Features Pertinent to the Destruction of Magnetic Alloy Products at the Dismantling Stage in the Course of NPP Unit Decommissioning

In the near future, in the course of mass-scale decommissioning of nuclear power plant units, a search for ways to preserve for further use the valuable rare earth and non-ferrous metals that were used in the power plant structures will become an important issue. The article presents a study of the features pertinent to the destruction of products made of magnetic alloys with the aim to elaborate technologies for the conversion of valuable materials, sensors, and other components of NPP I&C systems at the power unit decommissioning stage. To achieve this goal, the fracture physics and mechanics methodology and methods are used. Using the example of samarium-cobalt magnetic products, the article describes a methodology for studying the features of destruction of thin-film samples. The methodology was elaborated on the basis of the instrumental in-situ method of electron microscopy and the method of phenomenological description of the process through which product fracturing cracks emerge and develop. Based on the study results, input data have been obtained for constructing a model describing the destruction of products made of magnetic alloys of non-ferrous and rare earth metals. In dismantling the structures of an NPP unit in the course of its decommissioning, the proposed model can become a basis for elaborating advanced technologies for the conversion of valuable materials and their reuse in new products. The promising possibility of rationally using the conversion materials from products made of magnetic materials used at NPPs that have worked out their life and have a tendency to brittle fracture is shown. The study results provide a basis for constructing a digital multiunit model of NPP power units decommissioning in regard of subjecting the power unit materials to conversuon at the stage of destructive dismantling of NPP structures and equipment.