IRID plans to use a miniature robot to investigate (‘A2 Investigation’) the inside of the Fukushima Daiichi Unit 2 primary containment vessel (PCV). This investigation will see the robot make its way the point directly below the reactor pressure vessel and making full use of an onboard camera, in addition to other devices, measure radiation and temperature levels and have it collect vital data for the consideration of various decommissioning scenarios.
However, at present there are just under 140 blocks (maximum weight of 40kg) and three iron plates (thickness: approx.: 5mm/weight: 25kg per plate) acting as a radiation shield in front of the pipe through which the miniature robot will traverse (PCV penetrating part). These objects must therefore be removed prior to inserting the robot into the PCV.
IRID organization member Mitsubishi Heavy Industries, Ltd., is currently developing equipment it has dubbed ‘TEMBO’ (‘elephant’ in the Swahili language) to remove these piled up blocks and so forth via remote control.
TEMBO is comprised of a forklift acting as a motorized cart fitted with a manipulator and end effector, akin to a human arm and hand.
The manipulator ‘arm’ has a seven-axis configuration, enabling it to be maneuvered in very tight spaces, and with end effectors attached, it has a 60kg load capacity – enough to handle blocks that weigh up to 50kg.
In addition, table strokes along each axis for the cart that drives the manipulator were increased, the range of movement for the manipulator widened, and the ability of the equipment to smoothly lift and place the blocks in the collection box improved.
In addition to improving end effector specifications and enhancing their transporting capability, a range of end effectors were prepared on the supposition of various risks (retrieval when fallen over, loosening of iron plate bolts, cutting, peeling by chiseling, etc.).
IRID expert advisors on remotely controlled equipment inspected TEMBO and training operations on May 22, 2015, and offered various points of advice.
IRID plans to conduct further training with TEMBO using mockups and commence operations in Unit 2 at Fukushima Daiichi in mid-June.
|TEMBO overview||Wiring connection training|
|Placement of block collection box training||Remote control training|
|Adjusting positioning for lifting blocks||Block lifting|
|Moving block collection box||Retrieved blocks inside collection box|
|Inspection visit (1)||Inspection visit (2)|
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