Novovoronezh Nuclear Power Plant Research Articles

Application of the method of vacuum withdrawal inert radioactive gases to control of fuel rods leaking of nuclear reactors WWER types while operation

Currently, a comprehensive approach is being developed for the integrity control of fuel rod claddings in pressurized water reactor (PWR) nuclear power plants. One of the key stages is the reliable detection of leaking fuel rods within the reactor's active zone during power operation. This study examines the general trends in the activity of fission product radionuclides in the primary coolant of various generations and designs of PWRs. The experience of Novovoronezh Nuclear Power Plant is considered regarding the method of sampling and separation of inert radioactive gases from the primary coolant. A comparison is made between different methods of measuring inert radioactive gases in the primary coolant: direct spectrometry, cryogenic method, and vacuum extraction method. The issue of reliable detection of fuel rod leakage during reactor operation is discussed, using the example of Unit 5 at Novovoronezh Nuclear Power Plant. Comparative results are presented for the analysis of the integrity of fuel rod claddings based on key reference radionuclides. The most reliable results indicating fuel rod leakage were obtained through the control of specific activities and analysis of changes in the ratio of inert radioactive gases using the vacuum extraction method. Control of the specific activity of inert radioactive gases in the primary coolant enables a highly reliable assessment of the condition of physical barriers. The proposed method of sampling and separation of inert radioactive gases demonstrates high reliability and convergence of results, serving as an additional tool for integrity control of fuel rod claddings during power operation. Having representative data on the specific activities of inert radioactive gases allows for a reliable assessment of the condition of fuel rod claddings within the reactor core.

Application of risk-based approach in switching operations preparation at Novovoronezh NPP

The article discusses one of the problematic issues of operating nuclear power plants - revenue losses caused by staff mistakes. Existing methods and approaches to reducing the number of such incidents are analyzed. Despite the efforts made, the problem remains relevant. One of the directions for reducing the number of equipment failures is the study and use of internal and external operational experience. A description is given of a system for preventing the recurrence of negative operating experience, developed at the Novovoronezh Nuclear Power Plant, which is used in preparation for switching equipment. The system is an information base, the information in which is structured by types of equipment used at the Novovoronezh Nuclear Power Plant, allowing only the information directly related to the upcoming switches to be communicated to the operational staff. Suggestions for its further improvement, taking into account the recommendations of the International Atomic Energy Agency, are considered. A forecast is given for the dynamics of reducing the number of violations after the introduction of this system into industrial operation.​

Питание тиляпии мозамбикской (Oreochromis mossambicus) бактериально-водорослевыми матами в водоёме-охладителе Нововоронежской АЭС

The formation of stable periphyton communities is undesirable for all types of hydrotechnical systems, especially functioning watercooling systems. To combat the development of biological fouling in the cooling ponds of nuclear power plants bioreclamation species are widely used, which include Mozambican tilapia. It was unintentionally brought into the cooling reservoir of the Novovoronezh nuclear power plant; however, it formed a stable and numerous population there. The food base for the fish population in the cooling pond is depleted due to difficult (sometimes extreme) environmental conditions, which can lead to competition for food items. Under these conditions, tilapia switches to feeding on bacterial-algal mats, which develop abundantly in the warm-water part of the reservoir. In areas eaten by tilapia, the biomass of fouling is reduced by one and a half times and the content of mineral substances decreases. The study of the contents of the intestines of tilapia made it possible to confirm these observations, since representatives of the phytoperiphyton were found in the food bolus: cyanoprokaryotes, diatoms and green algae, for which even a taxonomic affiliation was established. The results of the research made it possible to clarify the mechanism o f integration of this southern species into the ichthyocenosis of the reservoir and its positive role in reducing biofouling.

Neotectonic structures and modern geodynamics of the middle flow region of the Don river (the territory of the Novovoronezh nuclear power plant)

