Chen Yunlin (2nd R front), president of the mainland-based Association for Relations Across the Taiwan Straits (ARATS) and Chiang Pin-kung (2nd L front), chairman of the Taiwan-based Straits Exchange Foundation (SEF) sign an agreement on cross-strait cooperation on nuclear power safety in north China's Tianjin Municipality, Oct. 20, 2011. (Xinhua/Zhang Chaoqun)