The purpose of the study is to estimate the efficiency of long-distance heat supply from nuclear power plants with the ability to vary the production of heat and electricity. The method of multi-factor system analysis taking into account the real cost of products produced: electricity, network water for heating and hot water supply were used. Differences in revenue from sales of heat and electricity in different months of the heating period, day and night, and also taking into account the forecast for the future, were taken into account. It is shown that only the price method of accounting for production at nuclear power plants by products can really assess the effectiveness of the multi-product production of NPPs.

Today the problem of maneuverability of nuclear power plants primarily related to those power systems where their market share is growing steadily, as in the center of the European part of the Russian Federation. One of the most effective technologies to fundamentally solve the problem of maneuverability of the water-cooled reactor is modernization of the main circulation pumps by installing variable frequency drives. These drives are used to increase the capacity of a nuclear power plant to a super-nominal, to control the frequency in the power system and to eliminate the system accidents. A technique for calculating the efficiency of variable frequency drives in the main circulation pumps of nuclear power plants with VVER reactors is proposed. The most important advantage achieved with the variable frequency drive of the main circulation pump is a possibility for an additional increase in the power up to 107 - 110% (at NPPs with VVER-1000 an increase up to 104% was achieved) without reducing the safety factor prior to the heat exchange crisis by increasing the coolant velocity. It is shown that an increase in the power, maneuverability, and acceleration capability of VVER nuclear power plants through installation of variable frequency drives in the main circulation pumps leads to an increase in the efficiency of NPPs.

The purpose of the article is to study the possibility and feasibility of participation of nuclear power plants (NPPs) with VVER in emergency frequency control in power systems with a high proportion of nuclear power units and, at the same time, of reducing the power consumption for the own needs of the main circulation pumps during modes with power below nominal. To solve these problems, it was proposed to increase the achievable speeds of power gain (load increase) due to the installation of frequency controlled drives of the MCP. Large system frequency variations (caused by large imbalances between generation and demand) may jeopardize electrical equipment, in terms of maintaining stable and reliable operating conditions. For NPPs, the task of preventing or localizing accidents is even more important than for TPPs, since in case of major system accidents, it is possible to completely stop external power supply of the NPPs own needs. Thus, besides the requirements for the primary control of the frequency of NPPs with VVER, today we need more stringent requirements for their emergency acceleration and mobility. The operation of NPPs with long-term non-recoverable active power shortage causes a decrease in the speed of the main circulation pumps of NPPs with VVER and a decrease in the coolant flow rate. It is shown that the installation of variable frequency drives of the MCPs at NPP with VVER is appropriate not only to save energy consumption for their drive in partial modes, but also to increase the power of NPP above the nominal (without reducing the reserve before the heat exchange crisis in the reactor core) for the elimination of system accidents, and thus to improve the safety of the NPPs included in the power system.

Today important is the scientific study of solutions to the problem of participation of nuclear power plants, both existing and newly built, in the regulation of load schedules.However unacceptable a significant reduction of the capacity factor of nuclear power plants. Sufficient flexible of NPP equipment is the basis not only of the stability of large power systems in modes with violation of the frequency but also safety of the nuclear power plants, Проблемы энергетики, 2017, том 19, № 7-8 95 which would ensure cooling of the reactor during an accident.Therefore, the necessary capabilities of rapid discharges and increase in the load in large nuclear power plants, selected for emergency frequency control. High voltage variable frequency drives (VFD) of the main circulation pumps are able to provide the necessary reserve of growth power.Installation VFD of the MCPs are suitable for saving energy consumption in their drive on the partial regimes and to improve the stability of the neutron-physical active zone characteristics in variable modes.Using VFD of the MCPs can reduce increase pressures in the steam generators in the respective modes, restricting flow the coolant with a constant average temperature in the active zone of reactor, and therefore to reduce the energy consumption of the feed pump.

