When all six units are in operation, they are expected to generate some 52 billion kilowatt-hours of electricity annually, and reduce carbon dioxide emissions by about 48.05 million metric tons a year, according to the project's plans.

　　Scale is one part of the challenge. Units 5 and 6, both using Hualong One technology, are under construction together with Units 1 and 2, which use the CAP1000 reactor design. These units are scheduled to be put into operation by 2030.

　　Xu Kai, an engineer with the security and protection department at CGN Lufeng Nuclear Power Co, said the construction site has about 30,000 authorized workers and more than 2,000 work activities of different risk levels on a normal construction day.

　　Engineers check the operation status of the project's power supply facilities. WANG YAJING/FOR CHINA DAILY

　　To keep such a complex site "visible, controllable and traceable", Lufeng has built an integrated command center, Xu said. Construction progress, worker qualification data, equipment status and environmental monitoring information are brought together on large screens, allowing managers to follow changing conditions in real time.

　　Each worker is linked to a digital file that includes pre-job training records, qualification certificates and health examination information. Access-control gates automatically check whether a worker has the required authorization before allowing entry into a work area.

　　The center can also display the real-time number of people entering or leaving each gate and connect the information with nearby cameras.