Russian Nuclear Power Plants Research Articles

Fuzzy logic algorithms for classification and parameterization of eddy-current signals

Safety of nuclear power plants operation depends on steam generator safe operation. Russian nuclear power plants with water-water energetic reactors WWER-440 and WWER-1000 use horizontal type steam generators which are cylindrical objects of 3 m diameter and 12 - 15 m length. Steam goes through steam generator tube sheets in the bottom from hot end and passes its energy through heat-exchanger tube system and become colder on the other tube sheet. Reactors WWER-440 have more than 5,000 tubes in one steam generator and reactors WWER-1000 have already 11,000 tubes in one steam generator. Each block of WWER-440 reactor has 6 steam generators, and each block of WWER-1000 reactor has 4 steam generators. A thin-walled steam generator tube can be a threat of nuclear fallout in case of high pressure in primary coolant loop. To be an effective barrier these tubes should be free from corrosion, thinning and cracks.

PR as a tool for the development of nuclear energy in Russia and abroad

The author estimates the impact of PR technologies on the development of nuclear power in Russia and in a number of foreign countries (USA, China, Japan, France). It is determined that as soon as at the stage of development of nuclear generation projects and other nuclear industry facilities, the use of public relations (PR), with a targeted impact on public opinion and interaction with target audiences (TA) at its core, has a significant impact on decision-making in favor of the construction of nuclear power plants, minimizes the protest behavior of the population. It is shown that the advantages of nuclear power among alternative energy sources for strengthening the socio-economic potential of states and increasing their environmental well-being are most clearly, quickly and effectively disclosed through using public relations tools. PR enables to form an adequate and correct understanding of the physical and chemical foundations of nuclear power engineering, the main threats and systems for their minimization or complete elimination at the conceptual, socio-psychological and socio-logical levels, as well as to form, in terms of specific objects and tools, the technological and organizational facilities for the development of nuclear energy projects both in Russia and in foreign countries. The activities of foreign and Russian companies aimed at ensuring loyal public opinion in relation to nuclear projects are critically described and analytically compared. The chronological framework covers the recent period: from the beginning of the 2000s to 2020. This period is noted as the most significant for the development of nuclear power in the world. Statistical data on changes in the attitude of the public in different countries to the prospects for the development of nuclear energy after the Chernobyl and Fukushima-1 disasters are presented. It is concluded that it is PR in its integrated application that contributes to government decision-making and public support in the construction of nuclear power plants in Russia and abroad.

РАЗРАБОТКА ПРОГРАММЫ МОНИТОРИНГА (КОНТРОЛЯ) ОБЕСПЕЧЕНИЯ БЕЗОПАСНОСТИ АТОМНЫХ ЭЛЕКТРОСТАНЦИЙ

Nuclear power plants (NPP), being complex technological systems, represent a source of increased risk, in particular, a specific risk of radiation exposure. Obtaining quantitative assessments of radiation risk is critical for risk reduction and accident prevention. Existing methods for assessing radiation risk do not take into account the influence of external factors, such as population composition, geographical features, anthropogenic environmental changes, etc.[1].
 Since 1997, in connection with changes in the norms and rules in the field of the use of atomic energy, it became necessary to perform a probabilistic safety analysis (PSA) at all nuclear power plants in Russia. Subsequently, a standard safety data sheet for a hazardous facility was developed. To fill out the second section of the safety data sheet, it is necessary to carry out a risk assessment of the objects in question. From this moment on, risk assessments were performed for all power units of all operating nuclear power plants in Russia. Today, in our country there are 14 nuclear power plants. On average, there are 3 power units per nuclear power plant. In order to systematize and centralize data on NPP risk assessments, it became necessary to develop a program for monitoring NPP safety.
 The aim of the work is to develop a monitoring (control) program for ensuring the safety of nuclear power plants, using modern technologies to systematize and group data on nuclear safety data sheets, as well as organize quick access to information.

Definition of requirements for REMIXand MOX-fuel effective employment for VVER-reactors

Abstract An important task of the current stage of development of the existing nuclear power system is to find a configuration in which it comes to full self-sufficiency in fuel. A significant share of Russian nuclear power plants at the current stage and in the near future are thermal VVER reactors operating in the open fuel cycle. The first stage of the transition to fuel self-sufficiency can be considered the option of loading these reactors with REMIX and MOX fuel, which will improve the fuel supply indicators. The paper presents a comparison of efficiency indicators presented by the fuel component of the cost and material balance for the scenarios of nuclear power plant development with VVER reactors loaded with classical uranium and REMIX/MOX fuel. The costs of fuel handling stages were considered as variable initial parameters. The calculations were carried out using the STEM-NES software developed at NRC \Kurchatov institute".

