• 한국안전학회지
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• 제39권2호
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• pp.28-37
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• 2024

The recent surge in the production and handling of hazardous materials in Korea necessitates developing and implementing robust emergency response plans. These plans are crucial in safeguarding the well-being of workers and residents in the event of an incident. The consequence analysis methodology outlined in the KOSHA guidelines provides a foundation for designing emergency response plans in the event of chemical accidents. However, the consequence analysis is evaluated based on assumed accident cases or worst-case scenarios. Consequently, the emergency response plan based on the consequence analysis may overestimate the damage area, complicating rescue efforts and unnecessarily increasing costs. More information and parameters become available after an accident, enabling more accurate consequence analysis. This implies that the results of consequence analysis based on this detailed information provide more realistic results than those based on assumed accidents. This study attempts to optimize the resource allocation and cost-effectiveness of emergency response plans for chemical accidents. Existing procedures and manuals are revised to elucidate the proposed model and conduct real-time consequence analysis. The existing emergency response plan is compared to verify the proposed model's efficacy. The obtained results indicate that the proposed model can exhibit better performance.

• 한국안전학회지
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• 제27권6호
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• pp.192-204
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• 2012

For a severe accident of nuclear power plant, an approach to estimation of the radiological source term using a severe accident code(MELCOR) has been proposed. Although the MELCOR code has a capability to estimate the radiological source term, it has been hardly utilized for the radiological consequence analysis mainly due to a lack of understanding on the relevant function employed in MELCOR and severe accident phenomena. In order to estimate the severe accident source term to be linked with the radiological consequence analysis, this study proposes 4-step procedure: (1) selection of plant condition leading to a severe accident(i.e., accident sequence), (2) analysis of the relevant severe accident code, (3) investigation of the code analysis results and post-processing, and (4) generation of radiological source term information for the consequence analysis. The feasibility study of the present approach to an early containment failure sequence caused by a fast station blackout(SBO) of a reference plant (OPR-1000), showed that while the MELCOR code has an integrated capability for severe accident and source term analysis, it has a large degree of uncertainty in quantifying the radiological source term. Key insights obtained from the present study were: (1) key parameters employed in a typical code for the consequence analysis(i.e., MACCS) could be generated by MELCOR code; (2) the MELOCR code simulation for an assessment of the selected accident sequence has a large degree of uncertainty in determining the accident scenario and severe accident phenomena; and (3) the generation of source term information for the consequence analysis relies on an expert opinion in both areas of severe accident analysis and consequence analysis. Nevertheless, the MELCOR code had a great advantage in estimating the radiological source term such as reflection of the current state of art in the area of severe accident and radiological source term.

• 한국화재소방학회논문지
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• 제13권4호
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• pp.1-6
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• 1999

본 연구에서는 위험물 취급설비에 대하여 4가지 화재유형으로 나누어 사고 시나리오를 작성하였다. 그리고 작성된 시나리오를 바탕으로 SuperChems Pro., 3.1, SAFER Trace Ver., 8.2, PHAST Pro., Ver., 5.2 등 외국의 사고결과 영향평가 프로그램을 이용하여 사고결과 영향평가 프로그램의 적용 특성을 분석·평가하였으며 이들 프로그램의 분석, 적용 평가 결과 및 관련이론을 활용하여 이를 전산화 할 수 있는 화재모델 및 서브모델을 선정하여 제시하였다.

• 한국안전학회지
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• 제19권4호
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• pp.60-68
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• 2004

Consequence analysis of flammable materials that affect to a risk of facilities was studied at the risk based inspection using API-581. We found that consequence areas (damage area of equipment and fatality area) by release accident of flammable materials showed high value for the case of liquid phase and auto-ignition likely, and that consequence areas of flammable gases decreased as temperature increased and the pipe diameter and pressure decreased at continuous release.

• 기술사
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• 제31권5호
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• pp.60-68
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• 1998

• 한국안전학회지
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• 제39권1호
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• pp.96-103
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• 2024

The demand for mass calculation of offsite consequence analysis to conduct exhaustive single-unit or multi-unit Level 3 PSA is increasing. In order to perform efficient offsite consequence analyses, the Korea Atomic Energy Research Institute is conducting model optimization studies to minimize the analysis time while maintaining the accuracy of the results. A previous study developed a model optimization method using efficient plume segmentation and verified its effectiveness. In this study, we investigated the possibility of optimizing the model through particle size distribution setting by checking the reduction in analysis time and deviation of the results. Our findings indicate that particle size distribution setting affects the results, but its effect on analysis time is insignificant. Therefore, it is advantageous to set the particle size distribution as fine as possible. Furthermore, we evaluated the effect of multithreading and confirmed its efficiency. Future optimization studies should be conducted on various input factors of offsite consequence analysis, such as spatial grid settings.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1516-1525
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• 2022

