• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.144-155
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• 2023

The core catcher is used as a passive safety system in new generation nuclear power plants to create a space in the containment for the placing and cooling of the molten corium under various severe accidents. This research investigates the role of the core catcher in the VVER-1000 reactor containment system in mitigating the effects of core meltdown under various severe accidents within the context of the Ex-vessel Melt Retention (EVMR) strategy. Hence, a comparison study of three severe accidents is conducted, including Station Black-Out (SBO), SBO combined with the Large Break Loss of Coolant Accident (LB-LOCA), and SBO combined with the Small Break Loss of Coolant Accident (SB-LOCA). Numerical comparative simulations are performed for the aforementioned scenario with and without the EX-vessel core-catcher. The results showed that considering the EX-Vessel core catcher reduces the amount of hydrogen by about 18.2 percent in the case of SBO + LB-LOCA, and hydrogen production decreases by 12.4 percent in the case of SBO + SB-LOCA. Furthermore, in the presence of an EX-Vessel core-catcher, the production of gases such as CO and CO2 for the SBO accident is negligible. It was revealed that the greatest decrease in pressure and temperature of the containment is related to the SBO accident.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2120-2134
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• 2022

A hypothetical core destructive accident (HCDA) has received widespread attention as one of the most serious accidents in sodium-cooled fast reactors. This study combined recent advantages in numerical methods to realize realistic modeling of the complex fluid-structure interactions during HCDAs in a full-scale sodium-cooled fast reactor. The multi-material arbitrary Lagrangian-Eulerian method is used to describe the fluid-structure interactions inside the container. Both the structural deformations and plug rises occurring during HCDAs are evaluated. Two levels of expansion energy are considered with two different reactor models. The simulation results show that the container remains intact during an accident with small deformations. The plug on the top of the container rises to an acceptable level after the sealing between the it and its support is destroyed. The methodology established in this study provides a reliable approach for evaluating the safety feature of a container design.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.937-946
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• 2020

The aim in the present work is to simulate accident scenarios of AP1000 during the small-break loss-of-coolant accident (SBLOCA) and investigate the performance and behavior of automatic depressurization system (ADS) during accidents by using MIDAC (The Module In-vessel Degradation severe accident Analysis Code). Four types of accidents with different hypothetical conditions were analyzed in this study. The impact on the thermal-hydraulic of the reactor coolant system (RCS), the passive core cooling system and core degradation was researched by comparing these types. The results show that the RCS depressurization becomes faster, the core makeup tanks (CMT) and accumulators (ACC) are activated earlier and the effect of gravity water injection is more obvious along with more ADS valves open. The open of the only ADS1-3 can't stop the core degradation on the basis of the first type of the accident. The open of ADS1-3 has a great impact on the injection time of ACC and CMT. The core can remain intact for a long time and the core degradation can be prevent by the open of ADS-4. The all results are significant and meaningful to understand the performance and behavior of the ADS during the typical SBLOCA.

• Journal of Radiation Protection and Research
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• v.49 no.2
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• pp.65-67
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• 2024

This review is based on articles published in Japanese Journal of Health Physics on "Radiation-exposed medical care and waste" related to Tokyo Electric Power Company Incorporated (TEPCO)'s Fukushima Daiichi Nuclear Power Station accident. Here, we have considered three original articles; one technical data, one special article, one 50^th anniversary article, one preface, three topics, and two cases of From Japan to the World (J to W). These articles have reported the system and standards that were established after the accident. Moreover, they have summarized rare experiences such as the fumbling response at the time and the evaluation of samples in that disaster. These articles constitute valuable records of the situation.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.20-28
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• 2015

Recently, railroad's preference greatly increased as the environment-friendly means of transportation as the importance in the aspects of environment and energy efficiency. So the government established the Korea Rail Network Authority which takes full charge of railroad construction in 20047 for regular railroad construction to combine major key points in the whole country with each other to be one city region by connecting them to each other to be within the commute time range of a hour and thirty minutes. And it has arranged large-scale railroad construction by establishing plans to build the 1st and 2nd national railroad networks as the national project and investing about 100 trillion won in it from 2006 to 2020. As large-scale railroad construction is promoted as the national project like this, there has been a string of safety accidents in it due to the large and complex construction project. As the government strengthened the safety accident prevention plans, safety accidents have tended to decrease in 2011. However, accidents of construction machinery have found to increase. Therefore, this study tried to investigate accident cases of the Korea Rail Network Authority for the recent 5 years and analyze accidents of construction machinery to prevent them in railroad construction sites and suggest accident prevention plans due to it by conducting, investigating, and analyzing the survey of its operators and superintendents of the construction sites and drawing the problems.

