Papers by Author: Petr Bezdička

Abstract: The civil structures of nuclear plants need to meet the most strict criteria in terms of safety and reliability not only during their design and construction, but during the duration of their life cycle. In addition, during the life-cycle of nuclear plant higher safety demands than the ones at the time of plant design may appear and the plant needs to prove meeting of such requirements. Validation of thermo-mechanical properties was required for the concrete structure of the containment building of Bohunice NPP in Slovakia. Identification of thermo-mechanical parameters of the material used in the containment structure was necessary to perform said analysis and detailed investigation on the concrete composition was performed. This paper describes the information that can be obtained using state-of-the art analytical methods – X-ray diffraction (XRD), X-ray fluorescence (XRF) and thermic analysis (TG/DTA).

Abstract: The civil structures of nuclear plants need to meet the most strict criteria in terms of safety and reliability not only during their design and construction, but during the duration of their life cycle. Regarding the specifics of nuclear plant operation the inspections of the said structures need to be fully non-destructive and visual inspection is the method mostly used. In rare occasions it is possible to obtain a material sample in the form of drilled powder or small diameter core. In this paper, an example of analysis of such material sample is given, showing the amount of information describing the structural material that can be obtained using state-of-the art analytical methods – X-ray diffraction (XRD), X-ray fluorescence (XRF) and thermic analysis (TG/DTA). The paper shows results for regular structural concrete and special concrete with enhanced capability of shielding ionizing radiation.

Abstract: This paper performs a new way of a resorbable surface on Ti alloy preparation. Precalcification of a chemically treated Ti or Ti alloy surface by a supersaturated calcification solution - SCS2 (high content of Ca2+ as well as (PO4)3- ions) allows to short of an induction period in SBF solution (practically immediate reaction stats a hydroxyapatite precipitation). Soluble octacalcium phosphate (Ca8H2(PO4)6. 5H2O was detected by RTG on the surface after calcification. Presumption is: a healing time of the calcified Ti alloy could be shortened.

Abstract: We are reporting the core-shell structured iron/graphite nanoparticles formed by annealing of a nanopowder. The original Fe-C-N based nanopowder has been synthesized by the laser pyrolysis of gas phase reactants. TEM, XRD, Raman spectroscopy, Mössbauer spectroscopy and magnetic measurements were used for its characterization. Nanopowder was heated up to 800°C at ~ 1 Pa vacuum. Presence of iron nanoparticles with the mean diameter of 40 nm in the annealed state of the nanopowder was confirmed from the width of α-Fe X-ray diffraction lines and their core-shell structure was observed under TEM.

Abstract: We present magnetic and morphological characterization of iron- and iron-carbide- based nanopowder obtained by the laser synthesis from sensitized gas phase mixture containing acetylene and iron pentacarbonyl vapors. The analysis was performed on the as-prepared material and the annealed material. The results of TEM, XRD, Mössbauer and magnetic measurements are reported. Phase transformations taking place during annealing of the nanopowder when core-shell nanoparticles appear are discussed.