ANKARA

The operator of Japan's Fukushima nuclear complex has said that it moved a "pebble-like" piece of melted fuel just outside a reactor container as part of its attempt to retrieve the radioactive debris for the first time since the plant was damaged by a massive earthquake and tsunami in 2011.

Tokyo Electric Power Company Holdings Inc. plans to determine the possibility of recovering the 5-millimeter-size debris, after checking its radiation level, possibly on Tuesday, according to the Kyodo News Agency.

Retrieving highly radioactive melted fuel is a serious challenge in the decades-long decommissioning plan for the Fukushima Daiichi complex.

Approximately 880 tons of fuel debris remains in the No. 1, 2, and 3 reactors, which experienced core meltdowns during the nuclear disaster.

If the debris' radiation level is higher, TEPCO will return the object to the reactor's containment vessel and consider extracting a different sample to send to a research facility for further testing.