• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.48-55
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• 2006

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.143.2-143
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• 1999

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.39-42
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• 2002

The nuclear transmutation technology to Incinerate the long lived radioactive nuclides and produce energy during the incineration process is believed to be one or the best solutions. HYPER(${\underline{HY}}brid {\underline{P}}ower {\underline{E}}xtraction {\underline{R}}$eactor)is the accelerator driven transmutation system which is being developed by KAERI(Korea Atomic Energy Research Institute). Lead-bismuth(Pb-Bi) is adopted as a coolant and spallation target material. In this paper, we performed the thermal-hydraulic analysis of HYPER target using the commercial code FLUENT, and also calculated thermal and mechanical stress of the beam window using the commercial code ANSYS. It is found that there is an optimum value for the window diameter and the maximum allowable beam current can be increased to 17.3 mA for the inner diameter of windows, 40 cm. Finally, the other shapes such as uniform or scanned beam were considered. The results of FLUENT calculations show that the uniform type is preferable to the other shapes of the beam in terms of the window and target cooling and the maximum window temperature is lower than that of the parabolic beam by $58 ^{\circ}C$ for the beam current, 13 mA.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.360-367
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• 2016

A windowless spallation target can provide a neutron source and maintain neutron chain reaction for a subcritical reactor, and is a key component of China's nuclear waste transmutation of coupling accelerator and subcritical reactor. The main issue of the windowless target design is to form a stable and controllable free surface that can ensure that energy spectrum distribution is acquired for the neutron physical design when the high energy proton beam beats the lead-bismuth eutectic in the spallation target area. In this study, morphology and flow characteristics of the free surface of the windowless target were analyzed through the volume of fluid model using computational fluid dynamics simulation, and the results show that the outlet cross section size of the target is the key to form a stable and controllable free surface, as well as the outlet with an arc transition. The optimization parameter of the target design, in which the radius of outlet cross section is $60{\pm}1mm$, is verified to form a stable and controllable free surface and to reduce the formation of air bubbles. This work can function as a reference for carrying out engineering design of windowless target and for verification experiments.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2650-2659
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• 2022

The dense granular flow spallation target is a new target concept proposed for an Accelerator-Driven Sub-critical (ADS) system. In this paper, the beam-target configurations of a tungsten granular flow target for the ADS with a thermal power of 1 GW is explored. The beam profile options using different scanning methods are discussed. The critical geometry parameters are adjusted to investigate the performance of the granular target from the aspects of neutron efficiency, stability and temperature distribution in target medium. To figure out how the target under accident conditions would behave, different clogging conditions are induced in the simulation. The dynamic processes are analyzed and some important parameters such as abnormal temperature rise and beam cutoff time window are obtained. The response of the sub-critical reactor to a clogging accident is also investigated. It is indicated that the monitoring of the granular flow by the neutron detectors in the sub-critical core will be effective.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.175-186
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• 2023

Effects of high-temperature environment and low-temperature environment on corrosion behaviours of 18Cr stainless steels (type 304L, type 441) in simulated selective catalytic reduction (SCR) environments were studied using weight loss test in each environment and rust analysis. With time to exposure to the high-temperature environment, type 441 was more resistant to corrosion than type 304L due to both higher diffusivity of Cr and lower thermal expansion coefficient in α-iron. The former provides a stable protective Cr₂O₃ layer. The latter leaded to low residual stress between scale and steel, reducing the spallation of the scale. With time to exposure to the low-temperature environment, on the other hand, type 304L was more resistant to corrosion than type 441. The lower resistance of type 441 was caused by Cr-depleted zone with less than 11% formed during the pre-exposure to a high-temperature environment, unlike type 304L. It was confirmed by results from the crevice corrosion test of sensitised 11Cr steel. Hence, to achieve higher corrosion resistance in simulated SCR environments, ferritic stainless steels having lower thermal expansion coefficient and higher diffusivity of Cr but containing more than 18% Cr are recommended.

