Swiss utility BKW will permanently shut down the single-unit Mühleberg nuclear power plant on 20 December, a move that according to the Swiss Nuclear Forum will see the country lose 5% of its electricity output.The forum said the need to replace capacity lost from Mühleberg is not “excessive”, but the closure and the loss of generation does provide a foretaste of potential supply problems when all nuclear plants are shut down. “Security of supply will then depend on electricity imports or the construction of gas power plants,” the forum said.“Meanwhile, nuclear power plants of the latest design are being built worldwide and various countries are starting to use climate-friendly nuclear energy.”