Diffusion of uranium in refractory BCC metals

Radiation defects generated in Mo formed by sub-MeV Xe ion implantations were studied by atomistic molecular dynamics based on interatomic potential matched to density functional calculations. The results of the simulations were qualitatively compared with defect distributions in CeO 2 and CeLaO 2 crystals used as surrogate materials for UO 2 obtained from experiments by implantation of these ions at a dose of 1×10 17 ions/cm 2 at several temperatures. A combination of in situ Transmission Electron Microscopy (TEM) and ex situ TEM experiments was used to study the evolution of defect clusters during implantation of Xe and Kr ions at energies of 150-700 keV, depending on the experimental conditions. The simulation and irradiation were performed on thin-film, single-crystal materials. The formation of defects, dislocation loops, and precipitates was studied by simulation and compared to experiment. Various sets of quantitative experimental results were obtained to characterize the dose and temperature effects of irradiation. These experimental results include size distributions of dislocation loops, voids, and gas bubble structures created by irradiation.

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“…The self-diffusion coefficient calculated (Fig. 3) is in good agreement with the experimental data available for pure Mo [17,18]. …”

Section: Ibmm 2010supporting

confidence: 78%

Simulation Of Ion Implantation Into Nuclear Materials And Comparison With Experiment

Insepov

Yun

et al. 2011

AIP Conference Proceedings

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“…Refractory metal Zr has been proposed as barrier layer between the U-Mo fuel and Al alloy matrix to reduce the interactions, since the diffusion of U in Zr is slow, [16][17][18] and the fabrication of Zr barrier is compatible with the current hot-rolling techniques used by Idaho National Laboratory (INL). [6] Furthermore, interaction products that form between U-Mo fuel and Zr appear to be stable during irradiation.…”

Section: Introductionmentioning

confidence: 99%

Interdiffusion Between Zr Diffusion Barrier and U-Mo Alloy

Huang

Park

Keiser

et al. 2012

J. Phase Equilib. Diffus.

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U-Mo alloys are being developed as low-enrichment uranium fuels under the Reduced Enrichment for Research and Test Reactor (RERTR) program. Significant reactions have been observed between U-Mo fuels and Al or Al alloy matrix. Refractory metal Zr has been proposed as barrier material to reduce the interactions. In order to investigate the compatibility and barrier effects between U-Mo alloy and Zr, solid-to-solid U-10wt.%Mo versus Zr diffusion couples were assembled and annealed at 600, 700, 800, 900, and 1000°C for various times. The microstructures and concentration profiles due to interdiffusion and reactions were examined via scanning electron microscopy and electron probe microanalysis, respectively. Intermetallic phase Mo 2 Zr was found at the interface, and its population increased when annealing temperature decreased. Diffusion paths were also plotted on the U-Mo-Zr ternary phase diagrams with good consistency. The growth rate of interdiffusion zone between U-10wt.%Mo and Zr was also calculated under the assumption of parabolic diffusion and was determined to be about 10 3 times lower than the growth rate of diffusional interaction layer found in diffusion couples U-10wt.%Mo versus Al or Al-Si alloy. Other desirable physical properties of Zr as barrier material, such as neutron adsorption rate, melting point, and thermal conductivity, are presented as supplementary information to demonstrate the great potential of Zr as the diffusion barrier for U-Mo fuel systems in RERTR.

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“…Fedorov et al [14] studied the impurity diffusivity of 95 Zr in bcc-U and 235 U in bcc-Zr from 1073 to 1338 K, both of which were shown to follow a rigorous Arrehenius relation. Afterward, however, the same research group [15] reported the latter as a curved Arrehenius plot.…”

Section: The U-zr Binarymentioning

confidence: 91%

“…There is some experimental diffusion data available for the U-Pu-Zr bcc alloys, including tracer, impurity, and interdiffusion coefficients [6,7,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. In the subsections that follow, the data is evaluated system by system.…”

Section: Evaluation Of Experimental Datamentioning

confidence: 99%