Workers take photos of the pressure vessel of a high-temperature gas-cooled reactor (HTGR) during its installation at the Huaneng Shidao Bay nuclear power plant, east China's Shandong Province, March 20, 2016. The pressure vessel of China's first fourth-generation nuclear energy system was put in place on Sunday. The cylindrical vessel, 25 meters high and weighing 610 tons, is the biggest, heaviest and most complicated pressure vessel for a nuclear reactor. (Photo: Xinhua/Guo Xulei)
