Security procedures at a Swedish nuclear plant turned up explosive material in a truck en route to a restricted area Wednesday.Vattenfall, the majority owner of the Ringhals plant, reported the object was found during routine inspections of cargo entering the plant. In a release, the utility said the explosives could not have caused serious damage.Samples of the material were sent to a state forensics lab for testing, police were on-site and the country’s nuclear regulator was notified. The testing later confirmed the material to be explosive, but no detonation device was found with it.Ringhals is the largest nuclear plant in Scandinavia, with four reactors producing almost 20 percent of Sweden’s power. The plant operates one boiling water reactor and three pressurized water reactors generating about 3,700 megawatts combined, according to the World Nuclear Association. The plant is located on the coast near Gothenburg.