RESIDUAL STRESS MEASUREMENTS IN TARGET MATERIALS

摘要

Transmutation refers to the elimination of long lived actinides and fission products from spent fuels discharged from operating nuclear reactors. An important component of the transmutation facility is a sub-critical target, which produces an intense neutron flux by impingement of accelerator proton beam onto it by a process known as spallation. Target structural materials are subjected to residual stresses, resulting from welding and plastic deformation. Therefore, measurements of residual stresses by available state-of-the-art techniques seem appropriate. This paper presents the results of residual stress measurements by both destructive and non-destructive techniques. These techniques include X-Ray Diffraction (XRD), Positron Annihilation Spectroscopy (PAS) and Ring-Core Method. Materials tested include Austenitic Type 304L Stainless Steel, and Martensitic Alloy EP-823. The results obtained so far indicate that compressive residual stresses were generated in bent (three-point) specimens on the convex side and tensile residual stresses on the concave side of the bent specimen, as measured by the XRD technique. Further, the results of PAS studies indicate that the extent of residual stresses generated in plates of both materials were significantly enhanced with increased level of cold-work. In essence, this paper discusses the applicability of both destructive and non-destructive methods in characterizing the nature and extent of residual stresses in materials for transmutation applications.