Two robots are cleaning up contamination inside Fukushima Daiichi 2. A new one is wiping down the walls while another continues to scrub the floor.
Although it suffered a core melt three years ago, unit 2 saw none of the hydrogen explosions that tore through other damaged reactors on the site. Its building is therefore relatively undamaged and well sealed, but this also means there is much contamination trapped inside that must be dealt with before workers can re-enter.
Since November last year a small robot dubbed the Raccoon has been systematically scrubbing and jet washing the floor of the plant's first level. On 9 June it was joined by a much larger sibling, a modified Husqvarna DX-140 from Sweden weighing almost one tonne.
|The new machine its put through its paces before deployment
The robot has been modified by Toshiba to include 12 cameras and a radiation dose meter as well as two attachments for its single arm: a chemical mop and a suction nozzle. Under remote control it will maneuvre on tracks, stabilize itself with four extending legs, and use its arm to clean areas of the walls 1.8-5.0 metres above the ground. Over a period of about six weeks it will clean walls, including ducts and cable trays as well as control panels and the surfaces of equipment.
The robots are deployed unit 2's first floor as this is the location of the containment vessel hatch that Tepco needs to inspect. This will require another remote-controlled operation, but access by workers is needed to open the hatch and set up equipment. Ultimately Tepco needs to find the status of the reactor core and develop a plan to remove its remains.
Researched and written
by World Nuclear News