• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.23-29
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• 2004

The design earthquake used for the seismic analysis and design of NPP (Nuclear Power Plant) is determined by the deterministic or probabilistic methods. The probabilistic seismic hazard analysis(PSHA) for the nuclear power plant sites was performed for the probabilistic seismic risk assessment. The probabilistic seismic hazard analysis for the nuclear power plant site had been completed as a part of the probabilistic seismic risk assessment. The probabilistic method become a resonable method to determine the design earthquakes for NPPs. In this study, the defining method of the probability based scenario earthquake was established, and as a sample calculation, the probability based scenario earthquakes were estimated by the de-aggregation of the probabilistic seismic hazard. By using this method, it is possible to define the probability based scenario earthquakes for the seismic design and seismic safety evaluation of structures. It is necessary to develop the rational seismic source map and the attenuation equations for the development of reasonable scenario earthquakes.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.13-24
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• 2009

This paper introduces various kinds of applications of the scenario-based seismic risk assessment in Taiwan. Seismic scenario simulation (SSS) is a GIS-based technique to assess distribution of ground shaking intensity, soil liquefaction probability, building damages and associated casualties, interruption of lifeline systems, economic losses, etc. given source parameters of an earthquake. The SSS may integrate with rapid earthquake information release system to obtain valuable information and to assist in decision-making processes to dispatch rescue and medical resources efficiently. The SSS may also integrate with probabilistic seismic hazard analysis to evaluate various kinds of risk estimates, such as average annual loss and probable maximum loss in one event, in a probabilistic sense and to help proposing feasible countermeasures.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1243-1254
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• 2009

The paper discusses the methodology and the use of probabilistic seismic hazard analysis (PSHA) for nuclear power plants from a European perspective. The increasing importance of risk-informed approaches in the nuclear oversight process observed in many countries has contributed to increasing attention to PSHA methods. Nevertheless significant differences with respect to the methodology of PSHA are observed in Europe. The paper gives an overview on actual projects and discusses the differences in the PSHA-methodology applied in different European countries. These differences are largely related to different approaches used for the treatment of uncertainties and to the use of experts. The development of a probabilistic scenario-based approach is identified as a meaningful alternative to the development of uniform hazard spectra or uniform confidence spectra.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.81-90
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• 2014

Modern systems can be characterized by ever-increasing complexity of both the functionality and system scale. Thus, due to the complexity the chances of accidents resulting from systems failure can then be growing. Even worse is that those accidents could result in disastrous damage to the human being and properties as well. Therefore, the need for the developed systems to be assured with systems safety is apparent in a variety of industries such as rail, automobiles, airplanes, ships, oil refinery, chemical production plants, and so on. To this end, in the industry an appropriate safety standard has been published for its own safety-assured products. One of the core activities included in the most safety standards is hazard analysis. A conventional approach to hazard analysis seems to depend upon the scenarios derived from the ones used previously in similar systems or based on former experience. The objective of this paper is to study an improved process for scenario-based hazard analysis. To achieve the goal, the top-level safety requirements have first been reflected in the scenarios. By analyzing and using them, the result has then lead to the development of safety-assured systems. The method of modeling and simulation has been adopted in the generation and verification of scenarios to check whether the safety requirements are reflected properly in the scenarios. Application of the study result in the case of rail safety assurance has also been discussed.

• Nuclear Engineering and Technology
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• v.37 no.2
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• pp.191-200
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• 2005

Shaking table tests of the seismic behavior of a steel frame structure model were performed. The purpose of these tests was to estimate the effects of a near-fault ground motion and a scenario earthquake based on a probabilistic seismic hazard analysis for nuclear power plant structures. Three representative kinds of earthquake ground motions were used for the input motions: the design earthquake ground motion for the Korean nuclear power plants, the scenario earthquakes for Korean nuclear power plant sites, and the near-fault earthquake record from the Chi-Chi earthquake. The probability-based scenario earthquakes were developed for the Korean nuclear power plant sites using the PSHA data. A 4-story steel frame structure was fabricated to perform the tests. Test results showed that the high frequency ground motions of the scenario earthquake did not damage the structure at the nuclear power plant site; however, the ground motions had a serious effect on the equipment installed on the high floors of the building. This shows that the design earthquake is not conservative enough to demonstrate the actual danger to safety related nuclear power plant equipment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.155-163
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• 2008

