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Takaya, Shigeru; Nagae, Yuji; Aoto, Kazumi; Yamagata, Ichiro; Ichikawa, Shoichi; Konno, Shotaro; Ogawa, Ryuichiro; Wakai, Eiichi
no journal, ,
Magnetic flux densities for neutron irradiated specimens of austenitic stainless steels were measured by using a flux gate (FG) sensor to investigate the nondestructive evaluation method of irradiation damage parameters, dose and He content. The range of dose, He content and irradiation temperature of the neutron irradiated samples studied in this paper were 0.01-30 displacement per atom (dpa), 1.0-17 appm and 470-560 
C, respectively. Magnetic flux density increased with dose although there may be a threshold dose for magnetic property to change between 2 and 5 dpa for 316FR. This result shows the possibility of nondestructive evaluation of dose by measuring magnetic flux density by an FG sensor. On the other hand, magnetic flux density did not depend on He content.
Takaya, Shigeru; Yamagata, Ichiro; Konno, Shotaro; Ichikawa, Shoichi; Ogawa, Ryuichiro; Nagae, Yuji
no journal, ,
We measured the magnetic flux densities and the magnetization curves on neutron irradiated fast reactor grade type 316 stainless steels by a flux gate sensor and a newly developed vibrating sample magnetometer, respectively. As the result, it was revealed that there is a good relationship between magnetic property and dose, one of representative irradiation damage parameters. This result shows the possibility of nondestructive evaluation of neutron irradiation damage based on magnetic properties.
Konno, Shotaro; Takaya, Shigeru; Nagae, Yuji; Yamagata, Ichiro; Ogawa, Ryuichiro; Akasaka, Naoaki; Nishinoiri, Kenji
no journal, ,
We are developing a method for evaluation of irradiation damage of structural materials in nuclear plants by using change in magnetic flux density due to irradiation damage. In this study, the magnetic flux density measurement technique has been improved by introducing a new magnetizer which enables local magnetizing by contacting the sample surface. We can magnetize samples, especially ferromagnetic samples, more precisely compared to the existing method. Furthermore, the new method provided the path for the application to real plants.
Konno, Shotaro; Takaya, Shigeru; Nagae, Yuji; Yamagata, Ichiro; Ogawa, Ryuichiro; Akasaka, Naoaki; Nishinoiri, Kenji
no journal, ,
We are developing a method for evaluation of irradiation damage on structural materials in nuclear plants by using change in magnetic flux density due to irradiation damage. In this study, the magnetic flux density measurement technique has been improved by introducing a new magnetizer which enables local magnetizing by contacting the sample surface, and the calibration method of the flux gate sensor for the magnetic flux density. We can magnetize samples, especially ferromagnetic samples, more precisely compared to the existing method. Furthermore, the new method can remove many limitations for the application to real plants.
Hayashi, Takehiro; Takaya, Shigeru; Nagae, Yuji; Konno, Shotaro; Yamagata, Ichiro
no journal, ,
Structural materials in nuclear plants are affected to aging degradation and irradiation damage. Nondestructive measurement of materials damage is a preferred method for the diagnosis of nuclear plants. The previous studies are focused on magnetic property, which is able to measure by nondestructive and sensitive for microstructure and variation of local chemical compositions. However, whole sample is needed to magnetize by large magnets in the previous method, and the sample is easily influenced by magnetic flux at the edge of sample. This issue makes magnetic method difficult to apply to nuclear plants. The pointing magnetization technique was developed for a local magnetization of samples with a small magnet. It is the first time to apply this method on austenitic stainless steels for fast reactor structural material. The measurement results show that austenitic steels have increased magnetic flux density as dose increases. And magnetic flux density is dependent on irradiation temperature. These results indicate pointing magnetize technique suggested the possibility of the irradiation damage evaluation of austenitic stainless steel.