  This study delves into the complex mechanisms of defect production and
accumulation in nanocrystalline tungsten under irradiation, with a particular
focus on the interplay between grain boundaries and free surfaces. Through
molecular dynamics simulations, the research explores how grain boundaries act
as sinks for irradiation-induced defects, a critical aspect in designing
nanomaterials with enhanced radiation tolerance. The investigation leverages a
novel Modified Wigner-Seitz Analysis to accurately quantify defect trends
amidst dynamic surface reconstruction, providing a nuanced understanding of
defect distribution in response to irradiation. This methodology underscores
the intricate relationship between defect dynamics and the nano-scale structure
of materials, specifically highlighting the role of interfaces in mediating
these dynamics. The findings reveal a complex balance between defect
production, surface interactions, and the influence of pre-existing defects and
temperature on the primary defect production process. Surfaces are shown to
amplify defect production due to biased accumulation of interstitials,
alongside suppressed defect recombination, emphasizing the nuanced nature of
defect dynamics in irradiated materials. This research contributes
significantly to the fundamental understanding of defect formation and
evolution in irradiated tungsten, offering insights that are instrumental in
the development of nanomaterials poised for applications in extreme irradiation
environments, such as fusion reactors, thereby advancing the field of materials
science and engineering.
