• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.8-14
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• 2004

Accidental releases of toxic gases heavily affect to the risk of process facilities. In this research, consequence analysis for accidental releases of ammonia and chlorine gases was studied using the risk based inspection, based on API-581 BRD. It was found out that consequence areas (toxic areas) decrease as temperature increases and as the pipe diameter and pressure decrease. For the same release condition, the toxic area by the release of chlorine gas was larger than that by the release of ammonia gas.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.105-109
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• 2011

Since a severe accident, which happens in low frequency, can cause serious damages, the interests in off-site consequence analysis for a nuclear power plant have been increased after Chernobyl, TMI and Fukushima accidents. Consequences, which are the effects on health and environment caused by released radioisotopes, are evaluated using MACCS II code based on the method of Level 3 PSA. To perform a consequence analysis for the reference plants, the input data of the code were generated such as meteorological data, population distribution, release fractions, and so on. Using these input data, acute and lifetime dose as an organ, CCDF for early fatalities and latent cancer fatalities, and average individual risk were analyzed by using MACCS II code in this study. These results might contribute to establishing accident management plan and quantitative health object.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.201-211
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• 2009

The types and quantities of Hazmat and Hazmat transportation are gradually increasing, keeping pace with industrialization and urbanization. At present the safety management for Hazmat transportation only considers reducing accident probability, but even when an accident involving Hazmat-carrying vehicles occurs, that is not regarded as a Hazmat-related accident if the Hazmats do not leak out from the containers carrying them. Thus the methods to reduce risk (Risk=Probability$\times$Consequence) have to be developed by incorporating accident probability and consequence. By using Geographic Information System (GIS), a technical method is invented and is automatically able to evaluate the consequence by different types of Hazmat. Thus this study analyzed the degree of risk on the links classified by the Hazmat transport pathways. In order to mitigate the degree of risk, a method of 7-step risk management on Hazmat transportation in railway industries can be suggested. (1st step: building up GIS DB, 2nd step: calculating accident probability on each link, 3rd step: calculating consequence by Hazmat types, 4th step: determination of risk, 5th step: analysis of alternative plans for mitigating the risk, 6th: measure of effectiveness against each alternative, and 7th step: action plans to be weak probability and consequence by the range recommended from ALARP). In conclusion, those 7 steps are used as a standardization method of optimum transportation routing. And to increase the efficiency of optimum transportation routing, optional route can be revise by verification.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.189-197
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• 2003

The Level 3 PSA being termed accident consequence analysis is defined to assess effects on health and environment caused by radioisotopes released from severe accidents of nuclear power plants. In this study consequence analysis on health effects depending on release characteristics of radioisotopes has been peformed using the 3 MACCS code in severe accidents. The results of this study may contribute to identifying the relative importance of various parameters occurred in consequence analysis as well as to assessing risk reduction accident management strategies. Especially three parameters for the purpose of consequence analysis, such as the release height, the heat content, and the duration time, are used to analyze the variation of early fatalities and latent cancer fatalities. Also, in this study risk assessment using the concept, 'products of uncertainty and consequences', has been performed using consequence of MACCS and frequency on source term category 19 scenarios from IPE (Individual Plant Examination) analysis.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1365-1375
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• 2009

The types and quantities of Hazmat and Hazmat transport are gradually increasing, keeping pace with industrialization and urbanization. There are currently more than 1,000 types of Hazmat,, and new types are added every year. At present the safety management for Hazmat transport only considers reducing accident probability, but even when an accident involving Hazmat-carrying vehicles occurs, that is not regarded as a Hazmat-related accident if the Hazmats do not leak out from the containers carrying them. Based on this principle, in turn., the methods to reduce risk (Risk=Probability$\times$Consequence) have to be developed by incorporating accident probability and consequence. By using Geographic Information System (GIS), a technical method was invented and is automatically able to evaluate the consequence by different types of Hazmat. Thus this study analyzed the degree of risk on the links classified by the Hazmat transport pathways. In order to mitigate the degree of risk, a method of 7-step risk management in transporting Hazmat on railway industries was suggested. The 7-step risk management is definded as the following: 1st step: buliding up GIS DB, 2nd step: calculating accident probability on each link, 3rd step: calculating consequence by Hazmat types, 4th step: determination of risk, 5th step: analysis of alternative plans for mitigating the risk, 6th: measure of effectiveness against each alternative, and 7th step: action plans to be weak probability and consequence by the range recommended from ALARP. In conclusion., those 7 steps are recommended as a standardization method in this study.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.368-372
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• 2016

