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Nemoto, Yoshiyuki; Keyakida, Satoshi*; Uchimoto, Tetsuya*; Takaya, Shigeru; Tsukada, Takashi
International Journal of Applied Electromagnetics and Mechanics, 35(2), p.123 - 139, 2011/02
Times Cited Count:1 Percentile:11.18(Engineering, Electrical & Electronic)JP, 2008-301850 Patent publication (In Japanese)This paper presents a study conducted to develop a diagnostic system that can detect IASCC precursors in stainless steels by measuring the magnetic properties of the material. The eddy current method and alternating current (AC) magnetization method were used, as these will be more practical for use in actual reactors. Probes were developed for these measurement methods, providing sufficient tolerance for environments in nuclear reactors. An attempt was also made to improve spatial resolution by manufacturing a smaller probe. A sensor system was designed for remote control, performance tests were conducted by measuring neutron-irradiated specimens and mock specimens, and magnetic data were evaluated by comparing the IASCC susceptibility of the specimens. It was proved that the sensor system developed in this study is capable of detecting IASCC precursors. Further developments necessary for application in actual nuclear reactors and the mechanism of correlation between magnetic properties and IASCC susceptibility were also discussed.
Oikawa, Ryota*; Uchimoto, Tetsuya*; Takagi, Toshiyuki*; Urayama, Ryoichi*; Nemoto, Yoshiyuki; Takaya, Shigeru; Keyakida, Satoshi*
International Journal of Applied Electromagnetics and Mechanics, 33(3-4), p.1303 - 1308, 2010/10
Times Cited Count:5 Percentile:35.04(Engineering, Electrical & Electronic)This paper discusses feasibility of non-linear eddy current method to evaluate material degradations of austenitic stainless steels associated with irradiation assisted stress corrosion cracking (IASCC). For the purpose, tensile test at elevated temperature was conducted using model alloys simulating radiation induced segregation (RIS), then magnetization curve of the specimens was measured by vibrating sample magnetometer (VSM), and microstructure of magnetization was observed by magnetic force microscopy (MFM). Moreover non-linear eddy current method was carried out. It was shown that the 3rd higher harmonic ration of the pick-up signal would relate to nominal strain of the specimens.
Takaya, Shigeru; Nagae, Yuji; Yoshitake, Tsunemitsu; Nemoto, Yoshiyuki; Nakano, Junichi; Ueno, Fumiyoshi; Aoto, Kazumi; Tsukada, Takashi
E-Journal of Advanced Maintenance (Internet), 1(1), p.44 - 51, 2009/05
As the result of comparing the magnetic flux density and the IASCC susceptibility evaluated by SSRT test on neutron irradiated model alloys, it was shown that there is the relation without depending on dose level and chemical compositions as long as the contribution of neutron irradiation to SCC was seen. Furthermore, measuring the magnetic flux density of unirradiated simulated degraded materials indicates that not only change in chemical compositions but also some defects are needed for the magnetic flux density to increase. These results show the possibility of non-destructive estimation of susceptibility to IASCC by measuring magnetic flux density.
Takaya, Shigeru; Nemoto, Yoshiyuki; Uchimoto, Tetsuya*; Keyakida, Satoshi*
Nihon AEM Gakkai-Shi, 17(1), p.156 - 161, 2009/03
In a previous study, authors showed experimentally the correlation between leakage magnetic flux density and irradiation assisted stress corrosion cracking susceptibility of high purity model austenitic stainless steels. This study aimed to investigate mechanism of the correlation. Tensile test at elevated temperature and aging test were conducted on materials simulating irradiation-induced segregation, and leakage magnetic flux density was measured before and after these tests in order to study the influence of chemical composition change and lattice defect to leakage magnetic flux density. Furthermore, dependency of magnetic moment on chemical composition and vacancy was evaluated by first principle calculation. As result, it was shown that leakage magnetic flux density of irradiated materials is thought to increase in severe irradiation-induced segregation region with and without vacancy.
Nemoto, Yoshiyuki; Keyakida, Satoshi*; Uchimoto, Tetsuya*; Takaya, Shigeru; Tsukada, Takashi
Hozengaku, 7(4), p.57 - 68, 2009/01
Authors previously reported leakage magnetic flux density measured by flux gate (FG) sensor seems to depend on irradiation assisted stress corrosion cracking (IASCC) susceptibility of neutron irradiated austenitic stainless steels. This study aimed to evaluate possibility to develop diagnostic method to detect symptom of IASCC by more practical methods such as Eddy current method and AC magnetization method. Magnetic properties of neutron irradiated specimens and mockup specimens were studied and dependence on IASCC susceptibility was revealed. Microstructure observation using transmission electron microscope (TEM) was conducted to study magnetic phase formation by radiation induced segregation. It was shown that measurement of magnetic signal changed by magnetic phase formation along grain boundaries caused by radiation induced segregation would be a mechanism of the diagnostic method to detect symptom of IASCC.
