Toshiba Corp. has unveiled a remote-controlled robot with tongs that it hopes will be able to probe the inside of one of the three damaged reactors at Japan's tsunami-hit Fukushima nuclear plant and manipulate chunks of melted fuel.

The device displayed on Monday is designed to slide down an extendable 11-metre (36-foot) long pipe and grip highly radioactive melted fuel inside the Unit 2 reactor's primary containment vessel.

An earlier robot captured images of pieces of melted fuel in the reactor last year, but other details of the fuel's status remain largely unknown.

Toshiba's energy systems unit said experiments with the new probe planned in February are key to determining the technologies needed to remove the fuel debris, the most challenging part of the decades-long decommissioning process.