Emergency Power Supply System Research Articles

Improving the quality of performing in-service inspections using manipulators

Many in-service inspections, mainly carried out by the ultrasonic method, were until recently carried out manually or semi-automated with the use of encoders. These types of inspections usually lack data recording and are dependent on the experience of the operator performing these inspections. For these reasons, in recent years one of the important activities carried out within the Research Centre Rez has been the development and production of manipulators for non-destructive testing. This article will describe in more detail the manipulators used for ultrasonic testing of the reactor head nozzles, nozzles of the emergency power supply system of steam generators treated with weld overlay, inspection of low-pressure blade dovetails and others. The developed manipulators will make it possible to refine and improve the repeatability of inspections that were previously carried out manually (more precise guidance of probes, etc.) or were not carried out at all due to inaccessibility for operators. Among other examples of the use of manipulators is in conditions where manual testing is not possible. One of the applications can be measurement using the phased array technique on pipelines during service, when the temperature on the surface of the pipeline can be up to 320°C (the maximum temperature of the primary pipeline of a nuclear power plant).

Multi-objective optimization for low hydrogen consumption and long useful life in fuel cell emergency power supply systems

The power system using hydrogen fuel cells (FCs) as the primary energy source holds significant potential for applications in emergency fields such as post-disaster relief and outdoor power supply. The operational environment of the FC emergency power supply system (FCEPSS) is challenging, with long continuous operation time, difficulties in hydrogen supply, high maintenance costs, and, accordingly, requirements for hydrogen consumption and useful life of FCs are heightened. Hence, this paper proposes a multi-objective energy management strategy (EMS) for FCEPSS. First, the structure of FCEPSS is designed based on the demand analysis in emergency scenarios. Then, the hydrogen consumption and life degradation models of FCEPSS are established. Aiming at the multi-objective optimization problem of minimizing hydrogen consumption and life degradation value in the FCEPSS, an improved multi-objective optimization algorithm is proposed. This paper converts complex constraints into the penalty term and incorporates it as one of the objectives, constructing a three-objective optimization model. To enhance the solution of multi-objective optimization problems, an improved strategy based on relaxation-tightening and three-objective sorting is proposed. Combining the fast non-dominated sorting genetic algorithm-II and the above improved strategy, an improved multi-objective optimization algorithm (IMOOA) is constructed. In the simulation, the advantages of the proposed IMOOA algorithm are verified. In the experimental part, compared with the logical threshold strategy, the proposed strategy saves 0.60% of hydrogen consumption and reduces 5.65% of life degradation within 24 h, respectively. Finally, the superiority of the multi-objective EMS utilizing the IMOOA is demonstrated.

Justification of measures aimed at ensuring the required fire resistance of structures enclosing NPP premises using CFD fire modeling

Introduction. The article presents a methodological approach to justifying measures designed to ensure the required fire resistance of structures enclosing NPP premises with the use of CFD (computational fluid dynamics) fire modeling. Approaches to justifying fire safety are considered using the fuel storage facility of an NPP standby diesel power plant as an example.Aim. To develop and analyze the methodological approach to justifying measures designed to ensure the required fire resistance of structures enclosing NPP premises with the use of CFD fire modeling.Materials and methods. The purpose and application scope of various methods for modeling fire dynamics was analyzed. Fire modeling used to justify measures for ensuring the required fire resistance of enclosing structures was considered using the fuel storage facility of an NPP standby diesel power plant as an example.Results. The performed analysis of different methods for modeling fire dynamics shows the possibility of using different fire simulation methods in the analysis of the fire hazard of buildings and facilities. The most dangerous fire development scenarios were modeled and the obtained results were analyzed on the example of a specific typical NPP facility in the NPP emergency power supply system. The redundancy requirements for these systems were taken into account to ensure tolerance to system failures in case of process failures and external effects on these systems.Conclusion. Since the CFD method is the most universal of the existing deterministic methods, it can be widely used to determine/revise the requirements for fire resistance of load-bearing and enclosing structures at NPP premises. It is possible to apply CFD-based fire modeling for the fire hazard of various buildings and facilities. This model is particularly effective in justifying the sufficiency of fire resistance requirements established for structures to prevent the spread of fire beyond the fire zone within the estimated burnout time of the entire fire load The obtained regularities can be used in the development/revision of regulatory documents on fire safety at operating NPPs and NPPs under construction.

