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Abstract—The article considers the efficiency and possibility of introducing into operation of VVER-1000 power units with the lifetime extended owing to the sliding pressure of the second circuit. The history of research by Russian nuclear engineers on VVER lifetime extension is reviewed. It is shown that reduction of fresh steam pressure within the allowed limits will make it possible to release additional reactivity through release of the temperature effect and to generate additional energy during the period of unit operation on the power effect. A mathematical model of changes in the main parameters of the reactor unit, including reactivity balance equations, Stodola–Flugel equation for the turbine, and heat balance and heat transfer equations in the steam generator, is compiled. The expected increase in power generation for modern fuel loadings of VVER-1000 reactors is calculated. The degree of compliance of the proposed mode with the current technological limitations of the large-series VVER-1000 power units is analyzed. The results of the analysis are confirmed by the numerical experiment on the multifunctional analyzer of the VVER-1000 unit modes developed by the National Research Nuclear University MEPhI built on the basis of the ENICAD environment and the certified diffusion neutronic code PROSTOR. Conclusions are drawn about the possibility of introducing the proposed mode into the operational practice of modern VVER-1000 power units. [ABSTRACT FROM AUTHOR]

Global concerns regarding greenhouse gas emissions and global warming have necessitated the speed up in using renewable energies and more efficient use of fossil fuels in the oil and gas industry. Harvesting gas turbine heat by organic Rankine bottoming cycles has raised as a potential solution to cut carbon dioxide emissions in offshore oil and gas installations. Offshore power cycles are expected to operate most of their operational life at part-loads where they suffer from poor efficiency. The purpose of this article is to boost the part-load efficiency of offshore organic Rankine cycles and keep it as close as possible to the design value. Here an operational strategy based on cooling water flow control is developed and added to a sliding pressure control logic and a variable area nozzle turbine control strategy. An in-house tool is developed for the design of organic Rankine cycles and the simulation of off-design control strategies. A design methodology is presented to optimize the cycle power output while minimizing the cycle footprint offshore. The proposed control strategy was successful in keeping the part-load efficiency close to design value and achieving a 5% reduction of annual carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

This paper presents an analytical study of the stationary response of a liquid loaded on its free surface by an ideal pressure step moving in a constant direction at a constant velocity. The acoustic pressure in the liquid is found, in four different examples, by means of the Fourier Transform. Two loading regimes are considered; subsonic and supersonic. Two configurations of liquid domains are also studied, the first one is a half infinite space while the second one is bounded by a rigid bottom at a finite depth. For the two supersonic cases, a simple reasoning based on the existence of a front of discontinuity in the liquid and on the property of reflection of waves confirms the result of the mathematical investigations. The results obtained for the steady state case are of intererest, even when the loading is not exactly stationary, such as the presure produced by an explosion occurring in the vicinity of the surface of a liquid. Two numerically resolved examples are presented, which confirm this assumption. [ABSTRACT FROM AUTHOR]