A tool equipped with a tiny video camera, a thermometer, a dosimeter and a water gauge was used to assess damage inside the containment chamber of Fukushima Daiichi plant's number 2 reactor for the second time since the tsunami swept into the complex more than a year ago.

The data collected on Tuesday showed the damage from the disaster is so severe that the plant operator will have to develop special equipment and technology to tolerate the harsh environment and decommission the plant. The process is expected to last decades.

The other two reactors that had meltdowns could be in even worse shape. The number 2 reactor is the only one officials have been able to closely examine so far.