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.     

Fishery and Fishculture Challenges in Lithuania

This paper focuses on the development of fishery and fishculture in Lithuania. It provides a brief review of fishery evolution in the Baltic Sea and World Ocean and focuses on Lithuania's inner waters, with a particular emphasis on fishculture in Soviet (1945–90) and post-Soviet (1990–2007) Lithuania. Data for the paper were obtained from statistical yearbooks, state and enterprises' reports, direct contact with institutions and personnel and field survey work. During the Soviet period, more than 20 large state fishculture enterprises were established, each with 500–1000 ha of fishponds. These enterprises also owned 4000–7000 ha of farmland, which were used for rearing ducks and geese, stockbreeding and arable farming. In the Soviet period fishculture was a profitable business because it was partly subsidized by the state and the cost of energy and fish fodder were artificially low, not corresponding to their real value. After Lithuania declared its independence, state support of fishculture ceased, fishponds were privatized and the costs of energy and fodder increased significantly. As a result, fishculture enterprises barely manage to survive in free market economic conditions. Energy costs can be up to 50% of the fishculture enterprises' expenditure. Therefore, it is necessary to look for methods to improve fishculture practices in Lithuania.     

Student progress assessment with the help of an intelligent pupil analysis system

Students and lecturers would like to know how well students have learned the study materials being taught. A formal test or exam would cause needless stress for students. To resolve this problem, the authors of this article have developed an Intelligent Pupil Analysis (IPA) System. A sufficient amount of studies worldwide prove an interrelation between pupil size and a person's cognitive load. The obtained research results are comparable with the results from other similar studies. The original contribution of this article, compared to the research results published earlier, is as follows: the IPA System developed by the authors is superior to the traditional pupil analysis research due to the integration of pupil analysis with subsystems of decision support, recommender and intelligent tutoring systems and innovative Models of the Model-base, which permit a more detailed analysis of the knowledge attained by a student. This article ends with a case study to demonstrate the practical operation of the IPA System.     

Silver nanostructured catalyst for modification of dielectrics surface

The preparation of nano-size Ag particles and their application for forming nanostructured catalysts on various surfaces are described. Silver colloid solutions were prepared by reduction of Ag(I) salt by tin(II) and characterized by electron microscopy, X-ray diffraction and light absorption spectra. Depending on the colloid preparation conditions metal particles of 5-100 nm size were obtained. According to XRD data, the colloid particles contain Ag and SnO₂ phases and no metallic Sn. The Ag nanoparticles were found to be efficient electrocatalysts for anodic oxidation of formaldehyde in alkaline solutions. The catalytic activity of a glassy carbon electrode with Ag surface coverage of 0.3-1 μg cm⁻² is similar or even exceeds that of the metallic electrode. The silver particles were used for the initiation of the electroless copper deposition process on dielectrics; for that 1-2 μg cm⁻² Ag is needed.     

Characteristics of Zinc Corrosion and Formation of Conversion Films on the Zinc Surface in Acidic Solutions of Cr(III) Compounds

The influence of the components of an acidic solution: Cr(III) nitrate-malonic acid-Co(II) salt and treatment conditions on zinc dissolution and formation of Chromate films as well as on their decorative and protective properties have been studied using the analytical, XPS, structural and accelerated corrosion test methods. An organic acid is the main component, which has an essential influence on zinc dissolution and formation of Chromate films as well as their decorative and protective properties. The influence of organic acid is directly related with the state of the Cr³⁺ ions in chromating solution. When the Cr³⁺ ions are in the form of hexaaquaions, the organic acid increases the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface (especially at 60°C). It also predetermines the formation of a thick, porous Chromate film with large cracks at 60°C. Its decorative and protective properties are rather poor. When Cr³⁺ ions are in the form of a complex with organic acid, the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface significantly decrease and thinner Chromate films with an even surface, good decorative appearance and high corrosion resistance are formed Decorative blue-bright Cr(VI)-free films with a slight iridescent tint, obtained in solution, containing Cr(III) nitrate (0.2), malonic acid (0.3) and Co(II) nitrate (0.02) mol dm^?3, at p H 1.6-2.0 at room temperature over 30–60 s, possess corrosion resistance (192–240 h in a salt spray chamber) similar to that of iridescent Chromate films, obtained in acidic Cr(VI) solution.     

Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin

Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but it is very little known about interaction of quantum dots with biological molecules. In this study, interaction of CdTe quantum dots coated with thioglycolic acid (TGA) with bovine serum albumin was investigated. Steady state spectroscopy, atomic force microscopy, electron microscopy and dynamic light scattering methods were used. It was explored how bovine serum albumin affects stability and spectral properties of quantum dots in aqueous media. CdTe–TGA quantum dots in aqueous solution appeared to be not stable and precipitated. Interaction with bovine serum albumin significantly enhanced stability and photoluminescence quantum yield of quantum dots and prevented quantum dots from aggregating.     

The Binding of Anionic Dyes by Cross-Linked Cationic Starches

Adsorption of anionic dyes on the cross-linked with epichlorohydrin starches containing quaternary ammonium groups (CCS) was investigated and compared with that of modified starches containing only quaternary ammonium groups (CS). The adsorption of anionic dyes on CS and CCS closely follows the Langmuir model of adsorption. The computed Langmuir saturation capacity Q _o increases with increasing degree of substitution (DS) of CS or CCS and has the value from 0.81 mol/kg to 3.22 mol/kg for CCS and from 0.88 mol/kg to 1.87 mol/kg for CS. The effectiveness of the cationic groups in dye binding was about 1 mol/equiv for CSS with DS from 0.47 to 0.62 and all the cationic groups had attached one anionic groups of the dye. Increasing DS of CS decreases the effectiveness of dye binding due to the increase in solubility of CS, and the soluble part of CS binds the dye as a typical soluble polyelectrolyte. CCS are more suitable than CS for the anionic dye adsorption from a textile dyeing solution. DS of CCS should be about 0.5–0.6. They adsorb the anionic dyes in few minutes and acts in the wide range of pH of the solutions. The Langmuir saturation capacity Q _o and the effectiveness of the cationic groups in dye binding increase with an increase of the adsorption temperature. The positive values of the enthalpy and entropy suggest that the adsorption is endothermic and during the adsorption of the anionic dye on CCS the randomness of the system increases.     

Thermal–hydraulic evaluation of the RBMK-1500 accident confinement system using CONTAIN 11AF

The response of the RBMK Accident Confinement System to a large break LOCA, medium break LOCA and small break LOCA is analyzed using the CONTAIN 11AF code. The effect of Condenser Tray Cooling System failure is investigated for the large break LOCA case. The analysis employs a best estimate mass/energy source and considers both short and long-term responses of the Accident Confinement System. Parametric studies are performed to evaluate the effects of water deposition on the short-term pressure peak and of by-pass leakage on long-term pressure increases.     

Comparative sensitivity study of the RBMK-1500 reactor one group distribution header blockage accident model

The article presents comparative sensitivity study of the Ignalina NPP RBMK-1500 reactor one group distribution header complete blockage accident model. The accident model was developed by RELAP5 thermal-hydraulic code and the accident scenario is one of the scenarios analyzed in the RBMK reactor safety analysis report. The sensitivity study comprised of the Fourier amplitude sensitivity test and the random sample based sensitivity measures (correlation coefficients and standardized regression coefficients). Two types of the model output were investigated: maximum temperature and dynamic temperature change during the progression of the accident. In addition, the effect of the input parameter distribution of different truncation levels and the effect of double standard deviation to the sensitivity results were studied.     

Integral analysis of large LOCA beyond design basis accident scenario in RBMK-1500

The integral analysis of severe accident scenario for RBMK-1500 was performed using combined approach with RELAP5, RELAP/SCDAPSIM, ASTEC and COCOSYS codes. The performed analysis covered response of the reactor core, the reactor cooling system and the confinement. There were performed several analyses: the first analysis assumed that operators take no action or their actions are not successful to provide the coolant injection to the reactor core; the other analyses were performed to investigate the accident management measures to restore the core cooling at different temperatures of the reactor core. The results of performed analyses showed that the operators have ∼5 h before the ruptures of fuel claddings occur and ∼8 h before the onset of exothermic steam-zirconium reaction. The coolant injection to the reactor core should be restored as soon as possible in order to prevent high hydrogen concentrations in the confinement and significant release of the fission products to the environment.