The micromechanics of ductile to brittle fracture in polycrystals

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Climate change is one of the most important challenges of our time that should be addressed. It is caused by the increase in the concentration of greenhouse gases. To reduce the emissions, several recommendations are made, e.g., the use of electric vehicles or the integration of combined renewable and non-emitting power production to the electricity grid. In Ontario, this has translated to $25B investment on the refurbishment of the CANada Deuterium Uranium (CANDU) nuclear reactors which has been taking place since 2013 and is scheduled to finish in 2033. As a source of reliable energy that stabilizes the electricity grid, CANDU reactors have been producing more than 50% of zero-emission electricity in Ontario, and 15% nationwide. To further maintain the production of clean nuclear energy, the National Resources Canada has recently prepared a roadmap for developing and deploying Small Modular Reactors (SMRs). To use such advanced technologies, however, there are several barriers that should be overcome. This includes improving the public acceptance of nuclear energy, and reducing the cost of running CANDUs or building SMRs by improving the lifespan of the materials used in the core of the reactors. Improving the lifespan of these materials requires the development of advanced toolboxes that help understand the underlying mechanisms that control their degradation. This program focuses on the development and validation of advanced multiphysics multiscale numerical models to study the degradation mechanisms of the metal alloys used in the core of nuclear reactors. The models will be used to study how short cracks nucleate at the nano and microscales and how they propagate and eventually affect the lifespan of engineering components. Most importantly, for the first time, the effects of neutron irradiation from fission reactions on the embrittlement and fracture of metal alloys will be studied. Attentions will be given to the materials used in the core of CANDU reactors and the potential candidates for SMRs. In addition, advanced diffraction-based and image-based experimental techniques will be developed or used to validate the numerical models. The results will be coupled with machine learning algorithms to enhance the efficiency of the developed methods. The outcomes of this program will help understand the underlying mechanisms that control both ductile and brittle failure of metal alloys. This will reduce the cost of excessive experimentation of reactor materials and will provide more accurate methods for estimating components lifespans. It will help relax the over-conservative safety standards used in nuclear industry which will subsequently help reduce the cost of running the reactors. In addition, this program is designed to improve the public acceptance of nuclear energy by improving equity, diversity, and inclusion in this field through training a diverse group of highly qualified personnel.