Date: Thursday, Feb 16th
Presenter: Ram Raprashad, Pacific Northwest National Laboratory
Fuels Research and Development: Currently, efforts are ongoing to develop new nuclear fuels to enable research and test reactors to use low-enriched uranium fuel instead of high-enriched uranium fuel, without significant loss in performance. A new monolithic fuel type that possesses the greatest possible uranium density in the fuel region is being developed, where the fuel region consists of a single foil encased inside an aluminum alloy cladding. Corrosion behavior is an important consideration in the fuel qualification process. No prior study comprehensively evaluated the corrosion behavior of uranium-10 weight percent molybdenum (U-10Mo) alloy for use in research and test reactors with the current composition, thermomechanical processing methods, dimension, cladding material, interface, water chemistry, temperature, and flow conditions. Hence, this work was performed to obtain baseline information about the corrosion behavior of U-10Mo alloy as a function of fabrication parameters, using deionized water in a non-flow condition. As a part of this study, the effect of homogenization and sub-eutectoid heat treatment on the corrosion behavior of U-10Mo was evaluated. The results of corrosion experiments along with the mechanical properties and microstructural analysis will be presented at the seminar.
Structural Materials Research and Development: Efforts are also ongoing to examine the feasibility of using oxide dispersion strengthened (ODS) alloys in advanced nuclear reactors. Conventional fusion welding of ODS alloys could cause various undesirable effects such as the coalescence of oxide dispersoids and generation of significant porosity. Hence, friction stir welding (FSW) was used to weld iron-based MA956 plates and nickel-based MA754 alloys separately in a bead-on-plate configuration. Higher weld efficiencies were achieved in both alloys. Microhardness and mini-tensile testing of the parent and processed materials were carried out to evaluate the mechanical properties. EBSD, TEM and APT were used to evaluate the microstructural characteristics of the parent and processed materials. Both parent and processed specimens were irradiated in the Advanced Test Reactor (ATR). The irradiated materials are currently being characterized, and the results will be presented at the seminar.
Ramprashad Prabhakaran is a Materials Scientist at the Pacific Northwest National Laboratory (PNNL). He has been actively involved in the nuclear fuels, cladding and structural materials research and development for over 12 years, and has worked at University of Nevada, Las Vegas (UNLV) and Idaho National Laboratory (INL) before joining PNNL. He has a Bachelor of Mechanical Engineering degree from the University of Madras, India, a Masters degree in Mechanical Engineering (majoring in Nuclear Materials) from UNLV and a second Masters degree in Nuclear Engineering (majoring in Nuclear Materials) from the University of Idaho. He has extensive experience in evaluating environment-induced degradations, measurement of mechanical properties and performing microstructural characterization on U-Mo fuels, cladding/structural materials and friction-stir-welded alloys; designing experiments, performing failure analysis and understanding material structure-property-processing relationships. He has authored 18 publications, presented over 35 papers/posters, and is currently serving as a Reviewer and Assistant Editor for a number of journals. He is an invited member of Tau Beta Pi and Phi Kappa Phi. He is the recipient of 2015 TMS SMD Young Leader Professional Development Award and several travel awards from a number of organizations (Oak Ridge Associated Universities, Los Alamos Neutron Science Center, USDOE, EPI, ASME, ANS and TMS) to attend conferences/seminars. He is actively involved with a number of professional society activities (technical and young leader committee leadership, division council, publications, outreach, professional development, programming, courses, journals, symposia organization and session chair). He was recently selected by the TMS, as one of the Rising Professionals to participate in the 2015 Emerging Leaders Alliance Conference.