[en] Improved performance and safety of European energy production systems is essential for providing safe, clean and inexpensive electricity to the citizens of the enlarged EU. The state of the art in assessing internal stresses, micro-structure and defects in welded nuclear components -as well as their evolution due to complex thermo-mechanical loads and irradiation exposure -needs to be improved before relevant structural integrity assessment code requirements can safely become less conservative. This is valid for both experimental characterization techniques and predictive numerical algorithms. In the course of the last two decades neutron methods have proven to be excellent means for providing valuable information required in structural integrity assessment of advanced engineering applications. However, the European industry is hampered from broadly using neutron research due to lack of harmonised and standardized testing methods. 35 European major industrial and research/academic organizations have joined forces, under JRC coordination, to launch the NET European Network on Neutron Techniques Standardization for Structural Integrity in May 2002. The NET collaborative research initiative aims at further development and harmonisation of neutron scattering methods, in support of structural integrity assessment. This is pursued through a number of testing round robin campaigns on neutron diffraction and small angle neutron scattering - SANS and supported by data provided by other more conventional destructive and non-destructive methods, such as X-ray diffraction and deep and surface hole drilling. NET also strives to develop more reliable and harmonized simulation procedures for the prediction of residual stress and damage in steel welded power plant components. This is pursued through a number of computational round robin campaigns based on advanced FEM techniques, and on reliable data obtained by such novel and harmonized experimental methods. The final goal of development of less conservative and more reliable procedures for structural integrity is pursued through feeding the results of such calibrated numerical models into existing or new codes of best practice. NET partners include major nuclear industries and most European neutron facilities from 10 EU member states and 2 Candidate Countries. During the last two years the NET Steering Committee has met 5 times and significant progress has been made in fine-tuning and in executing its work programme organized in three Task Groups (TG). A basic research pilot study on residual stress analysis of a single bead weld on a steel plate is pursued within TGI. The scope of this study includes two experimental (based on Neutron and X-ray diffraction) round robin exercises and one computational (based on 3-D FEM), which are conducted with the participation of ca. 15 partners._A parametric study aiming at the evaluation of stress relief heat treatment in welded Cr-Mo-V steel plates is the subject of TG2. Process parameters considered are temperature magnitude and time rate. Neutron diffraction (though thickness testing), X-ray diffraction (surface testing) and computational round robin campaigns are conducted with the participation of more than 15 partners. This study is viewed as a starting activity toward the development of novel heat treatment methods relevant to repair welding. Investigations of thermal ageing effect (microstructure analyses) on cast duplex stainless steels based on small angle neutron scattering (SANS) are addressed within TG3. Initial harmonization of the performance of the four participating SANS facilities are based on similar study performed on other material, which can also be investigated by more conventional methods for validation purposes. (author)