If decommissioning is not considered, operation is the last and longest stage of a nuclear project. The technical aspects of decommissioning are consid­ered in Chapter 24.

In this period, the quality assurance programme must retain criteria applied in previous stages, because design, construction and commissioning are still present to a lesser extent but with the same relevance. Additionally, the programme must have an operational focus to consider the three basic facts that characterize the nuclear generation of electricity:

• The large amount of energy stored in the reactor

• The necessity of removing the reactor’s residual heat for a long period of time

• The manipulation of radioactive products.

Safe and reliable operation of a nuclear power plant cannot be achieved without a sound quality assurance programme adequately established and implemented.

The IAEA has established internationally accepted criteria and practices on quality assurance in operation (IAEA, 1996d).