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55. Development of Three-Dimensional Velocity Vector Profiler Using Ultrasonic Pulsed Doppler Method

Author

Shoji, Naruki, Takahashi, Hideharu, and KIKURA, HIROSHIGE

Abstract

In March 2011, the severe accident of the Fukushima Daiichi (1F) nuclear power plant was happened by the earth quack and massive tsunami in Tohoku, Japan. And then, fuel debris was generated within the primary containment vessels (PCVs) of units 1, 2, and 3, respectively. Recently, the decommissioning of 1F is underway to remove the fuel debris, and the inside inspection with robots was conducted so far. Optical techniques have been applied for inspecting the PCVs, but information of the contaminated water leakage has been not unveiled due to non-clear water causing poor visibility of the camera. Therefore, non-optical techniques are required to unveil the leakage location, and we focused on the ultrasonic measurement technique. In this study, we have developed the ultrasonic velocity profiler (UVP) system for the investigation of leaking locations. The UVP is based on the pulsed Doppler method, and it can measure instantaneous velocity profile along an ultrasonic beam path. In the original UVP principle, it can measure only one-dimensional velocity measurement. Therefore, we extended the UVP to multi-dimensional measurement. To achieve this, a transducer array was used and an algorithm of three-dimensional (3-D) velocity vector reconstruction was developed. The 3-D vector measurement is realized by simultaneous receiving Doppler signal at each ultrasonic element. The measurement performance was evaluated by the rigid rotating flow measurement. In addition, we checked the validity of the system for leakage detection by measuring the simulated leakage flow.

Published
2022

77. Development of Extended Super Dragon Articulated Robot Arm with a Linear Telescopic Boom

Author

Nagai, Toshiya, Tei, Hyo, Takata, Atsushi, KIKURA, HIROSHIGE, Takahashi, Hideharu, and Endo, Gen

Abstract

It is necessary to explore the bottom of the RPV in order to accelerate the decommissioning of the Fukushima Daiichi Nuclear Power Plant. A coupled tendon-driven articulated robot arm, Super Dragon, has been developed to deploy the investigation equipment into the containment vessel. In this paper, we developed an extended Super Dragon with a length of 15.4 m by modifying and integrating the telescopic boom so that it can be mounted on the Super Dragon. Experiments were conducted to raise the telescopic boom vertically and to lift and hold the deployed telescopic boom horizontally. We confirmed the basic movements required to explore the bottom of the RPV.

Published
2022

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