All power plants, coal, gas and nuclear, have a finite life beyond which it is no longer economical to operate them. Generally speaking, Nuclear Power Plants (NPP’s) were designed for a life of about 30 years, though some have proved capable of continuing well beyond this term. Newer plants are designed for a 40 to 60 years operating life. To date, 70 commercial power reactors, over 250 research reactors and a number of fuel cycle facilities, have been retired from operation. Some of these have been fully dismantled. Assuming an average of about 25-years lifespan, almost 300 nuclear power plants would have to be decommissioned by the year 2010. By appropriate refurbishment, replacement or upgrading of some equipment, operations at many of these plants can probably be extended well beyond this conservative estimate.

However, ultimately it becomes either technically or economically advantageous to retire a facility from operation and, if necessary, replace it with a new plant.

In Italy 4 Nuclear Power Plants have been prematurely definitely shutdown and are now in different stages of decommissioning. They were operated by the National Electrical Utility ENEL, now partially privatized. In figure 1, the names and location of these plants are reported. The responsibility of carrying out the decommissioning projects and to manage the spent fuel has passed in the 1999 to SOGIN Company (which includes all nuclear competences of ENEL), which is now completely owned by the Italian Government (Ministry of Treasury). In Table 1 the main characteristics of these plants are summarized.