Degradation Assessment in Complex Systems

2006 ◽  
Author(s):  
Vaidas Matuzas ◽  
Juozas Augutis ◽  
Eugenijus Uspuras
Keyword(s):  
Mathematical Model ◽  
Complex Systems ◽  
Mathematical Models ◽  
Mathematical Description ◽  
Nuclear Power ◽  
Power Plants ◽  
Reliability Assessment ◽  
Main Process ◽  
Main Attention ◽  
Network Systems

Components condition could change dynamically because of various dependencies existing in complex systems since usually not only physical connections exist in the system. Various processes (as degradation or wear out, reliability decrease, failures) affecting one component have influence to condition of other components as well. Current paper is devoted to the analysis and development of mathematical models to the reliability assessment of network systems. Degradation as the main process in the network systems is taken into account. The main attention in present work was paid to the mathematical description of the degradation spreading mechanism in network systems. Developed recursive mathematical model allows assess degradation in network systems during various time moments. Developed methods can be applied for assessment of various risk estimates of hazardous systems such as systems at nuclear power plants.

Operating Reliability Assessment of FPGA-Based NPP I&C Systems: Approach, Technique and Implementation

2017 ◽  
Author(s):  
Eugene Babeshko ◽  
Ievgenii Bakhmach ◽  
Vyacheslav Kharchenko ◽  
Eugene Ruchkov ◽  
Oleksandr Siora
Keyword(s):  
Integrated Circuits ◽  
Nuclear Power ◽  
Power Plants ◽  
Failure Modes ◽  
New Technologies ◽  
Systems Approach ◽  
Reliability Assessment ◽  
Design Stage ◽  
Fpga Design ◽  
Operating Reliability

Operating reliability assessment of instrumentation and control systems (I&Cs) is always one of the most important activities, especially for critical domains like nuclear power plants (NPPs). Intensive use of relatively new technologies like field programmable gate arrays (FPGAs) in I&C which appear in upgrades and in newly built NPPs makes task to develop and validate advanced operating reliability assessment methods that consider specific technology features very topical. Increased integration densities make the reliability of integrated circuits the most crucial point in modern NPP I&Cs. Moreover, FPGAs differ in some significant ways from other integrated circuits: they are shipped as blanks and are very dependent on design configured into them. Furthermore, FPGA design could be changed during planned NPP outage for different reasons. Considering all possible failure modes of FPGA-based NPP I&C at design stage is a quite challenging task. Therefore, operating reliability assessment is one of the most preferable ways to perform comprehensive analysis of FPGA-based NPP I&Cs. This paper summarizes our experience on operating reliability analysis of FPGA based NPP I&Cs.

A Quantitative Approach for Reliability Evaluation of Safety I&C Systems in Nuclear Power Plants

2017 ◽  
Author(s):  
Liu Dongxu ◽  
Xu Dongling ◽  
Zhang Shuhui ◽  
Hu Xiaoying
Keyword(s):  
Probability Theory ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Boolean Algebra ◽  
Nuclear Power ◽  
Power Plants ◽  
Block Diagram ◽  
Reliability Assessment ◽  
Simple Approach ◽  
Assessment Approach

The probability that the safety I&C system fails to actuate or advertently actuates RT or ESF functions, in part, essentially determines whether a nuclear power plant could operate safely and efficiently. Since more conservative assumptions and simplifications are introduced during the analysis, this paper achieves solid results by performing the modeling and calculation based on a relatively simple approach, the reliability block diagram (RBD) method. A typical safety I&C platform structure is involved in the model presented in this paper. From the perspective of conservation and simplicity, some assumptions are adopted in this paper. A group of formulas is derived in this paper based on Boolean algebra, probability theory, basic reliability concepts and equations, to facilitate the calculations of probabilities that the safety I&C system fails to actuate or advertently actuates RT or ESF functions. All the inputs of the analysis and calculation in this paper, which includes the I&C platform structure, the constitution of the hardware modules, and reliability data, are referenced to the nuclear power plant universal database where applicable. Although the conclusion drawn in the paper doesn’t apply to the I&C platform assessment for a specific plant, the method of modeling and process of analysis provides an illustration of an alternative quantitative reliability assessment approach for a typical safety I&C system installed in the nuclear power plant.

