• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.489-494
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• 1997

주조 스테인레스강으로 제작된 원자로 냉각재배관은 고온에서 장기간 운전됨에 따라 열취화의 영향을 받을 수 있다. 장기간의 열취화는 재료의 연성 및 파괴인성을 저하시킬 수 있으며, 배관에 균열이 존재하는 경우 건전성을 위협할 수 있다. 따라서 본 논문에서는 원전수명연장을 위한 타당성 검토 측면에서 Chopra의 방법 등을 이용한 원자로 냉각재배관의 열취화 평가 및 민감도 분석을 수행하였다. 이를 통해 원자로 냉각재배관의 열취화 수준을 정량화하였고, 건전성 평가에 활용될 수 있는 J$_{IC}$ 값을 예측하였으며, 열취화에 영향을 미치는 주요 인자를 도출하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.527-536
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• 2019

This study examines the degradation of PTT BCF and fading behavior of disperse dye by heat treatment and UV irradiation. The behavior in strength degradation of PTT BCF after treat treatment was examined by measuring the tensile strength of samples. The strength retention of PTT BCF rapidly decreased with increasing exposure time at 150℃. The K/S value decreased with increasing temperature and its trend accelerated with increasing exposure time on heat. The behavior on strength degradation of PTT BCF and the fading of disperse dye on it were studied under UV irradiation at various temperatures. The tensile strength of PTT BCF and the K/S value of the sample dyed with disperse dye after UV irradiation decreased with increasing temperature and exposure time. PTT BCF exposed under UV irradiation exhibited lower strength and K/S value compared with the sample after heat treatment. Additional study on the effects of additives used to improve the resistance to fading of disperse dye and degradation of PTT BCF revealed that antioxidant and UV absorbent in PTT BCF showed a small improvement in the strength degradation of PTT BCF and the fading of dye.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.96-101
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• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal embrittlement at the reactor operating temperature. The objective of this study is to summarize the method of estimating ferrite content, Charpy impact energy and J-R curve and to evaluate the thermal embrittlement of the cast austenitic stainless steel piping used in the domestic nuclear power plants. The result of evaluation, two domestic nuclear power plants used CF-8M and CF-8A material has adequate fracture toughness after saturation.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.396-396
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• 2002

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.118-123
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• 2004

Cast austenitic stainless steel have been widely used for primary coolant piping in light water reactors. This material is subject to thermal embrittlement at reactor operating temperature. CF-8M and CF-8A cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. Thermal embrittlement results in spinodal decomposition of delta-ferrite leading to decreased fracture toughness. In this study, the specimens were prepared using an accelerated aging method. The measurement of ferrite content, Charpy impact test and J-R test were performed to verify the predicting equation for aged material properties. In case of above 25% ferrite content, predicted result of J-R curve might be non-conservative.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1174-1179
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• 2003

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. This study shows that ferrite content can be predicted by use of the artificial neural network. The neural network has trained learning data of chemical components and ferrite contents using backpropagation learning process. The predicted results of the ferrite content using trained neural network are in good agreement with experimental ones.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.460-466
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• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. This study shows that ferrite content can be predicted by use of the artificial neural network. The neural network has trained teaming data of chemical components and ferrite contents using backpropagation learning process. The predicted results of the ferrite content using trained neural network are in good agreement with experimental ones.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.131-136
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• 2003

CF8M cast austenitic stainless steel is used for several components such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. In this study, three kinds of the aged CF8M specimen were prepared using an artificially simulated aging method. The objective of this study is to summarize the method of estimating ferrite contents, Charpy impact energy and J-R curve, and to evaluate the thermal embrittlement of the CF8M cast austenitic stainless steel piping used in the domestic nuclear power plants.

• Proceedings of the KWS Conference
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• 1993.05a
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• pp.111-112
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• 1993

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.294.2-294
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• 2002