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Fukushima Daiichi Updates From IRID Part 2; New Robots & Work

As part of reviewing IRID’s updates on work progress for Fukushima Daiichi, new information about robots to be used and their proposed work has been released.

First Floor Robots, Floor Decontamination

Three robots are being tested for floor decontamination inside the reactor buildings.

Robot #1 uses a high pressure water jet to decontaminate by removing the top layer of concrete
Contaminated surface removal rate: over m²/h
Some additional shielding was added and changes to improve handling the water tank to reduce worker exposure.












Robot #2 uses a dry ice jet, built by Toshiba
Contaminated surface removal rate: over m²/h
An improved camera was added for better visibility and optical LAN connection for remote operation













deconrobot3 Robot #3 uses grinding and jetting, collects the removed material, built by Mitsubishi
Approx. 2 m²/h (vacuum decontamination)
Approx. 0.4 to 1 m2/h (blast decontamination)

Cabling was improved along with wider rotating brushes












Robot technology to decontaminate the upper floors of the reactor buildings is still under initial development. Equipment to decontaminate the floors of the lower levels appears to be ready to use or is already in use. Equipment to decontaminate the ceiling areas of the lower floors is somewhere in production.

Overhead Robots For First Floor

Overhead robot technologies in development to decontaminate the ceiling areas of the lower floors are planned to use similar technology as the floor robots by using jet blasting, grinding and vacuuming.


Overhead Robot 1
6 meter telescoping head with water jet decontamination removal








Overhead Robot 2
Scissor lift with dry ice and compressed air jet.
Has spraying, grinding and debris collecting capability







Overhead Robot 3
Crane arm with spraying, grinding and debris collecting capability
This appears to be developed in conjunction with NEDO






Robots For Upper Floors 

The robot concept for the upper floors is similar to the other robots already in testing. They would use the same concepts of jet spraying, grinding and capturing removed debris. The concept robot would also use the idea of multiple components connected together to form the total functions of the robot system.


Designation of each component (left to right) [Relay][support cart][cart][work truck]
Red dashed box defines a “shared cart”, possibly a common platform to be used for each.


Upper floor “work truck” robot with decontamination heads. Side view shows it in position to remove contaminated material.
Dimensions & Weight: L1200×W740×H1700 [mm],550 [kg]


Upper floor “support cart” robot
High pressure water jet cleaning: configuration
L2200 x W700 × H300 [mm], 600 [kg]


Upper floor “relay cart” robot
Does a debris removal role
L2000 × W1100 × H500 [mm],500 [kg]
Containment Inspection Robots

There are a series of robots in various stages of development for inspecting various systems related to the containment structure and future plans to possibly flood the containment structures for melted fuel removal.


Robot concepts and the general location they would be working in.


Upper containment robot

upperdrywell_concept_inspectionlocationRobot will lift up camera head to inspect pipe penetrations located on catwalk above the equipment hatch door.


Upper containment robot


Upper containment robot would look in to the air lock chamber through a hole cut in the top of the chamber box.


Torus downcomer inspection robot


Robot will be dropped through a hole cut in the first floor, floor deck. Will inspect the bellows joint of the downcomer and up into the hole where the downcomer pipe connects to the main containment structure.


Torus tube inspection robot (top), underwater rover (lower left), swimming robot (lower right). There are other robots with the last two functions already being used at Fukushima Daiichi.

Top left: inspect outer wall penetrations underwater crawler robot via ultrasound (some of this has already been done in unit 1)
Top right: inspect outer wall penetrations underwater using swimming robot via camera inspection (some of this work has been done in unit 1)
Lower left: upper torus tube crawler robot, inspect manhole covers of vacuum breakers (some of this work has been done in unit 1)
Lower right: triangle corner room, check for leaks using swimming robot via a hole in the 1st floor deck


Torus tube crawler robot


Crawler robot travels around the torus tube and underwater to look for damage and leaks. This has been in operation in unit 2 briefly but had issues staying connected to the tube.

As part of the research and development work for the robots, full scale partial mock ups have been built off site of Fukushima Daiichi to test the equipment as it is developed. This is intended to work out problems before they have to work in the high radiation environment at the plant.

research_mockupsFull size research mock ups. Left, torus tube (suppression chamber), right, downcomer vent tube with a steel mock up of the concrete hole in containment for the tube.

Penetration Checking Robot

Another robot using the long crane arm type robot would be equipped with a head that puffs nitrogen gas to look for leaks in pipe penetrations.



As mentioned among the robot details, some of these robots have been used initially in units 1 or 2, usually on single task missions so far. More robot work is planned for early 2015 according to the various roadmap documents.




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