• Journal of Environmental Health Sciences
• /
• v.44 no.3
• /
• pp.217-226
• /
• 2018

Objectives: Despite the positive effects of Off-site risk assessment (ORA) system such as prevention of chemical accidents, some problems have been constantly raised. The purpose of this study is to analyze the problems that have occurred through the implementation of the ORA system for the past three years and to suggest reasonable directions for improvement in the future. Methods: In order to identify the problems with the methodology and procedure of ORA system, we analyzed statutes, administrative rules and documents related to the ORA system. A survey of ORA reviewers in National Institute of Chemical Safety was conducted to investigate the weight of determinants considered when judging the level of total risk in ORA. Results: In this study, we found out the uncertainty of the estimation of the number of people in the impact range in the procedure of the risk assessment of individual handling facilities, the lack of quantitative risk analysis methods for environmental receptors, and the ambiguity of the criteria for the total risk. In addition to suggesting solutions to the problems mentioned above, we also, suggested a decision tree for total risk in ORA. Conclusion: We anticipate that the solutions including the systematic decision tree for total risk suggested will contribute to the smooth operation of the ORA system.

• Journal of Environmental Impact Assessment
• /
• v.29 no.4
• /
• pp.239-251
• /
• 2020

The Off-site Risk Assessment (ORA) for preventing chemical accidents estimates the chemical accident risk at chemical plants. The method of estimating the risk is made by multiplying the number of residents within the effect area of the chemical accident and the frequency of accidents at a chemical plant. At present, the ORA does not quantitatively consider environmental receptors when the damage types within the scope of the accident are environmental receptors. In order to solve this problem, this study proposes a method of estimating the risk considering resident and environmental receptors. Through these studies, it was confirmed that the ORA impact for the prevention of chemical accidents requires risk analysis considering environmental receptors in the medium and long term.

• Journal of the Korean Society of Safety
• /
• v.32 no.6
• /
• pp.46-53
• /
• 2017

The risk is expressed as consequence of damage multiplied by likelihood of failure. The installation of a protective system reduces the risk by reducing the likelihood of failure at the facility. Also, the protective system has different effects on the likelihood of failure according to the proof test cycle. However, when assessing risks in the Off-site Risk Assessment (ORA) system, the variation in risk was not reflected according to the proof test cycle of protective system. This study was conducted to examine the need for proof test and the importance of cycle setting by applying periodic proof test of the protective system to ORA. The results showed that the likelihood of failure and the risk increased with longer proof test cycle. The risk of a two-yearly proof test was eight times greater than that of a three-month cycle. From the results, the protective system needs periodic proof test. Untested protective system for a long term cannot be reliable because it is more likely to be failed state when it is called upon to operate. In order to reduce the risk to an acceptable level, it is effective to differently set the proof test cycle according to the priority. This study suggested a more systematic and accurate risk analysis standard than ORA. This standard is expected to enable an acceptable level of risk management by systematically setting the priority and proof test cycle of the protective system. It is also expected to contribute to securing the safety of chemical facilities and at the same time, will lead to the development of the ORA system.

• Journal of Environmental Health Sciences
• /
• v.44 no.2
• /
• pp.124-132
• /
• 2018

Objectives: All enterprises intending to install and operate hazardous chemical handling facilities should prepare an off-site risk assessment (ORA) report that evaluates the impact of potential chemical accidents on the surrounding environment and population. This study was conducted to introduce the process of development and the functioning of the Korea Off-site Risk Assessment support tool (KORA) developed by the National Institute of Chemical Safety and to suggest manners to increase its utilization. Additionally, this article provided an overview of KORA. Methods: In order to identify problems with and refinements for KORA, the required items for each phase of KORA were derived by analyzing the Chemical Control Act and related administrative regulations. Results: The functions of KORA made receptor-considered assessment of chemical accidents possible, but several limitations were found in particular phases, such as the analysis of impact range, consideration of sensitive receptors, and assessment of environmental receptors. Conclusion: In this study, we suggested manners to increase the utilization of KORA. It is anticipated that the further research suggested in the study could contribute to the stabilization of the KORA system.

