2006 Fiscal Year Final Research Report Summary
Correlation between degradation and magnetic properties under neutron irradiation in nuclear reactor materials
| Project/Area Number |
14102034
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| Research Category |
Grant-in-Aid for Scientific Research (S)
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| Allocation Type | Single-year Grants |
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| Research Field |
Nuclear engineering
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| Research Institution | Iwate University |
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Principal Investigator |
TAKAHASHI Seiki Iwate University, Faculty of Engineering, Professor, 工学部, 教授 (50003851)
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| Co-Investigator(Kenkyū-buntansha) |
ECHIGOYA Junichi Iwate University, Faculty of Engineering, Professor, 工学部, 教授 (00005539)
KAMADA Yasuhiro Iwate University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00294025)
KIKUCHI Hiroaki Iwate University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30344617)
KOBAYASHI Satoru Iwate University, Faculty of Engineering, Research Associate, 工学部, 助手 (30396410)
YOSHIDA Naoaki Kyusyu Univ, Research Institute of Applied Mechanics, Professor, 応用力学研究所, 教授 (00127317)
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| Project Period (FY) |
2002 – 2006
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| Keywords | Nondestructive Evaluation / Magnetism / Nuclear Reactor Materials / Radiation Damage / Lattice Defect / Plastic Deformation / Low Alloy Steel / Stainless Steel |
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| Research Abstract |
The study to evaluate the degree of material degradation by magnetic method has been carried out in nuclear reactor materials. The concept of nondestructive evaluation (NDE) in the present study is different from the currently employed methods and a way to predict the length of time before the appearance of cracks. The main work is in situ magnetic measurements under neutron radiation in the material of nuclear reactor pressure vessels (RPV). The maximum applied field is limited to 25 Oe owing to the limited space of an irradiation capsule for ring core samples. An analysis method of minor loops had been found in Fe metal and low carbon steel. Minor-loop coefficients deduced from simple relations between minor-loop parameters are independent of the magnetic field amplitude and much more sensitive to dislocations than coercive force. We have succeeded in the present in situ measurement by use of minor loop method. In Fe metal, minor-loop coefficients increase monotonically with the increase of neutron fluence. Dislocation loops which nucleate and grow during neutron radiation, make the minor-loop coefficients increase through magneto elastic coupling. On the other hand, in A533B steel, the minor-loop coefficients increase initially and show a maximum at the neutron fluence of 1 x 10^<19> cm^<-2> followed by a slow decrease with neutron fluence. The copper precipitates and dislocation loops gathering in the vicinity of dislocations would compensate the stress field of dislocations and make the minor-loop coefficients decrease that is confirmed by TEM observation. These radiation defects fixed around dislocation strongly make mechanical properties increase. The new magnetic NDE methods have been successfully discovered in the austenite stainless steel and Inconel 600 alloy..A magnetic device has been developed to evaluate the degree of material degradation of RPV for Charpy test pieces.
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Research Products
(70 results)
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[Journal Article] NDE of Pressure Vessel by Magnetic Method2004
Author(s)
S.Takahashi, T.Nakano, K.Ara, Y.Kamada, H.Kikuchi, M.Sato
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Journal Title
Electromagnetic Nondestructive Evaluation (VIII)(T.Sollier, D.Premel and D.Lesselier (eds.))Studies in Applied Electromagnetics and Mechanics(IOS Press) Vol.24
Pages: 139-145
Description
「研究成果報告書概要(欧文)」より
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