Composition of Safety and Cyber Security Analysis Techniques and Tools for NPP I&C System Assessment

Author(s):  
Ievgen Babeshko ◽  
Kostiantyn Leontiiev

Safety assessment of nuclear power plant instrumentation and control systems (NPP I&Cs) is a complicated and resource-consuming process that is required to be done so as to ensure the required safety level and comply to normative regulations. A lot of work has been performed in the field of application of different assessment methods and techniques, modifying them, and using their combinations so as to provide a unified approach in comprehensive safety assessment. Performed research has shown that there are still challenges to overcome, including rationale and choice of the safety assessment method, verification of assessment results, choosing and applying techniques that support safety assessment process, especially in the nuclear field. This chapter presents a developed framework that aggregates the most appropriate safety assessment methods typically used for NPP I&Cs.

Author(s):  
Eugene Babeshko ◽  
Vyacheslav Kharchenko ◽  
Kostiantyn Leontiiev ◽  
Oleg Odarushchenko ◽  
Oleksiy Strjuk

Safety assessment of nuclear power plant instrumentation and control systems (NPP I&Cs) is a complicated and resource consuming process that is required be done so as to ensure the required safety level and comply to normative regulations. A lot of work have been performed in the field of application of different assessment methods and techniques, modifying them and using their combinations so as to provide unified approach in comprehensive safety assessment. Anyway, performed research have shown there are still challenges to overcome, including rationale and choice of the safety assessment method, verification of assessment results, choosing and applying techniques that support safety assessment process, especially in the nuclear field. In our work we present developed framework that aggregates the most appropriate safety assessment methods typically used for NPP I&Cs. Key features that this framework provides are the formal descriptions of all required input information for every safety assessment method, possible data flows between methods, possible output information for every method. Such representation allows to obtain possible paths required to get necessary indicators, analyze the possibility to verify them by application of different methods that provide same indicators etc. During safety assessment of NPP I&Cs it is very important to address software due to its crucial role in I&C safety assurance. Relevant standards like IEC 60880 [1] and IEC 62138 [2] provide requirements for software related activities and supporting processes in the software safety lifecycle of computer-based I&C systems of nuclear power plants performing functions of safety category A, B and C, as defined by IEC 61226 [3]. Requirements and frameworks provided by IEC 60880 and IEC 62138 for the nuclear application sector correspond to IEC 61508, part 3 [4]. These standards define several types of safety related software and specify particular requirements for each software type. So as to verify software and confirm correspondence to required safety level, different techniques are suggested in normative documents. We share our experience obtained during software failure modes and effect analysis (software FMEA) and software fault insertion (software FIT) processes into FPGA-based platform, NPP I&C systems based on that platform, and RPCT, integrated development environment used by RPC Radiy and end users to design user application logic, specify hardware configuration etc. We apply software FIT to outputs of RPCT, considering source code, configuration files and firmware files. Finally, we provide a case study of application the developed safety assessment framework and software FMEA/FIT practices during practical assessment of FPGA-based NPP I&C system.


Author(s):  
Oleksandr Klevtsov ◽  
Artem Symonov ◽  
Serhii Trubchaninov

The chapter is devoted to the issues of cyber security assessment of instrumentation and control systems (I&C systems) of nuclear power plants (NPP). The authors examined the main types of potential cyber threats at the stages of development and operation of NPP I&C systems. Examples of real incidents at various nuclear facilities caused by intentional cyber-attacks or unintentional computer errors during the maintenance of the software of NPP I&C systems are given. The approaches to vulnerabilities assessment of NPP I&C systems are described. The scope and content of the assessment and periodic reassessment of cyber security of NPP I&C systems are considered. An approach of assessment to cyber security risks is described.


Author(s):  
Qingwei Xu ◽  
Kaili Xu ◽  
Fang Zhou

Safety assessment of a casting workshop will provide a clearer understanding of the important safety level required for a foundry. The main purpose of this study was to construct a composite safety assessment method to protect employee health using the cloud model and cause and effect–Layer of Protection Analysis (LOPA). In this study, the weights of evaluation indicators were determined using the subjective analytic hierarchy process and objective entropy weight method respectively. Then, to obtain the preference coefficient of the integrated weight more precisely, a new algorithm was proposed based on the least square method. Next, the safety level of the casting workshop was presented based on the qualitative and quantitative analysis of the cloud model, which realized the uncertainty conversion between qualitative concepts and their corresponding quantitative values, as well as taking the fuzziness and randomness into account; the validity of cloud model evaluation was validated by grey relational analysis. In addition, cause and effect was used to proactively identify factors that may lead to accidents. LOPA was used to correlate corresponding safety measures to the identified risk factors. 6 causes and 19 sub-causes that may contribute to accidents were identified, and 18 potential remedies, or independent protection layers (IPLs), were described as ways to protect employee health in foundry operations. A mechanical manufacturing business in Hunan, China was considered as a case study to demonstrate the applicability and benefits of the proposed safety assessment approach.


