Tokyo Electric has said that a remotely controlled robot investigating the inside of reactor 3 at the Fukushima No. 1 power plant has finally spotted objects that could be fuel debris — a potential milestone in the effort to clean up one of the worst atomic disasters in history.

This is the first time Tepco has found something likely to be melted fuel. When the utility sent a different robot into reactor 2 in January, it found black lumps sticking to the grating in the primary containment vessel but said they were difficult to identify.

The objects spotted this time look like icicles hanging around a control rod drive attached to the bottom of the pressure vessel, which holds the core, Tokyo Electric Power Company Holdings Inc. said at an evening news conference Friday.