Conservative Tritium Exposure Assessment in the Atmosphere from the Spray Ponds of the Balakovo NPP

Atmospheric tritium discharges from nuclear power plants (NPPs) may have a significant impact on the population and should be constrained by radiation safety requirements. In this study we show that the spray ponds used for water cooling in some Russian NPPs are liable to state registration and regulation in accordance with national legislation. A comparison of possible conservative approaches to assess the intensity of tritium releases from the spray ponds was carried out using the example of the Balakovo NPP. Estimates of the evaporated water amount varied from 35 000 to 60 000 m3 over the 82-day period of stable snow cover in 2016–2017. These estimates corresponded to the total tritium activity discharged into the atmosphere during the evaporation from all spray ponds in the range from 5.2 × 1011 to 9.7 × 1011 Bq. The power of the source was from 7.4 × 104 to 1.4 × 105 Bq/s according to the thermodynamic and thermophysical approaches, respectively. The results of the investigation confirm the assumption that the spray ponds of the Balakovo NPP are a standardized source of tritium releases and should be constrained by setting airborne discharge limits.

Открытые системы техводоснабжения атомных электрических станций как экологические регуляторы природно-технических систем

A fundamentally new vision of the ecological role of nuclear power facilities is substantiated. The materials given in the article are intended for a wide range of specialists working in this field and interested in forming an adequate image of their activities. Nowadays, lack of an unbiased and comprehensive assessment of the impact of nuclear power facilities on the environment does not make it possible to firmly argue against false information disseminated in the society. One of the arguments often used by opponents of nuclear power is that discharged spent cooling water has a negative impact on the environment. As a rule, these statements remain without having been duly refuted. This article is intended to change the situation. The results of the authors’ long-standing work on studying the ecological condition of cooling water reservoirs at Russian nuclear power plants (NPPs) served as the main factual material for this article. According to the data received, the spent cooling water discharged from the NPP service cooling water systems often has better quality than that of the initial cooling water supplied to them. Owing to artificial heating of water in fresh and marine water bodies, they gain enhanced levels of biological productivity and biodiversity. In addition, the positive aspects of service cooling water supply systems can be further enhanced by developing environmentally oriented innovative solutions both at the stage of NPP designing and during their operation. An extensive set of various economic facilities can be developed by using the service cooling water supply systems of NPPs as a basis. Thus, by arranging controlled supply of heated water, conditions for setting up manageable natural-technical systems are created. In developing countries, this will make it possible to solve the problems of insufficient food and water consumption resources. The implementation of these capabilities in elaborating pre-investment, pre-design, and design documentation for NPPs will help improve the competitiveness of nuclear power and the environmental safety of its facilities.

Применение удельного показателя для оценки объемов образования РАО при нормальной эксплуатации АЭС России

Generation of radioactive wastes (RW) is viewed a most urgent problem of radiation safety under normal operation of nuclear power plants (NPP). The paper demonstrates the application of a specifi c indicator (rate) of RW generation per unit of generated power (m3/GW·h) for a retrospective assessment and forecasting of RW generation volumes at Russian NPPs. Mean and median values of annual specifi c RW generation rates were calculated for each NPP based on published environmental reports of JSC Rosenergoatom Concern for the period of 2008—2018. Advantage of applying median values in retrospective and forecast assessments was shown. Medians for solid very low-level, low-level, intermediate-level and high-level radioactive waste amounted to 1.5·10−2 m3/GW·h, 3.3·10−2 m3/GW·h, 3.3·10−3 m3/GW·h and 2.8·10−4 m3/GW·h, respectively; for liquid low-level and intermediate-level waste these values accounted for 1.4·10−3 m3/GW·h, 2.5·10−3 m3/GW·h, respectively. NPPs with RBMK reactor units are characterized by the highest mean and median values of specifi c RW generation rates for all RW categories. Given various types of reactor facilities and their characteristic specifi c rates, retrospective estimates for the total volume of liquid RW was increased by 8 % and for solid RW — by 12 %. The forecast estimates based on specifi c rate medians, as well as on increased power generation planned for Russian NPPs indicates probable increase in RW generation volumes by 0.8—7.1 % (depending on waste category) from 2020 to 2027.

Cause and effect analysis of failures at Russian nuclear power plants between years 1992 and 2018

Multiple systems determine safe operation of every nuclear power plant. Elements of these system may periodically fail due to some reasons. This article contains annual failure statistics analysis of Russian nuclear power plants between years 1992 and 2018. It was also assessed the effectiveness of nuclear power plant safety improvement measures, aimed on failure elimination.

