The welding of the main pipe on the Karachi 3 unit, part of the HPR1000 reactor currently being built in Pakistan, was completed on March 2, seven months ahead of schedule, using the "pre-introduction" method.

The main pipe of a nuclear island is connected with the reactor pressure vessel, steam generator and the main coolant pump; it is an important part of the pressure boundary of the reactor coolant system. It consists of three circuits, with each of the circuits comprising of a hot section, cold section and transition section. 

As grade-A piece of safety equipment essential for nuclear safety, the main pipe of a nuclear island will withstand the high temperature and high pressure of the reactor coolant for a long period of time while in operation. Therefore, it can be deemed as the main artery of a nuclear power plant. 

China Zhongyuan Engineering Corporation of China National Nuclear Corporation (CNNC) achieved a world record by spending only six days completing the hoisting of three steam generators with the "pre-introduction" method –– where the main reactor equipment is installed before the dome of the containment building, and the “E-frame” method. 

The four HPR1000 units that are under construction by CNNC represent the world’s only third-generation pressurized water reactor nuclear power project constructed according to schedule. Currently, all phases of the HPR1000 project both at home and abroad are completed on schedule or ahead of schedule, while maintaining safety and quality at all times.