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[en] For a long time, safety has been recognized as a top priority in high-reliability industries such as aviation and nuclear power plants (NPPs). As advanced technology develops, it has been demonstrated by many accidents in the past that software (human) has greater influence on the safety than hardware (equipment). Therefore, the human of an organization should be emphasized in order to enhance the safety in the complex industries. Safety culture plays an important role in such organization software. The concept of safety culture in the nuclear power domain was first established in the International Atomic Energy Agency safety series, wherein the importance of employee attitudes for maintaining organizational safety was emphasized. The safety failure in nuclear industries means irreparable performance failure. Therefore, industries have been continuing their efforts to measure the safety culture awareness of workers and to improve the vulnerable areas. Safety culture assessment is a critical step in the process of enhancing safety culture. However, it is very difficult and highly uncertain to measure the safety culture awareness of workers. The results of safety culture assessment are mostly subjective, qualitative and inconsistent. Given the current situation, this paper suggests a quantitative methodology for safety culture assessment based on Bayesian networks. A proposed safety culture framework for NPPs would include the following: (1) a norm system, (2) a safety management system, (3) safety culture awareness of worker, and (4) Worker behavior. The safety culture awareness of workers at NPPs was reasoned through the proposed methodology. Then, vulnerable areas in NPPs were derived quantitatively through sensitivity analysis. The reliability of the suggested model was verified through the application to real accident cases. It is expected that this methodology will help the reduction of time and cost for safety culture assessment in NPPs, and providing the consistent results
[en] Periodic Safety Review (PSR) is a comprehensive study on a nuclear power plant safety, taking into account aspects such as operational history, ageing, safety analyses and advances in code and standards since the time of construction. In Korea, PSRs have been performed for 20 units and have been effectively used to obtain an overall view of actual plant safety to determine reasonable and practical modifications that should be made in order to obtain a higher level of safety approaching that of modern plants. Among many safety enhancements achieved from Korean PSRs, new safety analyses are the important methods to confirm plant safety by increasing safety margin for specific safety issues. Methods and effects of safety enhancements applied in Korean PSRs are reviewed in this paper in light of new safety analyses to obtain additional safety margins
[en] Human error is one of main contributors of reactor trip in nuclear power plants. Therefore, HFE application is essential in every field of nuclear power plants such as operating, maintenance, and plant design. However, HFE is an unfamiliar term and field for plant staffs. Lots of activities has been carried out to reduce human error and to enhance human performance. During these efforts, it is frequently asked where human factor guidelines are, and how the guidelines are applied to their usual activities. This paper explains e HFMP for this purpose
[en] The KHNP has been performing Periodic Safety Reviews (PSRs) for all nuclear power plants according to regulatory requirements. Sixteen units of the twenty power plants currently in operation in Korea have been operated for more than ten years as of year 2010. And the 10-year-basis Periodic Safety Reviews for these sixteen units (Kori no.1,2,3,4, Yonggwang no.1,2,3,4, Wolsong no.1,2, 3,4, and Ulchin no.1,2,3,4) have been completed. In 2000 the first PSR has been performed for Kori Unit 1, which was a comprehensive study to assess and confirm the safety of nuclear power plants and to identify areas for improvement to enhance the safety, taking into account aspects such as operational history, age of the plant, past safety analyses, and internationally recognized codes and standards. Additionally, the safety enhancements for a nuclear power plants are identified from the PSR results. The implementation plans for these safety enhancements are established and implemented in phases depending on the plant. Therefore, the safety of nuclear power plants is enhanced through these series of processes. The key examples of safety enhancements and the changes in the codes and standards applied during one cycle PSR are reviewed in this paper
[en] Human errors resulting from human factors deficiencies can be a significant contributing factor to incidents and accidents. And also, it is well known that Human Engineering Discrepancies (HEDs) can affect a system's performance and the reliability of NPPs. In order to resolve the problem from HEDs, the human factors of operating NPPs have been reviewed as a part of Periodic Safety Reviews (PSRs). According to the safety enhancement issues from the result of previous PSRs, the consistency of terms among the Main Control Room (MCR), the Remote Shutdown Panel (RSP), and the local control station is not well maintained. In this research, a practical human factors guideline for the use of terms is developed in consideration of the practicality and applicability
