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Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke; Muramatsu, Toshiharu
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
The aim of this work presented here is to demonstrate the potential of our method for remote controllable systematization, of testing reinforced concrete based on ultrasonic guided-wave on rebar. In order to investigate how the deteriorated phenomena has the effects on the ultrasonic guided-wave propagating on the rebar, following experiments are conducted. Test pieces used for the experiments are made of bare steel rod and cylindrically pored mortar to be representing the actual reinforced concrete. Irradiating the end face of the rod with nanosecond pulsed laser makes the ultrasonic guided-wave induced, at the other end face, the guided wave signal is measured with ultrasonic receiver. One test piece is with no damage and the other is deteriorated test piece. The deterioration is made by electrolytic corroded method. The guided-wave signal from the deteriorated test piece is measured with respect to each energization time, the change in the waveform is investigated. Analyzing the results from the experiments above, it is found that the deterioration of rebar has remarkable effects on the guided-wave signal. The signal from test piece with no damage has strong peak at both specific frequency and lower region, on the other hand, signals from deteriorated test piece has only at the specific frequency depending on the diameter of the steel rod. Finally, discussion concerning with the experimental results and future perspective for remote controllable systematization of our method is carried out.
Wakui, Takashi; Wakai, Eiichi; Naoe, Takashi; Shintaku, Yohei*; Li, T.*; Murakami, Kazuya*; Kanomata, Kenichi*; Kogawa, Hiroyuki; Haga, Katsuhiro; Takada, Hiroshi; et al.
Journal of Nuclear Materials, 506, p.3 - 11, 2018/08
Times Cited Count：3 Percentile：29.78(Materials Science, Multidisciplinary)The mercury target vessel is designed as multi-walled structure with thin wall (min. 3 mm), and assembled by welding. In order to estimate the structural integrity of the vessel, it is important to measure the defects in welding accurately. For nondestructive tests of the welding, radiographic testing is applicable but it is difficult to detect for some defect shapes. Therefore it is effective to do ultrasonic testing together with it. Because ultrasonic methods prescribed in JIS inspect on the plate with more than 6 mm in thickness, these methods couldn't be applied as the inspection on the vessel with thin walls. In order to develop effective method, we carried out measurements using some testing method on samples with small defect whose size is specified. In the case of the latest phased array method, measured value agreed with actual size. It was found that this method was applicable to detect defects in the thin-walled structure for which accurate inspection was difficult so far.
Ishihara, Masahiro; Shibata, Taiju
Dai-4-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu Koen Rombunshu, p.101 - 108, 2000/00
no abstracts in English
Sato, Satoshi; Hatano, Toshihisa; Furuya, Kazuyuki; Kuroda, Toshimasa*; Enoeda, Mikio; Takatsu, Hideyuki
JAERI-Research 97-092, 80 Pages, 1998/01
JAERI-Research-97-092.pdf:5.11MB
no abstracts in English
Ishihara, Masahiro; Iyoku, Tatsuo; Shiozawa, Shusaku; *
Transactions of the 13th Int. Conf. on Structural Mechanics in Reactor Technology (SMiRT),Vol. I, 0, p.575 - 580, 1995/00
no abstracts in English
Wakui, Takashi; Wakai, Eiichi; Naoe, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Takada, Hiroshi
no journal, ,
A mercury target vessel has been used for the spallation neutron source at J-PARC. It has a complicated multi-layered structure composed of a mercury target and surrounding double-walled water shroud, which is assembled with thin plates (minimum thickness of 3 mm) by welding. Thus, welding inspection during the manufacturing process is important. We investigated the applicability of new ultrasonic inspection, named as phased array ultrasonic method, to improve the accuracy of welding inspection for the mercury target vessel. It was measured that the new ultrasonic method could detect a 1-mm-long defect formed in a 3-mm-thick specimen with an error of about 7%. Moreover, simulations of the phased array ultrasonic method demonstrated that the outline of a 0.5-mm-long defect in a thin specimen got clearer in an ultrasonic echo image with increasing frequency of the sensor, suggesting a possibility of further improvement.
Wakui, Takashi; Wakai, Eiichi; Naoe, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Takada, Hiroshi
no journal, ,
A mercury target vessel has been used for the spallation neutron source at J-PARC. It has a complicated triple-walled structure, which is assembled with thin plates (minimum thickness of 3 mm) by welding. A structural analysis of the new vessel evaluated that allowable defect size not to influence structural integrity was 0.4 mm at a highest stress region. Radiographic testing using the sample with triple-walled structure could not detect the defect within allowable detection size. On the other hand, a non-contact immersion ultrasonic method, which is insensitive to distorted surface of the vessel after welding, was able to detect the defect of 0.2 mm by using a high frequency sensor. We inspected all welding lines (total length of ca. 17 m) of newly fabricated vessel, detecting only six defects and evaluated that their sizes never influence on the structural strength. The present development of the non-destructive inspection technique has improved the reliability of the vessel.
