• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.745-754
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• 2012

The correlations between Large Early Release Frequency (LERF) and Early Fatality need to be investigated for risk-informed application and regulation. In Regulatory Guide (RG) -1.174, while there are decision-making criteria using the measures of Core Damage Frequency (CDF) and LERF, there are no specific criteria on LERF. Since there are both huge uncertainties and large costs needed in off-site consequence calculation, a LERF assessment methodology needs to be developed, and its correlation factor needs to be identified, for risk-informed decision-making. A new method for estimating off-site consequence has been presented and performed for assessing health effects caused by radioisotopes released from severe accidents of nuclear power plants in this study. The MACCS2 code is used for validating the source term quantitatively regarding health effects, depending on the release characteristics of radioisotopes during severe accidents. This study developed a method for identifying correlations between LERF and Early Fatality and validates the results of the model using the MACCS2 code. The results of this study may contribute to defining LERF and finding a measure for risk-informed regulations and risk-informed decision-making.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.154-166
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• 2015

The in-core instrumentation measures core power distribution and coolant temperature in local regions of the core in pressurized water reactors. The installation types are distinguished by the designs of routing paths that exit either through reactor bottom mounted instrument nozzles or through reactor top mounted instrument nozzles. Although each type has unique advantages, it is generally known that top mounted design is more competitive with respect to emphasizing nuclear safety issues and ability to cope with severe accidents. The international nuclear vendors have provided various types of reactors with top mounted design. Nuclear power reactors in Korea, however, only have been designed to be applicable to the use of bottom mounted design, and it has been pointed out that the capabilities of Korean reactors against severe accidents should be further enhanced. The paper deals with technical issues on reactor internal and external design, in-core instrumentation, support assembly, sealing mechanism with nozzles, handling, and analytical issues in order to establish the ways of development.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1756-1768
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• 2021

The containment filtered venting system (CFVS) filters the atmosphere of the containment building and discharges a part of it to the outside environment to prevent containment overpressure during severe accidents. The Korean CFVS has a tank that filters fission products from the containment atmosphere by pool scrubbing, which is the primary decontamination process; however, prediction of its performance has been done based on researches conducted under mild conditions than those of severe accidents. Bubble behavior in a pool is a key parameter of pool scrubbing. Therefore, the bubble behavior in the pool was analyzed under various injection flow rates observed at the venturi nozzles used in the Korean CFVS using a wire-mesh sensor. Based on the experimental results, void fraction model was modified using the existing correlation, and a new bubble size prediction model was developed. The modified void fraction model agreed well with the obtained experimental data. However, the newly developed bubble size prediction model showed different results to those established in previous studies because the venturi nozzle diameter considered in this study was larger than those in previous studies. Therefore, this is the first model that reflects actual design of a venturi scrubbing nozzle.

• Journal of Auto-vehicle Safety Association
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• v.13 no.3
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• pp.69-77
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• 2021

Although accident data from the National Police Agency and insurance companies do not know the vehicle safety, the damage level information can be obtained from the data managed by the bus credit association or the bus company itself. So the accident severity was analyzed based on the side impact accidents using accident repair cost. K-means clustering analysis separated the cost of accident repair into 'minor', 'moderate', 'severe', and 'very severe'. In addition, the side impact accident severity was analyzed by using an ordered logit model. As a result, it is appeared that the longer the repair period, the greater the impact on the severity of the side impact accident. Also, it is appeared that the higher the number of collision points, the greater the impact on the severity of the side impact accident. In addition, oblique collisions of the angle of impact were derived to affect the severity of the accident less than right angle collisions. Finally, the absence of opponent vehicle and large commercial vehicles involved accidents were shown to have less impact on the side impact accident severity than passenger cars.

• Journal of Auto-vehicle Safety Association
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• v.6 no.1
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• pp.22-26
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• 2014

Fatality of accidents on curved roads where rollover accidents are likely to take place was higher than that on straight roads. We ought to investigate factors affecting injury severity of occupant in a vehicle rollover accident. From January 2011 to December 2013, we collected data about rollover motor vehicle crash accident. We surveyed occupant's injury, vehicle type, safety devices, type of rollover accident and the number of turn in accident. Of the 132 subjects, 56.1% were males, 50.8% were drivers, 48.5% fastened seat belt, and air bag deployed in 12.1%. Among injuries sustained head, chest and abdomen were major sites of severe injury(Abbreviated injury scale>2). Seat belt use, rollover type, and the number of 1/4 turn were found to have significant positive correlations with Injury Severity Score. The regression analysis herein found significance in safety belt use and the number of 1/4 turn. Seat belt use was a significant factor affecting injury severe of occupant in rollover accident.

• Nuclear Engineering and Technology
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• v.26 no.3
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• pp.411-419
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• 1994

The containment failure probability due to hydrogen burning during severe accidents proceeding in a low pressure sequence is calculated using Monte Carlo method. The probability distribution functions for this Monte Carlo calculation is obtained from the statistical method. The calculations are performed for Kori unit 2, and the sensitivity studies on the input variables-the amount of hydrogen generated at SFD, cerium diameter, cerium length, oxidation rate at FCI, and the amount of hydrogen generated during MCCI-are also performed. It is revealed that SFD is the main factor in hydrogen generation, but the other sources also cannot be neglected. The containment failure probability due to the hydrogen burning lies within 6% in case of Kori unit 2.