Development of the model to determine the fuel temperature field in a two-dimensional problem statement

Water-cooled water-moderated reactors (VVER) are widely used at Russian nuclear power plants. The VVER reactor core is formed by fuel assemblies consisting of fuel rods. The fuel in fuel rods is uranium dioxide. The safety of the reactor operation is ensured through stringent requirements for the maximum nuclear fuel temperature. Calculation of temperature fields within the reactor core requires associated problems to be solved to determine the internal energy release in fuel based on neutronic characteristics. Dedicated software for such calculations is not available to a broad range of users. At the present time, there are numerical thermophysical modeling packages available for training or noncommercial applications which are used extensively, including Elcut, Flow Vision, Ansys Fluent, and Comsol Multiphysics. Verification of the obtained results is becoming an important issue in building models using these calculation packages. An analytical solution was obtained as part of the study for the fuel temperature field determination. A program was developed in MathCAD based on this solution. A model was developed in Comsol Multiphysics to determine the fuel temperature field with constant thermophysical properties in a two-dimensional problem statement. The numerical model was verified using the analytical solution. The influence of the number of the grid nodes on the solution accuracy was established. The analytical solution can be used to determine the fuel temperature field at any radial coordinate of the reactor. The temperature field determination model developed in MathCAD can be used to verify numerical models of the fuel temperature field determination developed in dedicated packages.

Social development of Russian nuclear power plant cities

The article presents the analysis of the influence of historical factors on the development of Russian cities of nuclear power industry and the genetic types of these cities. Most of these cities are young, their socioeconomic state depends on the city-forming enterprise. The formation and development of nuclear power plant (NPPs) cities went in two ways: the city was built in parallel with the nuclear power plant (e.g., Novovoronezh, Desnogorsk, Kurchatov); the NPP was built near the settlement, and then NPP has influenced on socioeconomic development of the settlement, its employment structure, etc. (Volgodonsk and Balakovo). In USSR/Russia practice, the first way dominated, when an urban-type settlement was built near a NPP, such settlement then intensively grew and developed into a city. There are three types of Russian cities with NPPs: the cities formed and developed before the construction of the NPP; the cities developed due to the operation of NPPs, and the cities created and developed due to the operation of NPPs. It was found that the factor of formation of nuclear power industry in the city is decisive in the social development of almost all cities of NPPs and affects their current state.

Special monitoring results for determination of radionuclide composition of Russian NPP atmospheric releases

Abstract Measurements of activity concentrations of radionuclides in atmospheric releases were performed in 2017–2018 at vent stacks of seven Russian nuclear power plants. The selected instruments and research methods, with detection limits significantly lower than the existing detection limit of Russian NPPs routine control, allowed to reliably determine up to 26 radionuclides. Analysis of experimental data allows to determine the list of radionuclides for calculation the effective dose rates to public and the permissible annual discharge levels for each Russian NPP. Radiocarbon is determined as major contributor for the dose from the atmospheric releases of LWGR reactors – up to 98% for EGP-6 and RBMK-1000 (Smolensk NPP) reactors. For PWR reactors (VVER) radionuclides contribution to the annual dose from atmospheric releases is more complicated, but, in general, dose is formed by tritium, 14C and noble gases. The special monitoring results with ranking of measured radionuclides according to their contribution to the effective dose makes it possible to optimize the list of controlled radionuclides in airborne releases of Russian NPPs from 94 to 8–16 for different NPPs.

Local Flow-Accelerated Corrosion of Welds in NPP Power Unit Pipelines: Phenomenon Mechanism Features and Measures to Prevent Damage

