BEIJING: China 's first nuclear-powered submarine has been decommissioned after more than 40 years of military service, state media said today.After undergoing a thorough denuclearisation process, the submarine was towed to a wharf belonging to the Chinese Navy Museum in Qingdao, a port city in east China's Shandong province yesterday where it will be a public exhibit, state- run Xinhua news agency reported.The submarine's release from military service and the safe, thorough and reliable handling of related nuclear waste, nuclear reactor and other devices showed China's life-cycle maintenance ability, ranging from a nuclear submarine's production, operation, management to disposal, the report quoted the naval authorities as saying.China reported to have five nuclear submarines and 15 conventional ones with several others under construction.