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1.
Gintautas Dundulis Robertas Alzbutas Ronald F. Kulak Paul V. Marchertas 《Nuclear Engineering and Design》2005,235(17-19):1897-1908
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. 相似文献
2.
Gintautas Dundulis Eugenijus Uspuras Ronald F. Kulak Algirdas Marchertas 《Nuclear Engineering and Design》2007,237(8):848-857
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. 相似文献
3.
Derk J. Swider Luuk Beurskens Sarah Davidson John Twidell Jurek Pyrko Wolfgang Prüggler Hans Auer Katarina Vertin Romualdas Skema 《Renewable Energy》2008,33(8):1832-1842
This paper compares conditions and costs for RES-E grid connection in selected European countries. These are Germany, the Netherlands, the United Kingdom, Sweden, Austria, Lithuania and Slovenia. Country specific case studies are presented for wind onshore and offshore, biomass and photovoltaic power systems, as based on literature reviews and stakeholder interviews. It is shown that, especially for wind offshore, the allocation of grid connection costs can form a significant barrier for the installation of new RES-E generation if the developer has to bear all such costs. If energy policy makers want to reduce the barriers for new large-scale RES-E deployment, then it is concluded that the grid connection costs should be covered by the respective grid operator. These costs may then be recouped by increasing consumer tariffs for the use of the grid. 相似文献
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5.
Removal of free and complexed heavy-metal ions by sorbents produced from fly (Musca domestica) larva shells 总被引:4,自引:0,他引:4
Fly larva shells (FLS) are formed as a side product in the biological treatment of organic wastes, and chitin and chitosan produced from the FLS have been used as sorbents for heavy-metal ions. Sorbents are characterised by FT-IR measurements and pH-potentiometric titration and by determination of their surface area, and the content of main elements (C, N, P, S) and ashes. Free metal ions are sorbed best (up to 0.5-0.8 mmol g(-1)) onto chitin and chitosan. The sorption ability for free metal ions of chitin decreases in the order Fe(III) > Cu(II) (Pb(II) > Zn(II). > Ni(II) > Mn(II) and that of chitosan decreases in the order Cu(II) > Mn(II) > Ni(II) > Zn(II) > Pb(II) > Fe(III). The complexed metal ions are sorbed by the FLS up to 0.2-0.4mmol g(-1). The sorption ability for metal ions and ligands depends on pH, concentration of complexed metal ions and the ligand species in the solution. Glycine has the retarding effect on the sorption of Ni(II) and Cu(II) ions, and EDTA enhances the Cu(II) ion sorption. Ni(II) and glycine sorption obeyed the Langmuir isotherm. The observed sorption data show the promising potentialities of the FLS for the heavy-metal removal from the solutions, containing strong complexing agents. Mechanisms for the removal of free and complexed metal ions by chitin, chitosan and the FLS have been discussed. 相似文献
6.
Jurgis Barkauskas Justina Dak?evi? Remigijus Ju?k?nas Regina Ma?eikien? Gediminas Niaura Gediminas Ra?iukaitis Algirdas Selskis Inga Stankevi?ien? Romualdas Trusovas 《Journal of Materials Science》2012,47(15):5852-5860
Nanocomposite films and coatings were produced from the aqueous solutions containing different proportions of graphite oxide (GO) and Congo red by filtering through a polycarbonate membrane filter into alkaline media. They were examined by electron microscopy, Raman and FTIR spectroscopy, XRD, contact angle, and electrical conductivity measurements. It was established that the Congo red is able to interact through its amino groups with different functional groups of GO to form larger moieties composed of the nanoplatelets of GO. Raman spectroscopy revealed quinoid-like ring structure for dye adhering to the GO. In the case when the interaction occurs with the terminal functional groups located on the edges of the nanoplateletes of GO, larger crystallites in the nanocomposite are formed. The interaction between the Congo red and functional groups of GO situated in a basal plane leads to more compact structure of the nanocomposite. Pulsed laser treatment was used to reduce GO to graphene. Raman spectra of laser treated areas show positive effect of addition of the Congo red on the graphene yield in nanocomposite coatings after the laser treatment. 相似文献
7.
