Photo taken on Dec. 22, 2018 shows four generators of the Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Wang Chun)

Photo taken on Dec. 22, 2018 shows generators of the second phase at Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Wang Chun)

Photo taken on Dec. 22, 2018 shows the exterior of the Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Geng Yuhe)

Photo taken on Dec. 22, 2018 shows four generators of the Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Wang Chun)

Photo taken on Dec. 22, 2018 shows the exterior of the Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Geng Yuhe)

Photo taken on Oct. 27, 2018 shows the exterior of the Tianwan Nuclear Power Plant in Lianyungang city in east China's Jiangsu Province. With the completion of debugging efforts of the Unit 4 generator on Saturday, the second phase of the power plant was put into commercial operation. (Xinhua/Geng Yuhe)