• The Korean Nurse
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• v.36 no.4
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• pp.61-74
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• 1997

This study is a descriptive study which was done to examine the circumstances surrounding burn accidents in children in order to develop a burn prevention program. The subjects for the study were the mothers of 107 children admitted to two burn specialty hospitals in seoul and the mothers of 172 healthy children attending day care or kindergarten. The tool used in the study was developed by the researchers, pretested and refined. Cronbach's alpha was 0.72. Data collection was done between November 1995 and April 1996. Statistically analysis was done using SAS Version 6.04 and the data was analyzed using test, chi square, regression and logistic analysis. A suumary of the results shows the following : Eighty percent of the children in both groups lived in nuclear families but comparatively more of the children with burn accidents lived in apartments. More of the parents in the group of healthy children had university education and held white collar or professional jobs, while the parents of the children with burn accidents were slightly younger than the parents of the healthy children. but not significantly younger. A significantly greater number of families of children with burn accidents had more than one child and the characteristics of the children with burn accidents that they were more frequently boys, either first or last born and very active. Most of the burn accidents occurred in fall or winter. sometime between noon and midnight and the majority occurred in the home and were caused by hot liquid. In 86% of the cases emergency care was not given at home but the child was brought to the hospital emergency unit. Most of the burns were second degree or greater. involved the arms or legs. required admission, and 41.5% occurred when the parents were preparing or eating meals. In a test of knowledge of preventive measures, the mothers of children who had suffered burn accidents scored slightly higher than the mothers who had no experience with burn accidents, but this was not statistically significant. As to what to do in the case of a fire, the mothers of the healthy children had more knowledge about who to notify. but 70% of the mothers in both groups did not know how to escape from the house if it was of fire. 80 to 96% did not know what do to in case of a fire, such as rolling if clothes were on fire. 80% did not know what emergency care to give for a burn, and 74 to 87% did not know when it is appropriate to try to put out a fire. It can be concluded from this study that. since the results show that the most frequent situation which resulted in burn accidents was when the parents were not aware of the danger of burns or were not paying attention to the child. and when there were no protective devices to prevent burns. and that accidents most frequently occurred at home. the most effective way of preventing accidents is to develop in the parents a "safety mind", Since burn accidents in children are usually more severe than in adults. the physical. emotional. psychological and social damage is greater. In order to develop and awareness of this in the general public. the use of mass media. books and pamphlets and other educational media that provide education on prevention of burn accidents need to be utilized.

• Journal of Chest Surgery
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• v.52 no.2
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• pp.112-115
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• 2019

We describe aortic arch endarterectomy performed concomitantly with on-pump cardiac surgery in 2 patients with grade V arch atherosclerosis. In both patients, transesophageal echocardiographic findings led to the diagnosis of severe arch atherosclerosis associated with a mobile atheromatous plaque in the aortic arch. The severe arch atherosclerosis was managed with endarterectomy under deep hypothermic circulatory arrest. In patients with severe grade V atherosclerosis in the aortic arch, performing endarterectomy simultaneously with primary cardiac surgery may be justified as a way to reduce the risk of peripheral embolism, including cerebrovascular accidents, with minimal additional surgical risk.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.702-710
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• 2016

Global concern and interest in the safety of nuclear power plants have increased considerably since the Fukushima accident. In the event of a severe accident, the reactor vessel water level cannot be measured. The reactor vessel water level has a direct impact on confirming the safety of reactor core cooling. However, in the event of a severe accident, it may be possible to estimate the reactor vessel water level by employing other information. The cascaded fuzzy neural network (CFNN) model can be used to estimate the reactor vessel water level through the process of repeatedly adding fuzzy neural networks. The developed CFNN model was found to be sufficiently accurate for estimating the reactor vessel water level when the sensor performance had deteriorated. Therefore, the developed CFNN model can help provide effective information to operators in the event of a severe accident.

• Journal of the Korean Society of Systems Engineering
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• v.19 no.2
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• pp.32-45
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• 2023

Implementing Severe Accident Management (SAM) strategies is crucial for enhancing a nuclear power plant's resilience and safety against severe accidents conditions represented in the analysis of Station Blackout (SBO) event. Among these critical approaches, the In-Vessel Retention (IVR) through External Reactor Vessel Cooling (IVR-ERVC) strategy plays a key role in preventing vessel failure. This work is designed to evaluate the efficacy of the IVR strategy for a high-power density reactor APR1400. The APR1400's plant is represented and simulated under steady-state and transient conditions for a station blackout (SBO) accident scenario using the computer code, ASYST. The APR1400's thermal-hydraulic response is analyzed to assess its performance as it progresses toward a severe accident scenario during an extended SBO. The effectiveness of emergency operating procedures (EOPs) and severe accident management guidelines (SAMGs) are systematically examined to assess their ability to mitigate the accident. A group of associated key phenomena selected based on Phenomenon Identification and Ranking Tables (PIRT) and uncertain parameters are identified accordingly and then propagated within DAKOTA Uncertainty Quantification (UQ) framework until a statistically representative sample is obtained and hence determine the uncertainty bands of key system parameters. The Systems Engineering methodology is applied to direct the progression of work, ensuring systematic and efficient execution.