A first-principles study of hydrogen surface coverage on δ-Pu (100), (111), and (110) surfaces

Area of Science:

• Materials Science
• Corrosion Science
• Computational Chemistry

Background:

• Hydriding corrosion of plutonium causes surface damage and structural failure.
• Hydriding initiates at or near the plutonium surface.
• Systematic evaluation of hydrogen surface coverage on plutonium is lacking.

Purpose of the Study:

• To compute surface energies of face-centered cubic δ-Pu low facet surfaces.
• To determine adsorption free energies of hydrogen structures at varying coverages.
• To elucidate the progression of site filling with increasing H2 partial pressure.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Surface energy computations for δ-Pu facets.
• Adsorption free energy calculations for hydrogen.

Main Results:

• Calculated surface energies for low facet surfaces of δ-Pu.
• Presented adsorption free energies for low and high hydrogen coverage.
• Identified likely site-filling progression with increasing H2 pressure.

Conclusions:

• Provides a systematic evaluation of hydrogen surface coverage on plutonium.
• Offers insights into hydride nucleation under different pressure conditions.
• Informs strategies to mitigate plutonium hydriding corrosion and ensure structural integrity.