Flow-accelerated corrosion of metal caused by single- or two-phase flow of working fluid leads to thinning and destruction of welds in NPP power unit pipelines. Field experience gained from the operation of Russian and foreign nuclear power plants testifies that there have been many cases of damages inflicted to welds due to local flow-accelerated corrosion, the number of which tends to grow with the time for which the power units have been in operation. The article gives examples of the most typical places and characteristic features pertinent to the way in which the flow-accelerated corrosion of weld elements' metal takes place. The role and influence of the chemical composition of the weld metal and heat-affected zone metal on the location and rate of local flow-accelerated corrosion thinning in welds are determined. The flow hydrodynamic characteristics having an essential effect on the rate of flow-accelerated corrosion processes and the local thinning occurrence places are determined. Results from numerical modeling of the flow-accelerated corrosion weld thinning development process for different contents of chromium in the weld and heat-affected zone metal are given. The possibility of increasing the flow-accelerated corrosion rate in pipelines downstream of a weld with a preceding extended straight pipeline segment made of metal not prone to flow-accelerated corrosion is analyzed. Methods aimed at preventing the occurrence of damage to pipelines of NPP power units due to flow-accelerated corrosion are discussed. The article gives information on the results of activities for modifying the standard programs for in-service inspection of pipelines at VVER-based NPPs and also on the use, at Russian NPPs, of software systems providing support to the personnel on optimizing the arrangement and scheduling of in-service monitoring of flow-accelerated corrosion wear of heat-affected zones in welds of the pipelines used at NPP power units equipped with VVER-440, VVER-1000, and BN-600 reactors. It can be expected that the application of regularly updated software systems for supporting the personnel will make it possible to timely prevent inadmissible thinning and abrupt flow-accelerated corrosion-induced failures of pipeline welds in the power units of Russian nuclear power plants.

К 100-летию со дня рождения Бориса Михайловича Трояновского

The article is devoted to the scientific and pedagogical activities of B.M. Troyanovskii, Doct. Tech. Sci., Professor of the MPEI Chair of Steam and Gas Turbines named after A.V Shcheglyaev, on the occasion of his 100th anniversary. The article outlines the main results of scientific investigations that determined the development lines of large-capacity steam turbines for thermal and nuclear power plants in Russia and abroad, and the principles of designing the last stages of low-pressure cylinders for large-capacity steam turbines.

Russian Projects and Energy Cooperation in South Africa

The article discusses the problems and prospects for the development of a Russian nuclear power plants in South Africa, as well as other innovative energy projects in this country. Acute energy shortages in South Africa give Russia a unique chance to enter the African market and create a technological link between African countries and Russian innovations. An analysis of the political and economic situation in South Africa, as well as an assessment of the prospects for Russian business participation in the development of the South African energy sector were carried out using research conducted by the authors in South Africa in 2016, and interviews with Russian and South African civil servants and businesmen.

Modernization of moisture separator-reheaters of NPP with VVER-440 and VVER-1000 reactors

Moisture separator-reheaters (MSR) are designed to separate the moisture from steam and its subsequent overheating. The design moisture of the steam after drying in the MSR separator should not be more than 1%, however, in operation it exceeds this level, which affects the efficiency and reliability of the turbine. In connection with the expiry of the design lifetime, the SPP-220M and the SPP-1000 devices require replacement or modernization. The structures of SPP-220М and SPP-1000 are unified with SPP-500-1, and all these devices have common advantages and disadvantages. It is noted that the leading foreign companies that supply the MSR to NPPs are also working to improve their devices. The experience of the German company Balcke Durr, which took part jointly with JSC «NPO CKTI» in the modernization of SPP-500-1 at nuclear power plants in Russia, as well as independently in the project of modernization of the MSR at the Loviisa NPP in Finland, is presented. The results of the development of JSC «NPO CKTI» on the modernization of an SPP-220M for the power unit with a VVER-440 and an SPP-1000 reactor for the power unit with a VVER-1000 reactor are presented. The projects are executed on the basis of JSC «NPO CKTI»’s own experience and taking into account the experience of joint development with the Balcke Durr firm. The projects are designed taking into account the following conditions: new devices are installed on existing foundations; devices are fi t into the old dimensions; the location of connecting flanges allows to keep the existing pipelines. The design basis for the project included a computational experiment based on an MSR model developed by the authors, as well as thermal hydraulics calculations. Numerical simulation allowed to optimize the design of separation units. Thermohydraulic calculations made it possible to optimize the superheater design. Based on the calculation results, it is shown that the modernization of the apparatus will allow to dry the wet steam at 0.6%, to lower the hydraulic resistance along the wet steam path by 26% for the SPP-220M and 36% for the SPP-1000, and to reduce the weight of the apparatus by 12%. Recommendations are proposed for the modernization of existing and the creation of promising structures for MSR.