Presented is a study of the accident confinement system of the Ignalina nuclear power plant (NPP) with Russian acronym for ‘channelled large power reactor’ (RBMK)-1500 reactors for the ultimate design basis accident. The computation techniques described pertain to the strength analysis of the accident confinement system (ACS): the design of the ACS compartments, materials, and manner of reinforcement. In strength predictions of reinforced concrete to evaluate the carrying-ability of the structure and its performance by the technique of limit analysis. The ACS analysis with finite elements (FE) of several types yielded instantaneous reserve strength factors for static loads. Numerical results of dynamic effects to the strength evaluation for compartment which houses the downcomers of drum separators are presented. The behaviour of pressure and temperature were taken from the results of thermal hydraulics models. Because of the relatively slow rate of loading, the investigation has confirmed that dynamic effects do not contribute additional insight to regular static analysis. 相似文献
8.
Geotechnical and hydrochemical properties of sewage sludge 总被引:1,自引:0,他引:1
Jonas Diliūnas Kastytis Dundulis Saulius Gadeikis Arūnas Jurevičius Mykolas Kaminskas 《Bulletin of Engineering Geology and the Environment》2010,69(4):575-582
The geotechnical and geochemical properties of sewage sludge from Kaunas city, Lithuania, were investigated to assess whether
it could form a low permeability landfill cover. New sludge, sludge stored or kept in the atmosphere and old sludge were studied.
It was found that over time the strength of the sewage sludge increased due to self-consolidation and destruction of organic
material. The concentration of metals in the sewage extract was considerably lower than in the landfill leachate. It was concluded
that if kept in an open polygon for 1–2 years, the sewage sludge can be used as a low permeability landfill cover. 相似文献
9.
K. L. Hopkinson B. J. Marsden G. Dundulis V. Kopustinskas M. Liaukonis J. Augutis E. Uspuras 《Nuclear Engineering and Design》2003,223(2):117-132
To maintain thermal contact between the fuel assembly and the graphite moderator, RBMK design reactors employ graphite split rings, which are alternatively tight on the pressure tube or tight on the graphite brick central bore. The split in the graphite rings allows a helium/nitrogen gas mixture to flow up the fuel channel. This prevents oxidation of the graphite and can be sampled to detect pressure tube leaks. The initial clearance between the rings and pressure tube or graphite brick is approximately 2.7 mm (1.35 mm each side). Due to material property changes of the pressure tubes and graphite during operation of the reactor, the size of the clearance between the rings and the pressure tube/brick, called the “gas-gap”, varies. Closure of these gaps has been identified as a possible safety case issue by reactor designers and by independent reviews carried out as part of TACIS reviews and as part of the Ignalina Safety Analysis Report. The reasons for this are that gas-gap closure would cause the pressure tube to be tightly gripped by the graphite bricks via the split rings, which could lead to:
- • Extra loading on the upper pressure tube zirconium/steel transition joint, particularly during shut down and emergency transients.
- • Splitting of the graphite brick, leading to loss of thermal contact between the pressure tube and graphite. As approximately 5.6% of the heat in graphite-moderated reactor is generated within the moderator through neutron and gamma-heating, loss of thermal contact would result in higher graphite temperatures, accelerating the rate of graphite expansion and hence increasing the loading of the core radial restraint.
- • Graphite debris may become lodged in inter-brick gaps, leading to increased axial pressure tube loading during shut down and emergency transients.
10.
Gintautas Dundulis Renatas Karalevicius Sigitas Rimkevicius Ronald F. Kulak Algirdas H. Marchertas 《Nuclear Engineering and Design》2006,236(2):201-210
The Ignalina NPP has a pressure suppression type of confinement, which is referred to as the accident localization system (ALS). The ALS prevents the release of the radioactive material from the NPP to the environment during a loss-of-coolant accident (LOCA). Ten water pools are located in the two ALS towers (five pools in each tower), which separate the dry well from the wet well. These water pools condense the accident-generated steam and prevent high overpressures in the compartments.The steam distribution device (SDD), with the vertical vent pipes (nozzles) that are inserted under the water of the condensing pools, connects the dry well and the wet well. In case of an accident, these components must be capable of withstanding the dynamic loads generated by a LOCA for successful pressure suppression function.This paper presents the transient analysis of the SDD and their connections to the vertical steam corridors following a LOCA. A thermo-hydraulic analysis of the SDD was performed using the state-of-the-art COCOSYS code to determine pressure and temperature histories resulting from a LOCA. The finite element code NEPTUNE was used to evaluate the structural integrity of the SDD and its supporting reinforced concrete wall. Results show that, although portions of the SDD undergo plastic response and the outside surface of the vertical steam corridor reinforced concrete wall cracks, the structural integrity of the SDD and wall are maintained during a LOCA. 相似文献