The operator of Japan's Fukushima nuclear power plant began removing fuel rods Monday from one of three reactors that melted down in 2011.

The Tokyo Electric Power Company (TEPCO) said workers started removing the first of the used and unused fuel units from a cooling pool at reactor 3. The operation was was more than four years behind schedule, and had a short further delay Monday afternoon, after a problem with the equipment, but resumed after the mishap was addressed.

TEPCO has estimated that it will take up to two years to remove 566 of nuclear fuel rods from that reactor.