An engineer works at the underground powerhouse of the Three Gorges in Yichang, Central China's Hubei province, April 26, 2011. The No 32 underground turbine launched a water-filling test on Tuesday, starting the debugging of this unit. If the test goes well as planned, the turbine will be operating starting in May. Three of all six underground generators at the Three Gorges will be operational by this summer. The project mainly includes a 185-meter-high dam, a five-tier ship lock and 32 generators, 26 of which are on the river banks and had all gone operational by October in 2008. Six underground turbins have a total designed capacity of 4.2 million kw. [Photo/Xinhua]