Abstract

Ion irradiation as a simulation tool to study neutron damage has made significant contributions to our understanding of radiation effects in reactor materials. With rapid advance of computational tools and in situ experimental techniques, the full realization of the role of ion irradiation in simulating neutron damage has become increasingly promising. This talk will present a case study using a closely coordinated TEM with in situ ion irradiation and computer simulation to predict defect formation and evolution in neutron-irradiated materials. A series of in situ ion irradiation experiments was conducted at the IVEM-Tandem Facility at the Argonne National Laboratory to provide high-fidelity data of dislocation loops over a range of irradiation temperature, dose, dose rate and specimen thickness. A computer model was established by integrating molecular dynamic simulation of cascade displacement damage and reaction rate theory based cluster dynamics model to simulate the time/dose and spatial dependence of defect evolution in thin foils. The computer model was improved by iterative refinement of key material parameters using the experimental data. The validated model was used to predict neutron damage of bulk material and the simulation results were compared with the experimental data of Mo neutron irradiated to low doses at the reactor coolant temperature in the High Flux Isotope Reactor (HFIR). Reasonable agreement between model prediction and experimental data demonstrates a promising direction in understanding and predicting neutron damage using a closely coordinated approach of in situ ion irradiation experiment and computer simulation.

Biography

Meimei Li’s research seeks to understand reactor materials behavior using advanced characterization techniques and modeling tools to predict materials’ long-term performance in extreme environments of irradiation, temperature, stress, and corrosion, and to develop high-performance materials for nuclear energy applications. Of particular interest is studying the dynamics of microstructural evolution using advanced high-energy X-ray techniques and combined ion and electron beams for in situ studies of radiation damage. She received the Presidential Early Career Award for Scientists and Engineers (PECASE) in 2012. She has more than 140 publications in peer-reviewed journals, book chapters, conference proceedings, and technical reports. Before moving to Argonne she had worked at the China Institute of Atomic Energy, and Oak Ridge National Laboratory.  She received her B.S. degree in Materials Science and Engineering from Shanghai Jiao-tong University, China, and her M.S. and Ph.D. degrees in Nuclear Engineering from the University of Illinois at Urbana-Champaign.