​​Decommissioning (dismantling) is the last stage of a nuclear power plant lifecycle, after its building and operation stage. The decommissioning process generally involves removing fuel, carrying out the facility radiological characterisation, the decontamination of structures and, lastly, the site radiological characterisation. Any of these operations is carried out in a safe working place. This process also involves managing the radioactive waste stored in specific interim storage facilities, and all other materials resulting from dismantling operations such as iron, copper or concrete, which will be then reused or removed from the site to be recovered and recycled. The demolition of the power plant structures, the conditioning of radioactive waste and its storage in interim facilities ready to be transferred to the National Repository, lead the land to the stage of “brown field”.​

After the gradual transfer of radioactive waste to the National Repository, the interim storage facilities are also dismantled. At this stage, after having verified that no radiological risks are present, the brown field becomes a “green field” and the site can be reused by the community. ​​​

​​Centrale di Caorso - Smantellamento e decontaminazione dei componenti dell'edificio turbina
Dismantling and decontamination of the turbine building components of the Caorso nuclear power plant
​​Decommissioning is a challenge for engineers, because Italian nuclear power plants were designed without considering their possible future dismantling. An accurate planning is necessary for the implementation of decommissioning programmes, which must be carried out in parallel with the development of specific technological solutions, often prototypes, that cannot be produced on a large-scale.

In 2017, the plan for the decommissioning of Italian nuclear power plants was reviewed by the International Atomic Energy Agency (IAEA); in its final report, the Agency underlined the “robust” approach of Sogin’s decommissioning programmes, designed according to the best international practices. In 2018, the Agency drafted a Technical Review on Sogin’s projects for the dismantling of reactors (vessel and internals) in Trino and Garigliano power plants.​​

History of decommissioning in Italy

Italy was one of the first Countries worldwide to face nuclear decommissioning, when it decided to stop producing nuclear energy in 1987. Following a referendum, the Italian power plants of Latina, Trino (Vercelli) and Caorso (Piacenza) were stopped and turned to a “safe store”, condition already applied to the power plant in Garigliano, closed in 1982. In the same year, the construction of two new power plants (Trino2 and Montalto di Castro) were also halted. Same applied to the fuel cycle plants in Saluggia (Vercelli), Casaccia (near Rome), Rotondella (Matera) and to the nuclear fuel manufacturing facility in Bosco Marengo (Alessandria).
​​Construction of the Latina nuclear power plant
Construction of the Latina nuclear power plant
​​“Safe enclosure ” is the process to shut down a nuclear power plant which involves all the steps for the implementation of a “deferred dismantling”. This approach implies the facility decontamination and dismantling to be carried out after several decades from its closure; on the one hand this period allows the natural decay of greater part of radioactivity in the site, and, on the other hand, it helps fixing a financial framework and evaluating the costs for the disposal of radioactive waste.

The company Sogin was originally established to dismantle the power plants of Trino, Latina, Caorso and Garigliano; later on, in 2003, the dismantling programme was extended to the research centres owned by Enea: EUREX in Saluggia, ITREC in Rotondella, OPEC and IPU in Casaccia; finally, in 2005, the fuel manufacture facility of Bosco Marengo was included.​​​​​​​​​

​​Sogin is an international company called to face several factors such as:

  • Choosing a strategy to manage fuels, including dry storage and subsequent reprocessing in a foreign country;
  • Launching complex authorisation procedures, with several bureaucratic steps;
  • Facing the advanced age of the power plants, which require careful safety measures and several unexpected interventions;
  • Drafting project and tendering operations, often more complex than originally planned;
  • Re-orienting regulations, resources and know-how procedures towards decommissioning.
​​The experience gained and the competence acquired by Sogin in its twenty years of activity, allow this Company to identify the best technological solutions to perform the safe decommissioning of the power plants and manage radioactive waste. The excellent results achieved so far, show that Italy is successfully facing this challenge.