Reliability analysis of pipe whip impacts

A probability-based approach is presented as the integration of probabilistic methods and deterministic modelling based on the finite element method. An existing finite element software package was linked to an existing probabilistic package to analyse the complex mechanics that occur during the transient non-linear analysis of impact problems. This methodology is applied to a pipe whip analysis of a group-distribution-header, which results from a guillotine break, and subsequent impact with the adjacent building wall; this is a postulated accident for the Ignalina Nuclear Power Plant RBMK-1500 reactors. The uncertainties of material properties, component geometry data and loads were taken into consideration. The probabilities of failure of the impacted header and of the header support-wall were estimated given uncertainties in material properties, geometrical parameters and loading. The software ProFES was used for the probabilistic analysis and the finite element software NEPTUNE for deterministic structural integrity evaluation. The Monte Carlo Simulation, First Order Reliability method and Response Surface method were used in the probabilistic analysis.     

Oxidation of Cyclic Acetals as a preparative method of diol monoester production

Glycol monoesters were produced by oxidation of acetals with oxygen, hydroperoxides, hydrogen peroxide, hydrotrioxide and ozon. Addition of salts of metals of variable valency and crown-ether substantially increase the rate of oxidation and hydroxylation. The most efficient oxidizer is ozon.     

Evaluation of pipe whip impacts on neighboring piping and walls of the Ignalina Nuclear Power Plant

Stress corrosion cracks have been discovered in Group Distribution Headers (GDH) at the Ignalina and Chernobyl Nuclear Power Plants. This increases the probability that a guillotine pipe break can occur that creates a whipping pipe (GDH) with the potential to damage surrounding structures—i.e. adjacent GDH and its attached piping or adjacent reinforced concrete compartment wall. The GDH is the most important component for reactor safety in case of an accident. Emergency Core Cooling System (ECCS) piping is connected to the GDH piping such that, during an accident, coolant passes from the ECSS into the GDH.Presented in this paper is the transient analysis of a Group Distribution Header following a guillotine break at the blind end of the header. Using a very conservative force loading function, the transient response of a whipping RBMK-1500 GDH along with neighboring concrete walls and pipelines is obtained using finite element methodology.The results of the study, assuming that the impacted GDH does not suffer stress corrosion cracking, indicate that the structural integrity of the compartment should be maintained and failure should not propagate from GDH to GDH.     

Preparation of Bioactive Mesoporous Calcium Phosphate Granules

Mesoporous calcium phosphate granules ranging in mesopore size from 11 to 19 nm have been prepared using cryogenic processing (–18°C) of gels and extrusion of calcium phosphate paste. The granules based on acid calcium phosphates have a relatively small specific surface area (45 m²/g) in comparison with the neutral and basic calcium phosphates (84–155 m²/g). Preclinical in vivo trials on rats show that the presence of calcium phosphate granules in a bone defect considerably accelerates reparative osteogenesis in comparison with a control group of animals.     

Effect of hydrogen on room-temperature plasticity of B2 iron aluminides

Different sensitivities to hydrogen embrittlement for the disordered and ordered B2 FeAl alloys have been investigated. The plasticity of annealed alloys (before hydrogenating) has been found to decrease with increasing the long-range order parameter. An intrinsic weakness of FeAl phase grain boundaries revealed at a high degree of ordering. The results of bending tests on specimens annealed and cathodically charged with hydrogen have shown that the influence of hydrogen on the plasticity diminishes with the increase in the degree of FeAl phase ordering.     

Influence of ultrasound vibrations on the process of synthesis and the fine structure of combustion products in the titanium-silicon system

The burning rates and maximum combustion temperatures as functions of the ultrasound vibration amplitude are given for mixtures of titanium-silicon powders with different ratios of the initial components. The results of measurements of the crystal lattice parameters of the synthesized phases (Ti₅Si₃ and TiSi₂) are given. It is inferred that the use of ultrasound vibrations in the process of self-propagating high-temperature synthesis provides a method for controlling the crystalline structure of the synthesized materials.Institute of the Physics of Solids and Semicondutors, Academy of Sciences of Belarus, Vitebsk Branch, Vitebsk. Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 471–475, October, 1993.     

Testing Mechanical Stresses of Bearing Steel I-Beams of Automobile Overpass Using Magnetic and Tensometric Methods

Russian Journal of Nondestructive Testing - Magnetoelastic demagnetization of load-bearing I-beams of an automobile overpass in the city of  Tyumen during one month of its operation in...     

Special features of the distributed feedback lasers based on gyrotropic cubic crystals

The oscillation conditions were determined for the distributed feedback lasers based on gyrotropic cubic crystals. The frequencies of clockwise (counterclockwise) polarized longitudinal eigenmodes decrease (increase) by ω_ρ=ρc/n (ρ is the specific optical rotation of the crystal, n is the index of refraction, c is the speed of light in vacuum) relative to the Bragg frequency ω₀=πc/Λn (Λ is the phase grating period). The gain threshold is higher for the clockwise than for the counterclockwise polarized waves.