Corrosion and decommissioning
Résumé
More than 110 commercial nuclear reactors, 48 prototypes and 250 research nuclear reactors have been retired from operation. Only 17 of them had full decommissioning. For all the others, corrosion of key components for the confinement is been faced linked to the exposure to more or less corrosive environments. For the 12 reactors closed following an accident, including partial core melt for 8 reactors (for instance the last 4 damaged reactors of Fukushima), the cooling of the core melt is needed and has to be assumed over long period of time which leads to specific corrosion issues. The importance of corrosion management during decommissioning is outlined regarding (i) structural materials which have been chosen for reactor standard operation, but not for decommissioning conditions during which functions like tightness or mechanical resistance have still to be maintained; (ii) long term issues for deferred dismantling, (iii) and after core melt the behavior and the influence of corium interactions and fuel debris has to be investigated.The corrosion issues during decommissioning lead to increase the knowledge in several areas including thermodynamics (for the corium), material behavior and irradiation damages coupled with long term issues. Examples will be given and will illustrate also the importance of the modeling and simulation for coupling multi-corrosion issues faced during decommissioning.
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