Synergistic Irradiation, Corrosion, and Microstructural Evolution in Nuclear Materials: Advanced Techniques for Fundamental Understanding of Irradiation-Corrosion Processes
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: Djamel Kaoumi, North Carolina State University; Michael Short, Massachusetts Institute of Technology; Peter Hosemann, University of California, Berkeley; Stephen Raiman, University of Michigan; Raluca Scarlat, University of California, Berkeley; Aaron Kohnert, Los Alamos National Laboratory; Ryan Schoell, Sandia National Laboratory; Philip Edmondson, The University of Manchester; Celine Cabet, Commissariat a l'Energie Atomique

Thursday 8:30 AM
March 3, 2022
Room: 202A
Location: Anaheim Convention Center

8:30 AM  Invited
The Coupled Effects of Irradiation and Corrosion on Materials: Blas Uberuaga1; 1Los Alamos National Laboratory
    Within a nuclear reactor, materials experience multiple extreme environments, including corrosion and irradiation. While there have been decades of research examining these two environments individually, there has been relatively little work devoted to studying the coupled effects of these two environments on the evolution of materials. FUTURE – Fundamental Understanding of Transport Under Reactor Extremes – is an Energy Frontier Research Center dedicated to understanding how these two extreme environments couple. In this talk, we provide an update on recent progress from the Center. We highlight recent experimental results that shed light on how radiation damage effects mass transport and, ultimately, how those defects impact corrosion. Our computational results provide insight into the fundamental mechanisms that drive this coupling and suggest conditions over which this coupling is enhanced and when it is negligible. Together, our work provides new insight into the coupled effects of these two extreme environments.

9:00 AM  Invited
The Role of In Situ Analytical Electron Microscopy in Understanding the Behaviour of Structural Materials in Nuclear Power Systems: Examples and Opportunities: M Grace Burke1; Joven Lim2; 1University of Manchester; 2UK Atomic Energy Authority
    The fundamental research directed at the interaction of radiation, the environment (liquid or gaseous) and material at relevant temperatures to study the response of structural alloys for future fission and fusion reactors is ambitious and very challenging. Analytical electron microscopy (AEM) characterisation of non-irradiated and irradiated structural nuclear alloys in relevant environments can provide unique opportunities to assess the nanoscale defects, radiation-induced segregation via high spatial resolution STEM-EDX analyses, and environmental interactions using in situ stages, including studies of post-irradiation annealing/recovery of irradiation damage. A combined AEM-in situ platform provides opportunities to explore nanoscale reactions at temperatures up to 1000°C in gaseous environments. The new RadIAEM facility, which is part of the UK National Nuclear User Facilities and based in the Materials Research Facility at Culham, will provide the ability for both fission and fusion researchers to conduct in situ gas-metal reaction studies focused on existing and new materials.

9:30 AM  
4D-STEM and Atomic Resolution Analysis of He–rich Gas Bubbles Formed in Au Thin Films via He-ion Irradiation: Sean Mills1; Andrew Minor1; 1University of California-Berkeley
    Extreme nuclear reactor environments require materials to maintain their integrity all while a range of processes act in unison to degrade their performance. Complex interactions between point defects, such as stacking fault tetrahedra (SFTs), vacancy clusters, and gas-filled bubbles that form via irradiation directly contribute to radiation-induced hardening of FCC metals. Moreover, He embrittlement at higher temperatures must be understood for the development of next generation reactor structural materials. Here we implement novel high resolution imaging techniques to observe He-rich gas bubbles embedded in model Au thin films exposed to ion damage via helium ion microscope (HIM). The 4D-STEM technique is used to determine the associated strain behavior surrounding nanoscale bubbles and neighboring defects after in-situ aging designed to grow the bubbles to an observable size. HRSTEM captures spatial information of retained He atoms at near atomic resolution to provide new evidence of their role in forming irradiation defects.

9:50 AM Break

10:10 AM  
Quantification of the Oxidizing Effects of Neutron Activation Reactions in FLiBe: Lorenzo Vergari1; Ryan Hayes1; Massimiliano Fratoni1; Raluca Scarlat1; 1University of California- Berkeley
    Fluoride salts used in solid- and liquid-fueled molten salt reactors and in the blanket of fusion reactors are subjected to neutron irradiation. Activation of the salt constituents leads to the production of several activation products, most notably hydrogen (specifically tritium) and oxygen isotopes. Quantifying production rates of tritium and other hydrogen isotopes is important for the design of tritium management systems. Furthermore, each activation reaction leads to changes in the chemical composition and in the redox potential of the salt and can be a driver for the transfer of electrons from structural materials to component of the melts, thereby increasing corrosion rates as compared to the unirradiated case. In this talk, the production rates of the main activation products of 2LiF-BeF2 (FLiBe) in Fluoride-Salt-Cooled-High-Temperature-Reactors and fusion blankets are estimated and their impact on corrosion rates is discussed, making reference to previous experiments on irradiation-corrosion synergies in molten salts.

10:30 AM  Cancelled
Modelling the Primary Damage in Nickel and Nickel Based Alloys: Influence of Cascade Energy and Morphology in Displacement Cascades: Adithya Nair1; Charlotte Becquart2; Christophe Domain3; Andrée De Backer2; 1Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, F-59000 Lille, France; 2Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations,F-59000 Lille, France; EDF-CNRS Joint Laboratory EM2VM Study and Modeling of the Microstructure for Ageing of Materials (France); 3EDF R&D - MMC, Moret sur Loing (France); EDF-CNRS Joint Laboratory EM2VM Study and Modeling of the Microstructure for Ageing of Materials (France)
     The interaction between high energetic particles and metals causing primary radiation damage has been studied extensively using molecular dynamics. Five interatomic potentials for nickel differing either by their equilibrium part or by the hardening procedure have been included in this study. A characterization based on static non-equilibrium properties and threshold displacement energy (TDE) was done to look for correlations between the potential characteristics and the cascade properties.The dominating feature of this work is to explore extensive statistics of more than 7000 cascades for each interatomic potential with cascade energies ranging from 0.5 keV to 120 keV in pure nickel. This large database is analyzed using multivariate multiple linear regression analysis based on seven primary damage descriptors and three morphology descriptors. Besides the analysis mentioned, the investigation of displacement cascades in nickel-based alloys is also performed to comprehend the effect of the alloying on the primary damage.