Best compromise multi-objective optimization of testing interval in an NPP’s emergency power supply system considering the ageing effects

Best compromise multi-objective optimization of testing interval in an NPP’s emergency power supply system considering the ageing effects

Cooldown of a water-cooled reactor during the natural circulation mode using decay heat of the core and a low-power steam turbine

The Fukushima-1 nuclear power plant accident in 2011 confirms that NPP safety is one of the most urgent present-day problems. Moreover, a rapidly growing number of NPP units increases the risk of serious radiation accidents. The authors have developed a novel cooldown method for water-cooled reactors to be used under loss of connection with the power system using decay heat from the core and a low-power steam turbine. A distinctive feature of the method is financial viability of the steam turbine due to its possibility to generate additional electricity at the normal conditions of NPP operation. The aim of the invention is to ensure a high level of NPP safety while maintaining and increasing commercial efficiency and competitiveness of nuclear power plants. To implement the developed method, it is necessary to provide guarantee for reliability of NPP units at natural circulation of the primary coolant, since the primary circulation pumps will be shut off caused by a trip of a reactor. For this reason, the authors carried out an investigation into international practice theory and actual usage of natural circulation of water-cooled reactors. Experiments conducted at Kozloduy NPP and research of a number of scientists demonstrate a possibility to maintain constant decay heat removal that will ensure obtaining steam with stable parameters in the secondary circuit. The second part of the research deals with a new method aimed at beneficial usage of steam obtained by using the decay heat from the core under natural circulation of the primary coolant. The generated steam can be used in the additional low-power steam turbine to power supply the NPP's auxiliary needs. In our earlier research we performed a preliminary assessment of reliability of the developed system. The results of the research showed that a combination of a steam turbine and a standard three-channel emergency power supply system with diesel generators enables a safety level comparable to that of external heat exchangers in the passive heat removal systems. At the same time, passive heat removal systems require significant capital investments and maintenance costs, whereas according to the method developed by the authors, a low-power steam turbine can operate in the normal regime to generate additional electricity, as well as in combination with energy storage systems. This will ensure full cost recovery of the developed installations. To assess a reduction of risks of nuclear accidents in terms of cash equivalents when using the novel method, the authors analyzed the influence of various factors on damage expectancy in case of an accident at NPP, based on the example of Fukushima and Chernobyl NPPs. The investigation showed that a reduction of nuclear accident risk in terms of cash equivalents, when implementing the authors’ method aimed to supply the auxiliary NPP needs in blackout situations, reaches tens of millions of US dollars per year.

Структурное моделирование существующих и усовершенствованных алгоритмов управления тиристорных переключающих устройств агрегатов бесперебойного питания собственных нужд атомных станций

The article analyzes the operation of thyristor automatic switching devices for uninterruptible power supply units of nuclear power plants. They are part of the emergency power supply system for auxiliary electrical equipment with a rated voltage of 0.4 kV. In such a reliable power supply system for especially responsible consumers, alternative networks and backup sources are necessarily used. Typically, groups of consumers for auxiliary needs of nuclear power plants are powered from the inverter network, so that in the event of a shutdown of the backup bypass network, these loads continue to be powered by the uninterruptible power supply unit. It incorporates a charger – a controlled rectifier, a battery pack and a transistor inverter. The transition from one network to another in any direction must be “shockless” in order to avoid the operation of the protections of uninterruptible power units and other electrical protections of the reliable power supply system. If there are failures in the algorithms or their irrational organization, the processes of transition between networks may be accompanied by a violation of uninterrupted power supply or phase-to-phase short circuits. A structural simulation model has been created in the MatLab computer mathematics system for testing transition algorithms for various phase shifts of networks and transition directions. The algorithm of transition between networks for uninterruptible power units of one of the manufacturing companies that supplied equipment to nuclear power plants was analyzed. A safer optimal algorithm for controlling network switching with phase-by-phase control of the current drop in the disconnected network is proposed. The proposals are supported by the results of computer simulations.

