Remote nuclear device had miniscule amounts of radioactive substance . Follows protests over plans to restart existing nuclear reactors . controversy over nuclear policy stems from nuclear disaster after 2005 . Prime Minister Shinzo Abe was not in residence at the site .
Remote control device had miniscule levels of radioactive substance . Follows protests over plans to restart two nuclear reactors . Fears over nuclear policy stem from Fukushima disaster after tsunami . Prime Minister Shinzo Abe was not in residence at the time .