Operation Of Nuclear Power Stations Research Articles

Dynamic characteristics of tube bundles with crack subjected to cross-flow and loose support

Flow-induced vibration of the tube bundles subjected to cross-flow and loose support is an important issue in the security of a steam generator. In the operation of nuclear power station, the flow-induced vibration of the tube bundles may lead to crack initiation and propagation, which can affect the natural frequency and the dynamic response of the tube. However, there is seldom theoretical analysis to study the dynamic characteristics of cracked tube bundles subjected to cross-flow. Therefore, a mathematical model of a single cracked tube in a rotated triangular tube array subjected to cross-flow and loose support was presented in this paper. The model takes into account the variations of the tube natural frequency and mode of vibration owing to the crack damage. The effect of the crack damage on the dynamic characteristics of a flexible tube in tube bundles subject to cross-flow and loose support was investigated, and the dynamic responses of the cracked tube for three flow pitch velocity conditions were calculated.

EBSD studies on microstructure and crystallographic orientation of UO2-Mo composite fuels

The microstructure of the fuel pellet plays an essential role in fission gas buildup and release and is critical for the safe and continued operation of nuclear power stations. Structural analysis of uranium dioxide (UO2)–molybdenum (Mo) composite fuel pellets prepared at a range of sintering temperatures from 1300 to 1800 °C was performed. Mo micro and nanoparticles were used in making the composite pellets. A systematic investigation into the influence of processing parameters during Spark Plasma Sintering (SPS) of the pellets on the microstructure, texture, grain size, and grain boundary characters of UO2-Mo is presented. UO2-Mo composite show significant differences in the fraction of general boundaries and also special/coincident site lattice (CSL) boundaries. EBSD orientation maps demonstrated that <111> texturing was observed in the pellets fabricated at 1500 °C. The experimental investigations suggest that UO2-Mo composite pellets have favorable microstructural features compared to the UO2 pellet.

Программный комплекс РАДУГА-Т для моделирования полей нейтронов в ядерно-энергетических установках

Design and operation of nuclear power stations (NPS) are followed by simulation of neutron propagation in these stations. It is necessary to consider borders of multi-scale structural elements consisting of different materials. It is desirable to use parallel computer because of big size of NPSs. To keep such conditions, algorithms and codes for solving the integro-differential transport equation on unstructured grids are being developed. In the paper such algorithms included into the code RADUGA T are outlined. Grids, grid schemes, iterative methods to solve grid equations are presented. Calculation parallelization methods for hybrid computers are considered, MPI and OpenMP techniques are used. Methods of building, improvement, decomposition and visuzlisation of spatial grids are considered. Software implementation is described. The algorithms of the code RADUGA T are compared with methods of other codes. Computation parallelization efficiency study results are presented. The problem of neutron multiplication factor calculation in a light-water reactor model is solved. The multi-processor computer MVS-10P of the Joint SuperComputernal Center is used. Acceleration of each algorithm being used and summary acceleration are given.

Monitoring of Fine-Scale Warm Drain-Off Water from Nuclear Power Stations in the Daya Bay Based on Landsat 8 Data

Monitoring the drain-off water from nuclear power stations by high-resolution remote sensing satellites is of great significance for ensuring the safe operation of nuclear power stations and monitoring environmental changes. In order to select the optimal algorithm for Landsat 8 Thermal Infrared Sensor (TIRS) data to monitor warm drain-off water from the Daya Bay Nuclear Power Station (DNPS) and the Ling Ao Nuclear Power Station (LNPS) located on the southern coast of China, this study applies the edge detection method to remove stripes and produces estimates of four Sea Surface Temperature (SST) inversion methods, the Radiation Transfer Equation Method (RTM), the Single Channel algorithm (SC), the Mono Window algorithm (MW) and the Split Window algorithm (SW), using the buoy and Minimum Orbit Intersection Distances (MOIDS) SST data. Among the four algorithms, the SST from the SW algorithm is the most consistent with the buoy, the MODIS SST, the ERA-Interim and the Optimum Interpolation Sea Surface Temperature (OISST). Based on the SST retrieved from the SW algorithm, the tidal currents calculated by the Finite-Volume Coastal Ocean Model (FVCOM) and winds from ERA-Interim, the distribution of the warm drain-off from the two nuclear power stations is analyzed. First, warm drain-off water is mainly distributed in a fan-shaped area from the two nuclear power stations to the center of the Daya Bay. The SST of the warm drain-off is about 1–4 °C higher than the surrounding water and exceeds 6 °C at the drain-off outfall. Second, the tide determines the shape and distribution characteristics of the warm drain-off area. The warm drain-off water flows to the northeast during the flood tide. During the ebb tide, the warm drain-off water flows toward the southwest direction as the tide flows toward the bay mouth, forming a fan-shaped area. Moreover, the temperature increase intensity in the combined discharge channel during the flood tide is lower than that during the ebb tide, and the low temperature rising area during the flood tide is smaller than that during the ebb tide.

