Experience with irradiation of LiSoR test section no. 3

LiSoR (liquid metal–solid metal reaction) loop is a unique facility which was designed to investigate simultaneously the influence of flowing lead bismuth eutectic (LBE), static stress and irradiation by protons onto steel that might be used as structural material in a future ADS (accelerator driven system) reactor. LiSoR is worldwide the first LBE loop that is under operation while it is irradiated at the same time.Up to now five LiSoR test sections have been irradiated. In this paper the experience on LiSoR no. 3 is presented including irradiation experiment and dissembling of the test section and EDM wire cutting of the samples. Additionally the results obtained by SEM and EDX analyses on LiSoR specimen and on beam window are shown whereby the most interesting outcome is the finding of an oxide layer, which was clearly identified by X-ray mapping. This layer is located directly in the irradiated area having a total thickness less than 1 μm. Additionally solidified LBE was detected on some areas of the samples but no wetting of the steel or penetration of LBE into the steel matrix was observed. No enrichment or dissolution of steel elements such as Fe and Cr could be detected on the surface near area. The steel surface is still smooth without any indications of corrosion attack.     

Free amino acids by high performance liquid chromatography and peptides by gel electrophoresis in Mahon cheese during ripening

The free amino acids and peptides contents of Mahon cheese during four months of ripening were studied using high performance liquid chromatography and gel electrophoresis, respectively. The total content of free amino acids generally increased throughout the ripening period, except in one batch. Phenylalanine, valine, proline, glutamic acid and isoleucine were the most abundant free amino acids in all the tests throughout the four month period. They accounted for between 67 and 80% of the free amino acids. No difference was found between the pattern of traditionally made and industrially made Mahon cheeses. Electrophoresis of soluble nitrogen showed the main whey proteins as well as other bands corresponding to peptides.     

Interfacial stress singularities in a bimaterial wedge

In this paper methods of computing stress singularity factors for strain-hardening materials are reviewed. The methods are applied to calculation of these factors for a bimaterial wedge comprising two power-law hardening materials of arbitrary external and internal angles.     

0.27-dB/km attenuation achieved by MSP preform process [opticalfibers]

Mechanically shaped preforms (MSP) have been demonstrated to combine economic non-CVD (chemical vapor deposition) processing and low loss, with a published value of 0.63 dB/km and a size of 30 fkm/preform. Improved processing is proposed which results in a minimum loss of 0.27 dB/km at 1550 nm. Preforms capable of yielding 150 fkm have been produced. Reboiling during preform stretching and fiber pulling is identified as the last remaining problem of the process     

An experimental study of non-newtonian fluid flow in fluidized beds: minimum fluidization velocity and bed expansion characteristics

In this work, new experimental measurements of the minimum fluidization velocity and velocity-voidage characteristics are reported for a variety of liquid-particle systems in glass columns of two different diameters. Three types of liquids, namely, Newtonian, visco-inelastic, and visco-elastic fluids, were used to fluidize the beds of glass particles of four different sizes (1.27–15.8 mm). The results obtained with Newtonian liquids conform to the expected behaviour. The applicability of a variety of equations has been examined with a view to predicting the values of the minimum fluidization velocity and fluidization index for non-Newtonian systems. The experimental results reported herein embrace the following ranges of conditions: 1.27 < D_p < 15.8 mm; D_T = 50.8 and 101.6 mm, and 0.382 n 1.00.     

Elastic and Magnetoelastic Properties of an Iron–Carbon Powder Steel

The resonance frequency, internal friction, and emf of the double conversion are measured in samples of ZhGr steels of the variable density and carbon content by means of the resonance electromagnetic-acoustic conversion method. For the contactless excitation, the close correlation between the density (porosity) and the resonance frequency of the ultrasonic vibrations is obtained. It is shown that the magnetic state of the samples affects the internal friction. The dynamics of the field dependences of the emf is investigated with allowance for the internal friction in variation of the carbon content. This makes it possible to determine the optimum interval of the field for estimating this parameter.     

Supergain antennas: possibilities and problems

In principle, any desired amount of gain can be developed from an antenna of arbitrary size. The phenomena of high gain from very small antennas is called “supergain”. To see why this statement might be so, the author recalls the construction used in optics, known as Huygens' principle. This states that every point on a wavefront can be regarded as a source of radiation. At the end of a short period of time, the envelope of all of these individual wavelets forms the new wavefront. For example, this construct explains why a shadow is not perfectly sharp, and why interference fringes form. End fire antennas, dipole antennas, Yagi antennas and quad antennas are examined     

Experience in developing ultrahigh capacity compressor stages

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 2, pp. 4–7, February, 1992.     

Bestimmung der Abtragungsraten von Zirconium,Tantal und der Legierung Tantal-40Niob in fluoridhaltiger azeotroper Salpetersäure mit Hilfe der Radiotracer-Methode

The radiotracer technique as a means to investigate the corrosion of zirconium, tantalum, and a Ta-40Nb alloy in fluoride containing azeotropic nitric acid Zirconium and tantalum as well as the tantalum 40% niobium alloy are of considerable technical importance due to their high corrosion resistance against numerous corrosive media. With respect to corrosion testing in analytically pure azeotropic nitric acid in the temperature range between 20 and 121°C, corrosion rates were determined for zirconium: 7 · 10^?6 to 5 · 10^?4 mm/y, for tantalum: 10^?8 to 4 · 10^?6 mm/y, and for the Ta-40Nb alloy: 2 · 10^?7 to 8 · 10^?6 mm/y [1]. These corrosion rates will be markedly increased by adding small amounts of fluorides or by fluoride impurities. The radiotracer method after neutron activation was applied to determine the corrosion rates in azeotropic fluoride containing nitric acid. Even minute additions of fluorides strongly affect the corrosion resistance of zirconium. In the range between 0.15 and 10 ppm F^? and at a temperature of 108°C, corrosion rates between 5.3 · 10^?3 and 3.1 mm/y were measured. It was impossible to establish a limit for the fluoride concentration, below which the corrosion rate of zirconium will not be adversely influenced. The corrosion rates of tantalum and the Ta-40Nb alloy are considerably increasing above a fluoride concentration of 10 ppm. The highest corrosion rates measured were between 8.4 · 10^?3 mm/y at 50°C/280 ppm F^? and 1.4 · 10^?2 mm/y at 110°C/320 ppm F^?. Within the range of this investigation, the corrosion resistance of tantalum was higher than that of the Ta-40Nb alloy by one order of magnitude. The corrosion resistance of zirconium and tantalum was not influenced by any treatment of the samples before testing.