**About this Abstract** |

**Meeting** |
**2023 TMS Annual Meeting & Exhibition
** |

**Symposium
** |
**Microstructural, Mechanical and Chemical Behavior of Solid Nuclear Fuel and Fuel-cladding Interface
** |

**Presentation Title** |
Magnetism and Finite Temperature Effects in δ-UZr2: A Density Functional Theory Analysis |

**Author(s)** |
Shehab Shousha, Benjamin Beeler |

**On-Site Speaker (Planned)** |
Shehab Shousha |

**Abstract Scope** |
Uranium-Zirconium (U-Zr) fuels have been historically utilized in liquid metal fast breeder reactors and are candidates for microreactors and advanced reactor designs. However, the phase transformations of the U-Zr alloys, in particular, the phase stability and the chemical ordering of the δ-UZr2 phase, are not well understood. In this work, 0 K density functional theory (DFT) and ab-initio molecular dynamics (AIMD) were used to investigate the stoichiometric UZr2 phase, with and without electron localization corrections. DFT typically overestimates cell volume and predicts a ferromagnetic δ-UZr2 phase, contradicting experiments. The Hubbard U term enhances the ability to calculate formation enthalpies but gives unrealistic magnetic properties. It was found that through the inclusion of temperature via AIMD, both the magnetic state and the volume of UZr2 are more accurately predicted. Through the utilization of AIMD, thermodynamic quantities of the δ-UZr2 phase are predicted for the first time with an accurate magnetic state. |

**Proceedings Inclusion?** |
Planned: |