scholarly journals Assessment of operation of safety channel signal cables at nuclear power plants under fire conditions

2020 ◽  
Vol 29 (4) ◽  
pp. 51-58
Author(s):  
O. S. Lebedchenko ◽  
V. I. Zykov ◽  
S. V. Puzach
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Operating Temperature ◽  
Current Intensity ◽  
Reactor Facility ◽  
Time Period ◽  
Initial Stage ◽  
Modulated Signals ◽  
Gas Medium

Introduction. Signal cables of safety systems, installed at nuclear power plants (NPPs), retain the ability to conduct modulated signals during the time period needed to switch the reactor facility to a safe mode. However, the ability of signal cables to transmit signals correctly in the high temperature gas medium, which is typical for the early stage of a room fi re, has not been exposed to research.Aims and objectives. The co-authors offer a theoretical assessment of the ability of NPP safety system cables to correctly transmit modulated electric signals if exposed to fi re and current loads. The theoretical research into the temperature of the conductor of a signal cable at the initial stage of fi re has been performed towards this end.Theoretical background. The steady state heat conduction equation, describing heat transmission from the cable core to the environment through the cylinder-shaped insulation layer, is used to measure the temperature of the cable strand.Results and discussion. Temperature dependences describing the relation between the temperature of the conductor of a single - strand and single-wire cable KNEPng(А)-HF on the gas medium temperature are obtained. Relations between the temperature of the gas medium in the room on fi re and the current intensity in the electric cable (if the cable is laid vertically) are presented with account taken of the dependence between the specifi c resistance of the wire and the temperature if the maximal permissible operating temperature of cable strands is 70 °С, the maximal permissible operating temperature of cable strands in the overload operation mode is 80 °С, and the maximal cable strand heating temperature is equal to 160 °С when the short-circuit failure occurs. Maximal current intensity values are obtained for various operating modes in the condition of temperatures typical for the initial stage of an indoor fire, they allow to correctly conduct modulated signals within the time period needed to switch the reactor facility to a safe mode.Conclusions. The developed mathematical model and results of numerical experiments allow to assess the infl uence of the temperature in the room of a nuclear power plant in case of fi re on the ability of a signal cable of the safety system to transfer undistorted modulated signals depending on current loads and signal cable laying patterns (whether it is laid vertically or horizontally), and also to expand the range of the room temperature dependence on the current load provided in Electrical Installations Code (EIC).

scholarly journals Analysis of Systems Thinking Safety by Artificial Intelligence (AI) Algorithm in South Korean Nuclear Power Plants (NPPs)

2021 ◽  
Vol 11 (10) ◽  
pp. 56-62
Author(s):  
Chang Hyun Baek ◽  
◽  
Kyung Bae Jang ◽  
Tae Ho Woo
Keyword(s):  
Artificial Intelligence ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Critical Factor ◽  
Safety Analysis ◽  
The Other ◽  
South Korean ◽  
Initial Stage ◽  
Relative Value

The artificial intelligence (AI) is applied to the safety analysis in the South Korean nuclear power plants (NPPs). The reinforcement learning (RL) is one of promising skills in the wise manipulations for the nuclear safety analysis where the reward is a critical factor to make the modelling. In the simulations, Y-axis means the relative value which shows the quantity of the accident possibility. The highest value is 4.0 in 46.25th year in which the values are increasing gradually. Otherwise, the values in the case with Agent gradually decrease. The highest value is near initial stage, which means the operation in NPPs is comparatively unstable. In the result, the values in the AI based controller graphs are higher than those of the other one. The RL algorithm is expressed by the Agent in this modelling, which is the most important factor in the AI-based operation in NPPs.

scholarly journals Main Approaches to Cable Aging Management at Nuclear Power Plants in Ukraine

2019 ◽  
pp. 54-62
Author(s):  
T. Bilan ◽  
I. Rezvik ◽  
O. Sakhno ◽  
O. But ◽  
S. Bogdanov
Keyword(s):  
Service Life ◽  
Temperature Dependence ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Insulation Material ◽  
Term Operation

