Defect-induced strong localization of uranium dicarbide on the graphene surface

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Chemistry

Background:

• Neutron irradiation creates defects, like hexavacancies (V6), on graphite surfaces.
• These defects are crucial for immobilizing radioactive products from nuclear fuels.

Purpose of the Study:

• Investigate the interaction between uranium dicarbide (UC2) molecules and V6 defects on graphene.
• Understand the behavior of uranium carbide fuel species in nuclear reactor cores.

Main Methods:

• Density Functional Theory (DFT) calculations were performed.
• Analyzed the binding energy and nature of the U-C interaction.

Main Results:

• UC2 molecules are strongly trapped in V6 defects with binding energy exceeding 10 eV.
• UC2 saturates the dangling bonds of the V6 defect.
• The U-C interaction involves electrostatic and covalent forces, with significant U valence electron participation.

Conclusions:

• Strong UC2 binding to V6 defects reduces graphite's capacity to retain fission products.
• UC2 exhibits high chemical reactivity and localization on V6 defects in nuclear graphite.
• Findings offer insights for enhancing nuclear reactor safety at the atomic level.