• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.51-56
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• 2001

Vapor explosion is one of the most important problems encountered in severe accident management of nuclear power plants. In spite of many efforts, a lot of questions still remain for the fundamental understanding of vapor explosion phenomena. Therefore, KAERI launched a real material experiment called TROI using 20 kg of UO2 and ZrO2 to investigate the vapor explosion phenomena. In addition, a small-scale experiment with molten-tin/water system was performed to quantify the characteristics of vapor explosion and to understand the phenomenology of vapor explosion. A number of instruments were used to measure the physical change occurring during the vapor explosion. In this experiment, the vapor explosion generated by molten fuel water interaction is visualized using high speed camera and the pressure behavior accompanying the explosion is investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.397-400
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• 2002

Vapor explosion is one of the most important problems encountered in severe accident management of nuclear power plants. In spite of many efforts, a lot of questions still remain. So, KAERI launched a real experimental program called TROI using $UO_{2}$ and $ZrO_{2}$ to investigate the vapor explosion. Besides TROI tests, a small-scale experiment with molten-tin/water system was performed to quantify the characteristics of vapor explosion and to understand the phenomenology of vapor explosion. A vapor explosion was observed while the amount of air bubble and water temperature were systematically varied The mass and temperature of tin are $50\;g\;and\;150^{\circ}C$, respectively. Water temperature is set to $24^{\circ}C\;and\;50^{\circ}C$. The void fraction of air bubble ranges from $0\;to\;10\;{\%}$. The strength of vapor explosion was measured using dynamic pressure sensors attached in reactor tube wall. as a function of void fraction. In addition, a high speed video filming up to 1,000 flame/sec was taken in order to visually investigate the behavior of the vapor explosion .

• Nuclear Engineering and Technology
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• 제32권4호
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• pp.299-308
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• 2000

A safety assessment of reactor vessel lower head integrity under in-vessel vapor explosion loads has been performed. The core melt relocation parameters were chosen within the ranges of physically realizable bounds. The premixing and explosion calculations were performed using TRACER-II code. Using the calculated explosion pressures imposed on the lower head inner wall, strain calculations were peformed using ANSYS code. Then, the calculated strain results and the established failure criteria were used in determining the failure probability of the lower head, In the explosion analyses, it is shown that the explosion impulses are not altered significantly by the uncertain parameters of triggering location and time, fuel and vapor volume fractions in uniform premixture bounding calculations. Strain analyses show that the vapor explosion-induced lower head failure is not possible under the present framework of assessment. The result of static analysis using the conservative explosion-end pressure of 50 MPa also supports the conclusion. It is recommended, however, that an assessment of fracture mechanics for preexisting cracks be also considered to obtain a more concrete conclusion.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1996년도 학술발표회
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• pp.37-42
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• 1996

The assessment of catastrophic accidents such as BLEVE, vapor cloud explosion, and toxic material releases in the chemical process industries(CPI) shall be carried out according to the Requirement of PSM/SMS enforced by Korea Government Agencies, but reasonable models are not proposed for the practical application. The traditional models, TNT Equivalency Model, are well-known and helpful for the assessment of vapor cloud explosion. However, the estimated-damage-area using the traditional model has much more deviations comparing to the real damage caused by vapor cloud explosion suffered before. These are why an expert system for the assessment of vapor cloud explosion has been developed, which is based on theoretical, statistical and experimental data, and it would be helpful for CPI to evaluate the damage-area in case of vapor cloud explosion.

• 한국안전학회지
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• 제13권2호
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• pp.116-121
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• 1998

Various flammable vapors as energy source and raw material have been stored, transported in the industries, and accidental leakage of these vapors occurs occasionally. Without an appropriate protection system, flammable vapors can be ignited and serious damage results from them. To reduce the risk caused by explosion, we should know the explosion limit and explosion characteristics. In this study, the maximum explosion pressure, the maximum explosion pressure rise, the effect of temperature and mixing with other vapor were measured in a cylindrical vessel. Experimental results showed that maximum explosion pressure of flammable vapor was about 3.1~$4.2 kg/cm^2$ and it was reached 3.4 times faster than that at explosion limit. The lower explosion limit was coincided well with Le Chateilier's equation, however, upper explosion limit was not.

