Optimizing the process for chemically decontaminating the multiple forced circulation circuit of power units built around RBMK reactors

It is shown that, when the multiple forced circulation circuit of power units built around RBMK-1000 reactors undergoes chemical decontamination in accordance with the standard procedure, the decontaminating solution is unnecessarily kept in circulation over the circuit for as long as a few days. A criterion is proposed that establishes the moment at which the process of transfer of loose deposits from the surfaces of equipment into the volume of coolant reaches completion. This allowed us to reduce the time taken for the circulation to proceed by an order of magnitude and to increase the amount of radionuclides removed from the multiple forced circulation circuit by a factor of 15 as compared with that removed when the standard procedure of chemical decontamination is carried out.     

Effect of ball milling parameters on the particle size in nanocrystalline powders

A model describing the mechanical comminution (ball milling) of crystals to nanocrystalline powders is proposed. It is shown that a fraction of the energy deposited in the processed material is spent for the creation of microstresses ?, which slows down the comminution process.     

Role of the Purification Filter in Maintaining Water Coolant Quality in the First Loop of Marine Nuclear Power Systems

The effect of the purification filter for the first-loop water coolant in marine nuclear power systems on maintaining the regulated indicators (pH, ammonia concentration, chlorides, iron, and the total specific activity of radionuclides) at a prescribed level is examined. It is shown that constant operation of the purification system does not guarantee reliable accident-free operation of the nuclear power system. The operating regulations for the system should be changed as follows: purification is used on the removed cooled nuclear power system with small deviations of the content of chloride ions or in the process of stopping the nuclear power system if it is necessary to remove the loop the radionuclies contained in the surface deposits. __________ Translated from Atomnaya Energiya, Vol. 99, No. 5, pp. 372–376, November, 2005.     

High-current pulse switching by thyristors triggered in the impact-ionization wave mode

The operation of a thyristor switch triggered in the impact-ionization wave mode was investigated. The switch contained two series-connected Т253-800-24 thyristors of the tablet design with a semiconductor- structure diameter of 56 mm. When a triggering pulse is applied to the switch at a voltage rise rate dU/dt of more than 1 kV/ns, the transition time of the thyristors to the conducting state was shorter than 1 ns. It was shown that the maximum amplitude of the no-failure current increases with an increase in dU/dt at the triggering stage. The possible mechanism of the influence of the dU/dt value on the thyristor breakdown current is discussed. In the safe operating mode at dU/dt = 6 kV/ns (3 kV/ns per single thyristor), the switch discharged a storage capacitor with a capacitance of 1 mF, which was charged to a voltage of 5 kV, through a resistive load of 18 mΩ. The following results were obtained: the discharge-current amplitude was 200 kA, the initial current rise rate was 58 kA/μs, the pulse duration (FWHM) was 25 μs, and the switching efficiency of 0.97.     

Investigation of the Internal Amplification Effect on Planar (p +–n–n +) Structures Made of High-Resistivity Silicon

The first results of studies of special strip and pixel silicon detectors are presented. The detector structures allow the creation of high electrical fields (5 × 10⁵ V/cm) near p–n junctions that are powerful enough to initiate an avalanche multiplication of charge carriers. The possibility of internal amplification in a semiconductor detector similar to the proportional amplification in gas counters is shown. The spectrum of particles from ²³⁸Pu (E = 5.5 MeV) demonstrates an amplified peak at an energy of 70.2 MeV and an energy resolution FWHM = 10.2 MeV.     

Comprehensive study of the conditions for obtaining hydrogenated amorphous erbium- and oxygen-doped silicon suboxide films, <Emphasis Type="Italic">a</Emphasis>-SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>:H 〈Er,O〉, by dc-magnetron deposition

The results of a comprehensive study of the conditions for growing a-SiO _x :H 〈Er,O〉 films are presented. The effect of the composition of various erbium-containing targets (a-SiO _x :H <Er,O>, ErO _x , Er₂SiO₅, Er₂O₃, and Er), substrate temperature, and annealing temperatures in argon, air, and under conditions of SiH₄ + Ar + O₂ plasma glow is studied. In order to obtain a-SiO _x :H 〈Er,O〉 films with the highest photoluminescence intensity of erbium ions, it is recommended for the following technological conditions to be used: the substrate holder should be insulated from dc-magnetron electrodes and the working gas mixture should include silane, argon, and oxygen. Single-crystal silicon and metal erbium should be used as targets. The erbium target should be placed only in the Si-target erosion zone.     

Investigation of Microstructural Humid Deformations in Epoxy Fiberglass at Heat-Humidity Corrosion Using Fiber-Optic Deformation sensors

Protection of Metals and Physical Chemistry of Surfaces - In the present work, the possibility of using integrated fiber-optic deformation sensors (Bragg’s sensors) to control the state of...     

Floral Biosynthesis of Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> and Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanoparticles Using <Emphasis Type="Italic">Chaenomeles</Emphasis> sp. Flower Extracts for Efficient Medicinal Applications

Manganese oxide (Mn₃O₄) and iron oxide (Fe₂O₃) nanoparticles were successfully synthesized with the flower extracts of Chaenomeles sp. This is the first ever approach to synthesize nanoparticles from Chaenomeles sp. flower extracts. The organic molecules present in the flower extracts actively converted the nitrate precursor into its corresponding nanoparticles. The organic molecules that are involved in the synthesis of nanoparticles are identified using different phytochemical and gas chromatography–mass spectrometry analyses. The identified components are glycosides, alkaloids, terpenoids, saponins, flavonoids, quinines, and steroids. The structural and chemical compositions of the synthesized powder were also analyzed. The x-ray powder diffraction analysis revealed that the particles show tetragonal and rhombohedral crystalline phases. The Fourier transform infrared spectroscopy analysis showed the functional groups that are involved in the reduction of nitrates into the corresponding nanoparticles. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of the elements in the synthesized nanoparticles. Transmission electron microscopy images showed the formation of spherical nanoparticles with an average size of 30–100 nm. Antioxidant analysis showed that the synthesized nanoparticles had excellent antioxidant potential. The antibacterial study showed that they inhibit the growth of harmful bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes. Thus, this study proposes a new eco-friendly and nontoxic method to synthesize nanoparticles for medicinal applications.