Reliability Evaluation of an NPP’s Emergency Power Supply System Considering Uncertainty, Sensitivity and Testing Interval Analyses

Reliability Evaluation of an NPP’s Emergency Power Supply System Considering Uncertainty, Sensitivity and Testing Interval Analyses

Emergency Power Supply System for Critical Infrastructures: Design and Large Scale Hardware Demonstration

Emergency Power Supply System for Critical Infrastructures: Design and Large Scale Hardware Demonstration

Study on Efficiency of Compressed Air Emergency Power Supply System Based on MATLAB

Taking a new type of emergency power supply system with compressed air as power source and expander as engine as the analysis object, the working process analysis, and energy loss analysis of the system are made. On this basis, the system analysis model was established, and the relationship between the system efficiency and each influencing parameter was obtained through MATLAB simulation calculation of the system. According to the analysis, it was concluded that when the other parameters were certain, system efficiency with the rising of tanks of compressed gas pressure reduced gradually, the volume expansion ratio of the expander first increased and then decreased, and the increase of inlet pressure expander rose. Still, its growth rate decreased gradually with the increase of leakage coefficient and plummeted. Among various parameters that would influence each other, the pressure range of compressed air stored in the air storage tank needed to be determined according to the structural parameters of the expander. In order to achieve the highest energy utilization rate of compressed gas, according to different system parameters, it was necessary to reasonably match the parameters of the gas storage tank and expander through parametric design.

Application of hybrid renewable energy for supplying the emergency power supply system in case of station blackout in nuclear power plant

This paper introduces the applications of renewable energy in contributing to the improvement of the electrical system of the nuclear power plant, specifically with regard to energy sources in case of emergency to ensure that there is no malfunction in the cooling systems after unplanned shutdown. The Fukushima accident had an impact on reassessing the design of the electrical systems of nuclear power plants to avoid partial or complete blackout of the nuclear power plants because of its effects on the environment and the population. We proposed a new design to add Wind/PV/Battery power system to the electrical emergency system to enhance the safety and reliability of the electrical emergency systems. This hybrid energy system is used to feed the loads in the event of different scenarios such as startup, normal operation, planned shutdown and unplanned shutdown of the station and the interruption of traditional sources of the Egyptian first nuclear power plant at El-Dabaa site (1200 MWe). The proposed Renewable energy systems are designed and analyzed using electrical transient and analysis program (ETAP), version 19.0.1, assuming different load flow audit scenarios. The study has proven the extent to which renewable energy can be used to ensure the safety functions and protect the nuclear power plant in the event of complete blackout.

Electrodynamic speed stabilizer for emergency wind power unit of an aircraft

In this paper, a new technical solution is proposed for a deeper and faster speed stabilization of an emergency aviation wind power unit (EAWPU) using an electromagnetic brake. The principle of the electromagnetic brake operation is considered and a simplified block diagram of the aircraft emergency power supply system is presented. An example of the design electromagnetic brake for installation on an EAWPU is proposed, and the results of a finite element analysis magnetic field and current density in the rotating part of the electrodynamic speed stabilizer are presented. The study of various materials and the thickness of the electromagnetic brake rotor is carried out in order to find the highest value of the braking torque. The main dependences of the braking torque on the excitation current, the rotor thickness and the EAWPU rotation speed are obtained. The simulation of the thermal processes electromagnetic brake is carried out in order to find the maximum temperature of the rotor, according to the results of which the temperature dependences on the rotor speed are constructed at different excitation currents of the electromagnetic brake.

SIMO Converter Design as Emergency Power Supply Multi Output for Disaster Areas

This paper discusses the design of emergency power supply systems in disaster affected areas. Communication and information on post-disaster conditions is very important to be known by the family or authorities. However, a condition that often occurs after a disaster is that the communication system is cut off due to loss of electricity sources. The proposed system aims to provide backups of electrical energy especially in communication equipment such as cellphone chargers and Backup Battery systems on BTS. The flyback converter topology applied provides a multi output voltage of 5 volts for cellphone chargers and 13 volts for Battery systems on BTS, where each system is able to provide an SOC of 20-40%.

