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RT&A 2017, # 1(44) Vol.12


 

V. Rykov, A. Bochkov, E. Gnedenko

Editorial 

For the preceding year in the life of Gnedenko Forum and our journal there were essential changes. The President of the Forum came off duty and the members of the Editorial Board of the journal were considerably renewed. We hope that all of us together not only will keep spirit and the atmosphere of our journal, but also, we will manage to give to the business begun by Igor Ushakov, a new impulse.

 

M. Yastrebenetsky, A. Klevtsov, Y. Rozen, S. Trubchaninov

 

Fukushima Lessons for Safety of Critical Control Systems 

The accident at the Japan Fukushima-Daiichi nuclear power plant (NPP) influenced future development of nuclear energy as a whole and different NPP safety systems in particular, including control systems.  The lessons of this accident are applied, as a rule, to NPPs. The aim of this paper is to define the possibility to use the Fukushima lessons for non-nuclear applications such as safety of critical control systems (CCS).  The method involves analysis of NPP safety features and experience in post-Fukushima measures for NPP control systems.  The results are general proposals on CCS safety assurance in different industries. The examples include chemical, petrochemical, and gas industries, gas and oil transport, etc.  The conclusion is that the Fukushima lessons can be applied to improve safety of not only NPPs but also CCS in other industries.

 

I. Shubinsky, I. Rozenberg, L. Papic

Adaptive Fault Tolerance in Real-Time Information Systems 

Real-time information systems (IS) control mission-critical processes. Violation of functioning in these systems may lead to dangerous errors in control and to intolerable risks. The general disadvantage of traditional ways of IS reliability assurance is an autonomous implementation of fault tolerance mechanisms, as well as breaks of calculation which is unacceptable for real-time systems. All known ways to assure IS reliability are based on the application of large volumes of artificial structure and information redundancy. The technology of adaptive fault tolerance proposed in this article consists in the active use of natural time and structure redundancy, as well as in the active (and automatic) reassignment of available computer power not only for operational processing of information, but also for implementation of observability of the system under the conditions of limited control means. The technology of adaptive fault tolerance in information systems when solving real tasks in limited time conditions provides for a timely automatic detection and handling of failures and glitches by means of operational localization of faulty computation modules and by subsequent automatic rearrangement of the system with removal of faulty modules from the process of functioning.

 

V. Sklyar

 

Application of Reliability Theory to Functional Safety of Computer Control Systems  

The aim of this paper is to analyze the application of reliability theory to safety of critical computer control systems (CCS). The method includes taxonomy for dependability and security considerations, which have been updated to reflect all attributes and refine orthogonality relations between the attributes. Functional safety is a part of reliability that deals with safety functions and related dangerous failures. From this point of view, all the reliability theory methods, models, and indicators may be applied to the functional safety domain without any essential changes. As a result, three main types of architecture for modern critical computer control systems are considered (Embedded Systems, Industrial Control Systems, and Internet of Things). Application of reliability and safety indicators to Industrial Control Systems of nuclear power plants is described. Internet of Things has just started to be applied to critical safety systems in the last years. The conclusion is that a research and development program can be proposed for Internet of Things reliability and functional safety.

 

. Antonov, V. Chepurko

Mathematical Model for Calculating Reliability Characteristics NPP Equipment Under Honhomogeneous Flows Failure 

The aim of this paper is to describe a new method for analysis of statistical data on failures to allow considering potential nonhomogeneous event flows (in point stochastic process). The method includes review of the literature on different mathematical models for point stochastic processes (nonhomogeneous Poisson process, gamma process, geometric renewal process, trend renewal process, Kijima-Sumita process) and definition of the main features of the model normalizing the flow function to calculate the required parameters of reliability.  

The result is a model that underlies the methods for calculating NPP equipment reliability indicators that change with time. The specifics of the incoming statistical data are outlined. The conclusion is that a practical analysis of failures in some components of the reactor  protection control system of the Bilibino NPP is used as an example. This analysis is used for determining the equipment residual lifetime.

 

 

G. Johnson, A. Duchac

The Development of the New Idea Safety Guide for Design of Instrumentation and Control Systems for Nuclear Power Plants

The International Atomic Energy Agency (IAEA) is a United Nations organization that was formed to "accelerate and enlarge the contribution of nuclear energy to peace, health and prosperity throughout the world." The IAEA prepares Safety Standards that are organized into three levels: Safety Fundamentals, Safety Requirements, and Safety Guides. The aim of the paper is general description of the new Safety Guide devoted to instrumentation and control systems (I&C) for nuclear power plants (NPPs). The method for elaboration of this Guide was revision of existing guides focusing on NPP I&C, taking into account new topics such as use of field programmable gate arrays, acceptance of industrial digital devices and data communications, computer security, etc. The result is new IAEA Safety Guide SSG-39, agreed with positions of 100 experts in 22 countries, IEC and IEEE.  The conclusion is that SSG-39 provides a solid engineering basis to be covered in design or review of various aspects of I&C. This document is not binding on different countries, but may be adopted by them.

 

V. Koroliuk, D. Koroliouk

Heuristic Principles of Phase Merging in Reliability Analysis 

B.V. Gnedenko was the founder of reliability analysis for stochastic systems. His works [1]-[2] have inspirited, in reliability theory, the development of analytical methods of phase state merging principles for Markov and semi-Markov processes.

 

I. Gertsbakh, Y. Shpungin

System Reliability for Shock and Lottery Models 

In this note we consider how system signatures (D-spectra) can be used in computing system reliability for "shock" and "lottery" models of system reliability.

 

M. Manoharan , Vidhya G Nair

Evaluation of System Performance Measures of Multi State Degraded System with Minimal Repair 

There is a recent surge of interest in multi state systems mainly due to their wide applications in engineering. Multi state degraded systems have been used in modeling of power generating-supply systems, communication systems and transportation systems etc. In this article we propose a new approach ie, a combination of stochastic process approach and Universal Generating Function(UGF) technique by decomposing system in to several subsystems. Analyzing models through this approach, several system performance measures are evaluated. A real data obtained from a power station modeled as a MSS which has two subsystems with many states of degradation, has been used for illustration to apply the approach presented here.

 

 

 

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Copyright 2015, Alexander Bochkov. All rights reserved