Ueno, Fumiyoshi*; Nagae, Yuji; Nemoto, Yoshiyuki*; Miwa, Yukio*; Takaya, Shigeru; Hoshiya, Taiji; Tsukada, Takashi*; Aoto, Kazumi; Ishii, Toshimitsu*; Omi, Masao*; et al.
JNC TY9400 2005-013, 150 Pages, 2005/09
None
Ueno, Fumiyoshi; Nagae, Yuji*; Nemoto, Yoshiyuki; Miwa, Yukio; Takaya, Shigeru*; Hoshiya, Taiji*; Tsukada, Takashi; Aoto, Kazumi*; Ishii, Toshimitsu; Omi, Masao; et al.
JAERI-Research 2005-023, 132 Pages, 2005/09
JAERI and JNC have started a JAERI-JNC joint research program in fiscal year 2003, which has been aimed for efficient progress and synergistic effect on the research activities in both Institutes. This study has been chosen one of the joint research themes because it has been our common objective in the field of structural materials of FBR and LWR components. The purpose of the study is to clarify damage mechanism of structural materials used under irradiation, and then to develop the methods for damage evaluation and detection in earlier stage of progressing process of damage. In fiscal year 2004 and 2005, micro-corrosion measurement, electrochemical corrosion test and leakage magnetic flux density measurement apparatuses were developed and equipped in two hot facilities and irradiated and unirradiated crept specimens, irradiated high purity model austenitic stainless alloys were also prepared and applied to this study. These apparatuses and specimens were used for damage evaluation, and these feasibilities for nuclear power plant materials were studied.
Hoshiya, Taiji; Ueno, Fumiyoshi*; Takaya, Shigeru; Nagae, Yuji; Nemoto, Yoshiyuki*; Miwa, Yukio*; Aoto, Kazumi; Tsukada, Takashi*; Abe, Yasuhiro; Nakamura, Yasuo; et al.
JNC TY9400 2004-026, 53 Pages, 2004/10
Japan Nuclear Cycle Development Institute (JNC) and Japan Atomic Energy Research Institute (JAERI) have started a JNC-JAERI united research program cooperatively in 2003, which has been aimed for efficient progress and synergistic effect on the research activities of both Institutes in order to lead the facing task of unification between JNC and JAERI. This study has been chosen one of the united research themes, and the purpose of it is to clarify damage mechanism of structural materials under irradiation, and then to develop the methods for damage evaluation and detection in earlier stage of progressing process of damage. In fiscal year 2003, magnetic flux density distribution (JNC) and micro-corrosion (JAERI) measurement apparatus were newly developed and equipped in Hot Facilities in two Institutes, respectively. These apparatus were designed and produced in consideration of radiation resistance and remote-controlled operation to equip in hot cells. We will start the study on neutron irradiation damage by employing the two apparatus as the next step.
Hoshiya, Taiji*; Ueno, Fumiyoshi; Takaya, Shigeru*; Nagae, Yuji*; Nemoto, Yoshiyuki; Miwa, Yukio; Aoto, Kazumi*; Tsukada, Takashi; Abe, Yasuhiro*; Nakamura, Yasuo*; et al.
JAERI-Research 2004-016, 53 Pages, 2004/10
Japan Nuclear Cycle Development Institute (JNC) and Japan Atomic Energy Research Institute (JAERI) have started a JNC-JAERI united research program cooperatively in 2003, which has been aimed for efficient progress and synergistic effect on the research activities of both Institutes in order to lead the facing task of unification between JNC and JAERI. This study has been chosen one of the united research themes, and the purpose of it is to clarify damage mechanism of structural materials under irradiation, and then to develop the methods for damage evaluation and detection in earlier stage of progressing process of damage. In fiscal year 2003, magnetic flux density distribution (JNC) and micro-corrosion (JAERI) measurement apparatus were newly developed and equipped in Hot Facilities in two Institutes, respectively. These apparatus were designed and produced in consideration of radiation resistance and remote-controlled operation to equip in hot cells. We will start the study on neutron irradiation damage by employing the two apparatus as the next step.
Hoshiya, Taiji*; Takaya, Shigeru*; Ueno, Fumiyoshi; Nemoto, Yoshiyuki; Nagae, Yuji*; Miwa, Yukio; Abe, Yasuhiro*; Omi, Masao; Tsukada, Takashi; Aoto, Kazumi*
Transactions of the Materials Research Society of Japan, 29(4), p.1687 - 1690, 2004/06
JAERI and JNC have begun the cooperative research of evaluation techniques of structural material degradation in FBR and LWR, which based on magnetic and corrosion properties along grain boundaries. Magnetic method has been proposed as the one of the non-destructive detection techniques on the early stage of creep-damage before crack initiation for aged structural materials of FBRs. The effects of applied stress on natural magnetization were investigated on paramagnetic stainless steels having creep-damages. On the other hand, corrosion properties and magneto-optical characteristics of ion-irradiated stainless steels in the vicinity of grain boundaries were estimated by AFM and Kerr effect microscope, respectively. These degradations were induced by changes in characteristics in the vicinity of grain boundaries. It is found that the initial level of progressing process of damage can detect changes in magnetic and corrosion properties along grain boundaries of aged and degraded nuclear plants structural materials.
