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An assessment was made of the influence of underburning of hydrogen in a hydrogen-oxygen steam generator on the technical and economic efficiency of installing a hydrogen energy complex at a nuclear power plant, which is a well-known approach to solving an urgent problem of modern energy systems – ensuring the further development of nuclear energy as an environmentally friendly source of electricity based on the accumulation of off-peak electricity. An approach is considered and a diagram is presented for increasing the reliability of using the hydrogen energy complex at nuclear power plants by reducing underburning and eliminating the entry of unburned hydrogen into the main steam power cycle of the power unit. Several options for the level of hydrogen underburning and a range of system operating conditions for the hydrogen energy complex are considered. A comprehensive calculation of the technical and economic indicators of the hydrogen energy complex at nuclear power plants was carried out, and the conditions for its effectiveness were determined. As calculations have shown, underburning of hydrogen leads to a noticeable decrease in annual income and average annual profit from the sale of peak electricity. The achieved reduction is 11.67 and 35.01 million rubles/year at 5 and 15% hydrogen underburning, respectively. At the minimum tariff for off-peak electricity, the reduction in accumulated net present value is 96.6, 192.8 and 289.4 with an increase in hydrogen underburning to 5, 10 and 15%, respectively. The dependence of the marginal level of hydrogen underburning on the tariff for off-peak electricity, which ensures the efficiency of implementation of the considered hydrogen energy complex at nuclear power plants, is constructed. As calculations have shown, efficient operation of the hydrogen energy complex is achieved at a tariff for off-peak energy in the range from 0 to 0.45, 0.38, 0.3 and 0.24 rubles/kWh with hydrogen underburning of 0, 5, 10 and 15%, respectively. [ABSTRACT FROM AUTHOR]

The increase in the share of energy output from nuclear power plants and the emergence of new requirements of the system operator of the Unified Energy System (UES) of the Russian Federation raise the question of increasing the efficiency of nuclear power plants in alternating mode. At the same time, the operation of nuclear power plants is economically feasible with a maximum utilization rate of installed capacity due to significant capital investments and the low price of nuclear fuel. A possible solution to regulating the level of supplied electricity during off-peak hours of energy consumption is to direct its excess to produce hydrogen with its further sale to consumers without reducing the power of the power unit. According to the analysis, most enterprises that are potential consumers of hydrogen from nuclear power plants have their own modular installations for its production. In the work, a comparative analysis of centralized hydrogen production at nuclear power plants and hydrogen production at places of its consumption was carried out. The daily period of hydrogen production at nuclear power plants is limited to the night period, when there is an excess of generating capacity in the energy system. In this case, local hydrogen production can be carried out evenly throughout the day. This leads to an increase in the cost of hydrogen production at nuclear power plants due to a larger storage system and an increase in the number of compressor and electrolysis units. Nuclear power plants will require significant costs to transport the generated gas. At the same time, the advantage of a nuclear power plant is the cost of consumed electricity, taken at the level of the cost of its production. For industrial consumers, the electricity tariff is significantly higher. In the work, a comparative assessment of the cost of hydrogen production at nuclear power plants and at the site of its consumption was carried out taking into account a range of system conditions. A sales surcharge to the cost of hydrogen production at nuclear power plants was additionally adopted. Zones of competitive efficiency in the implementation of the hydrogen complex at nuclear power plants have been identified, in which the production of hydrogen at the site of its consumption requires greater costs than the purchase of commercial hydrogen from nuclear power plants. Based on the competitive range of the sales surcharge to the selling price of hydrogen at nuclear power plants and the accepted initial conditions, an assessment of the accumulated net present value and payback period of the hydrogen production plant was carried out during its production at nuclear power plants for sale. [ABSTRACT FROM AUTHOR]

The authors have developed an autonomous hydrogen energy complex and analyzed its economic efficiency. The developed energy complex is multifunctional. The main result of the work is the production and supply of electricity to the power system during hours of increased load. In addition, the low-power steam turbines included in the energy complex can provide plant-wide backup of the NPP's own needs in the event of a station blackout: based on the experimental data of the Balakovo NPP, it was previously shown that one power unit with a low-power turbine using the energy of the residual heat from the reactor can for a long time to provide electricity to required power units. Thanks to the installation of low-power turbines as part of the hydrogen energy complex, their constant warm state and self-sufficiency will be ensured by generating electricity for the power grid or for own needs in the normal mode. The paper considers options for installing an autonomous hydrogen power complex with and without replacing expensive external heat exchangers of the system for passive removal of heat from the reactor core. The efficiency of an alternative option without installing a storage system with the sale of off-peak electricity to the power system, which, in the option with AHC, is used to generate hydrogen/oxygen by electrolysis, depending on the tariff for off-peak electricity, is also calculated. Due to the lack of existing analogues of the hydrogen energy complex, several options for the proposed investment were considered. The results of the study revealed that the replacement of expensive equipment of the passive heat removal system significantly increases the economic efficiency of the proposed redundancy system. For the accepted options for capital investments, the boundary values of the off-peak selling tariff for electricity are shown, at which the use of the storage system is more efficient in comparison with the sale of nightly electricity to the power system. [ABSTRACT FROM AUTHOR]

The article deals with the assessment of impact of higher harmonics on the operation of variablefrequency electric drive systems used in processing units at mining enterprises. Beyond that, energy efficiency and operation experience of variable-frequency electric drive usage at mining enterprises were studied. The advantages and drawbacks of implementation of variable-frequency electric drive systems were found. They include energy saving and reducing maintenance costs for processing units on one hand, as well as losses due to their incorrect selection and electromagnetic compatibility distortion on the other hand.

