Nuclear Power Plant Accident is an event that has led to significant consequences to people, the environment or the facility. Worldwide, many nuclear accidents have occurred since the Chernobyl disaster in 1986. Two thirds of these mishaps occurred in the US. The French Atomic Energy Commission (CEA) has concluded that technical innovation cannot eliminate the risk of human errors in nuclear plant operation. The explosions and nuclear fuel rods melting at Japan's Fukushima nuclear power plant, following the Sendai earthquake and tsunami last week, have caused fears of what will happen next. Today Japan's nuclear safety agency has raised the nuclear alert level for Japan from four to five - making it two levels lower than the Chernobyl disaster in 1986.