Takahashi, Yoshikazu; Koizumi, Norikiyo; Nunoya, Yoshihiko; Takaya, Yoshiyuki*; Tsuji, Hiroshi
IEEE Transactions on Applied Superconductivity, 12(2), p.1799 - 1803, 2002/06
Times Cited Count:5 Percentile:35.12(Engineering, Electrical & Electronic)JAERI has been developing jelly-roll processed multifilamentary NbAl/Cu strands for the Toroidal Field (TF) coils of fusion tokamak machines since 1986, in cooperation with industries. One ton of mass-produced strands were successfully manufactured for the 13T-46kA NbAl insert which will be tested using the ITER Central Solenoid model coil. The critical current of the Nb3Al strand developed for the ITER project was measured in temperatures from 4.2 K to 15 K and in applied magnetic fields up to 16 T. An empirical equation for the critical current density was devised using these data and the pinning force scaling method. Good agreement between this equation and the measured data is obtained in the operating condition of the ITER machine. The equation is useful in evaluating the performance of the full-size conductor that consists of 1,152 strands and in establishing the optimum design criteria for the conductor in fusion machines.
Kato, Takashi; Tsuji, Hiroshi; Ando, Toshinari; Takahashi, Yoshikazu; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Kawano, Katsumi; Oshikiri, Masayuki*; et al.
Fusion Engineering and Design, 56-57, p.59 - 70, 2001/10
Times Cited Count:17 Percentile:74.89(Nuclear Science & Technology)no abstracts in English
Tsuji, Hiroshi; Okuno, Kiyoshi*; Thome, R.*; Salpietro, E.*; Egorov, S. A.*; Martovetsky, N.*; Ricci, M.*; Zanino, R.*; Zahn, G.*; Martinez, A.*; et al.
Nuclear Fusion, 41(5), p.645 - 651, 2001/05
Times Cited Count:55 Percentile:83.06(Physics, Fluids & Plasmas)no abstracts in English
Terasawa, Atsumi; Miura, Yushi; Ando, Toshinari; Nozawa, Masanobu*; Isono, Takaaki; Takaya, Yoshiyuki*; Tsuji, Hiroshi; Shimamoto, Susumi
ICEC16/ICMC Proceedings, p.1265 - 1268, 1996/00
no abstracts in English
Ueno, Fumiyoshi; Nemoto, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Ishii, Toshimitsu; Omi, Masao; Nagae, Yuji; Takaya, Shigeru; Aoto, Kazumi; Yoshitake, Tsunemitsu; et al.
no journal, ,
no abstracts in English
Yoshitake, Tsunemitsu; Nagae, Yuji; Takaya, Shigeru; Aoto, Kazumi; Hoshiya, Taiji; Matsumoto, Shinichiro; Ueno, Fumiyoshi; Nemoto, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; et al.
no journal, ,
no abstracts in English
Nemoto, Yoshiyuki; Ueno, Fumiyoshi; Nagae, Yuji; Takaya, Shigeru; Yoshitake, Tsunemitsu; Aoto, Kazumi; Tsukada, Takashi
no journal, ,
no abstracts in English
Nemoto, Yoshiyuki; Uchimoto, Tetsuya*; Keyakida, Satoshi*; Nagae, Yuji; Takaya, Shigeru; Ebine, Noriya; Tsukada, Takashi
no journal, ,
It was suggested by the authors that electromagnetic method could detect irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steel in advance of crack initiation. Authors investigated the mechanism using mock specimens of radiation induced segregation (RIS). SCC susceptibility and electromagnetic properties of the mock specimens were studied. Results were compared with the data of irradiated specimens and mechanism of electromagnetic diagnosis were discussed. A sensor system will be developed by application of these mechanism.
Nemoto, Yoshiyuki; Takaya, Shigeru; Ebine, Noriya; Tsukada, Takashi; Uchimoto, Tetsuya*; Keyakida, Satoshi*
no journal, ,
no abstracts in English
Wakai, Eiichi; Takada, Fumiki; Takaya, Shigeru; Kato, Shoichi; Kitazawa, Sin-iti; Okubo, Nariaki; Suzudo, Tomoaki; Fujii, Kimio; Yoshitake, Tsunemitsu; Kaji, Yoshiyuki; et al.
no journal, ,
no abstracts in English