Japan govt body detailed tsunami risks before March 11:documents

A handout picture by Tokyo Electric Power Co. (TEPCO) shows the Mega-Float, a huge steel floating structure used to store contaminated water from the tsunami-crippled Daiichi nuclear power plant in Fukushima, as it heads to the nuclear power plant from a port in Yokohama, south of Tokyo May 15, 2011.

TOKYO (Reuters) - A government body conducted analyses on the damage tsunamis of various scale would inflict on a nuclear power plant, according to documents made public on Sunday, adding to allegations that Japan and its largest utility failed to heed warnings.

The latest revelation, reported by the Mainichi daily, emerged as the government prepares to help Tokyo Electric Power (TEPCO) compensate victims of the crisis at the tsunami-crippled nuclear Fukushma Daiichi plant.

The government and Tokyo Electric Power have repeatedly described the combination of the magnitude 9.0 earthquake and the ensuing 15-meter (46.5 foot) tsunami on March 11 as beyond expectations.

The institution affiliated with the Ministry of Economy, Trade and Industry, however, analyzed the dangers of tsunamis ranging from 3 meters to 23 meters in a report originally published in December.

"Our analysis shows that a tsunami of a certain height (some 7 meters in the absence of a seawall and some 15 meters if one were present) or higher would have almost a 100 percent chance of damaging the reactor core...," the Japan Nuclear Energy Safety Organization said in the report.

"We presume a tsunami of at least 7 meters would destroy the functions of a seawater pump and that of at least 15 meters would destroy outside equipment such as an electrical transformer."

The government and TEPCO have explained that the Fukushima plant that leaked radiation following the disaster was designed to handle roughly a 6-meter wall of water.

Engineers are still struggling to bring the plant north of Tokyo under control two months after the disaster. More than 15,000 people were killed in the disaster and about 9,500 are still missing.

(Reporting by Rie Ishiguro; Editing by Ron Popeski)