Transboundary aspect of assessing the impact of NPPs under construction on aquatic ecosystems: Case study of the Baltiiskaya NPP

The environmental feasibility assessment of the construction and operation of nuclear power stations in near-border areas must take into account the requirements of the international and European environmental legislation. For the study on environment feasibility assessment of the Baltic NPP to meet the international standards, the following steps were taken: the content and the application practice of UNECE Convention on Environmental Impact Assessment in a Transboundary Context (Espoo) to NPP substantiation were analyzed and compared with the Russian procedure of environmental impact assessment (EIA); water quality standards for water bodies used for fishery and the approaches to assessing the damage to aquatic bioresources in Russia, Lithuania (EU), and Belarus were compared. A transboundary network for monitoring aquatic ecosystems was developed in the zone of potential influence of the Baltic NPP, and a permanent mathematical model was developed and used to forecast the effect of the anticipated water discharge from the station on the hydrodynamic, chemical, and temperature regime of the Neman R., whose results were used to forecast the impact of water intake and discharge facilities of the Baltic NPP on the food base and migration character of ichthyofauna.

Numerical analysis of transient pressure variation in the condenser of a nuclear power station

To research the characteristics of the transient variation of pressure in a nuclear power station condenser under accident condition, a mathematical model was established which simulated the cycling cooling water, heat transfer and pressure in the condenser. The calculation program of transient variation characteristics was established in Fortran language. The pump’s parameter, cooling line’s organization, check valve’s feature and the parameter of siphonic water-collecting well are involved in the cooling water flow’s mathematical model. The initial conditions of control volume are determined by the steady state of the condenser. The transient characteristics of a 1000 MW nuclear power station’s condenser and cooling water system were examined. The results show that at the condition of plant-powersuspension of pump, the cooling water flow rate decreases rapidly and refluxes, then fluctuates to 0. The variation of heat transfer coefficient in the condenser has three stages: at start it decreases sharply, then increases and decreases, and keeps constant in the end. Under three conditions (design, water and summer), the condenser pressure goes up in fluctuation. The time intervals between condenser’s pressure signals under three conditions are about 26.4 s, which can fulfill the requirement for safe operation of nuclear power station.

The Impact of Primary Circuit Coolant Average Temperature on the Secondary Circuit Thermal Efficiency at Nuclear Power Station

The variations of secondary circuit parameters are limited by the parameters of primary circuit during PWR nuclear power station operation, the primary circuit average temperature should vary at the range of nuclear reactor operating safely. In the existing analysis of secondary circuit thermal efficiency at nuclear power station, the impact of primary circuit average temperature on the secondary circuit thermal efficiency is not taken into consideration. In this paper, the changes of primary circuit average temperature in actual operation are considered, the secondary circuit parameters are calculated according to the model of heat flux transfer between primary and secondary circuit, the thermal efficiency of ideal cycle is chosen as the evaluating indicator of secondary circuit thermal efficiency, the thermal efficiencies of ideal cycle in secondary circuit are calculated under the conditions of varying coolant average temperature with the method of matrix, and the calculated results are basis for the safe and economic operation of nuclear power station.

The alternative strategies of the development of the nuclear power industry in the 21st century

This paper emphasizes the urgency of scientific-and-technical and sociopolitical problems of the modern nuclear power industry without solving of which the transition from local nuclear power systems now in operation to a large-scale nuclear power industry would be impossible. The existing concepts of the longterm strategy of the development of the nuclear power industry have been analyzed. On the basis of the scenarios having been developed it was shown that the most promising alternative is the orientation towards the closed nuclear fuel cycle with fast neutron reactors (hereinafter referred to as fast reactors) that would meet the requirements on the acceptable safety. It was concluded that the main provisions of “The Strategy of the Development of the Nuclear Power Industry of Russia for the First Half of the 21st Century” approved by the Government of the Russian Federation in the year 2000 remain the same at present as well, although they require to be elaborated with due regard for new realities in the market for fossil fuels, the state of both the Russian and the world economy, as well as tightening of requirements related to safe operation of nuclear power stations (NPSs) (for example, after the severe accident at the Fukushima nuclear power station, Japan) and nonproliferation of nuclear weapons.

