The operator of the crippled Fukushima nuclear plant cleared a major regulatory hurdle on Wednesday to restart two reactors in Japan, its first since the 2011 tsunami sparked the hazardous atomic accident in decades. <br/><br/>The Nuclear Regulation Authority provided Tokyo Electric Power Co. (TEPCO) preliminary approval to restart the two reactors at the Kashiwazaki-Kariwa plant, one of the world's biggest and the largest in Japan.<br/><br/>The plant, in the central Japan prefecture of Niigata, has been idle since the disaster as have been many other nuclear power plants in Japan. <br/><br/>Triggered by a 9.0-magnitude earthquake in March 2011, a massive tsunami overwhelmed reactor cooling systems at the Fukushima Daiichi plant in northeastern Japan. It caused reactor meltdowns, releasing radiation in the most dangerous nuclear disaster.