• Nuclear Engineering and Technology
• /
• 제44권8호
• /
• pp.919-928
• /
• 2012

The applications of computers and communication system and network technologies in nuclear power plants have expanded recently. This application of digital technologies to the instrumentation and control systems of nuclear power plants brings with it the cyber security concerns similar to other critical infrastructures. Cyber security risk assessments for digital instrumentation and control systems have become more crucial in the development of new systems and in the operation of existing systems. Although the instrumentation and control systems of nuclear power plants are similar to industrial control systems, the former have specifications that differ from the latter in terms of architecture and function, in order to satisfy nuclear safety requirements, which need different methods for the application of cyber security risk assessment. In this paper, the characteristics of nuclear power plant instrumentation and control systems are described, and the considerations needed when conducting cyber security risk assessments in accordance with the lifecycle process of instrumentation and control systems are discussed. For cyber security risk assessments of instrumentation and control systems, the activities and considerations necessary for assessments during the system design phase or component design and equipment supply phase are presented in the following 6 steps: 1) System Identification and Cyber Security Modeling, 2) Asset and Impact Analysis, 3) Threat Analysis, 4) Vulnerability Analysis, 5) Security Control Design, and 6) Penetration test. The results from an application of the method to a digital reactor protection system are described.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1995년도 추계학술발표회논문집(1)
• /
• pp.153-158
• /
• 1995

All of the nuclear power plants in Korea we operating with analog instrumentation and control (I&C) equipment which are increasingly faced with frequent troubles, obsolescence and high maintenance expenses. Electrical and computer technology has improved rapidly in recent years and has been applied to other industries. So it is strongly recommended we adopt modern digital and computer technology to improve plant safety and availability. The advanced I&C system, namely, Integrated Intelligent Instrumentation and Control System (I$^3$CS) will be developed for beyond the next generation nuclear power plant. I$^3$CS consists of three major parts, the advanced compact workstation, distributed digital control and protection system including Automatic Start-up/shutdown Intelligent Control System (ASICS) and the computer-based alarm processing and operator support system, namely, Diagnosis, Response, and operator Aid Management System (DREAMS).

• Nuclear Engineering and Technology
• /
• 제47권2호
• /
• pp.148-156
• /
• 2015

Several vendors have recently been actively pursuing the development of integral pressurized water reactors (iPWRs) that range in power levels from small to large reactors. Integral reactors have the features of minimum vessel penetrations, passive heat removal after reactor shutdown, and modular construction that allow fast plant integration and a secure fuel cycle. The features of an integral reactor limit the options for placing control and safety system instruments. The development of instrumentation and control (I&C) strategies for a large 1,000 MWe iPWR is described. Reactor system modeling-which includes reactor core dynamics, primary heat exchanger, and the steam flashing drum-is an important part of I&C development and validation, and thereby consolidates the overall implementation for a large iPWR. The results of simulation models, control development, and instrumentation features illustrate the systematic approach that is applicable to integral light water reactors.

• 한국전자통신학회논문지
• /
• 제9권6호
• /
• pp.681-687
• /
• 2014

원자력 산업계는 최근 원전 계측제어계통 설비의 단종과 같은 예상치 못한 환경에 직면해오고 있으며, 이러한 문제를 근본적으로 해결하고자 노력하고 있다. IAEA, IEC, 등의 연구결과에 따르면, FPGA는 단종이 예상되는 제어계통에의 대체수단으로 주목받고 있다. FPGA가 원자력 플랜트의 PLC(Programmable Logic Controller)를 대체하기 위해서는 높은 건정성과 신뢰성을 가져야 한다. 따라서, FPGA 기반 제어기의 건전성과 신뢰성을 향상시키기 위하여 HDL 개발수명주기를 적용하여 개발하였다. 또한, 원전 계측제어계통에 적용하기 위하여 번인시험과 환경시험의 기기검증이 수행되었다. 시험수행결과, 352시간의 번인시험과 92시간의 환경시험 중에 정상적인 기능 및 성능을 수행함을 확인할 수 있었다.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제10권2호
• /
• pp.149-160
• /
• 2010

This paper presents a study of an availability evaluation for I&C(Instrumentation and Control) System which it applied for nuclear power plant. The system availability assessment have been implemented to the reactor protection system by the adoption of Markov process. Results are satisfied to the requirement of EPRI and APR1400. Based on the research of I&C system assessment, it will contribute to improve the availability of system and impact the design concept with new design optimization.

