FMEDA and FIT-Based Safety Assessment of NPP I&C Systems Considering Expert Uncertainty

2018 ◽  
Author(s):  
Alexander Yasko ◽  
Eugene Babeshko ◽  
Vyacheslav Kharchenko
Keyword(s):  
Emotional Disorders ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Failure Modes ◽  
Reliability Assessment ◽  
Software Tool ◽  
Critical Systems ◽  
System Specification ◽  
Multiple Faults ◽  
Safety And Reliability

The complexity of modern safety critical systems is becoming higher with technology level growth. Nowadays the most important and vital systems of automotive, aerospace, nuclear industries count millions of lines of software code and tens of thousands of hardware components and sensors. All of these constituents operate in integrated environment interacting with each other — this leads to enormous calculation task when testing and safety assessment are performed. There are several formal methods that are used to assess reliability and safety of NPP I&C (Nuclear Power Plant Instrumentation and Control) systems. Most of them require significant involvement of experts and confidence in their experience which vastly affects trustworthiness of assessment results. The goal of our research is to improve the quality of safety and reliability assessment as result of experts involvement mitigation by process automation. We propose usage of automated FMEDA (Failure Modes, Effects and Diagnostic Analysis) and FIT (Fault Insertion Testing) combination extended whith multiple faults approach as well as special methods for quantitative assessment of experts involvement level and their decisions uncertainty. These methods allow to perform safety and reliability assessment without specifying the degree of confidence in experts. Traditional FMEDA approach has several bottlenecks like the need of manual processing of huge number of technical documents (system specification, datasheets etc.), manual assignment of failure modes and effects based on personal experience. Human factor is another source of uncertainty. Such things like tiredness, emotional disorders, distraction or lack of experience could be the reasons of under- and over-estimation. Basing on our research in field of expert-related errors we propose expert involvement degree (EID) metric that indicates the level of technique automation and expert uncertainty degree (EUD) metric which is complex measure of experts decisions uncertainty within assessment. We propose usage of total expert trustworthiness degree (ETD) indicator as function of EID and EUD. Expert uncertainty assessment and Multi-FIT as FMEDA verification are implemented in AXMEA (Automated X-Modes and Effects Analysis) software tool. Proposed Multi-FIT technique in combination with FMEDA was used during internal activities of SIL3 certification of FPGA-based (Field Programmable Gate Array) RadICS platform for NPP I&C systems. The proposed expert trustworthiness degree calculation is going to be used during production activities of RPC Radiy (Research and Production Corporation). Our future work is related to research in expert uncertainty field and extension of AXMEA tool with new failure data sources as well as software optimization and further automation.

Verification of FPGA Based NPP I&C Systems Considering Multiple Faults: Technique and Automation Tool

2017 ◽  
Author(s):  
Alexander Yasko ◽  
Eugene Babeshko ◽  
Vyacheslav Kharchenko
Keyword(s):  
Power Plants ◽  
Failure Modes ◽  
Fault Injection ◽  
Reliability Assessment ◽  
International Standards ◽  
Verification And Validation ◽  
Critical Systems ◽  
Multiple Faults ◽  
Safety And Reliability ◽  
Detailed Technique

Instrumentation and Control (I&C) systems for Nuclear Power Plants (NPP) are exceedingly complicated electronic solutions that include thousands of different components such as microcontrollers, Field-Programmable Gate Arrays (FPGAs), integrated circuits etc. Deployment of such safety-critical systems cannot be performed without complex safety and reliability assessment, verification and validation (V&V) activities that are addressed to exposing of overlooked faults. The examples of such activities are Fault Tree Analysis (FTA), Failure Modes and Effects Analysis (FMEA), Fault Injection Testing (FIT). Due to complexity of NPP I&C systems in most cases the process of assessment is very time consuming and the results mostly depend on experts’ qualification. Traditional safety and reliability assessment methods are being constantly modified and enhanced so as to comply with increasing demands of national and international standards and guidance, as well as to be applied for I&C systems that contain number of complex components like FPGA. Although much work related to analysis of FPGA-based systems has been performed, there is a lack of detailed technique for FPGA-based I&C systems failure identification that considers probability of several faults at the same time (multi-faults), development of preventive strategies for controlling or reducing of the risk related to such failures, as well as automation of this technique so as to make it utilizable for real NPP industry tasks. FIT as verification for Failure Modes, Effects and Diagnostics Analysis (FMEDA) was used during Safety Integrity Level 3 (SIL3) certification process of RadICS NPP I&C platform, while the parts of proposed technique were used as internal verification and validation activities applied on several modules of the platform.

scholarly journals STANDARD AND FUTURE-POTENTIAL METHODS FOR SAFETY AND RELIABILITY ASSESSMENT ILLUSTRATED BY AN AIRBORNE ELECTRIC SYSTEM EXAMPLE