Radiation risk safety limits for the public: operating Russian nuclear power plants; predictive estimates for the fast-neutron reactor BREST, operating under normal conditions

Radiation risk safety limits for the public: operating Russian nuclear power plants; predictive estimates for the fast-neutron reactor BREST, operating under normal conditions

Радиологические аспекты обращения с жидкими радиоактивными отходами атомных станций

Purpose: The prospects and scale of the further development of nuclear energy depend to a large extent on the solution of the radioactive waste management (RW) problem. Special attention is given to management of the liquid radioactive waste (LRW), which poses the main potential hazard to the public and the environment, since LRW storage can lead to leaks into the environment.
 The purpose of the paper is to examine the radiological aspects of LRW management from nuclear power plants (NPPs) operation and to study the influence of the list of radionuclides controlled in RW on the evaluation of the efficiency of LRW treatment technology and on the validity of radioactive waste characterization and classification.
 Material and methods: The work is based on analysis of public materials (scientific publications, legal documents, international standards, recommendations of international organizations) in the area of LRW treatment and conditioning technologies, and methods of radioactive waste characterization, including information about accepted lists of controlled radionuclides.
 Results: It is shown that an unreasonable reduction of the list of controlled radionuclides can lead to a significant underestimation of the radiological hazard of RW packages transferred for disposal. In order to optimize the volume of RW radiation control, the radionuclide vector technology was proposed. It is stated that the technology is not universal and its application in each specific case requires additional justification. It is shown that the correctness of accounting for the radiological characteristics of radioactive waste can significantly influence the evaluation of the efficiency of the radioactive waste treatment technology. A possible approach to determining the acceptability of LRW treatment technology based on the characteristics of the final products formed is suggested.
 Conclusions: There is no universal approach to solve the problems of LRW treatment at the moment. A survey of the characteristics of LRW (chemical, physical, radiation) accumulated and formed during the operation of NPP with various types of reactors (VVER, RBMK, BN) should be performed to determine the initial requirements for LRW treatment technologies. A comprehensive analysis of the efficiency of LRW treatment technologies at all Russian NPPs is of interest with taking into account radionuclides that determine the radiological hazard of radioactive waste after the final disposal.

Временной механизм воздействия опасных факторов пожара на персонал АЭС и комплексная защита от них

Проведен анализ пожаров на объектах атомной энергетики. С помощью расчетно-аналитических исследований динамики пожаров для типовых помещений АЭС определены критические времена достижения опасными факторами пожара критических значений для людей на уровне рабочей зоны. Дан анализ прибытия пожарных подразделений по охране АЭС на территорию станций при пожарах. Рассмотрен перечень средств защиты и технического оснащения оперативного персонала щитов управления АЭС. Разработаны мероприятия по комплексной защите оперативного персонала АЭС, проводящего специальные работы по выработке электрической энергии при пожарах в условиях воздействия опасных факторов. Проведены комплексные испытания технических средств для обеспечения действий оперативного персонала при пожаре с использованием учебно-тренировочных комплексов.

Water chemistry of the secondary circuit at a nuclear power station with a VVER power reactor

Results of implementation of the secondary circuit organic amine water chemistry at Russian nuclear power plant (NPP) with VVER-1000 reactors are presented. The requirements for improving the reliability, safety, and efficiency of NPPs and for prolonging the service life of main equipment items necessitate the implementation of new technologies, such as new water chemistries. Data are analyzed on the chemical control of power unit coolant for quality after the changeover to operation with the feed of higher amines, such as morpholine and ethanolamine. Power units having equipment containing copper alloy components were converted from the all-volatile water chemistry to the ethanolamine or morpholine water chemistry with no increase in pH of the steam generator feedwater. This enables the iron content in the steam generator feedwater to be decreased from 6–12 to 2.0–2.5 μg/dm3. It is demonstrated that pH of high-temperature water is among the basic factors controlling erosion and corrosion wear of the piping and the ingress of corrosion products into NPP steam generators. For NPP power units having equipment whose construction material does not include copper alloys, the water chemistries with elevated pH of the secondary coolant are adopted. Stable dosing of correction chemicals at these power units maintains рН25 of 9.5 to 9.7 in the steam generator feedwater with a maximum iron content of 2 μg/dm3 in the steam generator feedwater.

Comparison of the results of 85Kr transport modeling with the ACURATE field experiment data

Currently the Nuclear Safety Institute of the Russian Academy of Sciences (NSI RAS) jointly with the Hydrometcenter of Russia is developing the system for forecasting the transfer of radio-active substances in the atmosphere in case of radiation accidents at Russian nuclear power plants. The operation of the system is based on the numerical hydrodynamic model which allows forecasting meteorological parameters and is coupled with the mesoscale dispersion model of the transfer ofradioactive substances in the atmosphere. The results are presented of 85Kr transport modeling under the conditions of the ACURATE experiment with three transport models: FLEXPART, HYSPLIT, and the model from the NOSTRADAMUS software package. It is demonstrated that all three Lagrangian models can give a qualitative description of concentration fields from the ACURATE experiment with the best value of the RANK metric (2.5) based on three statistics.