Mathematical analysis of dynamic safe operation area of very large capacity lead-acid battery

Flooded lead-acid battery dominates the emergency power supply system of nuclear power plants. However, Valve-Regulated Lead-Acid (VRLA) battery occupies important parts in emergency power supply systems. Structure design for internal consistency of big capacity is a challenge. Electrical variables of battery fluctuate as hysteresis while aging. This paper decouples terminal voltage in deep discharge by concentration polarization of electrolyte. Voltages of both bulk electrolyte capacitance and internal resistance are constants. This principle presents a novel model of dynamic threshold of contacting resistance. The model is sensitive to the battery nonlinear hysteresis. The model alarms remaining useful capacity at the end of service life. Parallel experiments at 4200 (Ah) VRLA batteries verifies the model. A Microchip embedded management board runs the algorithm.

Reliability assessment of emergency auxiliaries of an NPP using an additional steam turbine under various modes of its utilization

Under complete blackout of a station, it is possible to cool-down the VVER-1000 type reactors using the energy of residual heat release of the reactors. The calculations from past works showed in the context of Balakovo nuclear power plant, that a single low-power steam-turbine unit by utilizing the energy of residual heat release from one reactor is capable to provide electricity for two VVER-1000 power units, including the cases when the first circuit in one of the units is depressurized. This work is a continuation of the investigation of the general-station reserve systems for nuclear power plants own needs. The effectiveness of the joint installation of an additional multifunctional steam turbine and a mobile general-station diesel generator was investigated taking into account the results of a large research of the causes for not starting diesel generators at nuclear power plants, conducted by scientists from the USA and Canada, according to which the interval of the percentage of their non-start ranges from 1 to 3%. It is shown that the reliability of such concurrent redundancy of the NPP’s own needs meets the IAEA requirements. Also in the work, the reliability of the developed emergency power supply system was investigated in the conditions of the additional steam turbine stop during the night off-peak hours of the electrical load. Research has shown that this is not acceptable for the accepted conditions from a safety point of view.

HARDWARE IMPLEMENTATION OF ENGINEERING AND TECHNICAL METHODS OF PREVENTION OF EMERGENCIES DUE TO FIRE IN THE CONDITIONS OF ELECTRIC POWER DAMAGE

The problem of formation of complex approaches to hardware realization of engineering and technical methods of prevention of emergency situations owing to a fire on potentially dangerous objects in the conditions of damage of power supply of systems of emergency counteraction is considered in the work. The analysis of warning methods used to detect emergencies due to fire at potentially dangerous objects proved that in specific operating conditions, namely damage to the power supply of emergency response systems, known protection methods (hazard identification as its initial stage) are ineffective. At the same time, the use of alternative methods, such as methods based on the phenomenon of acoustic emission, despite their proven ability in other areas of public safety, remains highly questionable because at present there is no appropriate mathemati-cal apparatus on which to form algorithmic and procedural basis. these innovative approaches. It is to solve this urgent problem, the formation of the mathematical apparatus of engineering and technical methods of emergency prevention due to fire in the event of damage to the power supply of emergency response systems, and the above research is directed. Based on the above, the purpose of the study is to form integrated approaches to the hardware implementa-tion of engineering and technical methods of emergency prevention due to fire at potentially dangerous objects in the event of damage to the power supply of emergency response systems. To ensure this goal, the following tasks are solved: the sequence of stages of processing acoustic signals is determined; the general requirements to hardware realization of engineering and technical methods and the gen-eral functional scheme of practical realization of the demanded approach are formed. During the research the sequence of the main stages of processing of acoustic signals from the source of an emergency situation as a result of a fire at a potentially dangerous object is generalized and determined. The general requirements to hardware realization of engineering and technical methods of the prevention of emergency situations owing to a fire on potentially dangerous objects in the conditions of damage of power sup-ply of systems of emergency counteraction are formed. The general example of realization of the functional scheme of engineering and technical methods of preven-tion of emergencies in energy difficult conditions of functioning of potentially dangerous object is considered. Recommendations concerning a possibility of application of required methods in practical activity are resulted. Keywords: emergency situation, engineering and technical methods, acoustic signal, emergency power sup-ply system

LOAD FLOW ANALYSIS FOR NON COMMERCIAL POWER REACTOR 10 MW ELECTRICAL EMERGENCY POWER SUPPLY

Load flow analysis has been carried out for the emergency power supply system on Non-Commercial Power Reactors. The function of the electric power supply is very important so if there is a failure of the electric power supply it can have an impact on the continuity of the reactor operation. The only emergency diesel generators available are enough to supply the power supply for equipment needs related to the reactor safety system. The RDNK electrical system is designed in such a way that it is able to supply reliable electrical energy to loads consisting of various safety classifications. From the results of the analysis of power flow using ETAP simulation shows that all electrical power requirements related to the reactor safety system can be done properly and safely.

