Safety conditions and lifetime extension of a Nuclear Facility (NF) are fundamental and a deep knowledge of ageing and creep processes linked with the involved materials and parts is essential to guarantee high levels of reliability and to face severe natural and plant–centred incidences. The analyses classically used in this case, involving non-destructive techniques (NDT) and in-service inspections required by the norms, can present a lack of information. The data acquired, consequently, need to be complemented. Decommissioning of NFs is an important chance to get materials and parts submitted for various years to ageing and degradation, consenting novel diagnostic activities beneficial to suggest eventual additional measures related to the installation of new components or in planning a postponed decommissioning, to increase safety and dependability. Neutron beam techniques (NBT) can be helpful to characterise, in a non–destructive and non-invasive way, materials and parts of nuclear/traditional interest. Positive recommendations exist to exploit neutron methods for reactor materials’ control. In this paper, ageing processes occurring in the NFs sector are briefly introduced and the main neutron techniques are briefly described. Some examples of applications, then are presented. The results obtained by neutron analyses, linked with information on nature and features of materials’ damages, assist to comprehend the trends of fracture and to evaluate a latent picture of preliminary degradation processes leading to any fast crash of material, including inoperability periods before the decommissioning activities.