• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.139-142
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• 2001

The one of important parameter involved in the calculation of internal radiation dose to the human body is the biological half-life of the radionuclide. The biological half-life is population specific and may differ from one population group to another. So the effective half-life of tritium exposure based on urinal bioassay measurement of Wolsong Nuclear Power Plants was investigated and studied.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1230-1244
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• 2022

This paper proposes an algorithm for signal validation using unsupervised methods in emergency situations at nuclear power plants (NPPs) when signals are rapidly changing. The algorithm aims to determine the stuck failures of signals in real time based on a variational auto-encoder (VAE), which employs unsupervised learning, and long short-term memory (LSTM). The application of unsupervised learning enables the algorithm to detect a wide range of stuck failures, even those that are not trained. First, this paper discusses the potential failure modes of signals in NPPs and reviews previous studies conducted on signal validation. Then, an algorithm for detecting signal failures is proposed by applying LSTM and VAE. To overcome the typical problems of unsupervised learning processes, such as trainability and performance issues, several optimizations are carried out to select the inputs, determine the hyper-parameters of the network, and establish the thresholds to identify signal failures. Finally, the proposed algorithm is validated and demonstrated using a compact nuclear simulator.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.88-96
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• 2018

Concerns over reliability assessments of the main components in nuclear power plants (NPPs) related to aging and continuous operation have increased. The conventional reliability assessment for main components uses experimental correlations under general conditions. Most NPPs have been operating in Korea for a long time, and it is predictable that NPPs operating for the same number of years would show varying extent of aging and degradation. The conventional reliability assessment does not adequately reflect the characteristics of an individual plant. Therefore, the reliability of individual components and an individual plant was estimated according to operating data and conditions. It is essential to reflect aging as a characteristic of individual NPPs, and this is performed through prognostics. To handle this difficulty, in this paper, the general path model/Bayes, a data-based prognostic method, was used to update the reliability estimated from the generic database. As a case study, the authors consider the aging for steam generator tubes in NPPs and demonstrate the suggested methodology with data obtained from the probabilistic algorithm for the steam generator tube assessment program.

• 방사선산업학회지
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• 제17권3호
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• pp.239-256
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• 2023

The classification of the radiation work performed in Korean nuclear power plants (NPPs) must be understood to provide workers with more comprehensive radiation protection. This study used annual reports on occupational exposure to investigate and analyze the similarities and differences in the radiation work performed in Korean NPPs with pressurized water reactors (PWRs) and pressurized heavy water reactors (PHWRs). The results showed that the radiation work performed in Korean NPPs could be classified into three categories. Category 1 contains work at the highest level. This work can be divided into individual tasks belonging to Category 2, which enables the evaluation of the radiation dose during the work. The work in Category 2 consists of tasks from Category 3, which contains basic detailed tasks that are not further subdivided. This study emphasized the need for the systematic management of the radiation work performed in both Korean PWRs and PHWRs, such as the tasks in Category 3, which are similar, with similar working conditions, for PWRs and PHWRs. It also suggested the need to establish a list of radiation work for decommissioning because Kori Unit 1 and Wolsong Unit 1 are currently in permanent shutdown and preparations are being made for their decommissioning.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권4호
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• pp.1-15
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• 2018

Despite of safety issues related to radiological hazards, 31 countries around the world are operating more than 450 nuclear power plants (NPPs). To operate NPPs safely, safety regulations from radiation protection organizations were developed and adopted in many countries. However, many cases of radionuclide releases at foreign NPPs have been reported. Almost all commercial NPPs routinely release radioactive materials to the surrounding environments as liquid and gas phases under control. These releases are called 'planned releases' which are planned, regularly monitored, and well documented. Meanwhile, the releases focused in this review, called 'unplanned releases', are neither planned nor monitored by regulatory and/or protection organizations. NPPs are generally composed of various structures, systems and components (SSCs) for safety. Among them, the SSCs near reactors are closely related to safety of NPPs, and typically fabricated to comply with stringent requirements. However, some non-safety related SSCs such as underground pipes may be constructed only according to commercial standards, causing the leakage of radioactive fluids usually containing tritium ($^3H$). This paper discusses SSCs of NPPs and introduces several cases of unplanned releases at foreign NPPs. The current regulation on the environmental radiological surveillance and assessment around the NPPs in South Korea are also examined.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1454-1463
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• 2021

Demographics, personality traits and attitudes are related to safety behaviors in varied workplaces, but their roles in nuclear power plants (NPPs) have not been fully understood. This study was conducted to explore the roles of a set of demographic, personality and attitudinal factors on self-reported safety behaviors (including safety participation and human errors) among NPP commissioning workers. Survey data were collected from 157 Chinese commissioning workers. Results showed that age and work experience were significantly associated with human errors, but not with safety participation. Neuroticism and conscientiousness were significantly related to human errors, while neuroticism, conscientiousness and agreeableness were significantly related to safety participation. Attitude towards questioning was observed as an antecedent of safety participation, and functioned as a mediating variable in the relation between conscientiousness and safety behaviors. The findings provide evidence-based implications on the design of diverse interventions and strategies for the promotion of safety behaviors in NPPs.

