Degraded or Loss of Voltage Protection of Class 1E Auxiliary Power Systems in a Nuclear Power Plant

1979 ◽  
Vol 26 (1) ◽  
pp. 888-894 ◽  
Author(s):  
S. Dasgupta ◽  
J. J. Murphy
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power Systems ◽  
Nuclear Power ◽  
Auxiliary Power

Dynamic Simulation Studies of Performed Additional Tests During FAT for Emergency Diesel Generators at Nuclear Power Plant

2016 ◽  
Author(s):  
Salah K. Kanaan ◽  
Amer Omanovic
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Electric Circuit ◽  
Diesel Generator ◽  
Safety Regulations ◽  
Auxiliary Power ◽  
Current Voltage ◽  
Measurement Results ◽  
Generator Sets

In 2004, a decision was made to perform a modernization and a new power uprate of unit 2 at Oskarshamn nuclear power plant in Sweden. Among the most important reasons for this decision were new safety regulations from Swedish Radiation Safety Authority and ageing of important components. A project was established and became the largest nuclear power modernization in the world. The modernization led to the need of analysing the auxiliary power system to ensure that it could supply the unit after the uprate, given tolerances on current, voltage and frequency. During the process of developing models for the diesel generator sets, it turned out that the suppliers could not deliver enough satisfactory material for modelling the diesel engines, the speed controllers and the magnetization systems. Therefore, Oskarshamn nuclear power plant with the help of the manufacturers of the diesel generator sets carried out additional measurements in order to collect data for modelling. Based on electric circuit diagrams provided by the manufacturers, block diagrams of the magnetization systems were made. For the speed controllers, no information was available at all so it was assumed that the controller was of PI-type. The parameters of the magnetization systems and the speed controllers were then tuned using the measurement results. Finally, a comparison between simulated results and the measurement results were made, showing good agreement. This is especially true in the most commonly used operating interval of the diesel generator sets.

A Simulation of Small Break Loss of Coolant Accident (SB-LOCA) in AP1000 Nuclear Power Plant Using RELAP5-MV

2017 ◽  
Author(s):  
Eltayeb Yousif ◽  
Zhang Zhijian ◽  
Tian Zhao-fei ◽  
A. M. Mustafa
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power Systems ◽  
Nuclear Power ◽  
Power Plants ◽  
Computational Simulation ◽  
Primary System ◽  
Transient Time ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant

To ensure effective operation of nuclear power plants, it is very important to evaluate different accident scenarios in actual plant conditions with different codes. In the field of nuclear safety, Loss of Coolant Accident (LOCA) is one of the main accidents. RELAP-MV Visualized Modularization software technology is recognized as one of the best estimated transient simulation programs of light water reactors, and also has the options for improved modeling methods, advanced programming, computational simulation techniques and integrated graphics displays. In this study, transient analysis of the primary system variation of thermo-hydraulics parameters in primary loop under SB-LOCA accident in AP1000 nuclear power plant (NPP) is carried out by Relap5-MV thermo-hydraulics code. While focusing on LOCA analysis in this study, effort was also made to test the effectiveness of the RELAP5-MV software already developed. The accuracy and reliability of RELAP5-MV have been successfully confirmed by simulating LOCA. The calculation was performed up to a transient time of 4,500.0s. RELAP5-MV is able to simulate a nuclear power system accurately and reliably using this modular modeling method. The results obtained from RELAP5 and RELAP5-MV are in agreement as they are based on the same models though in comparison with RELAP5, RELAP5-MV makes simulation of nuclear power systems easier and convenient for users most especially for the beginners.

