Thermal and sub-thermal neutrons are invaluable tools for investigations in fundamental, engineering and medical science. Neutron applications are mostly non-destructive, as neutrons penetrate deeply into most materials. In the engineering field, neutrons are nowadays predominantly employed in residual stress analysis. At the High Flux Reactor (HFR) in Petten, neutron assisted experimental techniques such as neutron diffraction, neutron radiography and small angle neutron scattering (SANS) are used for residual stress, micro-structural and defects analyses in nuclear structural components. HFR investigations aim at: evaluation of the effect of thermal and irradiation exposure to the evolution of internal stress, microstructure and defects in structural components and material specimens; optimization of process parameters for dissimilar metal welds; optimization of current practice in repair welds; evaluation of the performance of PWHT processes; reconstitution of residual stress fields in oversize (too big for neutron diffraction test facilities) welded structural components through neutron diffraction testing of sub-parts, strain evolution measurement during cutting process, and numerical modelling; assessing the influence of processes such as bending, rolling or shock quenching, on microstructure, defects and residual stress. Numerical methods are also used in order to develop sophisticated models for accurate determination of multi-pass welding residual stresses and to analyze the impact of defects on structural integrity. The present paper presents an overview of the facilities available at the HFR-Petten for structural integrity analyses and presents some related technical details. Furthermore several experimental results obtained on structural multi-pass welds are presented and strategies to overcome problems emerging from reference lattice parameter variations in and around thick structural weldments are illustrated. Finally an outlook to future related activities in the HFR is given.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
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