• 한국전자통신학회논문지
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• 제12권5호
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• pp.725-730
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• 2017

원전의 안전 유지를 위한 계측제어계통에 일반적인 IT 자원을 활용하는 사례가 증가하고 있다. 이에 따라 기존 IT 자원이 갖는 잠정적인 보안 취약점으로 인해 원전 사이버 보안 침해 사고가 발생할 수 있으며, 원전의 가동 중단뿐만 아니라 국가적 재난에 이르는 심각한 사고를 야기할 수 있다는 문제가 제기되고 있다. 국내 원자력 규제기관에서는 이에 대응하기 위해 원전 사이버 보안 규제지침을 개발하고 규제 대상 및 범위를 확대시키고 있지만, 원전의 일반적인 보안 문제뿐만 아니라 원전 취약점에 특화된 공격에도 대응할 수 있는 방안이 필요하다. 이에 본 논문에서는 R.G.5.71에서 규정하고 있는 내용 중 취약점 점검과 관련된 42개 항목을 선별하여 5가지의 유형으로 분류 분석하였다. 제안된 분석 내용을 바탕으로 취약점 점검 도구를 개발한다면 원전 사이버 보안 취약점 점검 효율성을 향상시킬 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제51권7호
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• pp.1791-1798
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• 2019

Instrumentation and Control (I&C) systems of nuclear power plants (NPPs) have been continuously digitalized. These systems have a critical role in the operation of nuclear facilities by functioning as the brain of NPPs. In recent years, as cyber security threats to NPP systems have increased, regulatory and policy-related organizations around the world, including the International Atomic Energy Agency (IAEA), Nuclear Regulatory Commission (NRC) and Korea Institute of Nuclear Nonproliferation and Control (KINAC), have emphasized the importance of nuclear cyber security by publishing cyber security guidelines and recommending cyber security requirements for NPP facilities. As described in NRC Regulatory Guide (Reg) 5.71 and KINAC RS015, challenge response authentication should be applied to the critical digital I&C system of NPPs to satisfy the cyber security requirements. There have been no cases in which the most robust response authentication technology like challenge response has been developed and applied to nuclear I&C systems. This paper presents a challenge response authentication mechanism for a Programmable Logic Controller (PLC) system used as a control system in the safety system of the Advanced Power Reactor (APR) 1400 NPP.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2467-2474
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• 2022

Nuclear Power Plants (NPPs) are the most protected facilities among all critical infrastructures (CIs). In addition to physical security, cyber security becomes a significant concern for NPPs since swift digitalization and overreliance on computer-based systems in the facility operations transformed NPPs into targets for cyber/physical attacks. Despite technical competencies, humans are still the central component of a resilient NPP to develop an effective nuclear security culture. Turkey is one of the newcomers in the nuclear energy industry, and Turkish Akkuyu NPP has a unique model owned by an international consortium. Since Turkey has limited experience in nuclear energy industry, specific multinational and multicultural characteristics of Turkish Akkuyu NPP also requires further research in terms of the Facility's prospective nuclear security. Yet, the link between "national cultures" and "nuclear security" is underestimated in nuclear security studies. By relying on Hofstede's national culture framework, our research aims to address this gap and explore possible implications of cross-national cultural differences on nuclear security. To cope with security challenges in the age of hybrid threats, we propose a security management model which addresses the need for cyber-physical security integration to cultivate a robust nuclear security culture in a multicultural working environment.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.335-341
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• 2017

The main control room (MCR) in advanced nuclear power plants (NPPs) has changed from analog to digital control system (DCS). Operation and control have become more automated, centralized, and accurate due to the digitalization of NPPs, which has improved the efficiency and security of the system. New issues associated with human reliability inevitably arise due to the adoption of new accident procedures and digitalization of main control rooms in NPPs. The LingAo II NPP is the first digital NPP in China to apply the state-oriented procedure. In order to address issues related to human reliability analysis for DCS and DCS + state-oriented procedure, the Hunan Institute of Technology conducted a research project based on a cooperative agreement with the LingDong Nuclear Power Co. Ltd. This paper is a brief introduction to the project.