Interfacing the output of severe accident analysis with the input of radiological consequence analysis is an important and mandatory procedure at the beginning of Level 3 PSA. Such interfacing between the severe accident analysis code MELCOR and MACCS, one of the most commonly used consequence analysis codes, is relatively tractable since they share the same chemical groups, and the related interfacing software, MelMACCS, has already been developed. However, the linking between MAAP, another frequently used code for severe accident analyses, and MACCS has difficulties because MAAP employs a different chemical grouping method than MACCS historically did. More specifically, MAAP groups by chemical compound, while MACCS groups by chemical element. An appropriate interfacing method between MAAP and MACCS has therefore long been requested by users. This study suggests a way of extracting relevant information from MAAP results and providing proper source term information to MACCS by an appropriate treatment. Various parameters are covered in terms of magnitude and manner of release in this study, and special treatment is made for a bypass scenario. It is expected that the suggested approach will provide an important contribution as a guide to interface MAAP and MACCS when performing radiological consequence analyses.

• 한국안전학회지
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• 제27권5호
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• pp.219-223
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• 2012

For an off-site consequence analysis at nuclear power plant, MELCOR Accident Consequence Code System(MACCS) II code is widely used as a software tool. In this study, the algorithm of web-based off-site consequence analysis program(OSCAP) using the MACCS II code was developed for an Integrated Leak Rate Test (ILRT) interval extension and Level 3 probabilistic safety assessment(PSA), and verification and validation(V&V) of the program was performed. The main input data for the MACCS II code are meteorological, population distribution and source term information. However, it requires lots of time and efforts to generate the main input data for an off-site consequence analysis using the MACCS II code. For example, the meteorological data are collected from each nuclear power site in real time, but the formats of the raw data collected are different from each site. To reduce the efforts and time for risk assessments, the web-based OSCAP has an automatic processing module which converts the format of the raw data collected from each site to the input data format of the MACCS II code. The program also provides an automatic function of converting the latest population data from Statistics Korea, the National Statistical Office, to the population distribution input data format of the MACCS II code. For the source term data, the program includes the release fraction of each source term category resulting from modular accident analysis program(MAAP) code analysis and the core inventory data from ORIGEN. These analysis results of each plant in Korea are stored in a database module of the web-based OSCAP, so the user can select the defaulted source term data of each plant without handling source term input data.

• 한국가스학회지
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• 제7권1호
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• pp.10-18
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• 2003

도시가스시설에서 사고가 발생할 때 그 영향을 평가하는 방법론에 대하여 현실을 고려한 모델을 개발하였다. 즉 사건수목분석(ETA)을 통하여 발생할 수 있는 사고의 형태를 도출하였고 가스의 누출 속도를 음속인 경우와 아음속인 경우에 대하여 계산하였다. 가스의 누출시 화재가 주로 피해를 유발하므로 화재가 발생하여 사망, 화상 및 건물에 피해를 줄 수 있는 경우 그 피해범위를 산정하는 방법을 제시하였다. 마지막으로 적절한 가정을 도입하여 사고로 인한 총 손실비용을 계산하는 방법을 제시하였다.

• Nuclear Engineering and Technology
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• 제37권3호
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• pp.245-258
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• 2005

This paper addresses two types of uncertainty: stochastic uncertainty and subjective uncertainty in probabilistic accident consequence assessments. The off-site consequence assessment code OSCAAR has been applied to uncertainty and sensitivity analyses on the individual risks of early fatality and latent cancer fatality in the population outside the plant boundary due to a severe accident. A new stratified meteorological sampling scheme was successfully implemented into the trajectory model for atmospheric dispersion and the statistical variability of the probability distributions of the consequence was examined. A total of 65 uncertain input parameters was considered and 128 runs of OSCAAR with 144 meteorological sequences were performed in the parameter uncertainty analysis. The study provided the range of uncertainty for the expected values of individual risks of early and latent cancer fatality close to the site. In the sensitivity analyses, the correlation/regression measures were useful for identifying those input parameters whose uncertainty makes an important contribution to the overall uncertainty for the consequence. This could provide valuable insights into areas for further research aiming at reducing the uncertainties.