Decompaction of electric load graphs under the condition of insufficiency of maneuverable capacities (especially in the power systems of the European part of the Russian Federation, with the increasing share of nuclear generation) determines the need to involve nuclear power units in maneuvering modes according to the dispatch schedule. In the long term, nuclear power plants should be ready for long-term operation with a certain (optimal) power reserve in the regime of readiness for a rapid increase of the load for emergency control of the frequency in the event of its fall and a rapid decrease of the load with an overabundance of generation in an unacceptable frequency increase situation. In the most severe situations with a long drop in frequency, the acceleration performance of a nuclear power plant with a WWER can be increased by introducing an additional regulation parameter - the coolant flow rate when installing the variable-frequency drive of the main circulating pump, which has long existed with reactors with fast neutrons, and also with some BWRs in USA. The article shows the additional advantages of the installation of variable frequency drive of the main circulation pump. Firstly, this makes it possible to amplify the impulses of the load change, much more quickly realizing them through a change in the coolant flow rate. Secondly, by increasing the number of revolutions of the main circulation pump, it is possible to increase the permissible value of the heat exchange crisis (DNBR), which will expand (in conjunction with other modernizations) the range of power increase.

The article considers the combination of a nuclear power plant (NPP) with water-cooled water reactors (WCWR) and a distillation desalination plant (DDP) with a horizontal-tube film evaporator (HTFE), their joint operation during periods of covering the dips of electric load schedules and thermo-economic efficiency. A number of advantages are presented in comparison with other methods of desalination, technical characteristics and cost of the DDP with a HTFE of made in Russia series, taking into account the costs not included (construction works, work on sea water supply, electric power, brine distillate, distillate). Such an energy complex makes it possible to increase the capacity factor of a nuclear reactor, as well as to solve the problem of lack of fresh water. The thermo-economic efficiency of this energy complex can be determined both by the complete and simplified algorithm by introducing the "thermo-economic index". Wherein the multi-product energy complex with steam supply from the turbine of the nuclear power plant to the DDP with HTFE should be compared with the version of work from special steam boiler plants (SBP). When analyzing the results of calculations using a simplified algorithm based on the thermo-economic index, the effect of the distillate cost factor on the market is noticeable, as well as the less efficient operation of the desalination plant fed with steam from the SBP as opposed to the steam extraction from the nuclear power plant, especially with increasing the number of hours of operation of the DDP of the HTFE.

The article observes the reliability of the desalination plant with horizontal-tube membrane evaporators, fed by steam from the nuclear power plant (NPP) selections. Structural reliability was taken into account, as well as the reliability of the power supply of the desalination plant with steam turbine from the NPP. The impact of fault tolerance was considered for different hardware diagrams of equipment. The number of autonomous sources of power supply is represented by the number of NPP units (one or two). It is concluded that the probability of failure-free operation of the desalination plant depends mainly on the reliability of the power supply source, the factors of structural reliability have a lesser effect on the reliability of the distillation-desalination plants with horizontally-film evaporation units under vacuum (DDP HEU).

In case of communication losses with the power system and violations of external power supply, difficulties arise with the removal of residual heat generation of stopped reactor plants of NPP with water-water power reactors (VVER). The structural share of these power units grows. That is why they should be responsible for successful emergency frequency control, preventing the collapse of the power system. This is especially important when the frequency decreases with a prolonged growing generation deficit. In this article, we consider the possibilities of increasing the acceleration of NPP with VVER due to the implementation of fast load surges, as well as through prolonged operation with a power higher than the nominal. In both cases, an increase in the rotational speed of the main circulation pumps by the regulation of their drive motors by frequency converters is proposed for NPPs with VVER to increase the values of the crisis heat flow and increase the permissible temperature at the outlet from the core for the same safety reserves. The article briefly analyzes the experience of the introduction and operation of the variable frequency drive of the main circulation pumps at nuclear power plants with fast neutron reactors BN-600 and BN-800. It is noted that due to the smooth regulation of the flow of sodium coolant by the pumps in the main circuits, the problem of the maneuverability of nuclear power plants with BN reactors was largely solved. These decisions, taken already at the design stage of the third and fourth power units of the Beloyarsk NPP and proven positively in operation, were implemented in the project of the 5 th power unit with a fast neutron reactor BN of 1200 MW.

