The major part of NPP commissioning covers a period of about 2-3 years from the finished erection of the first systems (electrical energization) up to the start of the commercial operation of the station. About 40-50 profes­sionals are usually assigned to perform the tasks for this activity. Major support will be provided by manufacturers with the participation of plant operation and maintenance personnel.

The overall manpower requirements for the stage of plant operation are not so much directed by the plant output capacity as by the policies regard­ing the uses of external contractors. For guidance, the manpower require­ments can be defined as an average of one worker for 1 megawatt electrical of gross capacity of the plant (680 MWe gross capacity would require approximately 680 workers). This average value of workers per MWe is not linear and tends to be as low as 0.7 as the plant gross capacity increases, especially for multiunit stations.