Abstract: This article analyzes the two main factors affecting collective dose during outage of nuclear power units- namely the reactor unit radiation levels and the total maintenance working hours -and their control methods. This article summarizes the experience gained from controlling collective dose during ten outages of two CPR1000 units at a particular nuclear power plant. Which includes enhancing radiation protection organizations, allocating collective dose targets, conducting hot spot flushing, developing innovative maintenance tools and techniques, improving maintenance processes, and managing high level radiation areas. These experiences have been validated through practical implementation and proven to be effective.

Key words: nuclear power plant, collective dose, CPR1000 units, outage