Improving the fuel qualification process through the use of microscale samples for describing bulk material properties

Over the past few decades, as experimental irradiation testing capabilities have become less available, experimental testing of mechanical properties of materials has evolved to focus on specimens that are smaller than ASTM standard sized specimens. However, there is presently a disconnect in the mechanistic understanding of the relationship between the quantities that are evaluated as part of the nuclear fuel qualification process using ASTM-standard sized samples and the empirical quantities acquired using sub-ASTM-standard sized specimens. A possible connection may be made through the analysis and assembly of data obtained using sub-ASTM-standard sized specimens (on the order of micrometer through millimeter scale), incorporating that data into models using the BISON code, and benchmarking those models against data obtained from testing of ASTM standard specimens. Here, the authors have developed a strategy that explores the assemblage of thermomechanical property data from microscale samples to represent bulk material properties. The current process for irradiated materials analysis can be reconfigured to provide more information on a shorter timeline. The resulting reduction in cost and resources may be accomplished while still providing statistically relevant, high-quality data. This can be realized through the use of progressive modeling and simulation (M&S) to increase the integrity of experimental matrices, and by reducing the length of each cycle through the use of automated sample testing processes and efficient data management and analysis. The use of traditional hot-cell facilities (such as the Hot Fuel Examination Facility at Idaho National Laboratory) can be supplemented by the development of specialized, reconfigurable, high-throughput, shielded modular cells that allow for human access to change the configuration and allow for repairs as needed. In this work, the authors will elaborate on the key objectives of this project, including an understanding of the connection between microscale and macroscale testing and develop effective models that can exploit this relationship during the development and qualification process, demonstration of an automated testing and data management process through the use of unshielded proof-of-concept facilities to assess the approach on unirradiated samples of materials of interest, and development of a design concept for an automated system for mechanical testing within a shielded modular adaptable cell, which can be deployed in facilities of the future.