Aviation ◽  
2016 ◽  
Vol 19 (4) ◽  
pp. 180-186
Author(s):  
Luboš Janhuba
Keyword(s):  
Safety Assessment ◽  
Reliability Assessment ◽  
General Aviation ◽  
Critical Systems ◽  
Electric System ◽  
System Components ◽  
Safety And Reliability ◽  
Future Potential ◽  
Potential Methods ◽  
Short Presentation

This paper is focused on the description of complex airborne safety and reliability assessment methods mostly used in general aviation. It is a short presentation of standard approaches, principles and methods for the evaluation of aircraft critical systems. There are many techniques that may be used during safety and reliability assessment of an airborne system. The complexity of airborne system components and their interconnection is rapidly growing. System safety assessment is an essential part of an airplane certification process. Therefore, the means of safety and reliability have to evolve. This paper presents one of future potential concepts of safety and reliability analysis. The conclusion of this paper gives a brief summary of a standard and a future-potential technique.

scholarly journals Safety and Reliability Assessment of NPP Instrumentation and Control Systems Considering Different Communication Architectures

2020 ◽  
pp. 38-43
Author(s):  
E. Babeshko ◽  
O. Illiashenko ◽  
V. Kharchenko ◽  
E. Ruchkov
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Reliability Assessment ◽  
Assessment Model ◽  
Analytical Models ◽  
Critical Systems ◽  
Safety Critical ◽  
Communication Architectures ◽  
Safety And Reliability ◽  
And Control

Safety and reliability assessment of instrumentation and control (I&C) systems used in different safety-critical industries is a responsible and challenging task. Different assessment models recommended by international and national regulatory documents and used by experts worldwide still have disadvantages and limitations. Therefore, studies of assessment model improvements and refinements are essential. This paper proposes that the assessment models be improved by taking into account different architectures of communications both between different systems and within one particular system. In most models, communication lines are considered absolutely reliable, but the analysis performed shows that the communications should be necessarily addressed. Several analytical models are described to assess the reliability of safety-critical systems for nuclear power plants with different communication options.

FMEDA-Based NPP I&C Systems Safety Assessment: Toward to Minimization of Experts’ Decisions Uncertainty

2016 ◽  
Author(s):  
Alexander Yasko ◽  
Eugene Babeshko ◽  
Vyacheslav Kharchenko
Keyword(s):  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Failure Modes ◽  
Electronic Components ◽  
Life Cycle Stages ◽  
Safety And Reliability ◽  
The One ◽  
And Control ◽  
Criticality Analysis

There are many techniques for the Nuclear Power Plants Instrumentation and Control (NPP I&C) systems safety assessment. Each of them is suitable for specific types of I&C systems and life cycle stages. Though general procedures of techniques application are specified by standards and described by guides, there is no universal solution that could be unambiguously applied to any NPP I&C system. The Failure Modes, Effects and Diagnostics/Criticality Analysis (FME(D/C)A) is the one that is most often used. Using this technique, the process of assessment is not trivial because of dimensionality problem that is especially critical for modern NPP I&C systems that contain many complex electronic components. Another challenge is the need of compliance to varying requirements of standards. Furthermore, modern I&C systems are based on different platforms (FPGA, microcontrollers). Most of safety and reliability assessment techniques, including mentioned FME(D/C)A, are based on expertise and thereby results are dependent on experts’ decisions very much. This could be a serious challenge, because it is very difficult to find universal experts that have sufficient experience to be equally qualified in different electronic components (FPGA, microcontrollers etc.) used in modern I&C systems. The goal of this paper is to analyze the ways of automation of FMEDA-based NPP I&C systems safety assessment and minimization of uncertainty degree of experts’ decisions. Possible experts’ errors and the uncertainty degree of their decisions are analyzed. We propose integration of all existing FMEA-based techniques into XME(D/C)A that includes Functional FMEA, Design FMEA, Software FMEA, Hardware FMEA etc. Such approach allows performing more comprehensive analysis. Developed tool AXMEA (Automated XMEA) represents an integrated solution that provides the automation of stages of FMEDA technique applied to NPP I&C. The case study is the application of proposed technique and tool during SIL3 certification of the modular RadICS™ platform.

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 Variable Ordering Heuristic Based on Zero-Suppressed Binary Decision Diagrams

2010 ◽  
Author(s):  
Ya-zhou Li ◽  
Jin Wang ◽  
Li-qin Hu ◽  
Yi-can Wu
Keyword(s):  
Nuclear Power ◽  
Safety Assessment ◽  
Large Scale ◽  
Binary Decision Diagrams ◽  
Decision Diagrams ◽  
Binary Decision ◽  
Minimal Cut Sets ◽  
Variable Ordering ◽  
Safety And Reliability ◽  
Event Trees

