Based on the existing AP1000 nuclear power unit auxiliary steam and shaft seal steam system design

the normal operation steam source of auxiliary steam and shaft seal supply steam was optimized. For auxiliary steam system normal operation

the fifth extraction steam was added. For shaft seal steam system

the Hot reheat steam was increased as normal operation steam source

while add an attemperator. After modification

the energy waste caused by using high quality main steam as source of auxiliary steam and shaft seal steam is reduced

the actual generating capacity of the unit is increased. The economic benefits are considerable.