Radiation Effects in Metals and Ceramics: Synergy of Irradiation and Corrosion Processes
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: Djamel Kaoumi, North Carolina State University; Thak Sang Byun, Oak Ridge National Laboratory; Dane Morgan, University of Wisconsin-Madison; Maria Okuniewski, Purdue University; Mahmood Mamivand; Geoffrey Beausoleil, Idaho National Laboratory; Philip Edmondson, The University Of Manchester; Khalid Hattar, University of Tennessee Knoxville; Aurelie Gentils, Université Paris-Saclay; Joel Ribis, Cea
Monday 2:30 PM
February 24, 2020
Room: Theater A-7
Location: San Diego Convention Ctr
Session Chair: Djamel Kaoumi, North Carolina State University; T. S. Byun, Oak Ridge National Laboratory
2:30 PM Invited
Future: Fundamental Understanding of Transport Under Reactor Extremes: Blas Uberuaga1; 1Los Alamos National Laboratory
Materials for nuclear energy experience a range of hostile environments, including irradiation and corrosion. These work in concert to impact the structure and properties of materials. FUTURE -- an Energy Frontier Research Center -- is dedicated to understanding how the fundamental mechanisms of corrosion are impacted by irradiation-induce defects. Combining novel experimental capabilities with state-of-the-art modeling, FUTURE is developing a predictive understanding of these coupled extremes. FUTURE is focused on three primary questions: what are the nature of non-equilibrium defects produced under irradiation, how do those defects couple to species to modify the chemical and phase structure of the material, and how do they impact the rate of reactions at interfaces that drive corrosion. I will present an overview of the goals of the project and highlight recent results that enhance our understanding of how materials respond in nuclear reactor environments.
3:00 PM
Design and Results of the Irradiation Corrosion Experiment (ICE): Franziska Schmidt1; Yongqiang Wang2; Peter Hosemann1; 1University of California, Berkeley; 2Los Alamos National Laboratory
The coupled effects of simultaneous irradiation and corrosion on metals are still poorly understood at the atomic scale, in particular for molten salts or liquid metals. This leads to considerable difficulties in the design of reliable materials for use in advanced reactors. Our work presents the design and improvement of the already existing irradiation corrosion experiment (ICE) and first experimental results. Detailed data on the previously irradiated ICE II (lead-bismuth eutectic) sample is presented in addition to initial data and design changes on ICE III, which is designed to study the interaction between molten salt corrosion and displacement. TEM and high resolution cross section work has been completed on ICE II and first experiments on ICE III with LiCl-KCl and a pure Fe sample indicate a strong affinity for ferrous metals, which varies with Ni content, and the production of a stable oxide film.
3:20 PM
Metal-ionic Phase Reactions in Molten Salt ionic Liquids:
Experimental, Thermodynamic and Kinetic Analysis of the Alteration of Preformed-oxides on Fe-Cr and Ni-Cr Alloys: Marlene Wartenberg1; Junsoo Han1; Peter Hosemann2; Nan Li3; John Scully1; 1University of Virginia; 2University of California, Berkeley; 3Los Alamos National Laboratory
This research seeks to develop a better understanding of the effects of various “harsh” environments on the passive preformed-oxide developed on model structural materials. Systematic studies were conducted on a range of model Fe-Cr and Ni-Cr alloy systems after passivation in aqueous solutions or by thermal “pre-oxidation in air”. The samples were subsequently exposed to various aqueous solutions and room temperature ionic liquids with various salt species in isolation. These may alter or dissolve the preformed-oxide film and ultimately govern the corrosion behavior. The sample was also tested in classes of ionic liquids and molten salts, with and without radiation. EIS was used to first characterize the preformed-oxide. Capacitance and Mott-Schottky plots were utilized in order to quantify film thickness, oxide dissolution rates versus time, semiconductor dopant type, electronic defect type, and densities. Altered oxides and intact oxides were compared and contrasted after investigation by XPS, SIMS and FIB-TEM.
3:40 PM
Structural and Chemical Heterogeneities at the Nanoscale affecting Passive Film Formation during Irradiation and Corrosion: Sandra Taylor1; Timothy Lach1; Matthew Olszta1; Karen Kruska1; Danny Edwards1; Thak Sang Byun1; Daniel Schreiber1; 1Pacific Northwest National Laboratory
In this study we probe atomic transport mechanisms driving corrosion and material degradation under irradiation at the nanoscale using correlative scanning transmission electron microscopy (STEM) and atom probe tomography (APT). In particular the formation and evolution of passivating oxide layers during stress corrosion cracking on neutron irradiated 304 stainless steel is investigated. The analyses reveal a complex interplay of corrosion- and radiation-induced elemental segregation and defect formation impacting the nature of the passivating films. Nominally protective thick oxide films can form but still penetrate into the alloy via linear defects and dislocation loops, while other surfaces form thin oxide films that effectively passivate on less defective surfaces. Experiments using isotopic tracers and APT are also being developed to probe oxide formation mechanisms, in turn providing insight into oxide passivity and atomic transport through the passive films under irradiation.
