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TEPCO deploy shape-shifting robot to inspect inside Fukushima reactor building

TOKYO, April 10 (Xinhua) -- The operator of the damaged Fukushima Daiichi nuclear plant on Friday has once again resorted to using robots to inspect the condition of the No.1 reactor's containment vessel as the high levels of radiation make it impossible for the vessel to be checked by humans.

The plant's operator, Tokyo Electric Power Company (TEPCO), said it was at least the third time they have had to rely on robots for a critical task, such as inspecting the containment vessels, since the earthquake-triggered tsunami struck in March 2011, causing the plant's key cooling functions to fail resulting in multiple meltdowns in the reactors.

In March 2014 TEPCO deployed robots to the roof of the building that contains the No. 2 reactor and used a machine to drill for samples from the concrete floor to be tested for radiation. Once again, robots were used as the task would have proved fatal for humans due to lethal levels of radioactivity.

In November 2013, the utility also used a robotic probe to confirm that contaminated water was indeed leaking from the No. 1 reactor's containment vessel.

In the latest robotic maneuvers, TEPCO said it ultimately plans to inspect the bottom of the containment vessel where a wedge of nuclear fuel waste may amassing. The difficulty, however, lies in the fact that TEPCO's robot is not waterproof and hence cannot be deployed into the radioactive water, a by-product of cooling nuclear fuel.

The embattled utility said it is working to develop a waterproof version of the robot that can effectively assess the situation, but, as for Friday, the robot is expected to obtain readings on the current radiation level, temperature in the containment vessel and visual data of the upper side of the unit.

A more detailed inspection will continue as the robot is deployed for a second time on Monday next week, TEPCO said.

The robot being used Friday, equipped with cameras, a thermometer and a dosimeter, has been developed by Hitachi-GE Nuclear Energy Ltd. and the International Research Institute for Nuclear Decommissioning, but TEPCO has had issues with using robots in the past.

Such problems include limited operating life, failing circuitry and malfunctions, and unclear images obtained due to high levels of radiation. Some robots used in the past have also been lost due to getting stuck on debris in the containment vessels or in narrow spaces, or on uneven surfaces and have been irretrievable

The robot deployed Friday is expected to circumnavigate some of these problems as it has the ability to change shapes to fit into its surrounding, with its most significant function being able to shift into a U-shape to better fit inside the vessel, said TEPCO.

TEPCO said it plans to inspect the inside of the No.2 reactor as well, but the intensity of radiation makes this plan problematic as fuel inside the Nos. 1 to 3 units has likely melted through pressure vessels and is amassing in the outer containers.

But the severity of the problem has remained largely unknown since the disaster, due to the intensity of radiation, made it nearly impossible to effectively gather the necessary data, even by deploying robots.

Manual methods have been used up until now and tests using cosmic rays have verified the fact that the majority of the fuel, at least in the No.1 reactor has melted and dropped into the containment vessel, causing radiation levels to spike. The situation is almost certainly the same in the other two reactors.

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