An underwater robot deployed into one of Fukushima's defunct nuclear reactors discovered what appeared to be hunks of melted fuel debris. Video recorded by the robot showed "lava-like" lumps inside the submerged No. 3 reactor. The robot was sent into the reactor through a pipe meant to prevent the escape of radioactive gas, Reuters reported Thursday. Operators aimed for the machine to locate radioactive melted fuel rods in order to remove them and continue decommissioning the plant. Discovering the melted fuel would mark a major accomplishment for plant's cleanup process.

A robot sent into Fukushima's defunct nuclear power plant found what could potentially be melted nuclear fuel debris -- hanging in the form of "icicles." The machine was deployed to locate the source of the melted debris and potentially clean it up. Officials from the Tokyo Electric Power Company (TEPCO), the company tasked with decommissioning the power plant, said the objects the robot spotted were inside the interior of reactor three. The icicle-like objects were hanging onto a control rod drive attached to the bottom of a pressure vessel which holds the core, the Japan Times reported Friday. Read: Fukushima's'Unimaginable' Nuclear Radiation So Destructive, Not Even Robots Can Survive The robot, nicknamed "the Little Sunfish," was sent into the plant Wednesday.

A renewed attempt to survey reactor 2 at the damaged Fukushima No. 1 nuclear power plant failed Thursday when the latest robot probe became obstructed. The robot was inserted into the primary containment vessel at around 7:50 a.m. to approach the metal grating directly underneath the pressure vessel, where a black mass has been found. Tokyo Electric Power Company Holdings Inc. had hoped to take a closer look at what could be melted nuclear fuel, but it was forced to abandon the operation shortly after 3 p.m. The robot didn't reach its objective, Tepco said, and the utility eventually severed its controller cable. Having detected an extraordinarily high radiation level --estimated at 650 sieverts per hour -- in a preparatory survey, Tepco had hoped to obtain more precise readings, images and data needed to remove fuel and other debris to decommission the plant.