• Korean Journal of Occupational Health Nursing
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• v.9 no.2
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• pp.121-131
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• 2000

This study was conducted to acquire data in order to institute an effective industrial accident compensation insurance(IACI) system. The subjects were employers and employees in small scale industries which have less than 5 employees. The questionnaires consisted of questions on perception and need for IACI. A total of cases were 181 employers and 105 employees participated in the study. Perception and need of employers and employees were assessed using the ANOVA, t-test. The results were as follows ; 1. Workplaces examined mostly in manufacturing(78.9%), industries with one employee(44.1%). Beneficiary rate of IACI 4.4%. 2. 60.0% of employees had experienced an industrial accident and in most cases employers paid the cost of medical treatment. 45.0% of employers nd 50.0% of employees were not aware that IACI had been put into effect starting July, 1, 2000. 52.0% of employers had no type of industrial accident compensation. 3. The need of outcome measures, especially of employers and employees who had an IACE, were higher than those without an IACI. Employers and employees who had experienced an industrial accident outnumbered those who hadn't. The results of this study reveal that there is a great need for the institution of an IACI and health promotion policy in small scale industries.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.171-177
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• 2008

As the risk of traffic accidents caused by mists emerged as a social problem, recently safety facilities to be prepared for mists are being actively installed when designing roads. But in some part, the facilities are being installed imprudently without analyzing the extent of occurrences of mists that would increase the risk of traffic accidents and appropriate countermeasures against the occurrences of mists are not being suggested. For that reason, in this study, first questionnaire surveys were executed on road users in order to draw the factors affecting the traffic accidents caused by mists, a mist traffic accident predicting model was developed and an accident seriousness determining model that can determine accident seriousness was developed. In this way, by extracting major factors affecting mist traffic accidents to grasp risk factors in roads to be caused by mists, safety of roads can be enhanced and traffic accidents in road operations can be decreased. As the affecting factors influencing mist traffic accidents, were extracted sightable distances, durations of mists and whether daytime or nighttime as major factors and the plan to install the facilities for the prevention of mist traffic accidents was suggested to prevent the traffic accidents to be caused by those factors and also the plan to operate roads considering sightable distances was suggested to solve the problem of insufficient sightable distances to be caused by mists was suggested. It is judged that the road safety in the areas where mists occur can be improved through foregoing methods.

• Journal of Korean Public Health Nursing
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• v.17 no.1
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• pp.96-112
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• 2003

The purpose of this study was to determine how often toddlers and preschoolers in kindergartens have accidents and what factors affect the accident rate. The study population consisted of 150 children who were attending at nursery schools and 150 children who were attending at kindergartens. The data was collected from ten nursery schools and five kindergartens from five districts in Daegu. The questionnaires were distributed to teachers of participating nursery schools and kindergartens to be completed using nursing care records in the institutions and by interviewing children's parents about all of the accidents happened in a previous year. Data were collected during the period of August 1 through 31, 2002. The results of the study are as follow: 1. Among 300 children, 282 had 506 accidental injuries during the study period. 2. The month, the day and the time with the highest accident rate were April. Monday, and between 2 and 4 o'clock in the afternoon, respectively. 3. Locations where the injury took place most included nursery schools or kindergartens, around the homes of the children, and inside the home. 4. Most accidents were occurred due to lack of carefulness of the children, and the most prevalent forms of injury was abrasions. 5. Most frequently injured part of the body was legs of the children. 6. Most injuries were healed within three days and required first aid measures to disinfect the wound. Mostly, these were performed by family members at home. Some children go to the hospital to suture the open wound. Most frequent type of complication was scar formation and the cost of the treatment ranged from 9,000 to 30,000 won. 7. Children's age. sex, birth order. personality. type of family composition. type of residency. father's occupation, father's age, and mother's age were significantly related to the frequency of injury among children. Children who were in nursery schools and kindergartens need their assessment for accident involving condition according to seasons, time. place. This study provided a very useful and important data to prepare accident prevention education program and accident prevention strategies, and to develop Injury Surveillance System.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.863-869
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• 2018

Due to recent changes in the maritime traffic environment, naval warship accidents are constantly occurring. Especially in 2017, serious loss of life was caused by a US navy destroyer accident. The purpose of this study is to analyze the characteristics of naval warship accident cases and construct an accident scenario by using naval training materials, adjudication of naval warship accidents and US navy destroyer accident reports. Based on the surveyed data, the status of accidents was identified and cases were analyzed. We reproduced 17 accident cases in accordance with accident reproduction procedure and constructed naval warship accident scenarios. As a result of analyzing the CPA, TCPA and PARK model for risk, reproducing 17 naval ship accident cases, collision risk increased on average 5-6 minutes before an accident. The result of this study represents basic data for naval and simulation education materials, contributing to the prevention of marine accidents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.17-22
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• 2004

Ship is bring operated under a highly dynamic environments and many factors are related whit marine accident and those factors are interacting. An analysis on the marine accident is very important to prepare countermeasures which will ensure the safe navigation. This paper aims to build a model of the causes and improved policy for marine accident using SD(System Dynamics} approach and to measure a effect which is risk control countermeasures of marine accident. The methodology of this paper is to perform the causes and improved policy for marine accident using Brainstorming method and was to changed by quantitutive, qualitative factors and their feedback loops in casual map. This model was performed over 23 years($1997\~2020$) in a standard simulation model and 4 policy simulation models.