An analysis of the resource base of gas deposits in a number of areas of the Middle Volga region has been carried out, it is shown that small power plants can be built on the basis of these deposits. The analysis of technical characteristics of internal combustion engines and gas turbines of low power is carried out. The variants of the power plant construction depending on the gas flow rate of the field are substantiated. It is stated that it is possible to build a power plant with a capacity of 1.2 – 1.9 MW on the basis of the Yuzhno-pervomajskoe field, 16.0 – 24.0 MW on the basis of the Perelyubskoe field and 10.0 – 13.4 MW on the basis of the Zapadno-Vishnevskoe field. Based on the methodology of project financing, the efficiency of the construction of power plants using low-power internal combustion engines and gas turbines has been determined. An analysis of the risks and sustainability of the solutions obtained was carried out. It is stated that the construction of power plants based on internal combustion engines with a unit capacity of 630 kW and 1,400 kW provides the cost of electricity production in the amount of 0.40 – 0.51 rubles / kWh, depending on the initial technical and economic factors. The construction of power plants based on a gas turbine with a unit capacity of 2.5 – 20.0 MW provides the cost of electricity production at 0.31 – 0.545 rubles / kWh. The results obtained can be used for design studies of construction and decision-making on financing the construction of the power plant.

The analysis of operation of gas-pumping units (GPUs) with various types of supercharger drives (gas turbine and electric drives) is presented. The assessment of overall system effect due to the conversion of a number of compressor stations (CSs) to combined supercharger drive is provided taking into account the concomitant environmental effect. For the successful development of the infrastructure of settlements of roadside consumers, the size of operations areas and environmentally-acceptable (in terms of emissions and noise) distances to the boundaries of the protection zone of CS of the main gas pipeline (MGP) are important. The method of determining the distance from the CS at which the air quality standard is observed is formalized and calculations of boundary distances for CS of MGP are carried out. The functional diagram for calculation of ecological factors during the modernization of CSs at the conversion to combined supercharger drive is made. The calculated characteristics of dispersion options for emissions from the CS with gas turbine drive are presented. Graphical dependences of the value Cx / Cm on the distance to the point of maximum emission concentration in the surface air layer are obtained. The conversion of a number of CSs to combined drive is able to provide the following benefits: during the off-peak periods the electric power supply of the electric drive of GPU of the CS of MGP is carried out by additional load of nuclear power units; load of the electric drive at night is better because of the greater temperature difference between the exhaust gases of the gas turbine and the outside air, and at the same time, either smaller number of gases are evacuated through the mouth of the exhaust pipes (fragmentary conversion to the electric drive), or there is no flue gas emission at all (complete conversion to the electric drive); the project sanitary withdrawal of residential and agricultural land in the area of CS of MGP under the conditions of excess air pollution is reduced. At the high price of land near the right-of-way of CS of MGP this can result in additional tangible effect: more "close" abutting to the industrial site of the CS with combined drive (permitted by air quality standards), which causes less capital-intensive logistics solutions along the heating main.

The article discusses the combining nuclear power plants (NPP) with pressurized water reactors and distillation-desalination plants (DDP), their joint mode of operation during periods of coating failures of the electric power load graphs and thermo-economical efficiency. Along with the release of heat and generation of electric energy a desalination complex with the nuclear power plant produces distillate. Part of the selected steam "irretrievably lost" with a mix of condensation of this vapor in a desalination machine with a flow of water for distillation. It means that this steam transforms into condition of acquired product - distillate. The article presents technical solutions for the return of the working fluid for turbine kappa-1000-60/1500-2 kappa-1200-6,8/50, as well as permissible part of low pressure regime according to the number of desalination units for each turbine. Patent for the proposed two-product energy complex, obtained by Gagarin State Technical University is analyzed. The energy complex has such system advantages as increasing the capacity factor of a nuclear reactor and also allows to solve the problem of shortage of fresh water. Thermo-economics effectiveness of this complex is determined by introducing a factor -" thermo-economic index". During analyzing of the results of the calculations of a thermo-economic index we can see a strong influence of the cost factor of the distillate on the market. Then higher participation of the desalination plant in coverage of the failures of the graphs of the electric loading then smaller the payback period of the NPP. It is manifested more clearly, as it's shown in the article, when pricing options depend on time of day and the configuration of the daily electric load diagram. In the geographical locations of the NPPs with PWR the Russian performance in a number of regions with low freshwater resources and weak internal electrical connections combined with DDP might be one of the ways to improve the competitiveness of NPPs, especially for foreign coastal areas.

