Underwater robot captures images of damaged reactor at Japan's Fukushima nuclear plant

This May 28, 2012 file photo shows the reactors of the tsunami-stricken Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, northeastern Japan. Photo / AP

An underwater robot has entered a badly damaged reactor at Japan's crippled Fukushima nuclear plant, capturing images of the harsh impact of its meltdown.

Plant operator Tokyo Electric Power Co says the robot, nicknamed "the Little Sunfish", successfully completed Wednesday's work inside the primary containment vessel of the Unit 3 reactor at Fukushima, which was destroyed by a massive earthquake and tsunami in March 2011.

This image captured by an underwater robot shows a part of a control rod drive of Unit 3 at Fukushima Dai-ichi nuclear plant. Photo / AP

Spokesman Takahiro Kimoto says the robot captured views of the underwater damage that has not been previously seen.

However, the images contain no obvious sign of the melted nuclear fuel that researchers hope to find.

The robot was left inside the reactor and is expected to go deeper inside on Friday in hopes of finding the melted fuel.

Part of equipment housing a control rod drive system of Unit 3. The underwater robot has captured images and other data inside Japan's crippled nuclear plant. Photo / AP

A damaged platform inside of Unit 3 primary containment chamber at Fukushima Dai-ichi nuclear plant in Okuma town, northeastern Japan. Photo / AP

The remote-controlled robot, about the size of a loaf of bread, is equipped with lights, manoeuvres with five propellers and collects data with two cameras and a dosimeter, which measures exposure to ionising radiation.

The robot was co-developed by Toshiba and a government-funded consortium.

It is on a mission to study the damage and find the fuel that has melted, breached the core and mostly fallen to the bottom of the primary containment chamber, where it has been submerged by highly radioactive water as deep as 6m.

Remote-controlled robots are key to the decades-long decommissioning of the damaged plant but super-high levels of radiation and structural damage have hampered earlier probes at two other reactors at the plant.

- AAP