Author(s):  
Zhilin Chen ◽  
Ping Huang ◽  
Chunhui Wang ◽  
Zhiyuan Chi ◽  
Fangjie Shi ◽  
...  

It’s the trend to extend the operating license time, called Operating License Extension (OLE) in China, of nuclear power plants (NPPs) in the future. It needs to be adequately demonstrated by licensees and approved by the regulator to gain an extended license time, such as 20 years. The demonstration methods for OLE are different among countries due to the different management systems for NPPs. Safety assessment, environment effect evaluation and update of the final safety analysis report (FSAR) will be the main aspects during OLE demonstration of NPPs in China according to the technical policy issued by National Nuclear Safety Administration (NNSA). Technical methods for scoping and screening, aging management review and time-limited aging analyses, which are the main contents of safety assessment are established based on the technical policy drafted by NNSA and international experiences in order to assist the operators to implement the safety assessment for OLE of NPP.


Author(s):  
Jingbin Liu ◽  
Yan Feng ◽  
Ning Qiao ◽  
Yunbo Zhang ◽  
Zhongqiu Wang

At present, there is still lack of detailed software V&V guidance standards in China, while a number of US nuclear power units and I&C platform are introduced and applied. So the software verification and validation work in our country usually cited the methods in IEEE 1012. With reference to the requirements of IEEE 1012, the V&V process of the software can be mainly divided into three forms: audit evaluation, special analysis and testing. This paper focuses on these parts and gives a detailed description and annotations of the technical methods and their life cycle stages in IEEE 1012, which cover multiple V&V phases. At the same time, the author puts forward his own understanding of the special analysis approach and procedure, such as criticality analysis, interface analysis, traceability analysis, hazard analysis, risk analysis and security analysis, and gives his own experience and related recommendations.


Author(s):  
Pengyi Peng ◽  
Weidong Liu ◽  
Zhichao Yang

Instrumentation and control (I&C) systems in nuclear power plants (NPPs) have the ability to initiate the safety-related functions necessary to shut down the plants and maintain the plants in a safe shutdown condition. I&C systems of low reliability will bring risks to the safe operation of NPPs. A sufficient level of redundancy and diversity of I&C design to ensure the safety is a major focus when designing a new reactor. Usually multiple signal paths are included in an I&C system design. Meanwhile, besides the protection and safety monitoring system (PMS), other sub-systems of I&C such as the diverse actuation system (DAS) will be included as a diverse backup of PMS to perform the functions of reactor trip and engineered safety features actuation systems (ESFAS). However, the construction costs increase as the level of system redundancy and diversity grows. In fact, from the perspective of deterministic theory, an I&C system of only two chains can meet the single failure criterion. So how to obtain the balance of safety and economy is a challenging problem in I&C system designing. Probabilistic Safety Assessment (PSA) is the most commonly used quantitative risk assessment tool for decision-making in selecting the optimal design among alternative options. In this paper, PSA technique was used to identify whether the I&C system design offers adequate redundancy, diversity, and independence with sufficient defense-in-depth and safety margins in the design of a new reactor. Firstly, detailed risk assessment criteria for I&C design were studied and identified in accordance with nuclear regulations. Secondly, different designs were appropriately modeled, and the risk insights were provided, showing the balance of safety and economy of each design. Furthermore, potential design improvements were evaluated in terms of the current risk assessment criterion. In the end, the optimal design was determined, and uncertainty analyses were performed. The results showed that all four designs analyzed in this paper were met the safety goals in terms of PSA, but each design had a different impact on the balance of risk. As the support systems of the NPP we analyzed were relatively weak, loss of off-site power and loss of service water were two main risk contributors. The common cause failure of reactor trip breakers and the sensors of containment pressure were risk-significant. After identifying the major risk factors, the I&C design team can perform subsequent optimizations in the further design based on the PSA results and achieve an optimal balance between safety and economy.


Author(s):  
Ibrahim A. Alrammah

This paper discusses some technical issues related to applying Probabilistic Safety Assessment (PSA) to a novel Nuclear Power Plant (NPP) design. These aspects include: initiating events, passive systems modeling, reliability and common-cause failure (CCF) data, modeling of novel design features, modeling of preventive maintenance and technical specifications, human reliability analysis (HRA), modeling of instrumentation and control (I&C), external hazards, PSA supporting studies and interpretation of PSA results for new plants.


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