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

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.

Determination of trace impurities in advanced metallic nuclear fuels by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS)

Development of a common analytical methodology for the determination of trace impurities in U–Ti, U–Zr and U–Mo alloy fuels by inductively coupled plasma mass spectrometry.

Hot Cell Sample Preparation of Metallic Nuclear Fuels

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Modeling of In, Tl, Ga, Sb, and Pd as lanthanides binding agents in U-Zr metallic nuclear fuels

ABSTRACTAtomistic modeling is used to study the role of different alloying additions to metallic U-Zr nuclear fuels in terms of their ability to reduce lanthanide migration to the outer surface of the fuel and thus reduce their interaction with cladding. The Bozzolo-Ferrante-Smith (BFS) method for alloys is used to examine the behavior of each addition, the resulting phase structure, and the evolution of the fuel surface. Different behaviors are observed for each of the additives (In, Tl, Ga, Sb, Pd), all a result of the competition between the formation of bulk precipitates and the tendency of each additive to segregate to the surface. For each case, characteristic temperatures are determined indicating the range of temperatures in which each additive performs a different role. Sb and Pd additives are determined to be the most effective additions, properly balancing their ability to bind lanthanides in the fuel with their own segregating tendencies.

Ab Initio Study of Advanced Metallic Nuclear Fuels for Fast Breeder Reactors

ABSTRACTDensity-functional formalism is applied to study the ground state properties of γ-U-Zr and γ-U-Mo solid solutions. Calculated heats of formation are compared with CALPHAD assessments. We discuss how the heat of formation in both alloys correlates with the charge transfer between the alloy components. The decomposition curves for γ-based U-Zr and U-Mo solid solutions are derived from Ising-type Monte Carlo simulations. We explore the idea of stabilization of the δ-UZr2 compound against the α-Zr (hcp) structure due to increase of Zr d-band occupancy by the addition of U to Zr. We discuss how the specific behavior of the electronic density of states in the vicinity of the Fermi level promotes the stabilization of the U2Mo compound. The mechanism of possible Am redistribution in the U-Zr and U-Mo fuels is also discussed.