The mechanisms of cable ageing at nuclear power plants (NPPs) mainly depending on the insulation material, as well as the damaging factors affecting cables that are determined by the operating conditions are considered in the paper. The main and additional mechanisms of aging resulting from the effects of damaging factors are provided. The paper presents the main methods of cable aging management: determining the actual service life and testing using field methods and other means. The basic principles for the arrangement of cable aging management at Ukrainian NPPs, as well as the methods used to investigate the technical condition of cables, are presented. A list of mandatory lists has been defined when performing activities on cable aging management. A methodology is described for lifetime extension of cables, and conditions for extending the service life of cables that are in service are provided. A number of methods of testing cables for aging management are considered: visual inspection of insulation and measurement of crack size, discoloration, etc.; insulation hardness test; insulation chemical analysis; electrical insulation tests; tensile strength measurement; measurement of elongation at break; measurements of dielectric loss at low frequency or sweep frequency; testing by dynamic reflectometry method; AC and DC current impedance measurements. The paper presents results of separate laboratory studies for selected 1 kV representative power cables with PVC insulation of SUNPP-1, ZNPP-1 and KhNPP-2 conducted within Ukrainian NPP long-term operation, which included a stage of laboratory examination and examination of cable samples in operating conditions. The following results were obtained: dependence of VVGng 4x6 cable lifetime on operating temperature; dependence of AVVG cable lifetime on operating temperature; dependence of AVVG (a) cable lifetime on operating temperature. There are possibilities and conditions under which the use of cables within long-term operation is permissible.

Work structure in nuclear power plants

1983 ◽  
Author(s):  
Marjorie B. Bauman ◽  
Richard F. Pain ◽  
Harold P. Van Cott ◽  
Margery K. Davidson
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Work Structure

Life Extension of Nuclear Power Plants: World Situation and the USA Case

2010 ◽  
pp. 50-56 ◽  
Author(s):  
Pablo T. León ◽  
Loreto Cuesta ◽  
Eduardo Serra ◽  
Luis Yagüe
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Life Extension ◽  
The Usa

Evaluation of System Effectiveness of Multifunctional Hydrogen Complex at Nuclear Power Plants

2019 ◽  
pp. 24-39
Author(s):  
R. Z. Aminov ◽  
A. N. Bayramov ◽  
M. V. Garievskii
Keyword(s):  
Cyclic Loading ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Frequency Control ◽  
Economic Effect ◽  
Current Frequency ◽  
Main Equipment ◽  
Primary Frequency ◽  
Primary Frequency Control

The paper gives the analysis of the problem of the primary current frequency regulation in the power system, as well as the basic requirements for NPP power units under the conditions of involvement in the primary regulation. According to these requirements, the operation of NPPs is associated with unloading and a corresponding decrease in efficiency. In this regard, the combination of nuclear power plants with a hydrogen complex is shown to eliminate the inefficient discharge mode which allows the steam turbine equipment and equipment of the reactor facility to operate in the basic mode at the nominal power level. In addition, conditions are created for the generation and accumulation of hydrogen and oxygen during the day, as well as additionally during the nighttime failure of the electrical load which allows them to be used to generate peak power.  The purpose of the article is to assess the systemic economic effect as a result of the participation of nuclear power plants in combination with the hydrogen complex in the primary control of the current frequency in the power sys-tem, taking into account the resource costs of the main equipment. In this regard, the paper gives the justification of cyclic loading of the main equipment of the hydrogen complex: metal storage tanks of hydrogen and oxygen, compressor units, hydrogen-oxygen combustion chamber of vapor-hydrogen overheating of the working fluid in the steam turbine cycle of a nuclear power plant. The methodological foundations for evaluating the working life of equipment under cyclic loading with the participation in the primary frequency control by the criterion of the growth rate of a fatigue crack are described. For the equipment of the hydrogen complex, the highest intensity of loading is shown to occur in the hydrogen-oxygen combustion chamber due to high thermal stresses.  The system economic effect is estimated and the effect of wear of the main equipment under cyclic loading is shown. Under the conditions of combining NPP power units with a hydrogen complex, the efficiency of primary reg-ulation is shown to depend significantly on: the cost of equipment subjected to cyclic loading; frequency and intensity of cyclic loading; the ratio of the tariff for peak electricity, and the cost of electricity of nuclear power plants.  Based on the developed methodology for assessing the effectiveness of the participation of nuclear power plants with a hydrogen complex in the primary frequency control, taking into account the damage to the equipment, the use of the hydrogen complex is shown to provide a tangible economic effect compared with the option of unloading nuclear power plants with direct participation in frequency control.

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