• Fire Science and Engineering
• /
• v.32 no.3
• /
• pp.76-87
• /
• 2018

This study describes the damage effects modeling for a quantitative prediction about the hazardous distances from pressurized chlorine saturated liquid tank, which has two-phase leakage. The heavy gas, chlorine is an accidental substance that is used as a raw material and intermediate in chemical plants. Based on the evaluation method for damage prediction and accident effects assessment models, the operating conditions were set as the standard conditions to reveal the optimal variables on an accident due to the leakage of a liquid chlorine storage vessel. A model of the atmospheric diffusion model, ALOHA (V5.4.4) developed by USEPA and NOAA, which is used for a risk assessment of Off-site Risk Assessment (ORA), was used. The Yeosu National Industrial Complex is designated as a model site, which manufactures and handles large quantities of chemical substances. Weather-related variables and process variables for each scenario need to be modelled to derive the characteristics of leakage accidents. The estimated levels of concern (LOC) were calculated based on the Gaussian diffusion model. As a result of ALOHA modeling, the hazardous distance due to chlorine diffusion increased with increasing air temperature and the wind speed decreased and the atmospheric stability was stabilized.

• Journal of the Korean Institute of Gas
• /
• v.22 no.3
• /
• pp.84-90
• /
• 2018

We researched the way to minimize the damage when the chlorine-leak accident take place in a purification plant. Since the level of risk based on the Off-site Risk Assessment(ORA) is a combination of proportional to the number of residents in the damaged area and frequency of accidents, we suggested the adequate conditions to reduce the number of residents in the damaged area by means of the operating temperature of a handling facility, installation of a emergency shut-off valve, and the analysis of the variation of the damaging range in accordance with the type of enclosure. The coverage of damage was calculated by the 'KORA(Korea Off-site Risk Assessment Supporting Tool) program. The research shows that the lower operating temperature gets, the more emergency shut-off valve being installed and the higher enclosure level of facility becomes, the extent of damage gets decreased. The decreasing rate of worst case was 17.6%, 71%, 34.5% respectively, the decreasing rate of alternative case was 31.6%, 69.0%, 34.8% respectively.

• Journal of the Korean Society of Safety
• /
• v.34 no.6
• /
• pp.13-21
• /
• 2019

Leakage accidents in businesses dealing with hazardous chemicals can have a great impact on the workers inside the workplace, as well as residents outside the workplace. In fact, there were cases where hazardous chemicals leaked from many businesses. As a result, the Chemicals Control Act(CCA) was enacted in 2015, the Ministry of Environment introduced an Off-site Risk Assessment(ORA). The purpose of the ORA is to secure safety from the installation of the design of the workplace facilities so that chemical accidents of hazardous chemical handling facilities do not cause human or physical damage outside the workplace. In general, the ORA qualitatively determines where a protected facility is within the scope of the accident scenario. However, elderly who belong to the sensitive group is more sensitive than the general group under the same chemical accident effect, and the extent of the damage is serious. According to data from the Korea National Statistic Office, the number of elderly people is expected to increase steadily. Therefore, a quantitative risk analysis considering the elderly is necessary as a result of a chemical accident. In this study, accident scenarios for 14 locations were set up to perform emergency evacuation due to toxic gas leakage of Cl₂(Chlorine) and HF(Hydrogen Fluoride), and the effects of exposure were analyzed based on the evacuation velocity difference of age 20s and 60s. The ALOHA(Areal Locations of Hazardous Atmospheres) program was used to calculate the concentration for assessing the effects. The time of exposure to toxic gas was calculated based on the time it took for the evacuation to run from the start point to the desired point and a methodology was devised that could be applied to the risk calculation. As a result of the study, the relative risk of the elderly, the sensitive group, needs to be determined.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.73-73
• /
• 2017