The thermal power of NPP with VVER-100 can be increased by increasing the flow of reactor water by increasing the number of revolutions of the main circulation pump. The computational method proposed in the present article makes it possible to determine, for prescribed relations between the reactor water flow and the crisis of heat exchange in the reactor setup with known geometry of flow over the fuel elements and with the prescribed heightened coolant flow, the admissible power increment for constant safety margin of the heat-engineering reliability of the core. The expected effects and problems in implementing the method of operating the reactor are examined and evaluated.

The effectiveness of combining nuclear power plants equipped with water-cooled water-moderated power-generating reactors (VVER) with other sources of energy within unified power-generating complexes is analyzed. The use of such power-generating complexes makes it possible to achieve the necessary load pickup capability and flexibility in performing the mandatory selective primary and emergency control of load, as well as participation in passing the night minimums of electric load curves while retaining high values of the capacity utilization factor of the entire power-generating complex at higher levels of the steam-turbine part efficiency. Versions involving combined use of nuclear power plants with hydrogen toppings and gas turbine units for generating electricity are considered. In view of the fact that hydrogen is an unsafe energy carrier, the use of which introduces additional elements of risk, a procedure for evaluating these risks under different conditions of implementing the fuel-and-hydrogen cycle at nuclear power plants is proposed. Risk accounting technique with the use of statistical data is considered, including the characteristics of hydrogen and gas pipelines, and the process pipelines equipment tightness loss occurrence rate. The expected intensities of fires and explosions at nuclear power plants fitted with hydrogen toppings and gas turbine units are calculated. In estimating the damage inflicted by events (fires and explosions) occurred in nuclear power plant turbine buildings, the US statistical data were used. Conservative scenarios of fires and explosions of hydrogen-air mixtures in nuclear power plant turbine buildings are presented. Results from calculations of the introduced annual risk to the attained net annual profit ratio in commensurable versions are given. This ratio can be used in selecting projects characterized by the most technically attainable and socially acceptable safety.

Article is devoted comparative efficiency of construction storage power station and hydrogen superstructures on the atomic power station at non-uniform electric power consumption. Consecutive scenarios of realizations of input of hydrogen superstructures on the atomic power station are proved.

A low-cost version of modernizing a nuclear power station is considered in which the main profile (standard size) of the power unit is retained and insignificant changes are made in the turbine unit’s operational parameters. These changes consist in that steam supplied to the high-pressure cylinder is subjected to slight initial superheating, and that that the design superheating of steam upstream of the low-pressure cylinder is increased to some extent. In addition, different versions that can be used for heating the working steam to the required temperatures in the H2/O2 steam generator’s mixing chamber are analyzed.

A train of a few tens of high-power subnanosecond laser pulses with a repetition period of 10 ns is generated in the Iskra-5 facility. The laser pulse train has an energy of up to 300 J and contains up to 40 pulses (by the 0.15 intensity level), the single pulse duration in the train being ∼0.5 ns. The results of experiments on conversion of a train of laser pulses to a train of X-ray pulses are presented. Upon irradiation of a tungsten target, a train of X-ray pulses is generated with the shape of an envelope in the spectral band from 0.18 to 0.28 keV similar to that of the envelope of the laser pulse train. The duration of a single X-ray pulse in the train is equal to that of a single laser pulse.

The margin to critical level of heat exchange of thermal power and coolant temperature at the core exit as well as the nonuniformities of the energy release under the operating conditions of a nuclear power plant with VVER-1000 above nominal power is analyzed for the No. 2 unit of the Balakovo nuclear power plant. It is confirmed that the safety criteria comply with OPB-88/97. The content of each of the three main stages of operation is presented. Conclusions are drawn and recommendations are made concerning updating the technical design of the reactor facility in order to increase the power level.