Efficient ways for setting up the operation of nuclear power stations in power systems in the base load mode

The results obtained from studies of efficient ways and methods for organizing the operation of developing nuclear power stations in the base load mode are presented. We also show comparative efficiency of different scenarios for unloading condensing thermal power stations, cogeneration stations, combined-cycle power plants, nuclear power stations, and using off-peak electric energy for electricity-intensive loads: pumped-hydroelectric storage, electric-powered heat supply, and electrolysis of water for producing hydrogen and oxygen.

Recent eutrophication and human disturbance in Daya Bay, the South China Sea: Dinoflagellate cyst and geochemical evidence

Recent trends in eutrophication and human disturbance were evaluated using dinoflagellate resting cysts and geochemical parameters. Analyses were performed on three sediment cores from Daya Bay, South China Sea covering the past hundred years. Changes in cyst assemblages as well as geochemical parameters including biogenic silica (BSi), organic carbon (OC) and total nitrogen (TN) reflected environmental change in the area. The clear increase in overall cyst concentration and the prominence of Scrippsiella cysts suggested an increase in cultural eutrophication which began in the 1970s and become evident since 1985. Large fluctuation in cyst assemblages and BSi in the upper 22 cm signaled the influence of construction and operation of nuclear power stations on phytoplankton community and environments, with an increase in the early stage of construction, a rapid decline in the late stage of construction and early operation, and then a sharp increase thereafter. High Alexandrium cyst abundance in shallowest sediments was consistent with high PSP levels and PSP events in the area, and the persistent toxicity suggests recurrent seeding from the rich cyst bed in these surface sediments.

A system for monitoring the reliability of pump equipment during the operation of nuclear power stations

We describe the objectives and the main stages of the development of a system for monitoring the operational reliability of equipment in the course of operation of nuclear power stations and present the structure of a developed computer database on the reliability of this equipment. We also give some results from a statistical analysis of data on the experience gained with the operation of withdrawable parts and glands of the shafts of the reactor coolant pumps used in the reactor coolant circuit of a large-capacity pressure-tube reactor.

Thermodynamics of a desalination system at nuclear power stations

Nuclear power engineering is developing steadily in industrial countries. This is caused by features of using nuclear fuel and high environmental safety of nuclear power stations. At the same time, the thermodynamic efficiency of nuclear power stations is lower than indices of thermal power stations operating on gas, coal or oil fuel. This efficiency does not usually exceed 30–35%. Hence more than 60% of the energy of nuclear fuel being used escapes into the environment through turbine condensers at nuclear power stations. Cogeneration turbines that reduce heat loss by 20–30% are used at thermal power stations for efficiency upgrading. However, cogeneration schemes have not found wide utility at nuclear power stations due to safety conditions. Thus, it is possible to use, in addition, a major part of nuclear fuel energy for desalination at nuclear power stations located on the coast. In this case, some main problems are solved: production of fresh water consumed by nuclear power station for technological purposes and sold to external consumers; upgrading of effectiveness of using nuclear fuel including the cost of steady operation of nuclear power stations at high loads; reduction of non-productive thermal pollutants from nuclear power stations into the environment. It is required to provide maximum upgrading of power station heat efficiency and high capacity of distillers when connecting desalination installations to the thermal scheme of nuclear power stations. The use of energy of the heat carrier's low-temperature flows being emitted by turbine condensers into the environment is of particular value. In this case, different thermodynamic analysis methods are used for the justification of optimal engineering solutions In the article under consideration some results of research of thermodynamics of cycles of nuclear power stations where thermal schemes includes different types of thermal desalination installations are given. From the analysis of thermodynamic processes carried out at nuclear power stations, recommendations related to improvement of desalination installations' thermal schemes providing power system efficiency upgrading have been obtained.

Plutonium content of tissues of members of the general public

Operation of nuclear power stations and reprocessing plants entails some risk, both to people working in the installations and to the general public, of contamination with plutonium. Any such contamination can be assessed only by comparing concentrations of plutonium in tissues of exposed persons with corresponding concentrations in people not occupationally exposed to plutonium and not living near to a nuclear installation. Few data have been published for such unexposed subjects in the UK. Therefore plutonium concentrations have been measured in samples of lung, liver, vertebra including marrow and vertebral marrow alone, taken at autopsy from twelve people who died in West Yorkshire in 1980 or 1981. The measurements of bone marrow alone were considered to be particularly important because it has been suggested that plutonium in marrow may give rise to leukaemia or other blood dyscrasias. Median concentrations in the four tissues were 1.9, 14.2, 7.5 and 0.9 mBq/kg respectively. The resulting dose equivalent rates to lung, liver, marrow and osteogenic cells lining bone surfaces were 1.5, 6.5, 2.1 and 2.8 mu Sv/a respectively. These dose equivalent rates are all much less than those received from natural sources.

