Climb just beginning at Japan reactor

OKUMA, Japan - High atop Fukushima's most damaged nuclear reactor, the final pieces of a cylindrical cover are being put in place to seal in highly radioactive dust.

Blown apart by a hydrogen explosion in 2011 after an earthquake and tsunami hit Japan's Fukushima Dai-ichi plant, reactor Unit 3 is undergoing painstaking construction ahead of a milestone that is the first step toward dismantling the plant.

The operating floor from where new fuel rods used to be lowered into the core has been rebuilt and if all goes as planned, huge cranes will begin removing 566 sets of still-radioactive fuel rods from a storage pool just below it later this year.