High Quality Content by WIKIPEDIA articles! The Fessenheim Nuclear Power Plant is located in the Fessenheim commune in the Haut-Rhin department in Alsace in north-eastern France, 15 km (9.3 mi) north east of the Mulhouse urban area, within 1.5 km (0.93 mi) of the border with Germany, and approximately 40 km (25 mi) from Switzerland. Nearly 100,000 people live within 20 km (12 mi) of the plant, which is located in the third most densely populated region in Metropolitan France and in the centre of the European Backbone. As of March 2011, it is the oldest operational nuclear power plant in France.