An engineering plastic plant that exploded and caused the death of three workers in August will go back on-line after undergoing repairs, Hyundai EP Co. said Saturday. The company said it has been repairing the destroyed polystyrene production facility in Ulsan, 414 kilometers southeast of Seoul, with the plant to be ready for operations by February. The facility is needed to make engineering plastic products. It said both in-house and outside safety reviews have been sought as part of its effort to restart operations. Under South Korean law the government and state-run Korea Occupational Safety and Health Agency can ask for a thorough inspection of industrial facilities that have caused serious accidents. Besides the three killed, five workers were hurt in the explosion. Police, meanwhile, have charged three supervisors for not doing their job to safeguard against accidents at the plant, although they have yet to decide whether to arrest them or not.