Two approaches have been proposed to solve the large-scale fault trees or event trees for Probabilistic Safety Assessment in a nuclear power plant. The first one consists in MCS/ZBDD, which uses ZBDDs (Zero-suppressed Binary Decision Diagrams) to implement classical MCS (Minimal Cut Sets) algorithm. The second consists in designing heuristics and strategies to reduce the complexity of the BDDs (Binary Decision Diagrams) construction. This paper was motivated to combine the MCS/ZBDD and designing heuristics for ZBDDs together. A heuristic, which took the failure rate of basic event into account and utilized that truncation could be implemented on ZBDDs during the calculating process, was proposed. This heuristic accelerated the analysis progress by bringing forward the truncation and reducing the complexity of the intermediate ZBDDs. RiskA, a Zero-suppressed Binary Decision Diagram package extended to safety and reliability analysis, has adopted this heuristic. RiskA’s truncation strategies, which had some relations with the ordering scheme, were also introduced. The correctness and efficiency of this new heuristic were verified by some practical models’ analyses.

scholarly journals Failure Propagation Modeling and Analysis via System Interfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Lin Zhao ◽  
Krishnaiyan Thulasiraman ◽  
Xiaocheng Ge ◽  
Ru Niu
Keyword(s):  
Safety Assessment ◽  
Failure Modes ◽  
System Development ◽  
Critical Systems ◽  
Operational Environment ◽  
Modeling And Analysis ◽  
Safety Critical ◽  
Propagation Modeling ◽  
Systems Model ◽  
Safety Critical Systems

Safety-critical systems must be shown to be acceptably safe to deploy and use in their operational environment. One of the key concerns of developing safety-critical systems is to understand how the system behaves in the presence of failures, regardless of whether that failure is triggered by the external environment or caused by internal errors. Safety assessment at the early stages of system development involves analysis of potential failures and their consequences. Increasingly, for complex systems, model-based safety assessment is becoming more widely used. In this paper we propose an approach for safety analysis based on system interface models. By extending interaction models on the system interface level with failure modes as well as relevant portions of the physical system to be controlled, automated support could be provided for much of the failure analysis. We focus on fault modeling and on how to compute minimal cut sets. Particularly, we explore state space reconstruction strategy and bounded searching technique to reduce the number of states that need to be analyzed, which remarkably improves the efficiency of cut sets searching algorithm.

scholarly journals Application of enhanced methods for safety assessment of FADEC

2021 ◽  
Vol 23 (1) ◽  
pp. 63-73
Author(s):  
Jiri Hlinka ◽  
Rostislav Kostial ◽  
Michaela Horpatzka
Keyword(s):  
Fuzzy Logic ◽  
Decision Analysis ◽  
Safety Assessment ◽  
Quantitative Assessment ◽  
Development Process ◽  
Reliability Assessment ◽  
Multiple Criteria Decision Analysis ◽  
Control Units ◽  
Development Costs ◽  
Safety And Reliability

The paper deals with safety and reliability assessment as an integral part of the development process for modern aviation products with potentially critical functions. Focus is on digital engine control units, their development process and tools offering potential savings in otherwise time demanding and expensive safety assessment processes. The paper shows application of several approaches, which together form an innovative way for safety assessment of aerospace products (otherwise strictly limited by regulation procedures). It is focused on practical ways towards reduction of development costs during safety assessment, which do not compromise its comprehensiveness. Described approaches are based on experience from development of numerous aerospace products in last nearly 20 years. As an addition, possibility to further enhance the proposed innovative effect classification by application of FMECA was shown. Possible methods for quantitative assessment using Fuzzy logic and/or multiple-criteria decision analysis were discussed.

scholarly journals PRACTICAL ASPECTS OF OPERATING AND ANALYTICAL RELIABILITY ASSESSMENT OF FPGA-BASED I&C SYSTEMS

2020 ◽  
pp. 75-83
Author(s):  
Eugene Babeshko ◽  
Vyacheslav Kharchenko ◽  
Kostiantyn Leontiiev ◽  
Eugene Ruchkov
Keyword(s):  
Integrated Circuits ◽  
Control Systems ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Failure Modes ◽  
Reliability Assessment ◽  
Operating Reliability ◽  
Analytical Reliability ◽  
And Control

Operating reliability assessment of instrumentation and control systems (I&Cs) is always one of the most important activities, especially for critical domains such as nuclear power plants (NPPs). It is an important source of I&C reliability information preferable to lab testing data because it provides information on I&C reliability under real use conditions. That is the reason that now it is a common practice for companies to have an established process of collecting operating reliability data on a large variety of used components on regular basis, maintaining a database with failure information, total operation time, typical failure modes, etc. The intensive use of complicated components like field-programmable gate arrays (FPGAs) in I&C which appear in upgrades and newly-built nuclear power plants makes the 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 the 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 instrumentation and control systems at the design stage is a quite challenging task. Therefore, operating reliability assessment is one of the most preferable ways to perform a comprehensive analysis of FPGA-based NPP I&Cs. Based on information in the literature and own experience, operational vs analytical reliability could be pretty far apart. For that reason, analytical reliability assessment using reliability block diagrams (RBD), failure modes, effects and diagnostics analysis (FMEDA), fault tree analysis (FTA), fault insertion testing (FIT), and other techniques and their combinations are important to meet requirements for such systems. The paper summarizes our experience in operating and analytical reliability assessment of FPGA based NPP I&Cs.

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