Latchup comparative experimental and software simulation research were performed at various laser wavelengths, pulse durations and spot sizes. Single event to dose rate latchup correlation was found that provides the possibility of SEL threshold energy prediction based on laser dose rate test results.

According to the Technical Requirements for Generating Equipment of Participants in the Wholesale Market of the Unified Energy System (UES) of Russia, from 2016 to participate in the general primary frequency regulation (PFR), the maneuverable characteristics of generating equipment of nuclear power plants with VVER reactors put into operation before 2009 should ensure frequency deviations guaranteed realization of the required primary power for loading up to 2% of the nominal electric power. For this, the current capacity of the reactor installation should be maintained at a level of not more than 98% of the nominal thermal power. The fulfillment of this requirement significantly reduces the installed capacity utilization factor (ICUF) of reactor plant. In addition, at present in the UES of the Russian Federation there is a tendency towards an increase in the deficit of peak and half-peak capacities. The majority of fossil fuel-fired thermal stations are switched to the half-peak mode, which negatively affects their efficiency and reliability. In addition, the rise in price of natural gas makes it more profitable to sell it abroad instead of burning at power plants. On the other hand, an increase in the share of nuclear power plants is observed in the UES, which exacerbates the problems associated with the passage of minima and maxima of the daily load in the power system, due to the economically and technically justified need to load NPPs with maximum CUF. The authors developed an approach to solving this problem by combining NPPs with an environmentally friendly energy source – an autonomous hydrogen power complex (AHPC), which includes heat accumulators and an additional multifunctional steam turbine unit. The developed energy complex will allow energy to be accumulated during hours of minima load in the power system due to the electrolysis of water to produce hydrogen and oxygen, as well as the accumulation of hot water in the storage tanks. The accumulated energy can be used to generate super-nominal electricity to cover the half-peak load zone in the power system. In addition, the presence of a low-power steam turbine installation will ensure uninterrupted power supply to consumers of their own needs at the NPP by using the energy of the residual heat from the reactor when the station is completely de-energized. Based on the proposed power complex, a method has been developed to ensure the participation of NPPs in the PFR in an energy system with a constant CUF. To assess the effectiveness of the proposed solution, a methodology for thermodynamic analysis of the power complex based on the combination of NPPs with AHPC was developed. The dependence of the required hydrogen fuel consumption and the efficiency of using off-peak electricity on the temperature of the feed water supplied to the hydrogen-oxygen steam generator from the hot water tanks is constructed. Based on the results obtained, the technical and economic efficiency of the developed power complex is considered. The accumulated net present value was determined depending on off-peak electricity tariffs with three variants of the forecast dynamics of the half-peak electricity tariff, taking into account natural gas savings, reduced investment in NPP safety systems and the economic effect of ensuring the participation of NPPs in the PFR with the plant load at 100%. [ABSTRACT FROM AUTHOR]

A magneto-optical method is applied to observe surface electrical currents in microelectronic devices. The precise methods of high resolution magneto-optics, used open new opportunities for the designers and investigators of microelectronic devices in diagnostics, failure localizations, and determination of local current regimes.

The paper deals with the problems of hydrogen combustion in an oxygen environment to produce high-temperature steam to be used in electricity generation at various power stations including nuclear power plants (NPP). For example, the use of H 2 /O 2 steam generator within a hydrogen energy complex may allow increasing the NPP power and efficiency under operating conditions due to hydrogen steam superheating of the main working fluid in a steam-turbine unit. In addition, the use of the hydrogen energy complex may allow adapting NPP to variable electric load schedules with the increasing share of such power stations as well as developing environmentally friendly technologies for electricity generation. In the paper, a new solution to the problem of the effective and safe use of hydrogen energy at NPP with a hydrogen energy complex has been proposed. Technical solutions to hydrogen combustion in an oxygen environment using direct injection of cooling water or water steam into combustion products may have a significant weakness, namely the "quenching" phenomenon occurring during water/water steam injection resulting in the recombination efficiency decrease during the cooling of combustion products which is reflected in the increased proportion of non-condensable gases. In this case, the supply of such mixture to the steam-power cycle may be unsafe, as it could result in the increased concentration of unburned hydrogen in the steam turbine flow path. In the paper, a closed hydrogen cycle along with the hydrogen steam superheating system on its basis has been proposed to solve this problem. The closed-circuit system of hydrogen combustion preventing hydrogen permeation into the working fluid of a steam cycle completely as well as ensuring its full oxidation due to some excess of circulating oxygen has been investigated by the authors. Two types of H 2 /O 2 combustion chambers for the system of safe hydrogen steam superheating in NPP cycle by using the closed-circuit system of hydrogen combustion in an oxygen environment have been considered in the study. The required parameters of H 2 /O 2 steam generator with regard to operating temperature conditions as well as the power range of H 2 /O 2 steam generators with the proposed combustion chamber construction design have been determined by mathematical modeling of the combustion and heat-mass-exchange processes. [ABSTRACT FROM AUTHOR]