• Nuclear Engineering and Technology
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• v.37 no.5
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• pp.433-446
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• 2005

The development of accelerator science and technology has been accommodating ever increasing demand from scientific community of the beam energy and intensity of proton beams. The use of high-powered proton beams has extended from the traditional application of nuclear and high-energy physics to other applications, including spallation neutron source replacing nuclear reactor, nuclear actinide transmutation, energy amplification reactors. This article attempts to review development of proton accelerator, both linear and circular, and issues related to the proton beam energy, intensity as well as its output power. For related accelerator physics and technical review, one should refer to the recent article in the Reviews of Modem Physics [1]

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1201-1202
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• 2010

• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.609-616
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• 1999

심폐바이패스시 발생할 수 있는 튜브 마모 및 파쇄는 롤러펌프의 반복되는 압박에 의해 롤러펌프에 장착된 튜브 내벽에 균열이 생기고 이로 인해 미세한 비생물적 조각들이 혈액중으로 떨어져 나가는 현상을 말하는데, 임상적으로 치명적인 색전증을 초래할 수 있다. 그러나 아직 롤러펌프 튜브로 사용되는 PVC 및 실리콘 튜브 중 어느 쪽이 마모 및 파쇄 관점에서 더 우수한지는 체계적으로 밝혀지지 않고 있다. 이에 본 연구는 두 종류의 튜브를각각 일정 기간 롤러펌프에 장착하여 작동시킨 뒤 튜브내외면을 육안 및 주사형 전자현미경으로 관찰하였다. 즉 PVC 및 실리콘 튜브 (내경 1/2 인치의)들을 미리 정해진 폐쇄도 조절에 의해 폐쇄 회로 심폐비이패스 롤러펌프 헤드에 장착시키고 4.500ml/min에서 각각 4차례씩 1,2,4,6 시간 작동시켰다. 파쇄에 의한 색전 관찰 실험에서는 회로 중간에 동맥여과기를 설치하고 각각 6,9시간 씩 롤러펌프를 작동시켰다. 실험 후 튜브 및 여과기들을 수거한 후 육안 및 주사형 전자현미경 분석을 시행하였다. 실험후 튜브 및 여과기들을 수거한 후 육안 및 주사형 전자현미경을 분석을 시행하였다. 튜브 외부의 육안 관찰 결과 일반적으로 실라스틱 튜브에서의 외부 마모가 PVC 튜브에 비해 현저하였다. 주사형 전자현미경 관찰에서 PVC 튜브에서의 홈은 좁으면서 경계선이 뚜렷한 특징을 보였고 3시간 이상 롤러와 접촉한 튜브들에게서는 깊은 균열이 간헐적으로 관찰되었다. 반면, 실라스틱에서의 홈은 좁으면서도 경계선이 뚜렷한 특징을 보였고 3시간 이상 롤러와 접촉한 튜브들에게서는 깊은 균열이 간헐적으로 관찰되었다.반면 실라스틱에서의 튜브들에서는 홈이 상대적으로 넓고 경계가 덜 명확했으며, 특징적으로 V 자 모양의 융기부들이 간헐적으로 관찰되었다. 실라스틱 및 PVC 튜브 모두에서 50u 전후의 Craters 가 간헐적으로 관찰되었다. 여과기의 여과망에 대한 주사형 전자현미경 분석 결과 실라스틱과 PVC 튜브 실험군 모두에서 색전입자로 의심되는조각들이 발견되었으나 두군간 정량적 비교는 어려웠다. 결론적으로 롤러펌프에 의한 튜브 마모 및 파쇄현상은 실리콘 및 PVC 튜브의 재질에 따라 그 양상에는 차이가 있으나 임상적인 측면에서는 어느 쪽도 상대적인 우수성이 입증되지 못하였다.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.526-535
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• 1994

For the evaluation of the corrosion behavior of the aluminum cladding in the KMRR(Korea Multipurpose Research Reactor) fuel, a modified Griess correlation was derived by introducing a heat flux factor derived from the comparison of the measured in-reactor corrosion data with the prediction of the Griess correlation. As a design criterion on the corrosion to maintain the KMRR fuel integrity, prevention of the oxide spallation was conservatively selected, which is conservatively assumed to occur when the temperature difference across the oxide layer exceeds 114$^{\circ}C$. A bounding power history of the KMRR fuel was determined by examining all the power histories of the KMRR fuel from cycle 1 to equilibrium cycle, and used to predict the maximum possible corrosion. Results of the corrosion prediction of the KMRR fuel with the bounding power history showed that the maximum local thickness of the oxide layer would be below 50$\mu$m and the design criterion on the oxide spallation would be satisfied with a factor of two margin. Therefore, it can be said that corrosion of the cladding will not impair the integrity of the KMRR fuel. Nevertheless, the applicability of the modified Griess correlation to the KMRR needs to be further verified through the KMRR fuel corrosion surveillance.