(BBC) More than eight years after the Fukushima nuclear disaster a Japanese court has cleared three former executives of the firm operating the plant of professional negligence. It was the only criminal case to arise out of the disaster which was the worst since Chernobyl in 1986. In 2011 a plant operated by Tokyo Electric Power (Tepco) was hit by a tsunami causing a triple meltdown. More than 470000 people were evacuated from their homes as a result. Nearly 18500 died or are missing from the wider disaster. The three former executives - ex-chairman Tsunehisa Katsumata 79 and vice-presidents Sakae Muto 69 and Ichiro Takekuro 73 - were indicted for failing to implement tsunami countermeasures leading to the deaths of 44 people.