Helium-induced damage in U₃Si₅ by first-principles studies

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Uranium silicide (U3Si5) is a promising nuclear fuel for enhancing light water reactor accident tolerance.
• Understanding its defect behavior and helium interaction is critical for fuel performance.

Purpose of the Study:

• To investigate primary and secondary point defects in U3Si5.
• To study helium gas dissolution and its impact on defect formation.
• To provide theoretical insights into helium irradiation-induced damage in U3Si5.

Main Methods:

• First-principles calculations were employed.
• Analysis of point defect formation energies.
• Investigation of helium atom interactions with vacancies.

Main Results:

• Silicon vacancies (Si1) are prone to forming single vacancies initially.
• U-rich U3Si5 phases are more likely than Si-rich phases.
• Helium atoms preferentially occupy interstitial sites near uranium vacancies and can form gas bubbles by promoting secondary vacancies.

Conclusions:

• The study provides theoretical insights into defect and helium behavior in U3Si5.
• Findings can guide the design of accident-tolerant nuclear fuels, such as UN-U3Si5 composites.
• Understanding He irradiation damage is key for advanced nuclear fuel development.