• 화약ㆍ발파
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• 제36권4호
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• pp.26-34
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• 2018

인화성 물질을 보유하고 있는 시설물에서 인화성 물질이 유출되어 형성된 증기운의 폭발이 국내와 해외에서 자주 발생하고 있다. 본 연구에서는 증기운 폭발에 따른 폭풍 효과를 모사하기 위해서 TNT 등가법과 다중에너지법을 적용하였다. TNT 등가법은 단순하고 직접적인 적용이 가능하기 때문에 증기운 폭발을 해석하기 위해서 지금까지 널리 사용되고 있다. 그러나 TNT 등가법은 증기운 폭발로부터 발생하는 연소에너지와 이를 TNT 등가량으로 환산하는데 필요한 적절한 상관관계를 선택하는 것이 어렵다는 근본적인 단점을 가지고 있다. 다중에너지법에서는 증기운 폭발의 강도가 증기운이 확산되는 지역에서의 확산 경로의 레이아웃에 따라 달라진다고 가정한다. 즉 증기운의 잠재적 폭발력은 혼잡지역의 혼잡정도에 따라 달라진다. 본 연구에서는 TNT 등가법과 다중에너지법의 적용성을 평가하기 위해서 Flixborough 폭발사고를 사례연구로 분석하였다. 분석 결과 TNT 등가계수와 폭발강도계수를 현장상황에 맞게 적절히 선택하는 경우 TNT 등가법과 다중에너지법은 증기운 폭발 사고를 분석하는데 적합할 것으로 예상된다.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.95-103
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• 2019

Vapor explosions can be classified in terms of modes of contact between the hot molten fuel and the coolant, since different contact modes may affect fuel-coolant mixing and subsequent vapor explosion energetics. It is generally accepted that most vapor explosion phenomena fall into three different modes of contact; fuel pouring into coolant, coolant injection into fuel and stratified fuel-coolant layers. In this study, we review previous stratified steam explosion experiments as well as recent experiments performed at the KTH in Sweden. While experiments with prototypic reactor materials are minimal, we do note that generally the energetics is limited for the stratified mode of contact. When the fuel mass involved in a steam explosion in a stratified geometry is compared to a pool geometry based on geometrical aspects, one can conclude that there is a very limited set of conditions (when melt jet diameter is small) under which a steam explosion is more energetic in a stratified geometry. However, under these limited conditions the absolute energetic explosion output would still be small because the total fuel mass involved would be limited.

• Nuclear Engineering and Technology
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• 제26권2호
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• pp.257-264
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• 1994

원자력발전소 중대사고시 용융된 노심과 잔류냉각수가 증기폭발을 일으켜 원자로 격납용기의 건전성을 위협할 수 있다. 본 연구에서는 증기폭발을 모사할 수 있는 실험 장치를 제작하고, 물과 프레온을 사용하여 증기폭발실험을 수행하였다. 이때 고속카메라를 사용하여 폭발현상을 관측하였고, 동압측정기와 압력분출관을 이용하여 생성되는 폭발압력과 기계적인 에너지를 계측하였다. 이를 토대로 증기폭발의 중요인자들(물의 온도, 물의 주입속도, 물의 주입 시간, 그리고 냉매의 깊이)에 대한 민감도 분석을 수행하였다. 그리고, 압력용기 바닥의 구조물이 용융/냉각재의 반응에 미치는 영향을 살펴보기위하여 실험용기 내부에 그리드를 설치하여 폭발실험을 실시하였다. 물/프레온의 폭발실험에서 계측된 기계적에너지를 이용한 에너지효율은 0.5∼l.6%인 것으로 계산되었다.

• 한국안전학회지
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• 제25권1호
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• pp.44-49
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• 2010

This paper is estimation of structure damage caused by Explosion in LPG(Liquefied Petroleum Gas) filling station. As we estimate the influence of damage which occur at gas storage tank in filling station. We can utilize the elementary data of safety distance. In this study, the influence of over-pressure caused by VCE(Vapor Cloud Explosion) in filling station was calculated by using the Hopkinson's scaling law and the accident damage was estimated by applying the influence on the adjacent structure into the probit model. As a result of the damage estimation conducted by using the probit model, both the damage possibility of explosion overpressure to structures of max 265 meters away and to glass bursting of 1150 meters away was nearly zero in open space explosion.

• 한국전산구조공학회논문집
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• 제37권1호
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• pp.1-8
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• 2024

본 논문에서는 확률론적 처리기법을 적용하여 플랜트 시설물의 폭발 재현주기에 따른 폭발 위험도를 분석하였다. HSE에서 제공하는 누출 데이터, DNV에서 제시한 플랜트당 연간 누출 빈도, 다양한 연구진이 제시한 점화 확률을 고려하여 누출량에 따른 폭발 재현주기를 산정하였다. 산정된 폭발 재현주기를 통해 폭발 위험도를 증기운의 부피 및 반경, 폭발하중에 대하여 평가하였다. 재현주기에 따른 증기운의 반경과 과거 실제 증기운 폭발 사례, 내폭설계 가이드라인을 비교 분석하여 설계폭발하중 모델을 위한 기준거리를 제시하였다. 멀티에너지법을 통하여 폭발 재현주기에 따른 폭발하중의 범위를 분석하였으며, 설계폭발하중 모델의 기준이 되는 재현주기를 제안하였다. 본 연구의 결과로 플랜트 시설물에 대한 성능기반 내폭설계의 간략한 표준안으로 활용이 가능하다.