Background: Methodologies for a series of radiological consequence assessments show a distinctive difference according to the design principles of the original nuclear suppliers and their technical standards to be imposed. This is due to the uncertainties of the accidental source term, radionuclide behavior in the environment, and subsequent radiological dose. Both types of PWR and PHWR are operated in Korea. However, technical standards for evaluating atmospheric dispersion have been enacted based on the U.S. NRC's positions regardless of the reactor types. For this reason, it might cause a controversy between the licensor and licensee of a nuclear power plant. Materials and Methods: It was modelled under the framework of the NRC Regulatory Guide 1.145 for light-water reactors, reflecting the features of heavy-water reactors as specified in the Canadian National Standard and the modelling features in MACCS2, such as atmospheric diffusion coefficient, ground deposition, surface roughness, radioactive plume depletion, and exposure from ground deposition. Results and Discussion: An integrated accident consequence assessment code, ACCESS (Accident Consequence Assessment Code for Evaluating Site Suitability), was developed by taking into account the unique regulatory positions for reactor types under the framework of the current Korean technical standards. Field tracer experiments and hand calculations have been carried out for validation and verification of the models. Conclusion: The modelling approaches of ACCESS and its features are introduced, and its applicative results for a hypothetical accidental scenario are comprehensively discussed. In an applicative study, the predicted results by the light-water reactor assessment model were higher than those by other models in terms of total doses.

• Journal of the Korean Society of Safety
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• v.37 no.6
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• pp.166-173
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• 2022

A variety of input parameters are taken into consideration while performing a Level 3 PSA. Some parameters related to plume segments, spatial grids, and particle size distribution have flexible input formats. Fine modeling performed by splitting a number of segments or grids may enhance the accuracy of analysis but is time-consuming. Analysis speed is highly important because a considerably large number of calculations is required to handle Level 2 PSA scenarios for a single-unit or multi-unit Level 3 PSA. This study developed a sensitivity analysis supporting interface called MACCSsense to compare the results of the trials of plume segmentation with the results of the base case to determine its impact (in terms of time and accuracy) and to support the development of a modeling approach, which saves calculation time and improves accuracy. MACCSense is an automation tool that uses a large amount of plume segmentation analysis results obtained from MUST Converter and Mr. Manager developed by KAERI to generate a sensitivity report that includes impact (time and accuracy) by comparing them with the base-case result. In this study, various plume segmentation approaches were investigated, and both the accuracy and speed of offsite consequence analysis were evaluated using MACCS as a consequence analysis tool. A simultaneous evaluation revealed that execution time can be reduced using multi-threading. In addition, this study can serve as a framework for the development of a modeling strategy for plume segmentation in order to perform accurate and fast offsite consequence analyses.

• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.36-40
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• 2022

Recently, the biggest topic in the industry is the area of industrial safety and health management. Since city gas is flammable gas and has a high risk of fire and explosion, much effort is required to prevent serious industrial and citizenry disasters. As part of city gas safety management, this study attempted to quantitatively predict the scope and degree of damage in the event of an explosion accident caused by city gas leakage through the Consequence Analysis. As a result, there was a difference in the accident result value according to various leakage conditions such as pressure and weather conditions. Through this study, a scenario of explosion due to city gas leakage will be prepared when performing city gas safety management work and used to prepare more effective accident prevention and emergency action plans.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1996.11a
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• pp.53-56
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• 1996

In order to propose the method of the consequence analysis for fire accidents by the heavy gas release and to obtain optimum conditions of parameter selections, the consequence analysis for jet fire by the accident of xylene vapor release were performed. And the effect and the sensitivity analysis of parameters affecting the consequence were investigated. Simulation results showed that important parameters affecting results of the xylene vapor release accident were mainly hole diameter, interested distance, wind speed, and so on. For the jet fire, the accident result and the sensitivity of thermal radiation were increased with the decrease of interested distance and the increase of hole diameters, and the accidental result was increased as the increase wind speed, but the sensitivity of thermal radiation was decreased.

• Journal of Environmental Impact Assessment
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• v.13 no.1
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• pp.1-8
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• 2004

A wide spectrum of risk assessments including qualitative and quantitative approaches and the analyses of its consequence were performed for an environmentally sensitive object such as incineration facility. To find out the major risk concerns, HAZOP(Hazard and Operability) were performed. Then, the frequency of hazardous gas release scenarios was calculated. Finally consequence analyses were performed for the gas release scenarios. On the basis of analyses through evaluation, a more innovative way for making a better control system or the enhancement of operation procedure was given. The results from these analyses would act as a substantial benefits for the incineration facility operator, and giving some measured information for the neighbors and the people involved.