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  • Author or Editor: Luís Pereira x
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Abstract  

We prove that the cardinal estimates given by Shelah’s bound on the Galvin-Hajnal norm can be obtained via PCF topology alone.

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Authors: Ivone Sato, Luiz Pereira, Marcos Scapin, Marycel Cotrim, Cristiano Mucsi, Jesualdo Rossi and Luis Martinez

Abstract  

Brazilian nuclear power reactor (PWR type) use, as nuclear fuel, sintered UO2 pellets with Zircaloy cladding. The cladding material has to present high mechanical strength and corrosion resistance, which are related to the material chemical composition and microstructural characteristics. Zircaloy machining scraps were remelted using VAR process, resulting in a billet, and its elemental composition was determined. The major elements Zr, Sn, Fe, Cr and Ni were determined by EDXRFS; Hf and contaminants were determined by WDXRFS. The chemical analysis did not show changes in the alloy elemental composition, except for Fe and Cr, which their out-off content can be attributed to contamination from steel scraps. The found Cu contamination may be related to the contact of the melted Zircaloy droplets with copper crucible. The billet microstructure was evaluated using optical and scanning electron microscopy and showed the typical zirconium alloy microstructures (needle and plates) resulting from the high cooling rate and thermal gradients, present during the solidification.

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