THE THERMAL MODE OF LARGE-SPAN EXCA VATIONS DURING THE CONSTRUCTION OF NUCLEAR POWER FACILITIES

2020 ◽  
Vol 2 (1) ◽  
pp. 289-301
Author(s):  
I.P. KARNACHEV ◽  
◽  
V.G. NIKOLAEV ◽  
V.V. BIRYUKOV ◽  
S.A. GUSAK ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Mathematical Models ◽  
Experimental Research ◽  
Nuclear Power ◽  
Power Plants ◽  
Phase Transfer ◽  
Thermal Mode ◽  
Large Span ◽  
Transfer Processes

The paper observes particular experimental research results on increase of stability of mining excavations in a permafrost area under low positive temperatures. The authors discuss the tasks on determining the temperature field parameters around the different-section excavations of underground small nuclear power plants at the construction stage. The mathematical models were designed for heat transfer processes in frozen rocks. The rocks were simulated as pore media filled with water with phase transfer under heating. This allowed creating virtual computing stands on which it became possible to work out the thermal modes of excavation driving.

Dynamical mathematical models of nuclear power plants

Atomic Energy ◽  
2000 ◽  
Vol 88 (6) ◽  
pp. 431-442
Author(s):  
A. A. Abagyan ◽  
A. E. Kroshilin ◽  
V. E. Kroshilin ◽  
V. N. Maidanik ◽  
E. F. Seleznev ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants

Reliability Assessment of Piping in a Nuclear Power Plant Considering Flaw Detection Probability

2004 ◽  
Author(s):  
Hideo Machida ◽  
Norimichi Yamashita ◽  
Shinobu Yoshimura ◽  
Genki Yagawa
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Detection Probability ◽  
Nuclear Power ◽  
Power Plants ◽  
Plant Stress ◽  
Flaw Detection ◽  
Reliability Assessment ◽  
Flaw Detection Probability

This study was performed to clarify the effects of flaw detection probability on piping reliability of a nuclear power plant. Stress-corrosion cracking (SCC) is still sporadically detected in austenitic stainless steel piping in Japanese BWR plants. The suitability for continued service of cracked pipes is basically evaluated by using the “Rules on fitness -for service for nuclear power plants.” Here future inspection rules are employed. However, the possibility of undetection of existing cracks and that of inaccurate measurements cannot be eliminated in UT-based inspection. Thus a probabilistic fracture mechanics (PFM) analysis was carried out referring measured flaw size, and the reliability of piping was evaluated considering the possibility of undetection of existing cracks and that of inaccurate measurements. The results of the analysis indicate that, if the interval and quality of the inspection are maintained at a certain specified level, the possibility of undetection of existing cracks and that of inaccurate measurements less affect failure probability.

scholarly journals Verification on application program generation and loading for safety systems of nuclear power plants based on the reverse engineering method

2018 ◽  
Vol 4 (4) ◽  
pp. 223-228
Author(s):  
Mikhail Belonosov ◽  
Vladimir Kishkin
Keyword(s):  
Mathematical Models ◽  
Nuclear Power ◽  
Power Plants ◽  
Automated Verification ◽  
Application Software ◽  
Original Design ◽  
Program Code ◽  
Design Data ◽  
Verification Method ◽  
Safety Systems

The article describes an automated verification method used for application software of control safety systems based on the TPTS-SB equipment. Verification is performed by comparing two mathematical models (oriented graphs): one obtained by processing the original design data, i.e., graphical functional diagrams, and the other formed by reversing the program code loaded from the controller. The vertices in both graphs are functional blocks of mathematical and logical operations; the edges are connections between them. The constructed mathematical models undergo a comparison, covering the vertices and edges of the graphs as well as the memory cells and values of constants. The equivalence of mathematical models proves the correspondence between the program code and the initial set of design functional diagrams. The proposed automated verification method makes it possible to prove that no distortion is introduced into the program during the process of converting graphical functional diagrams into the program code with its subsequent translation and loading into the controller. It is postulated that any distortions will be detected during the verification procedure, which is performed every time after loading the code into the controller. The solution provides an acceptable speed when large volumes of vector graphics stored in a relational database are processed, and makes it possible to visualize the verification results. The proposed method is implemented in the GET-R1 instrumentation tools for TPTS-SB and is used in designing and verifying the application software of the safety systems at the Belarusian NPP.

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