[en] The technique for neutron activation analysis is described to determine residual quantities of microalloying additions and deoxidizing impurities in steels. Steel samples were irradiated with a thermal neutron flux in a nuclear reactor. Energy spectra were measured by means of a Li-drifted Ge detector in a combination with a multichannel amplitude pulse analyzer and with a variable threshold amplifier. Determined were La, Ce, Nd, U and CaSiBa, which were added to steel in the form of alloying additions of various compositions. Energy spectra were processed using a computer. It was shown that the detection limits for the present method were 10^-6% for La and 10^-5% for Ce, Nd, U

[en] Six steel melts with silicocerium, lanthanum, neodymium and samarium additions were analyzed by irradiation over 40 hours using the WWR-S-Prague nuclear reactor. Spectra were measured with a Ge(Li) detector 18 cm³ in volume manufactured by UJV Rez, connected to a 400-channel analyzer. It was found that the cerium residue should not exceed 0.03%. The effect, formation and classification of inclusions in steel are discussed. (M.K.)

[en] A constant linear combination of the concentrations of radionuclides formed in the depth studied is obtained by selecting the type and energy of activating particles and the cooling period of the activated surface of the material of an investigated part and/or of a medium containing particulates of abrasion and/or corrosion products from the activated layer. The linear combination coefficients are deternined experimentally using standards with a known depth dependence of concentration of the individual radionuclides. In the surface layer under study, the linear combination of residual activities of the individual radionuclides is determined whose decrease is directly proportional to the layer thickness loss. In the medium containing the particulates of abrasion and/or corrosion products, the linear combination is determined of activities of the individual radionuclides proportional to the concentration of particulates from the activated layer of the medium. (J.P.)

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[en] Short communication

[en] Radioactive tracers were used for the investigation of the corrosion resistance of ceramic materials to the effects of aqueous media. The method is based on the activation of samples in a nuclear reactor and the measurement of the gamma radiation of the individual components eluted from the samples into test baths. The work was aimed at studying the stability of ceramic material samples for high-voltage insulators with a semiconductive glaze developed by the Research Institute of Electrical Engineering Ceramics in Hradec Kralove. The measurements were performed using a spectrometric system with a Ge(Li) semiconductor detector. The results were computer processed. The corrosion resistance of different newly developed types of semiconductive glazes was estimated in comparison with the standard type PVG-MR. The sensitivity of the employed method permits the determination in 10 ml volumes of eluate of the glaze constituents in quantities as low as 10^-8 g chromium and 10^-6 g iron. (author)

[en] To determine process of wear for improvement of machine parts and structures in the machine-building, now, in the frameworks of the speeded up testing for the life-time and reliability determination, radionuclides are used. One of the new methods is the surface activation of the working surfaces of machine parts by the accelerated particles. During activation, radionuclides are produced only in the thin surface lay of metal, and with this total activity of the machine parts remains low, which permits to use activated machine parts in the exploitation conditions. Relative activity of the surface layers is high which permits to obtain high enough sensitivity in measurement of wear. Applicability of this method has been shown on the examples of the data obtained during testing of the course of wear in wear in gear-boxes. Comparison was done of the lubricating oils and structural materials. Tests were conducted on the activated tooth gearing for lorries and city buses. In the tooth gearing tested, working planes of engagements of teeth were activated by different charged particles, for example: by neutrons with 12 MeV energy. The thickness of activated layer in these conditions was equal about 200μm. Dependence of the surface activity on the degree of wear can be considered being linear up to the layer depth equal to 50μm. Results of these tests, conducted without dismantling of gear-boxes, permit to obtain in the short period of time, information about the process of wear, which is impossible to get by any other mehod

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