[en] The aim of this study is to introduce quantitative evaluation methods for Nuclear Safety Culture (NSC) by three aspects of Nuclear Power Plant (NPP): individuals, operation team, and organization. Various NSC evaluation methods have been developed, and the Korea NPP utility company has conducted the NSC assessment according to international practice. However, the results are often qualitative, subjective, and mainly dependent on evaluator's judgement, so the assessment results can be interpreted from different perspectives. To resolve limitations of present evaluation methods, quantitative NSC evaluation methods for individual, operation team, and organization have been developed 3 in Nuclear I and C and Information Engineering (NICIE) Lab. at Korea Institute of Science and Technology (KAIST). In this study, three methods will be introduced and verification process and applications of the methods will be reviewed. (author)
[en] Highlights: • Approach for safety culture evaluation in accident situation of NPPs was proposed. • Basic information for accident analysis was collected from the related literature. • Weak safety culture traits contributing to NPP accident were analyzed. • How vulnerable barriers in a NPP contribute to an accident was identified. - Abstract: As advanced technology develops, it has been demonstrated by many accidents in the past that software (human) has a greater influence on safety than does hardware (equipment). Therefore, the software (human) of an organization should be focused on in order to enhance the safety in complex system industries. Safety culture plays an important role in the software of such organizations. Attempts to measure the worker safety culture awareness and to capture signs of their degradation are very difficult and highly uncertain. However, safety failures in the nuclear industry can lead to irreparable performance failures. Therefore, the industry has been continuing its efforts to measure the worker safety culture awareness and to improve weaknesses in organizations. It was confirmed in several studies that the probability of an accident is high at an organization with a low level of worker safety culture awareness (Vinodkumar and Bhasi, 2009, Morrow et al., 2014, Shirali et al., 2016). The previous paper suggested the method to quantitatively assess safety level of nuclear power plants. In this paper, the purpose is perform case studies in order to apply the suggested method to real nuclear power plant accidents. Weak safety culture traits through case studies assuming accident situation were analyzed and how the barriers of a nuclear power plant became vulnerable and how they contributed to the accident was identified. If this method proposed is applied to the real accident situation and extends to minor accidents at a nuclear power plant, workers can learn and understand how to behave in an accident situation and severe accidents can be proactively prevented. In addition to, the high frequency of weak safety culture traits analyzed, as a lagging indicator, could show which areas of a nuclear power plant are vulnerable, and their improvement will contribute to strengthen the safety of the nuclear power plant.
[en] Highlights: • A safety culture framework and a quantitative methodology to assess safety culture were proposed. • The relation among Norm system, Safety Management System and worker's awareness was established. • Safety culture probability at NPPs was updated by collecting actual organizational data. • Vulnerable areas and the relationship between safety culture and human error were confirmed. - Abstract: For a long time, safety has been recognized as a top priority in high-reliability industries such as aviation and nuclear power plants (NPPs). Establishing a safety culture requires a number of actions to enhance safety, one of which is changing the safety culture awareness of workers. The concept of safety culture in the nuclear power domain was established in the International Atomic Energy Agency (IAEA) safety series, wherein the importance of employee attitudes for maintaining organizational safety was emphasized. Safety culture assessment is a critical step in the process of enhancing safety culture. In this respect, assessment is focused on measuring the level of safety culture in an organization, and improving any weakness in the organization. However, many continue to think that the concept of safety culture is abstract and unclear. In addition, the results of safety culture assessments are mostly subjective and qualitative. Given the current situation, this paper suggests a quantitative methodology for safety culture assessments based on a Bayesian network. A proposed safety culture framework for NPPs would include the following: (1) a norm system, (2) a safety management system, (3) safety culture awareness of worker, and (4) Worker behavior. The level of safety culture awareness of workers at NPPs was reasoned through the proposed methodology. Then, areas of the organization that were vulnerable in terms of safety culture were derived by analyzing observational evidence. We also confirmed that the frequency of events involving human error decreases when the level of safety culture is high. It is anticipated that the causality between the safety culture awareness of worker and the state of safety at NPPs can be verified using the proposed methodology.