Background. Structural and geodynamic studies are conducted in the region of the middle flow of the Don river.Aim. An identification and evaluation of neotectonic structures, determination of geodynamic conditions for their formation and an analysis of intensive exogenous geological processes in connection with the need to ensure the safety of the Novovoronezh nuclear power plant (NPP) located in this area, the largest in the central part of the Eastern European platform.Materials and methods. According to the concept of deep geodynamic systems, the lithological, structural-geomorphological and neotectonic conditions of the territory were studied. Field observations and publications based on geological survey data were the factual material for the studies.Results. Various types of uplifts and troughs, geodynamically active zones and lineaments were identified. The formation of structures is associated with deep (intracortical) stresses of compression and tension, under the influence of which the tectonic-gravity and suffosion-karst processes negative for the territory of the nuclear power plant are activated. Among the ancient Precambrian faults of the crystalline basement, the latitudinal Sudzhen-Ikorets and submeridional Semiluki-Lipetsky faults are active. The latter is considered as a geodynamically active zone. At the NPP site and in its vicinity, the zones of increased fracturing and permeability were identified, which is consistent with the buried forms of the relief — paleo-reliefs of the Don river and its tributaries. These zones are found to be deeply embedded in the Cretaceous and Devonian carbonate rocks, which is the reason for the increased leaching of these rocks and the removal of fine particles from the fluvioglacial strata. A quantitative assessment of summary and step-by-step amplitudes and speeds of neotectonic movements was carried out.Conclusion. The territory of the Novovoronezh NPP is geodynamically calm, the movement speeds (both calculated and according to instrumental measurements) are relatively low; however, these movements activate exogenous processes, which in turn negatively affect the stability of the Novovoronezh NPP site.

Modernization of the control system for the steam turbine of the Novovoronezh nuclear power plant based on the capabilities of anylogic

The theory of the possible use of modeling tools based on AnyLogic for the modernization of the control system of the NPP turbine unit is presented. Graphical dependencies showing the unstable operation of electro-hydraulic valves are presented. An analysis of the effective automatic control system and the structure of the Novovoronezh nuclear power plant are carried out. Keywords CAM, TP, NPP, turbine unit, regulation system, resonance, valve

Simulating operation of power units 1 and 2 at Novovoronezh NPP II with two electrical feed pumps disabled and the backup pump not enabled

Introduction. The article analyzes the operation of Unit 1 and 2 of Novovoronezh Nuclear Power Plant II (equipped with VVER-1200 reactors) with two electrical feed pumps disabled and the backup pump not enabled. These operating conditions are subsequently simulated using the power unit model software-hardware package (PUM SHC) developed by LLC IF SNIIP ATOM. Research objectives. The objective of this work was to check the reliability of the forecasts of changes in the power unit parameters obtained using the PUM SHC, based on operational data. Methods. The simulated power unit parameter changes in transient conditions were in good agreement with the data collected in real tests. During the simulation, the power unit dynamic stability was preserved, i.e., the operational parameters were within the design limits and did not exceed the protection operation set points. Results. The results of the work suggest the possibility of using current NPP power unit simulations: for developing proposals for adjusting the operation control algorithms in case of malfunctions and emergency modes with the main equipment shutdown and power unit protection actuation; and for verifying design solutions for updating the power unit systems, which are associated with the use of new equipment or changes in flow diagrams. Conclusion. Current power unit models can be applied both for existing power units and for new ones that are being commissioned.

Erratum to: “Development and application of an information–analytic system on the problem of flow accelerated corrosion of pipeline elements in the secondary coolant circuit of VVER-440-based power units at the Novovoronezh Nuclear Power Plant”

Erratum to: “Development and application of an information–analytic system on the problem of flow accelerated corrosion of pipeline elements in the secondary coolant circuit of VVER-440-based power units at the Novovoronezh Nuclear Power Plant”

Personnel dose assessment due to the normal operations with the artificial radiation sources according to the data from the unified system of individual dose control (USIDC)

The aim of the study was personnel dose assessment due to the normal operations with the artificial radiation sources. The article is based on the data from the Unified System of Individual Dose Control and Voronezh Region’s radiation-hygienic passport. The data from No.1-DOZ “Information on personnel exposure doses under normal operation of technogenic ionizing radiation sources” and over a period of 2006-2010 years were analyzed. In 2006-2015, the number of organizations, which submitted form No.1-DOZ “Information on personnel exposure doses under normal operation of technogenic ionizing radiation sources”, increased from 175 to 229. In amount of the radiation facilities, Novovoronezh Nuclear Power Plant is the first. Novovoronezh NPP has 1512 sources, which amounts to 51,9% from all sources in Voronezh Region (2915). Health care facilities have 869 radiation sources or 29,8%. X-ray machines are the main part of these sources (844 health care facilities or 97,1% of all medical sources). Industrial sources occupy third place with 305 facilities or 10,5% of all considered sources. In 2015, according to the data from Voronezh Region’s radiation-hygienic passport, the number of “A” group personnel were 4237, the number of “B” group personnel were 2341. The average individual dose for personnel was over the range from 0.66 to 2.02 mSv. Collective dose was from 4.16 to 11.79 man-sieverts per year. The increase of number of the radiation sources has attended with the decrease of individual and collective doses. The most likely it is related to using the modern facilities. In 2015, the maximum value of the average individual dose of “A” group personnel was registered in Voronezh regional hospital (6.17 mSv y–1). There are medical facilities with unsealed and sealed sources in this hospital. In 2006-2015, the average individual doses of personnel of all radiation facilities that use radiation sources in Voronezh region were significantly below the dose limits established by the Radiation Safety Standards NRB-99/2009.

