 In 1991, NU was the prime contributor to the Rotvoll controversy, a fight to preserve a rich cultural area on the fringe of the city of Trondheim.In the EU referendum in 1994, NU worked actively against EU membership.During the late 1990s, the main focus was on trying to prevent the building of natural gas power plants in Norway and in the 2000s (decade), stopping the opening of the Barents Sea for petroleum production.