• 디지털산업정보학회논문지
• /
• 제19권3호
• /
• pp.25-38
• /
• 2023

Instrumentation and control systems measure and control various variables of nuclear facilities to operate nuclear power plants safely. A diverse protection system, a representative instrumentation and control system, generates a reactor trip and turbine trip signal by high pressure in a pressurizer and containment to satisfy the design requirements 10CFR50.62. Also, it generates an auxiliary feedwater actuation signal by low water levels in steam generators. Cybersecurity has become more critical as digital technology is gradually applied to solve problems such as performance degradation due to aging of analog equipment, increased maintenance costs, and product discontinuation. This paper analyzed possible cybersecurity threat scenarios in the diverse protection system using attack trees. Based on the analyzed cybersecurity threat scenario, we calculated the probability of attack occurrence and confirmed the cybersecurity risk in connection with the asset value.

• 에너지공학
• /
• 제24권2호
• /
• pp.154-166
• /
• 2015

The in-core instrumentation measures core power distribution and coolant temperature in local regions of the core in pressurized water reactors. The installation types are distinguished by the designs of routing paths that exit either through reactor bottom mounted instrument nozzles or through reactor top mounted instrument nozzles. Although each type has unique advantages, it is generally known that top mounted design is more competitive with respect to emphasizing nuclear safety issues and ability to cope with severe accidents. The international nuclear vendors have provided various types of reactors with top mounted design. Nuclear power reactors in Korea, however, only have been designed to be applicable to the use of bottom mounted design, and it has been pointed out that the capabilities of Korean reactors against severe accidents should be further enhanced. The paper deals with technical issues on reactor internal and external design, in-core instrumentation, support assembly, sealing mechanism with nozzles, handling, and analytical issues in order to establish the ways of development.

• Nuclear Engineering and Technology
• /
• 제50권4호
• /
• pp.570-581
• /
• 2018

Recently, a software program has been used in nuclear power plants (NPPs) to digitalize many instrumentation and control systems. To guarantee NPP safety, the reliability of the software used in safetycritical instrumentation and control systems must be quantified and verified with proper test cases and test environment. In this study, a software testing method using a simulation-based software test bed is proposed. The test bed is developed by emulating the microprocessor architecture of the programmable logic controller used in NPP safety-critical applications and capturing its behavior at each machine instruction. The effectiveness of the proposed method is demonstrated via a case study. To represent the possible states of software input and the internal variables that contribute to generating a dedicated safety signal, the software test cases are developed in consideration of the digital characteristics of the target system and the plant dynamics. The method provides a practical way to conduct exhaustive software testing, which can prove the software to be error free and minimize the uncertainty in software reliability quantification. Compared with existing testing methods, it can effectively reduce the software testing effort by emulating the programmable logic controller behavior at the machine level.

• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1192-1205
• /
• 2016

Field programmable gate array (FPGA)-based systems are thought to be a practical option to replace certain obsolete instrumentation and control systems in nuclear power plants. An FPGA is a type of integrated circuit, which is programmed after being manufactured. FPGAs have some advantages over other electronic technologies, such as analog circuits, microprocessors, and Programmable Logic Controllers (PLCs), for nuclear instrumentation and control, and safety system applications. However, safety-related issues for FPGA-based systems remain to be verified. Owing to this, modeling FPGA-based systems for safety assessment has now become an important point of research. One potential methodology is the dynamic flowgraph methodology (DFM). It has been used for modeling software/hardware interactions in modern control systems. In this paper, FPGA logic was analyzed using DFM. Four aspects of FPGAs are investigated: the "IEEE 1164 standard," registers (D flip-flops), configurable logic blocks, and an FPGA-based signal compensator. The ModelSim simulations confirmed that DFM was able to accurately model those four FPGA properties, proving that DFM has the potential to be used in the modeling of FPGA-based systems. Furthermore, advantages of DFM over traditional reliability analysis methods and FPGA simulators are presented, along with a discussion of potential issues with using DFM for FPGA-based system modeling.

• Nuclear Engineering and Technology
• /
• 제53권11호
• /
• pp.3694-3703
• /
• 2021

Instrumentation and Control systems (I&C) play a significant role in nuclear power plants (NPP) and other safety critical systems (SCS). We have conducted a rigorous study and discussions with experienced practitioners worldwide the strategy for the development of I&C systems to investigate the several aspects related to their dependability. We discussed with experienced practitioners that work on nuclear domain with the intention of knowing their approach, they use day-to-day for the development of such systems. The aim of this research is to obtain to provide guidance to those building I&C systems of NPP and have implications on state engineering licensure boards, in the determination of legal liability, and in risk assessment for policymakers, corporate governors, and insurance executives.