Control of the energy distribution and safety of a VV�R-1000 reactor when operating in the variable mode

The main operations in the proposed algorithm for, controlling the distribution of energy under variable-load conditions are carried out at a reduced power level. When the power falls, all the control rods are found in the rated position. We show that the main problems in controlling the energy distribution can be solved within the framework of a single computer procedure based on the quadratic programming method. When the proposed algorithm is set up in the computer, together with a realization of the optimum control actions, found from a digital model, we can expect to achieve an increase in efficiency in the work of the operating staff, and as a result, an increased level of safety in the operation of nuclear power stations.

Basis of the principal indices of the technological media of a number of systems and circuits, ensuring the operation of nuclear power stations with RBMK-1000 reactors

Basis of the principal indices of the technological media of a number of systems and circuits, ensuring the operation of nuclear power stations with RBMK-1000 reactors

Training of Technical Staff for Nuclear Power Station Operation

The paper discusses the statutory training requirements covering the technical staff in the CEGB (Central Electricity Generating Board). Details of the training programmes emphasize the importance of the staff having a thorough understanding of the nuclear processes involved in the station operation and not relying solely upon a mechanistic approach to operating procedures. The paper also examines the impact of this philosophy on the design of training simulators and makes a brief comparison with the training philosophies in other countries.

Evaluation of the economic effectiveness of reconstructing hydroelectric stations for converting them to combined hydroelectric and pumped-storage stations

1. Under conditions of intensive construction and operation of nuclear power stations and reduction in the proportion of special flexible power stations the problem of covering the variable part of the load curve, especially its half-peak part, and filling the nighttime off-peak period is becoming rather complex. 2. One of the ways to reconstruct the existing hydroelectric stations in the European USSR is to install at them reversible hydroturbine equipment or pumping stations in order to convert then to HES-PSS. This measure will make it possible to increase the firm power of the HES, to use nighttime power in the system, and will improve the operating regimes of nuclear power stations and possibilities of covering the variable part of the load curve. 3. To estimate the economically permissible capital investments when reconstructing HES to convert them into HES-PSS, a method is proposed which takes into account changes in the structure of the generating capacities of the power system. 4. An analysis of the permissible investments in reconstruction of HES as a function of the influencing factors shows that in the case of charging the HES-PSS from a NPS the permissible specific investment increases with increase of the charging time of the HES-PSS and increase of the firm power and the more so, the greater the expenditures of fuel. 5. It is necessary to begin works to determine such existing HES in the European USSR at which reconstruction can be accomplished to convert them to HES-PSS. The significance of this measure increases especially in the case of a large share of nuclear stations in the power system, since hydroelectric stations and especially pumped-storage stations and their combination increase the operating reliability and “viability” of power systems, and along with this the reliability of supplying power to consumers.

Radioactivity release to the environment by thermal power stations using coal as a fuel

Coal contains naturally occurring radionuclides arising from the uranium and thorium series and 40K. Coal burning is thus one of the sources of technologically enhanced exposures to natural radionuclides. Emissions from thermal power stations in gaseous and particulate form contain the radioisotopes, which are discharged to the environment causing radiation exposure to the population. This paper gives the results for coal and fly-ash samples from four thermal power stations in India. The radiation exposures due to the naturally occurring radionuclides discharged from these thermal power stations and those resulting from operation of nuclear power stations of Boiling Water Reactors (BWR) and Heavy Water Reactors (HWR) type are compared. From this study it is observed that exposure to the general population from ionising radiation originating from radionuclides from thermal power stations burning coal is as hazardous, if not more so, than exposure to radionuclides emitted from nuclear power stations of the type operating in India.

Nuclear power station safety

There has never been a time since October 1957, on the occasion of the first generation of electrical power from nuclear energy, when the attention of the public has been more focused on the needs for safeguards in the operation of nuclear power stations and on the effects to the environment and ecology of radioactive effluents and wastes discharged from these stations.

Radiation safety in the operation of nuclear power stations

Radiation safety in the operation of nuclear power stations