4:00 PM Break
4:20 PM
Microstructure and Microchemistry Characterization of Neutron Irradiated M5® and X2® Fuel Cladding: Zefeng Yu1; Kory Linton2; Lingfeng He3; Mukesh Bachhav3; Xiang Liu3; Adrien Couet1; 1University of Wisconsin; 2Oak Ridge National Laboratory; 3Idaho National Laboratory
ZrNb alloys have significant advantages over Zircaloys due to the reduced irradiation induced growth and corrosion kinetics. Such enhancements have been hypothesized to be related to the precipitation of irradiation induced platelets (IIP) / nanoclusters in the Zr matrix. However, there are only a few reports giving detailed characterizations on IIP in the Zr metal of neutron irradiated industrial samples. The stability (dissolution, amorphization, oxidation) of IIP/nanoclusters in the oxide has not been reported yet. To understand the neutron irradiation induced microstructure and microchemistry, neutron irradiated M5® and X2® have been studied using (S)TEM/EDS to investigate the size, density, and crystallography of IIP in both metal and ZrO2. APT analysis on the Nb concentration in the Zr solid solution has been performed on X2®, in an effort to support the hypothesis that irradiation induced Nb reduction in solid solution is responsible for the lowered in-reactor corrosion kinetics of ZrNb alloys.
4:40 PM
Neutron Radiation Damage of β Phase and its Impact on In-core Corrosion of Zr-Nb alloy: Guanze He1; Junliang Liu1; Anne Callow1; Jing Hu2; Mir Anamul Haq3; Sergio Lozano-Perez1; Chris Grovenor1; 1Department of Materials. University of Oxford; 2Argonne National Laboratory ; 3University of Huddersfield
Zirconium alloys have been widely used as cladding materials in Water Cooled Reactors and one of the major degradation mechanisms is the water facing corrosion enhanced by neutron radiation. Among various types of zirconium alloys, β-phase containing Zr-Nb alloys have shown a relative good resistance to this radiation-enhanced corrosion, which is relative to the damage behaviour of β-Zr and β-Nb phases embedded in the metal Zr matrix under radiation. We have conducted a series experiments to study the damage of the β phases under radiation. These include using TEM in-situ heavy ion irradiation and Energy Dispersive X-Ray Spectroscopy (EDX) to study the damage mechanisms of β-Nb particles, and using Electron Energy Loss Spectroscopy (EELS) and Atom Probe Tomography (APT) to study the damage of β-Zr phase under neutron irradiation. We have shown the micro-chemical and micro-structural changes can be a beneficial factor to the in-core corrosion of the Zr-Nb alloys.
5:00 PM
Influence of Zircaloy Alloying Elements and Impurities on Point Defects Formation in ZrO2 Corrosion Films and Resultant Zircaloy Corrosion Rate: William Howland1; Richard Smith1; Bruce Kammenzind1; Mikael Christensen2; Volker Eyert2; Erich Wimmer2; 1Naval Nuclear Laboratory; 2Materials Design, Inc.
A typical composition of nuclear-grade zirconium alloys is more than 98 percent zirconium and less than 2 weight percent of tin, niobium, iron, chromium, nickel and other metals. A percentage of these impurities go into solution in the corrosion based zirconium oxide film. The alloying elements in zirconia solution will demand a response from intrinsic point defects such as oxygen anion vacancies and conduction band electrons. Additionally, contaminants such as Nitrogen can greatly enhance corrosion rates as point defects in zirconia by both influencing transport of corrosion species through the protective oxide barrier layer, by influencing corrosion transition, or both. To this end, this work determines the influence of Nitrogen on the transport properties of oxygen anion vacancies and conduction band electrons and the mitigating effects of common alloying elements such as Sn and Nb. The evolution of these point defects under irradiation is discussed.
5:20 PM
Understanding the Effect of Gamma Radiation on the Corrosion of Zirconium Alloys: Choen-May Chan1; Paul Binks1; Douglas Rishel2; Aliaksandr Baidak3; 1Wood; 2Naval Nuclear Laboratory; 3Dalton Cumbrian Facility
Gamma radiation is suspected of playing a contributing role in accelerating the in-reactor post-transition corrosion kinetics of zirconium alloys such as Zircaloy-4. Previous work has shown that it is possible to infer the role of gamma radiation on corrosion by comparing instances where variations exist in gamma flux levels relative to neutron flux levels within different regions of a reactor or from one reactor to another reactor. To definitively determine whether gamma radiation plays a role in zirconium alloy corrosion, electrochemistry tests have been conducted using a mini-autoclave situated in the gamma irradiator at the Dalton Cumbrian Facility at dose rates ranging from 22 to 37 Gy/min under PWR water chemistry conditions using Zircaloy-4 working electrodes with pre-transition and post-transition thick oxide films. Data from open circuit potential measurements and electrochemical impedance spectroscopy will be presented that support the hypothesis that gamma radiation impacts corrosion under post-transition conditions.