Advanced nuclear energy holds promise as a reliable, carbon-free energy source capable of meeting our nation’s commitments to addressing climate change. A wave of investment in fission and fusion power within the United States and around the world indicates an important maturation of academic research projects into the commercial space. The design, certification, and licensing of novel reactor concepts pose formidable hurdles to the successful deployment of new technologies. The high cost of integral-effect nuclear experiments necessitates the use of high-fidelity numerical simulations to ensure the viability of nuclear energy in a clean energy portfolio. The objective of this research is to provide the high-fidelity simulation capabilities essential to this mission by developing unprecedented insight into large-scale multi-physics phenomena. First-of-their-kind, full-core hybrid Reynolds-averaged Navier-Stokes (RANS) calculations and large eddy simulation (LES) of fission reactors are being carried out on DOE supercomputers. Simulations of unprecedented scale are being conducted for fusion energy systems, approaching full-device multiphysics modeling of breeder blankets and for a novel reticulated foam tritium extraction system. 

This research is situated at the opportune moment for leadership computing facilities to impact the trajectory of advanced nuclear. These first-of-a-kind large-scale simulations will usher in a new era where such simulations are possible and firmly establish the nuclear field as a leader in exascale computing.