The development of advanced nuclear energy systems, both fission and fusion, has accelerated the search for a new class of materials with superior radiation resistance. Degradation of materials properties is attributed to the accumulation of early irradiation induced point defects such as vacancies and interstitials followed by the formation of more complex extended defects such as dislocations, twins and voids that lead to macroscopic changes such as hardening and embrittlement. Therefore, the ability to remove the incipient point defects is a key material characteristic which can enhance the radiation tolerant behavior of nuclear fuel, clad and structural materials. Recently it is hypothesized that grain boundaries and interfaces can act as sinks for radiation–induced point defects. This suggests that materials with a large volume of internal interfaces can exhibit enhanced radiation resistance. Polycrystalline materials with grain sizes that are of the order of 100 nm, often classified as nanocrystalline (nc) materials, exhibit superior strength as well as appealing thermo–mechanical properties. As nanocrystalline materials also have a large volume of interfaces compared to conventional materials with micrometer sized grains, they are candidate materials for enhanced radiation tolerance.
