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Robot finally abandoned in containment vessel

April 13, 2015

Tepco gives up on rescuing shape-shifting reactor robot




FUKUSHIMA – Tokyo Electric Power Co. has given up on retrieving the shape-shifting robot it sent into the damaged primary containment vessel of reactor 1 of the crippled Fukushima No. 1 power station, the company said.

Tokyo Electric Power Co. has given up on retrieving the shape-shifting robot it sent into the damaged primary containment vessel of reactor 1 of the crippled Fukushima No. 1 power station, the company said.

The robot, tasked with surveying the damage caused by the March 2011 meltdown, was expected to survive 10 hours in the high radiation environment but died in less than 3 hours.

Before it quit, the robot succeeded in taking video of the damaged PCV and collecting radiation and temperature data at 14 of the 18 planned survey points.

The robot, which is not waterproof, was sent into the vessel on Friday morning to check the actual conditions inside so it can draft a plan to extricate the molten nuclear fuel and other debris, which is believed to have puddled at its bottom.

The remote-controlled robot was initially scheduled to examine half of the area on the first floor of the PCV but stopped moving after completing two-thirds of the route. In that time, however, it managed to collect video and other data from the area leading to the basement, where the fuel debris is thought to be, Tepco said.

On Monday, a survey that was planned to be conducted by a similar remote-control robot on the other half of the vessel’s first-floor area was postponed.

The Fukushima No. 1 nuclear power station was badly damaged in March 2011 by a triple core meltdown caused by a tsunami-triggered station blackout in the wake of the offshore Great East Japan Earthquake.


'Transformer' robot breakdown leaves TEPCO in the dark at Fukushima nuclear plant




An unresponsive robot means it's back to the drawing board for officials at Tokyo Electric Power Co. in determining how to decommission reactors at their crippled Fukushima No. 1 nuclear power plant.

The sleek, shape-changing robot, which was expected to deliver a preliminary view of the inside of the No. 1 reactor, failed to complete its mission when it stalled just hours after entering its containment vessel on April 10.

TEPCO officials announced April 12 that they had abandoned plans to retrieve the stranded robot as well as postponing the entry of another robot that had initially been scheduled for April 13.

Work will now proceed to cut the cable connecting the first robot to the outside world.

TEPCO had sent in the robot on April 10 to photograph the interior of the reactor containment vessel and record temperatures and radiation levels.

But the failed mission was not deemed a complete waste of time as the robot was able to check on 14 of the planned 18 locations within the containment vessel that were on its initial agenda, said TEPCO officials.

There was no indication as to why the device stalled.

The robot was developed by the International Research Institute for Nuclear Decommissioning to chart areas inside the containment vessel where humans cannot enter because of high radiation levels.

Measuring 60 centimeters long in its normal state, the robot can change its shape depending on the space it is trying to enter and is operated via a connecting cable.

The robot is essential in leading the way for a full-blown investigation scheduled for the end of this fiscal year. It is part of the preparatory work required to eventually retrieve melted nuclear fuel, the toughest part of the decommissioning process.


TEPCO fails to retrieve survey robot from Fukushima reactor vessel



TOKYO (Kyodo) -- The operator of the crippled Fukushima Daiichi nuclear plant said Monday it has failed to retrieve a survey robot sent into the No. 1 reactor's containment vessel after it stopped working last week during its first inspection of the vessel's interior since the nuclear crisis at the plant.

Tokyo Electric Power Co. cut the cables connected to the non-functional robot and decided to postpone another survey that it initially planned to conduct on Monday morning using a different robot.

It is the first time that TEPCO has deployed a robot to check the interior of a reactor's primary containment vessel since the March 2011 three-reactor meltdown triggered by a huge earthquake and tsunami. The survey was a step toward discovering the condition of melted fuel debris in detail.

Fuel inside the Nos. 1 to 3 units is believed to have melted through the reactor pressure vessels and has been accumulating in the outer containers. But the exact conditions remain unknown more than four years after the nuclear crisis began due to extremely high levels of radiation.

Nonetheless, the disabled robot, equipped with cameras, dosimeter and thermometer, was able to record data on radiation levels and temperatures in 14 locations out of the initially targeted 18 and footage inside the highly radioactive container. TEPCO plans to release the data soon.

During the remote-controlled robot survey that began Friday morning, the robot was expected to go halfway around the container. However, it suddenly stopped functioning after crawling some 10 meters inside the vessel.

The cause remains unknown, a TEPCO spokesman said.

April 13, 2015(Mainichi Japan)


 April 12, 2015

TEPCO abandons robot in reactor



Apr. 12, 2015 - Updated 22:51 UTC+2

The operator of the crippled Fukushima Daiichi nuclear plant has given up recovering a robotic probe that has remained stationary inside one of the reactors at the complex.

Tokyo Electric Power Company inserted the remote-controlled robot for the first time into the containment vessel of the No.1 reactor on Friday.

The 60-centimeter-long, snake-like robot was supposed to survey internal damage to the vessel. But it stalled after moving about 10 meters.

TEPCO and other engineers suggest the possibility that the robot or its remote-control cable has become caught on something.

The workers used the robot's camera to confirm the state of the reactor. They also operated the robot's maneuvering belt and manually pulled the cable.

But the robot has remained immobile and is not showing any sign of improvement. That's forced the company to give up recovering the device.

Company officials also postponed plans to conduct a similar survey on the same vessel using another robot on Monday. They say this is because the first robot's cable in the vessel's pipe is blocking the entry of the second probe.

TEPCO officials say they have yet to decide when to conduct the second survey as they have to first complete an investigation into the accident.


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