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.
À. 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.