The Necessity of Independent Configuration of the DC Power Supply System Used for Power Supply and Auxiliary Power Supply in Nuclear Power Plant

2018 ◽  
Author(s):  
Zhang Zhichao
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power System ◽  
Power Supply ◽  
Nuclear Power ◽  
Power Supply System ◽  
Power Source ◽  
Dc Power ◽  
Auxiliary Power ◽  
Ac Power

At present, in the typical design of China’s nuclear power plant, main generation system is connected to the power grid by 500 kV system. 500 kV system as a priority power source, 220kV system as an auxiliary power source. Independent operation of 500kV and 220kV system, improved the reliability of power supply of nuclear power plant. However, the DC 220V power system used to control the 500kV and 220kV system in the switch station of partial nuclear power project is not independently configured, and the design form of one set of DC system is used in the transformer station. In recent years, there are many accidents that AC power enters into the DC power system, resulted in the loss of power source in the transformer station. The loss of external power source in the whole plant is very significant. In this paper, the influence of AC power entering into DC power system on relay protection device is analyzed, the measures to prevent the AC power into DC power system are discussed, the necessity of independent configuration of DC control power system for the 500kV priority power system and 220kV auxiliary power supply system is analyzed.

An intelligent diagnosis model of accidents in nuclear power plant

2021 ◽  
pp. 1-8
Author(s):  
Yanqi Liu ◽  
Li Zhang ◽  
Zhenghua Xu ◽  
Xueyang Liu
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power Systems ◽  
Nuclear Power ◽  
Characteristic Vector ◽  
Monitoring Result ◽  
Relational Degree ◽  
Diagnosis Model ◽  
Grey Relational ◽  
Fuzzy Diagnosis

This essay focus on the situation when the operator of the main control room can not handle the accident in time or make wrong judgment under accident condition in nuclear power plant, which may lead to the occurrence of major accidents or even more accidents concurrently. An intelligent fuzzy diagnosis model based on Grey Relational degree is constructed in this paper, by establishing accident-state correlation matrix and accident-state probability matrix, defining the vector of information weights for accident characteristic vector and monitoring result vector with linear transform, using Grey Relation to measure the relevance degree between monitoring result vector and accident characteristic vector, Searching for suspected accidents approaching to real solutions in iterative recursive algorithms, realizing automatic fuzzy diagnosis of multiple accidents. The results of simulation experiments of LOCA accidents indicate that the model and algorithm can diagnose various common accidents accurately and rapidly in complex nuclear power systems, providing strategy for operator’s diagnosis decision.

scholarly journals The Research of High Voltage Auxiliary Power System Neutral Point Grounding Modes between the Nuclear Power Plant and Conventional Fossil Fuel Power Plant

2015 ◽  
Vol 4 (4) ◽  
pp. 15
Author(s):  
Yunfeng Zhang ◽  
Hourong Pan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power System ◽  
High Voltage ◽  
Nuclear Power ◽  
Power Plants ◽  
Fossil Fuel ◽  
Neutral Point ◽  
Auxiliary Power ◽  
Fossil Fuel Power Plant

<p>Currently, in power plants, the application of the extinction coil in high voltage auxiliary power system neutral point is less experienced. A research done on nuclear power plant and conventional fossil fuel power plant proved that using an auxiliary power system’s different characteristics was leading to different demands of the grounding modes. Thus, this research was done by selecting the grounding mode of high voltage auxiliary power system neutral point on the main nuclear power plants and the partial fossil fuel power plants together with the calculation of practical engineering, and optimal design schemes. The high voltage auxiliary power system neutral point grounding modes have been induced in the large-scale into the nuclear power plant and the conventional fossil fuel power plant. Methods in determining the neutral point grounding modes are used by analyzing the principles commonly used grounding modes and requirements of related codes. First, choose the suitable grounding mode according to the calculation result of capacitive current. Then, choose more conducive grounding mode to the operation of power plant according to the operation of technology equipment. The power is required from the configuration, connection of auxiliary power and the cut from the accident of auxiliary power. As some power plants which are under-construction will be putting into operation one after another, the whole set of perfect security arrangements and operating experiences will also be accumulated inevitably. As a conclusion, high voltage auxiliary power system neutral point grounding modes directly affect the running of the auxiliary power system and even affect the security of the nuclear safety and the operation of the power plant. I hope this article can play a role for reference on the selection of the auxiliary power system grounding modes.</p>

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