\u27s dissertation for the Ph.D. degree from the University of Nevada, which he is scheduled to complete at the end of 2004. This project has made significant progress and has produced important data since its inception in mid-FY2002: 1. All work has been performed under the control of the UCCSN Quality Assurance Program, which is approved by the DOE YMP. Data generated to date are being submitted to the Technical Data Archive (TDA). 2. Experimental apparatus specifically designed for this task has been built, thoroughly tested, and proven to generate high-accuracy data. 3. Data have been collected for approximately two-thirds of the first of three conditions identified in the experimental matrix developed in the Scientific Investigation Plan. 4. Data generated include cyclic polarization, electrochemical impedance spectroscopy (EIS), potentiostatic passive current density (Ip), and Ip transients in response to step changes in potential. Conditions for which these data have been generated are listed below. 5. Crevice corrosion of Alloy-22 has been observed and documented. 6. Significant variability of corrosion behavior and microstructure among mill-annealed specimens has been observed and documented

Constraints and Categories of Vadose Zone Monitoring Devices

UA affiliates can use the link in "Additional Links" to access this article.Traditional monitoring methods using chemical analysis of ground water samples to detect pollutant migration are being superseded or used in conjunction with innovative approaches. A need to detect pollutants before they reach the water table has drawn interest to vadose (unsaturated) zone monitoring and brought together hydrogeologists, soil scientists and agricultural engineers who have been working on this subject for years. Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility. Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site-specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy; degree of operational complexity; direct versus indirect methods; applicability to alternate media; effect on flow regime; and effect of hazardous waste on sampling or measurements. Application of the selection criteria is discussed in Everett et al. (1982a).This item is part of the Water Resources Research Center collection. It was digitized from a physical copy provided by the Water Resources Research Center at The University of Arizona. For more information about items in this collection, please contact the Center, (520) 621-9591 or see http://wrrc.arizona.edu