Japan said Wednesday it will conduct stress tests on all the countrys nuclear plants to ease heightened concerns about disaster preparedness after this years tsunami sparked the worst nuclear crisis since Chernobyl. The March 11 earthquake and tsunami in north-eastern Japan knocked out power at the Fukushima Dai-ichi plant, sending it toward meltdown in a crisis that engineers are still struggling to contain. The plant operator has come under heavy criticism for failing to sufficiently prepare for the disasters. The government already ordered exhaustive safety checks on all the countrys 54 nuclear reactors following the disaster, and it was not immediately clear what additional measures would be added by the stress tests. Officials provided few details. However, Minister of Economy, Trade and Industry Banri Kaieda said the new safety checks will gauge the facilities defences against extreme events like big earthquakes.