환경부는 화학물질로 인한 국민건강 및 환경상의 위해(危害)를 예방하고 화학물질을 적절하게 관리하고, 화학물질로 인하여 발생하는 사고에 신속히 대응함으로써 화학물질로부터 모든 국민의 생명과 재산 및 환경을 보호하기위한 법률인 "화학물질관리법"을 2015년 1월 1일부터 시행하였다. 화학물질관리법에서는 유해화학물질의 취급기준과 유해화학물질 취급시설의 설치 및 관리 기준을 준수토록 하고 있으며, 유해화학물질 취급시설을 설치 및 운영 시에는 사전에 화학사고 발생으로 사업장 주변 지역의 사람이나 환경 등에 미치는 영향을 평가하여 유해화학물질 취급시설의 설치단계에서 안전성을 확보하기 위한 유해화학물질 화학사고 장외영향평가서를 작성 및 제출하도록 하고 있다. 또한 사고대비물질을 규정 수량이상 취급하는 경우 위해관리계획서를 작성하여 지역사회에 고지하도록 하고 있다. 법 시행 이전에 유해화학물질 취급시설을 설치한 사업장은 사업장 규모에 따라 장외영향평가서의 제출 유예기간인 2019년 12월 31일까지 제출하여야 하며, 사고 대비물질의 영업허가를 득해야하는 사업장은 2017년 내 장외영향평가서를 제출하여야 한다. 장외영향평가(off-site risk assessment(ORA)) 제도는 유해화학물질 취급시설의 기본평가정보(공정 정보), 장외평가정보(사고 시나리오 선정 및 위험도 분석), 타 법령과의 관계정보로 구성되어 있다. 장외영향평가의 효율적인 작성을 위하여 현장과 일치된 공정정보(공정개요 및 공정도면 등의 자료)의 확보가 필수적이다. 본 발표에서는 복잡한 장외영향평가 제도로부터 기업의 대응을 위한 장외영향평가 운영 절차와 장외영향평가서의 효율적인 작성을 위한 사전 준비 자료 및 작성 방안을 제시하여, 사업장에서 장외영향평가 제도를 이행하는데 도움을 주고자 한다.

• Journal of the Korean Institute of Gas
• /
• v.22 no.3
• /
• pp.38-44
• /
• 2018

Ammonia is used primarily as a refrigerant in refrigeration facility and SCR of a plant, and is frequently involved in leakage accidents. This study was conducted by selecting ammonia, a material with a wide influence range when evaluated, as a material with higher vapor pressure and lighter than air. In this study, the influence ranges were computed using KORA(Korea Off-site Risk Assessment supporting tool) with four different environmental factors : ground roughness, sealing, operating temperature, pressure, and leakage hole size. As a result, the difference in the influence range of ground roughness is approximately 4.62 times, while the ammonia storage tank shows a difference in the reduction rate of 0.64 when sealed. The extent of impact increased with increasing leakage depending on storage temperature and pressure, and when storing higher than the saturation vapor pressure, the impact range showed an average growth rate of 3.45 % per 0.1 Mpa($45^{\circ}C$). The influence ranges based on the size of the leakage holes is shown to be proportional to the area of the leakage zone.

• Journal of the Korean Institute of Gas
• /
• v.20 no.2
• /
• pp.49-57
• /
• 2016

Aqueous ammonia is widely used in household cleaners, fertilizers and denitrification process. It is usually treated in concentrations from 10 % to 30 %, and release accidents have occurred frequently. In this study, we developed a simplified estimating method and equation to calculate threat zone easily in case of emergency due to release accident of aqueous ammonia. We calculated the consequence distance for toxic endpoints of aqueous ammonia(concentration 10 % ~ 30 %) at different puddle areas($1m^2{\sim}500m^2$) using the ALOHA program. Based on the result, we analyzed the relationship between concentration and puddle area with the threat zone and created the equation.