Radioecological description of the soil–plant cover and water objects within the impact zone of the Novovoronezh Nuclear Power Plant

The work considers the accumulation and redistribution of 137Cs and 60Co among the components of natural ecosystems (soils, bottom sediments, surface waters, and plants of different ecological groups (mesophytes, hygrophytes, hydrophytes, and hydathophytes)) within the impact zone of the Novovoronezh Nuclear Power Plant. It is shown that the current radioecological situation on this territory is satisfactory. Each of the studied parameters complies with the radiation safety standards.

Development and application of an information-analytic system on the problem of flow accelerated corrosion of pipeline elements in the secondary coolant circuit of VVER-440-based power units at the Novovoronezh nuclear power plant

Specific features relating to development of the information-analytical system on the problem of flow-accelerated corrosion of pipeline elements in the secondary coolant circuit of the VVER-440-based power units at the Novovoronezh nuclear power plant are considered. The results from a statistical analysis of data on the quantity, location, and operating conditions of the elements and preinserted segments of pipelines used in the condensate-feedwater and wet steam paths are presented. The principles of preparing and using the information-analytical system for determining the lifetime to reaching inadmissible wall thinning in elements of pipelines used in the secondary coolant circuit of the VVER-440-based power units at the Novovoronezh NPP are considered.

Erratum to: “The concept of extending the service life of the VVER-440-based power units at the Novovoronezh Nuclear Power Plant”

Basic statements of the Concept of Extending the Service Life of the VVER-440-Based Power Units at the Novovoronezh NPP beyond 45 years are considered. This topic is raised in connection with the fact that that in December 2016 and in December 2017 the extended service lives of Units 3 and 4 at this NPP will expire. The adopted concept of repeatedly extending the service life of the Novovoronezh NPP Unit 4 implies fitting the power unit with additional reactor core cooling systems with a view to extend the (ultimate) design-basis accidents (which have hitherto been adopted to be a loss of coolant accident involving a leak of reactor coolant through a break with a nominal diameter of 100 mm) to a reactor coolant leak equivalent to rupture of the main reactor coolant pipeline. The modified Unit 4 will also use the safety systems of Unit 3 that is going to be decommissioned. Preliminary calculated assessments of the new design-basis accident scenario involving rupture of the reactor coolant pipeline in Unit 4 fitted with a new configuration of safety systems confirmed the correctness of the adopted concept of repeatedly extending the service life of Unit 4.

Development and implementation of monitoring for the reactor core of unit No. 5 of the Novovoronezh nuclear plant by local parameters

In the course of upgrading the unit no. 5 reactor core of the Novovoronezh nuclear power plant, operational limits by local parameters, which limit the admissible linear power density and the relative power of fuel elements, were established. Due to applying modern computer technologies in systems of the in-core monitoring, the calculation of power density for all fuel elements in the real-time mode is implemented. To monitor the power density of fuel elements, the algorithm for determining the limiting linear power density is developed depending on the reactor core height and on the average nuclear fuel burnup. The admissible relative power of fuel elements is determined. In the course of the performed work, the excessive conservative limitations on nonuniformity of the reactor power density are excluded. The monitoring of power density by local parameters instead of indirect Kq (fuel-assembly relative power) and Kv (relative power of the fuel assembly section) made it possible to increase the fuel efficiency and to improve the economic parameters of fuel cycles of the unit no. 5 reactor core of the Novovoronezh nuclear power plant.

Developing and applying modern methods of leakage monitoring and state estimation of fuel at the Novovoronezh nuclear power plant

The results of developing and implementing the modernized fuel leakage monitoring methods at the shut-down and running reactor of the Novovoronezh nuclear power plant (NPP) are presented. An automated computerized expert system integrated with an in-core monitoring system (ICMS) and installed at the Novovoronezh NPP unit no. 5 is described. If leaky fuel elements appear in the core, the system allows one to perform on-line assessment of the parameters of leaky fuel assemblies (FAs). The computer expert system units designed for optimizing the operating regimes and enhancing the fuel usage efficiency at the Novovoronezh NPP unit no. 5 are now being developed.

