• Nuclear Engineering and Technology
• /
• v.47 no.1
• /
• pp.26-32
• /
• 2015

During the course of a severe accident in a light water nuclear reactor, large amounts of hydrogen can be generated and released into the containment during reactor core degradation. Additional burnable gases [hydrogen ($H_2$) and carbon monoxide (CO)] may be released into the containment in the corium/concrete interaction. This could subsequently raise a combustion hazard. As the Fukushima accidents revealed, hydrogen combustion can cause high pressure spikes that could challenge the reactor buildings and lead to failure of the surrounding buildings. To prevent the gas explosion hazard, most mitigation strategies adopted by European countries are based on the implementation of passive autocatalytic recombiners (PARs). Studies of representative accident sequences indicate that, despite the installation of PARs, it is difficult to prevent at all times and locations, the formation of a combustible mixture that potentially leads to local flame acceleration. Complementary research and development (R&D) projects were recently launched to understand better the phenomena associated with the combustion hazard and to address the issues highlighted after the Fukushima Daiichi events such as explosion hazard in the venting system and the potential flammable mixture migration into spaces beyond the primary containment. The expected results will be used to improve the modeling tools and methodology for hydrogen risk assessment and severe accident management guidelines. The present paper aims to present the methodology adopted by Institut de Radioprotection et de $S{\hat{u}}ret{\acute{e}}$ $Nucl{\acute{e}}aire$ to assess hydrogen risk in nuclear power plants, in particular French nuclear power plants, the open issues, and the ongoing R&D programs related to hydrogen distribution, mitigation, and combustion.

• Journal of Korean Society of Transportation
• /
• v.30 no.2
• /
• pp.101-116
• /
• 2012

Accident prediction models have been utilized to predict accident possibilities in existing or projected freeways and to evaluate programs or policies for improving safety. In this study, a traffic accident prediction model for freeways was developed for the above purposes. When selecting variables for the model, the highest priority was on the ease of both collecting data and applying them into the model. The dependent variable was set as the number of total accidents and the number of accidents including casualties in the unit of IC(or JCT). As a result, two models were developed; the overall accident model and the casualty-related accident model. The error structure adjusted to each model was the negative binomial distribution and the Poisson distribution, respectively. Among the two models, a more appropriate model was selected by statistical estimation. Major nine national freeways were selected and five-year dada of 2003~2007 were utilized. Explanatory variables should take on either a predictable value such as traffic volumes or a fixed value with respect to geometric conditions. As a result of the Maximum Likelihood estimation, significant variables of the overall accident model were found to be the link length between ICs(or JCTs), the daily volumes(AADT), and the ratio of bus volume to the number of curved segments between ICs(or JCTs). For the casualty-related accident model, the link length between ICs(or JCTs), the daily volumes(AADT), and the ratio of bus volumes had a significant impact on the accident. The likelihood ratio test was conducted to verify the spatial and temporal transferability for estimated parameters of each model. It was found that the overall accident model could be transferred only to the road with four or more than six lanes. On the other hand, the casualty-related accident model was transferrable to every road and every time period. In conclusion, the model developed in this study was able to be extended to various applications to establish future plans and evaluate policies.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.9 no.2
• /
• pp.243-247
• /
• 2016

Driving Event Data such as the rapid acceleration, the rapid deceleration, the sudden braking, and the sudden departure, and over speeding provide important information to predict or analyze the driving habits and accident risk of a driver. Most of the data that represent the driver's driving habits generally fit to the parametric distribution, whereas extreme parts of the data to estimate the accident risk of a driver may not. This paper presents an empirical distribution that is divided into two regions, one is from the normal distribution, and the other is from the general pareto distribution for the driving habits of a driver.

• Nuclear Engineering and Technology
• /
• v.47 no.1
• /
• pp.66-73
• /
• 2015

Background: A numerical simulation was carried out to investigate the difference between internal and external heat-flux distributions at the reactor vessel wall under in-vessel retention through external reactor vessel cooling (IVR-ERVC). Methods: Total loss of feed water, station blackout, and large break loss of coolant accidents were selected as the severe accident scenarios, and a transient analysis using the element-birth-and-death technique was conducted to reflect the vessel erosion (vessel wall thickness change) effect. Results: It was found that the maximum heat flux at the focusing region was decreased at least 10% when considering the two-dimensional heat conduction at the reactor vessel wall. Conclusion: The results show that a higher thermal margin for the IVR-ERVC strategy can be achieved in the focusing region. In addition, sensitivity studies revealed that the heat flux and reactor vessel thickness are dominantly affected by the molten corium pool formation according to the accident scenario.

