The central government and Tokyo Electric Power Co. fell into chaos when the triple meltdown crisis started at the Fukushima No. 1 nuclear plant, and the U.S. Nuclear Regulatory Commission also faced a tough crisis-management situation characterized by limited information and mounting pressure to act, a former chief of the NRC said.

"The key characteristic is that information is always confusing, conflicted and simply often not there. Communication is difficult and impossible. Actions and events do not transpire according to plans and drills," Gregory Jaczko, who chaired the NRC during the early stage of the Fukushima crisis, said of crisis management in a speech Tuesday at a Tokyo symposium.

According to the book "Countdown to Meltdown" written by journalist Yoichi Funabashi, although the NRC sent staff to Japan, they had a hard time getting enough information from the government and Tepco to grasp what was really going on in the first stage of the disaster.