Atomic Simulations of U-Mo under Irradiation: A New Angular Dependent Potential

Wenhong Ouyang,Jianbo Liu,Baixin Liu,Jiahao Li,Wensheng Lai

doi:10.3390/met11071018

Abstract

Uranium-Molybdenum alloy has been a promising option in the production of metallic nuclear fuels, where the introduction of Molybdenum enhances mechanical properties, corrosion resistance, and dimensional stability of fuel components. Meanwhile, few potential options for molecular dynamics simulations of U and its alloys have been reported due to the difficulty in the description of the directional effects within atomic interactions, mainly induced by itinerant f-electron behaviors. In the present study, a new angular dependent potential formalism proposed by the author’s group has been further applied to the description of the U-Mo systems, which has achieved a moderately well reproduction of macroscopic properties such as lattice constants and elastic constants of reference phases. Moreover, the potential has been further improved to more accurately describe the threshold displacement energy surface at intermediate and short atomic distances. Simulations of primary radiation damage in solid solutions of the U-Mo system have also been carried out and an uplift in the residual defect population has been observed when the Mo content decreases to around 5 wt.%, which corroborates the negative role of local Mo depletion in mitigation of irradiation damage and consequent swelling behavior.

Highlights

Pure uranium (U) is limited to a considerable extent in the production of fuel elements due to its questionable properties. α-U, which is stable at low temperatures, has pronounced anisotropy and comparatively low strength characteristics at elevated temperatures
High corrosion resistance in water of high parameters and reliable dimensional stability under irradiation are deciding factors governing the choice of U-Mo alloys as fuel materials
The functions defining the newly the literature and First Principle (FP) parameters calculationsare as shown supplements, especially for phases not observed in developed Angular-Dependent Potential (ADP)

Summary

Introduction

Pure uranium (U) is limited to a considerable extent in the production of fuel elements due to its questionable properties. α-U, which is stable at low temperatures, has pronounced anisotropy and comparatively low strength characteristics at elevated temperatures. Alloying U with Mo remarkably improves its mechanical properties, corrosion resistance, and dimensional stability, along with providing other benefits such as high thermal conductivity and low thermal expansion [3,4]. Enhanced mechanical properties enable U-Mo alloys to be utilized for the production of cores of fuel elements of arbitrary configurations. High corrosion resistance in water of high parameters and reliable dimensional stability under irradiation are deciding factors governing the choice of U-Mo alloys as fuel materials. It is deemed expedient in all cases for U-Mo alloys to be included in the construction of fast-neutron reactors [1]

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Results

Discussion

Conclusion