Nuclear energy in Japan

Japan restarted on Tuesday its first nuclear reactor since the Fukushima disaster, which took place in 2011.

All nuclear power plants in Japan were gradually turned off after a series of meltdowns at Fukushima caused by the powerful earthquake and resulting tsunami in 2011.

A drone marked with a radioactive sign landed on the roof of Japanese Prime Minister Shinzo Abe's office on April 22 and  tested positive for a "minuscule" amount of radiation, media reported. 

Police found the radiation to be low enough not to be harmful to humans, media said.