Fundamental study of thermal transport healing via precision control of micro- and nano- ion beam engineered radiation damage annealing promoted by grain boundaries (GB) in crystalline materials. Proposed study aims to attain a strong predictive atomic-to-microscale scale understanding of interface-driven sinking of radiation point defects in bi-crystalline (BC), micro-crystalline (MC) and nano-crystalline (NC) solids ultimately aiding the design of nanostructured radiation tolerant structural reactor components without sacrificing heat conductive perfromance for next generation nuclear plants (NGNPs)