Design of an Emergency Power Supply System for a Research Reactor

In order to guarantee the safe operation of a new research reactor in China, the design criterion, system structure, function and equipment composition of Emergency Power System of the reactor are introduced, and the key elements are analyzed, which should be considered in the capacity determination process of diesel generator set, uninterrupted power supply(UPS) and Class 1E batteries. An Emergency Power System was designed as a special safety facility of the new research reactor, and then its capacity were calculated. The results show that the capacity of diesel generator set is 1000 kV?A, the maximum capacity of UPS is 600 kV?A, and the maximum capacity of Class 1E batteries is 5000 Ah. When the two outside powers are lost, this emergency power system can supply 72 h power to the reactor safety system continuously, and it can guarantee the safe operation of the reactor.

Analysis of fuel properties applied at a structure of aircraft

The article presents the current status of liquid fuels used in aviation. The physicochemical properties of these liquids are discussed against the background of the type of aviation and mission. Aviation fuels are mixtures of hydrocarbons most often obtained from conservative or processing crude oil, supplemented with additives improving their exploitation properties. Currently, aviation fuels occur in two basic types: fuels for turbojet engines and fuels for piston engines. The basic fuel for commercial air transport and military aviation is fuel for turbo-propeller engines. Synthetic compounds and various types of alternative fuels are used more rarely as aviation fuels. A specific role is played by hydrazine used in the emergency power supply system of aircraft, for example, in multi-purpose fighter planes F-16.

Optimization for Postearthquake Resilient Power System Capacity Restoration Based on the Degree of Discreteness Method

The occurrence of a natural disaster such as a strong earthquake affects not only the capacity of a city’s power supply system but also the normal operation of other lifeline systems. An urban emergency power supply system is used to manage the power supply restoration with the consumers divided into three types based on their impact and importance during a power failure. In this study, a power supply system equipped to meet the requirements of different restoration level facilities and enable the restoration of power after the occurrence of an earthquake was developed. A three‐stage power restoration curve was formulated based on the postearthquake recovery process. The relative importance factors of consumers can be calculated with a normalization model based on membership degree. These relative importance factors were then combined with the postearthquake recovery capabilities of each consumer to calculate the overall recovery capability and equilibrium degree of the urban power system. Using the two foregoing indicators, the power supply recovery level of the power system after an earthquake was quantitatively analyzed, and the power supply scheme of the consumers with different power supply guarantee types was rationally optimized.

A comprehensive analysis of emergency power supply systems at NPPs with WWER-1000 type reactors based on additional steam turbines in the context of Balakovo NPP

An emergency power supply system for NPPs based on additional steam-turbine units is pro-posed. Under complete blackout of a station, it is possible to cool-down the VVER-1000 type reactors using the energy of residual heat release of the reactors. While maintaining the temperature of the primary coolant at the constant level, it will be possible to use additional steam-turbine units for electricity generation. The system is considered in the context of two units of Balakovo nuclear power plant. The calculations showed that a single low-power steam-turbine unit by utilizing the energy of residual heat release from one reactor is capable to provide electricity for two VVER-1000 power units, including the cases when the first circuit in one of the units is depressurized. It is shown that in line with IAEA requirements, the proposed system makes it possible to ensure the safety of nuclear power plants in case of complete blackout. At the same time, under standard operating conditions of NPP, additional steam-turbine units participate in generation of electricity. On the basis of statistical and probability analysis, we determined the annual reduction in the risk of the core damage. The technical and economic efficiency of the proposed redundancy system was assessed, taking into account the annual reduction in the risk of the core damage and cases with no damage. It is shown that the system is cost effective due to electricity generation under the regular NPP operation mode, even without any account for lowering the risks of the core damage.