• The Korean Journal of Emergency Medical Services
• /
• v.25 no.2
• /
• pp.99-112
• /
• 2021

Purpose: The study aimed to analyze the current status of traffic accident victims who were transported by 119 ambulances within the administrative district of Chungnam province and provide essential data for accident prevention. Methods: The pre-hospital care records of patients who called the 119 emergency service in 2019 were obtained from the Chungnam Fire Department. Data pertaining to 13,663 traffic accident victims who were transported to hospitals were analyzed. Results: Patients in those aged ≥60 years accounted for 49.8% of the total cases. In patients aged ≥80 years(n=2,154), motor cycle accidents were highest as 28.3%. In addition, cultivator (n=135) and buggy car (n=79) accident victims were the highest in aged ≥80 years as 66.7% and 67.1%, respectively. Traffic accident victims-population ratio in Chungnam was 0.65%, wherein 2.03% included population aged ≥80 years. Conclusion: It was clear that accidents varied across administrative districts depending on the age group of population distribution. Thus, safety measures for preventing motorcycle, cultivator, and buggy car accidents are necessary for areas with many older people aged ≥80 years.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05b
• /
• pp.663-668
• /
• 1996

A two-dimensional continuum model for the prediction of the hydrogen mixing phenomena in the containment compartment under the severe accident conditions is developed. The model could predict well the distribution of time-dependent hydrogen concentration for selected HEDL Experiment. For a simulation of these experiments, the hydrogen is mixed uniform over the test compartment. To predict the extent of non-uniform distribution, the dominant factors such as the geometrical shape of obstacle and velocity of source injection in mixing phenomena are investigated. If the obstacle disturbing the flow of gas mixture exists in the compartment, the uniform distribution of hydrogen may be not guaranteed. The convective circulation of gas flow is separately formed up and down of the obstacle position, which makes a difference of hydrogen concentration between the upper and lower region of the compartment. The recirculation flow must have a considerable mass flow rate relative to velocity of the source injection to sustain the well-mixed conditions of hydrogen.

• Journal of Korea Water Resources Association
• /
• v.55 no.spc1
• /
• pp.1235-1249
• /
• 2022

This study applied the web crawling technique for extracting big data news on water quality accidents in the water supply system and presented the algorithm in a procedural way to obtain accurate water quality accident news. In addition, in the case of a large-scale water quality accident, development patterns such as accident recognition, accident spread, accident response, and accident resolution appear according to the occurrence of an accident. That is, the analysis of the development of water quality accidents through key keywords and sentiment analysis for each stage was carried out in detail based on case studies, and the meanings were analyzed and derived. The proposed methodology was applied to the larval accident period of Incheon Metropolitan City in 2020 and analyzed. As a result, in a situation where the disclosure of information that directly affects consumers, such as water quality accidents, is restricted, the tone of news articles and media reports about water quality accidents with long-term damage in the event of an accident and the degree of consumer pride clearly change over time. could check This suggests the need to prepare consumer-centered policies to increase consumer positivity, although rapid restoration of facilities is very important for the development of water quality accidents from the supplier's point of view.

• Journal of the Ergonomics Society of Korea
• /
• v.35 no.5
• /
• pp.465-472
• /
• 2016

Objective:This study is on the characteristics of motorcycle accidents occurring in the mail delivery process by skill level. Background: The tendency of delivery postmen's driving in a hurry may become the cause of accidents since there is a constraint that delivery should be completed within a limited time. Method: This study analyzed the traffic accident data of 259 delivery postmen, who had been approved as occupation-related industrial accident victims from 2009 to 2012, by their work experience in view of season, day of the week of an accident occurrence, accident occurrence time, accident cause, collision type, and driving situation. Results: Accident characteristics of delivery postmen show that the ratio of accidents occurring to those who had less than 10 years of work experience was high. There were many motorcycle collisions in winter and summer by season and an unexpected object, along with road condition, took up 70.7% of the accident sources. There were no differences in accident occurrence time, the day of the week, season, accident source, and collision type between the group of delivery postmen with less than 10 years of work experience and those with 10 years or more of work experience. However, there was a difference in distribution of driving condition. Conclusion and Applications: The results of this study can be used to present the policies or guidelines for the accident prevention of delivery postmen since the results show the characteristics of the injured and accident occurrence characteristics in relation with the delivery postmen's motorcycle collisions.

• Journal of the Society of Disaster Information
• /
• v.18 no.3
• /
• pp.560-565
• /
• 2022

Purpose: It is intended to prevent similar and similar disasters in advance by classifying the types of industrial accidents by type of distribution center and establishing countermeasures. Method: Development of improvement measures by analyzing in detail the types of occurrences of each type of 5 years in the distribution center. Result: Through the analysis of industrial accidents that occurred in the distribution center, it was possible to find ways to reduce disasters. Conclusion: It is expected to help reduce the disaster rate of the distriution center by presenting a disaster reduction plan through the analysis of industrial accidents in the distribution center.

• Journal of Distribution Science
• /
• v.20 no.3
• /
• pp.23-31
• /
• 2022

Purpose: The purpose of this study is to analyze the Safety and Logistical Distribution Management system in Thailand's Highway Work Zone based on data from Logistics drivers. Accidents in highway construction zones have caused enormous casualties in Thailand yearly. Statistical data shows evidence of correlation between numbers of accidents and drivers' recklessness. Research design, data, and methodology: In this study, we conducted an in- depth interview with 414 logistics drivers and highway construction workers in Khon Kaen province, Thailand. The data was collected based on 63 questionnaires aiming at capturing factors contributing to the risk of safety and cause of accidents in logistic infrastructures such as Highway work zone. Results: The result reveals two significant factors affecting safety in highway work zone, which includes construction environment and safety management system. Moreover, the result shows that feeling of afraid and confused while driving within the construction zones significantly affecting driver's risk of having an accident. Conclusions: The findings of this study offer that a strategic planning and evaluation of the logistics drivers' satisfaction and construction workers' participation to mitigate highway accidents at construction zones and that drivers' knowledge and perception toward construction safety management plays a significant role in preventing highway accidents at the construction areas.