A team of international nuclear safety experts from 12 countries, created by the Vienna-based U.N. International Atomic Energy Agency, submitted to Japanese authorities its preliminary assessment report on the Fukushima nuclear crisis, set off by the March 11 magnitude-9 earthquake and the 45-foot tall tsunami.
Team leader Mike Weightman of Britain said his experts were "humbled by the enormous damage inflicted by the tsunami on Japan," and noted "the dedication of Japanese workers" working to bring the crisis under control.
The report said Japan's response to the crisis was exemplary and that its long-term response, including the evacuation of the area around stricken reactors, was impressive.
However, the report said, the "tsunami hazard for several sites was underestimated."
Much of the damage to the Fukushima plant was caused by the tsunami that followed the earthquake. Critically, the waves knocked out four of the plant's six reactors, setting off radiation emissions which continue to plague the plant nearly 10 weeks after the disaster.
The IAEA experts said nuclear plant designers and operators "should appropriately evaluate and protect against the risks of all natural hazards" and periodically update those assessments methodologies.
"The Japanese accident demonstrates the value of hardened on-site emergency response centers with adequate provisions for handling all necessary emergency roles, including communications," the report said.
Weightman said everyone with responsibility for nuclear safety across the world should learn "from this unique event."