Experience gained at the Novovoronezh nuclear power plant with development and introduction of a unified automated system for accounting and control of radioactive substances and radioactive wastes

A unified automated system for accounting and control of radioactive substances and radioactive wastes was developed at the Novovoronezh nuclear power plant. The system consists of several interconnected subsystems, which can be developed and put in operation in a stage-wise manner. As of the first quarter of 2013, the subsystems for accounting liquid and solid radioactive wastes, very low-active wastes, and tracers have been developed. The experience gained from the development and putting in use of these systems showed that this is an efficient, timely, and much needed software product.

Prediction of the radiation situation during conditioned radioactive waste storage in hangar-type storage facilities

An original technology for the conditioning of solidified radioactive waste was developed by the Novovoronezh nuclear power plant (NPP) staff. The technology provides for waste placement inside NZK-150-1.5P containers with their further storage at light hangar-type storage facilities. A number of technical solutions were developed that allow for reducing the gamma-radiation dose rate from the package formed. A methodology for prediction of the radiation situation around hangars, depending on the radiation characteristics of irrecoverable shielding containers (ISCs) located in the peripheral row of a storage facility, was developed with the purpose of assuring safe storage. Based on empirical data, the field background gamma-radiation dose rate at an area as a function of the average dose rate at the hangar surface and the average dose rate close packages, placed in the peripheral row of the storage facility, was calculated. The application of the developed methodology made it possible to reduce by ten times the expenditures for the conditioning and holding of solidified radioactive waste (SRW) while unconditionally providing storage safety.

On the possibility of connecting a non-operating main circulation pump with three pumps in operation without preliminary coast-down of power-generating unit No. 5 in the Novovoronezh nuclear power plant

The subject of this paper is a transient caused by connection of a standby loop to three operating circulation pumps at the initial reactor heat rate equal to 70% of the rated value without preliminarily reducing it to 30% of the rated level as required by the safe operation regulations.

The concept of extending the service life of the VVER-440-based power units at the Novovoronezh nuclear power plant

The concept of extending the service life of the VVER-440-based power units at the Novovoronezh nuclear power plant

Upgrading the fuel-handling machine of the Novovoronezh nuclear power plant unit no. 5

The calculation of safety parameters was carried out in the process of upgrading the fuel-handling machine (FHM) of the Novovoronezh nuclear power plant (NPP) unit no. 5 based on the results of quantitative safety analysis of nuclear fuel transfer operations using a dynamic logical-and-probabilistic model of the processing procedure. Specific engineering and design concepts that made it possible to reduce the probability of damaging the fuel assemblies (FAs) when performing various technological operations by an order of magnitude and introduce more flexible algorithms into the modernized FHM control system were developed. The results of pilot operation during two refueling campaigns prove that the total reactor shutdown time is lowered.

Fifty years of safe operation of the Novovoronezh nuclear power plant

Information on the experience gained from safe operation of the Novovoronezh nuclear power plant from the moment its first power unit was commissioned and till now is presented. The following modifications and design solutions on improving the equipment and systems of the Novovoronezh nuclear power plant units that were introduced during plant operation are of special importance: Information about the modernization and service life extension of the Novovoroneh Units 3–5 beyond the 30-year design service life is presented together with substantiating the residual life of power unit elements important to safety.

Improving the transient stability of VVER-1000 reactor-based nuclear power plant units

Ensuring transient stability of nuclear power plant units in transient modes of their operation is one of the goals aimed at achieving enhanced safety and reliability of nuclear power plants. Field experience shows that for nuclear power plants equipped with VVER-1000 reactors, matters relating to transient stability in modes involving disconnection of the power unit main equipment, such as reactor coolant pumps, turbine-driven feedwater pumps, and turbine generator, are of most concern. Specialists of the Institute for Nuclear Power Plant Research perform comprehensive investigations of the technological processes aimed at working out measures for achieving better transient stability of nuclear power plant units. The article presents the results of joint activities carried out by specialists of the Institute for Nuclear Power Plant Research and the Novovoronezh nuclear power plant on enhancing the transient stability of Unit 5 at the Novovoronezh nuclear power plant.