A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS
The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected...
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| Format: | Article |
| Language: | English |
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Elsevier
2013-08-01
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| Series: | Nuclear Engineering and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S173857331530036X |
| _version_ | 1811233322594992128 |
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| author | HANSUB CHUNG HONG-DEOK KIM SEUNGJIN OH MYUNG HWAN BOO KYUNG-HWAN NA EUNSUP YUN YONG-SEOK KANG WANG-BAE KIM JAE GON LEE DONG-JIN KIM HONG PYO KIM |
| author_facet | HANSUB CHUNG HONG-DEOK KIM SEUNGJIN OH MYUNG HWAN BOO KYUNG-HWAN NA EUNSUP YUN YONG-SEOK KANG WANG-BAE KIM JAE GON LEE DONG-JIN KIM HONG PYO KIM |
| author_sort | HANSUB CHUNG |
| collection | DOAJ |
| description | The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between 4th and 9th TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the 8th refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably than U3 SGs since the manufacturing residual stress in Y5&6 tubes is substantially lower than in U3 tubes, while the microstructure is similar with each other. |
| first_indexed | 2024-04-12T11:18:42Z |
| format | Article |
| id | doaj.art-2f696c169c14440083419ada71cd5095 |
| institution | Directory Open Access Journal |
| issn | 1738-5733 |
| language | English |
| last_indexed | 2024-04-12T11:18:42Z |
| publishDate | 2013-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Engineering and Technology |
| spelling | doaj.art-2f696c169c14440083419ada71cd50952022-12-22T03:35:26ZengElsevierNuclear Engineering and Technology1738-57332013-08-0145451352210.5516/NET.07.2012.090A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPSHANSUB CHUNG0HONG-DEOK KIM1SEUNGJIN OH2MYUNG HWAN BOO3KYUNG-HWAN NA4EUNSUP YUN5YONG-SEOK KANG6WANG-BAE KIM7JAE GON LEE8DONG-JIN KIM9HONG PYO KIM10Central Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaCentral Research Institute, Korea Hydro Nuclear Power, 70 1312-gil Yuseong-Daero Yusung-Gu Daejeon, 305-343, KoreaNuclear Gaterials Research Division, Korea Atomic Energy Research Institute Daejeon, 305-353, KoreaNuclear Gaterials Research Division, Korea Atomic Energy Research Institute Daejeon, 305-353, KoreaThe ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between 4th and 9th TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the 8th refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably than U3 SGs since the manufacturing residual stress in Y5&6 tubes is substantially lower than in U3 tubes, while the microstructure is similar with each other.http://www.sciencedirect.com/science/article/pii/S173857331530036XSGTubeODSCCMicrostructureResidual StressSludgeAlloy 600(HT)MA |
| spellingShingle | HANSUB CHUNG HONG-DEOK KIM SEUNGJIN OH MYUNG HWAN BOO KYUNG-HWAN NA EUNSUP YUN YONG-SEOK KANG WANG-BAE KIM JAE GON LEE DONG-JIN KIM HONG PYO KIM A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS Nuclear Engineering and Technology SG Tube ODSCC Microstructure Residual Stress Sludge Alloy 600(HT)MA |
| title | A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS |
| title_full | A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS |
| title_fullStr | A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS |
| title_full_unstemmed | A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS |
| title_short | A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS |
| title_sort | review on the odscc of steam generator tubes in korean npps |
| topic | SG Tube ODSCC Microstructure Residual Stress Sludge Alloy 600(HT)MA |
| url | http://www.sciencedirect.com/science/article/pii/S173857331530036X |
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