No abstract available

No abstract available

[en] Short communication

[en] Short communication

[en] Short communication

[en] The thermal conductivity correlations of actinides (U, Pu, Np, Cm, Am) and alloys of U–Zr, U–Pu–Zr and U–Pu–TRU–Zr were developed for the use in TRU burning reactors as a function of temperature and alloy composition, using the available data in the literature and extrapolating information obtained in the literature. Because of the scarcity in the measured data for thermal conductivities of TRU elements in the literature, estimations for the thermal conductivities of Pu, Am, Np, and Cm were made. A correlation for U–Zr alloy was also developed and extended to U–Pu–Zr and U–Pu–TRU–Zr alloys

[en] An amorphous alloy containing uranium and a member selected from the group N, P, As, Sb, Bi, S, Se, Te, Po and mixtures thereof; and use thereof for storage medium, light modulator or optical isolator. (author) figs

[en] Thorium determination in uranium and uranium alloy by dissolution in hydrochloric acid, extraction of uranium, iron and zirconium by a long-chain amine, formation of the complex thorium-thorin in the aqueous phase and spectrophotometry at 545 nm. The method is applicable to thorium content between 0.4 to 250 ppm

[en] The excessive interaction between the U-Mo alloys and their surrounding Al matrix lead to and excessive local swelling called 'pillowing'. For this reason, KAERI suggested several remedies such as alloying U-Mo with Ti, or Al matrix with Si. In addition, silicide, or nitride coatings on the surface of U-Mo particles have also been proposed to hinder the growth of interaction layer. In this study, centrifugally atomized U-7Mo alloy powders were coated with silicide layers at varying T (T = 900 and 1000 .deg. C) for 30 min, respectively. U-Mo alloy powder was blended with Si powders and subsequently heat-treated to form uranium-silicide coating layers on the surface of U-Mo alloy particles. For an annealing test, silicide-coated U-Mo alloy powders were made into a compact, and Al powders were used as a matrix. From EDS results, transformed uranium aluminide intermetallic compounds were mainly U(Al,Si)3. U(Al,Si)3 phase left the silicide coating layer behind, and formed inside of U-7Mo particles, as shown in Fig. 3(a) and (b). In the case of sample B, Al could not penetrate the silicide coating layer and the coating layers were remained constant, as shown in Fig. 3(c) and (d). From the results, we made a comparison between the compacts of sample A and B, and it was shown that Al can easily diffuse into unreacted Si and U_3Si_5 mixed layer while U_3Si_2 acted as a good diffusion barrier at 550 .deg. C though those layers had the same thickness

[en] We investigated the point defect structure of oI20 UAl₄ in order to study aluminum diffusion. We performed ab initio calculations within a pseudopotentials method implemented in the Vienna Ab initio Simulation Package (VASP) to obtain point defect formation energies: vacancies (V^U and V^Al ) and antisites (Al^U and U^Al). Using a statistical-thermodynamic model we calculated defects concentrations as function of temperature and deviation from stoichiometry. For stoichiometric UAl₄ antisites are the dominant thermal defects. In off-stoichiometric UAl₄, antisites are the constitutional defects. For U-rich UAl₄, the thermal defect is called Entre Ramas, where one antisite U atom is replaced by five Al vacancies. For Al-rich UAl₄, the thermal defect is also an Entre Ramas, where four antisite Al atoms are replaced by five U vacancies. Our first principles results were used to model UAl₄ intermediate phase with a two sublattices Wagner-Schottky model. The Thermocalc data bases previously used were modified, including antisites and vacancies in both sublattices of the UAl₄ intermediate phase: (U,Al,VA)_0.2: (Al,U,VA)_0.8. We obtained a consistent thermodynamic database able to reproduce the entire U-Al equilibrium phase diagram (author)