About 700 employees of Chubu Electric Power Co. participated in a drill Friday simulating complete loss of electricity at its Hamaoka nuclear plant in Omaezaki, Shizuoka Prefecture.

The exercise assumed that an earthquake with a seismic intensity of upper 6 had generated gigantic tsunami that breached the coastal facility's 18-meter-high breakwaters.

The plant workers started up emergency generators to keep the reactors cool, closed 7-meter-tall reinforced doors to prevent seawater from entering reactor buildings and evacuated to higher ground.

The utility set up mobile radiation monitoring equipment in case the facility's permanent device became inoperable.

It is the first time Chubu Electric has closed the reinforced doors and used the mobile radiation monitoring equipment in one of its disaster drills.

The company has completed building an 18-meter-high seawall at the plant but decided to add another 4 meters after an in-depth analysis showed that tsunami could reach 21.4 meters at breakwater.