This paper presents a novel framework for analysis of power system wide-area blackout based on so called fault cascading scenarios. For a given power system operating state, "triggering" faults or a "seed faults" are chosen based on the probabilities estimated from the hazard rates. The fault probabilities reflect both the load and the weather conditions. Effects of hidden failures in protection systems are also reflected in establishing the fault propagation scenarios since they are one of the major causes for the wide-area blackouts. A tree type data structure called a PS-BEST(Power System Blackout Event Scenario Tree) is proposed for construction of the fault cascading scenarios, in which nodes represent various power system operating states and the arcs are the events causing transitions between the states. Arcs can be either probabilistic or deterministic. For a given initial fault, the total probability of leading to wide-area blackout is estimated by aggregating the individual probability of each fault sequence route leading to wide-area blackout. A case study is performed on the IEEE RTS-79(24 bus) system based on the fault data presented by the North American Electrical Reliability Council(NERC). Test results demonstrate the potentials and the effectiveness of the proposed technique for the future wide-area blackout analysis.

• Journal of Radiation Protection and Research
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• v.48 no.1
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• pp.52-57
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• 2023

Background: Korea Atomic Energy Research Institute (KAERI) operates several nuclear research facilities licensed by Nuclear Safety and Security Commission (NSSC). The emergency preparedness requirements, GSR Part 7, by International Atomic Energy Agency (IAEA) request protection strategy based on the hazard assessment that is not applied in Korea. Materials and Methods: In developing the protection strategy, it is important to consider an accident scenario and its consequence. KAERI has tried the hazard assessment based on a hypothesis accident scenario for the major nuclear facilities. During the assessment, the safety analysis report of the related facilities was reviewed, the simulation using MELCOR, MACCS2 code was implemented based on a considered accident scenario of each facility, and the international guidance was considered. Results and Discussion: The results of the optimized protective actions were 300 m evacuation and 800 m sheltering for the High-Flux Advanced Neutron Application Reactor (HANARO), the evacuation to radius 50 m, the sheltering 400 m for post-irradiation examination facility (PIEF), 100 m evacuation or sheltering for HANARO fuel fabrication plant (HFFP) facility. Conclusion: The results of the optimized protective actions and its distances for the KAERI facilities for the maximum postulated accidents were considered in establishing the emergency plan and procedures and implementing an emergency exercise for the KAERI facilities.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.75-84
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• 2018

This study presents the reliability-based analysis of nonlinear structures using the analytical fragility curves excited by random earthquake loads. The stochastic method of ground motion simulation is combined with the random vibration theory to compute structural failure probability. The formulation of structural failure probability using random vibration theory, based on only the frequency information of the excitation, provides an important basis for structural analysis in places where there is a lack of sufficient recorded ground motions. The importance of frequency content of ground motions on probability of structural failure is studied for different levels of the nonlinear behavior of structures. The set of simulated ground motion for this study is based on the results of probabilistic seismic hazard analysis. It is demonstrated that the scenario events identified by the seismic risk differ from those obtained by the disaggregation of seismic hazard. The validity of the presented procedure is evaluated by Monte-Carlo simulation.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.161-169
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• 2005

In this paper, we provide safety requirements and advices to guarantee the safety of an interface in a level crossing system which is an interface between the conventional facilities and the new ATP (Automatic Train Protection) system, as well as we accomplish a safety management for the facilities of a country that has a different standard with already standardized ATP system. The system model has been made based on a safety activity of the international standard, and then a tolerance of a risk by the safety activity through PHA (Preliminary Hazard Analysis) has been analyzed. finally we achieved HIA (Hazard Identification and Analysis) for the assumptions that have been produced from a operating scenario and a functional interface. Thus, the safety requirements for the interface has been provided from the safety plan of HIA, and we showed the safety activity to guarantee the system safety through HIA which was depend on the design.

• IE interfaces
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• v.15 no.2
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• pp.114-125
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• 2002

The objective of this paper is to describe a systematic accident scenario analysis method(SASA) adept at creating accident scenarios for the design of safer products. This approach was inspired by the Quality Function Deployment(QFD) method, which is conventionally used in quality management. In this study, the QFD provides a formal and systematic scheme to devise accident scenarios while maintaining objectivity. SASA consists of three key stages to be broken down into a series of consecutive steps:(1) developing an accident analysis tableau,(2) devising the accident scenarios using the accident analysis tableau,(3) performing a feasibility test, a clustering process and a patterning process, and finally(4) performing quantitative evaluation of each accident scenario. The SASA was applied to a case study of child safety seats. The accident analysis tableau devised 2828(maximum) accident scenarios from all possible relationships between the hazard factors and situation characteristics. Among them, 270 scenarios were devised through the feasibility test and the clustering process. The patterning process reduced them to 29 patterns representative of all accident scenarios. Based on an intensive analysis of the accident patterns, design guidelines for a safer child safety seat were recommended. The implications of the study on the child safety seat case were then discussed.