Point defects significantly impact the performance of a variety of materials employed for nuclear energy applications. Typically, these defects originate from radiation, and are often responsible for the degradation of materials properties. However, as will be shown, defects may also enable functionality important for specific applications. Nevertheless, due to the ubiquity of defects in nuclear energy materials, improved understanding of how properties evolve as a function of radiation exposure is an important challenge. In this talk, three aspects of the nuclear fuel cycle will be specifically addressed: (1) improved understanding of fission gas diffusion in UO<sub>2</sub>, (2) the effect of chemically disparate daughter product formation on the stability of crystalline nuclear waste forms, and (3) the development of improved radiation detectors for safeguards applications. For each of these topics, atomistic simulation techniques were used extensively, but frequent comparisons to experimental data will be made.