• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.05a
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• pp.40-45
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• 2002

일반적으로 마모 손상된 원자력 발전소의 증기발생기의 전열관은 소성변형의 불안정에 의하여 파열이 발생된다. 이에 본 연구예서는 증기발생기 전열관에 평면형(flat type), 원주형(circumferential type)의 마모가 존재한다고 가정하고 소성 불안정(plastic instability) 해석에 기초하여 파열압력을 구하였다 또한 실험 결과와 비교하여 본 연구 해석 결과와 잘 일치함을 보였다.(중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.11a
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• pp.257-262
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• 2000

원전을 가동함에 따라 전열관에서는 SCC(stress corrosion cracking), 프레팅(fretting) 등과 같은 다양한 종류의 결함이 발생된다. 이러한 결함이 발생된 전열관에 대해서는 건정성 평가를 수행하여 계속 가동을 수행하던가, 전열관 막음(plugging) 또는 재생보수(sleeve) 등의 보수 작업을 수행하게 된다. 현행 전열관의 구조 건정성 확보를 위한 방안 중의 하나로 결함의 종류, 위치 등에 관계없이 모든 결함에 대하여 40% 관두께 기준을 적용하고 있다［1］. 그러나 현재 적용되고 있는 40% 관두께 보수기준은 전열관의 파열사고 가능성을 완벽하게 차단하지 못하면서도 과도하게 보수적인 측면이 있다.(중략)

• Journal of Energy Engineering
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• v.22 no.2
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• pp.148-155
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• 2013

The steam generators of OPR-1000 plants have Alloy 600 and Alloy 690 as the tube material and its tube expansion method is the explosive expansion method. According to the experience of these plants, circumferential cracks were largely occurred in steam generator tubes expanded by the explosive expansion method and their locations were the outer surface of tube expansion transition region surrounding with piled-up sludge. But even though tubes have the same conditions, tubes with the hydraulic expansion method shows the prevail trend of axial cracks compared to circumferential cracks. Therefore in this study, in order to identify the difference of such phenomena as above, configurations of tube and tubesheet were modeled and at operating conditions, stress values applied in the tube expansion transition area in accordance with tube expansion methods were calculated by using computational program and the direction and the predominance of cracks were evaluated.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.103-109
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• 2015

A heat recovery steam generator consists of inlet expansion duct and heat transfer tube bank modules. For the enhancement of heat transfer in the tube bank modules, the flow should be uniform before the 1st heat transfer tube bank module. The present study has been carried out to analyze the flow characteristics in the inlet expansion duct of a heat recovery steam generator by using numerical flow analysis. The aim of the present study is to establish the proper heat transfer mechanism in the heat transfer tube bank modules by the comparison of the heat transfer models, the case with the constant heat loss per unit volume and the case with heat loss by using inner and outer convective heat transfer coefficient of heat transfer tube. From the present research, it could be seen that the heat transfer mechanism with using inner and outer convective heat transfer coefficient derives more proper temperature distribution results and the acceptance criteria of the temperature distribution within ${\pm}10^{\circ}C$ before SCR is satisfied with using this heat transfer mechanism.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.28-41
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• 2019

We carried out performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor. We analyzed transient-dynamic behavior of fluids inside the steam generator to vent into a sodium dump tank or a water dump tank when tubes in the steam generator were broken to cause a large-water-leak accident. Accordingly, we preliminarily evaluated design requirements of our system. Our results showed that sodium in the shell side of the steam generator and in Intermediate Heat Transport System was completely vented within 50 s and feed water in the tube side of the steam generator was completely vented within 2.5 s. It was analyzed that pressure of the tube side of the steam generator was higher than pressure of the shell side of the steam generator, which showed that sodium in the shell side did not flow into the tube side. Our results are expected to be used as basis information to performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.29-39
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• 2010

In this study, experimental test and numerical analysis were conducted to investigate the heat transfer characteristics and fiber performance of high strength concrete. The fire characteristics of the high strength concrete that couldn't be obtained through the test due to specific requirements and restrictions were forecast using numerical analysis approach. The outcome from the numerical analysis and the test were compared to verify and improve the reliability of the analysis. A numerical analysis of 80 and 100 MPa high strength concrete cases were carried out to identify the heat transfer characteristics and fire behavior using software, ABACUS (V6.8) From the results of verification experiment, a 25~55% level of beam shrinkage reduction was observed compared to the concrete without Fiber-Cocktail, indicating the improved fire resistance performance, which appeared to be attributable to the function of Fiber-Cocktail that was able to control the heat transfer characteristics and ultimately result in enhancing the fire resistance performance.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.20.2-20.2
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• 2005

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.38-43
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• 2003

증기발생기 전열관의 마멸은 유체 유발 진동(flow induced vibration)에 의한 전열관과 증기발생기 상부 지지구조물 사이에서 발생하게 되며 원통 지지대(stay cylinder)상부의 중앙 공공(central cavity) 주변에 집중적으로 발생되는 것으로 보고되고 있다. 국내에서는 1997년 영광 4호기의 증기발생기에 마멸 손상이 보고된 이후 영광 3호기와 울진 3, 4호기에서도 마멸 손상이 발견되고 있으며, 외국에서는 1992-1993년 기간동안 대략 500∼600 개의 전열관이 마멸에 의해 관막음(p1u99ing)된 것으로 보고되었다.(중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5676-5683
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• 2012

In this study, numerical analysis was performed on three shapes of heat transfer plates (chevron, wave and dimple type), which are currently used as fillers of cooling towers. Results show that heat transfer rates per consumed power were larger for enhanced plates as compared with that of plain plate. Highest heat transfer coefficient was obtained for wave shape followed by chevron and dimple shape. For wave shape, cross corrugations induced significant mixing of fluids, which enhanced the heat transfer. Friction factor yielded a similar trend with the heat transfer coefficient. However, heat transfer rate and pressure drop per sheet was the largest for chevron shape, due to the largest heat transfer area per sheet.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.85-91
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• 1996

원전 증기발생기 시제 전열관으로 제조된 Alloy 600 및 690 에 대하여 ASTM 규정 (B163-86a)에 따라 확관실험을 실시하여 평가하였으며, 관 요소에 작용하는 응력을 해석하였다. 실험 결과 시제 전열관은 ASTM에서 요구하는 확관율 30% 및 그 이상의 35% 까지 확관할 경우에도 양호한 확관상태를 보였다. 확관에 따른 유동곡선의 축력은 Alloy 690 이 Alloy 600 에 비해 높았으며, 확관율의 증가에 따라 차이가 점진적으로 크지는 경향을 보였다. 얇은 벽 튜브의 확관에 대한 응력 해석식은 Modified Tresca's Yield Criterion를 도입하여 얻었으며, 소성변형식을 이용하여 확관율에 따른 응력을 예측하였다. 유동곡선의 이론 계산치와 실험치를 비교한 결과 Alloy 600의 경우 이론치는 실험치보다 약간 낮은 값으로 잘 일치되었으나, Alloy 690 경우는 Alloy 600에 비하여 확관율의 증가에 따라 차이가 커지는 경향을 보였다.