Search

Reduced-pressure electron beam (EB) plate butt welds were manufactured in two low-alloy pressure-vessel steels, SA508 Gr 3 Cl 1 and SA508 Gr 2, at two thicknesses in both steels, 30 mm and 130 mm. Transient temperatures during welding were recorded using thermocouple arrays. Residual stresses in the as-welded condition and after post-weld heat treatment were measured using diverse methods: neutron diffraction and the contour method at 30 mm thickness; and deep hole drilling and the contour method at 130 mm. Incremental centre hole drilling measurements were performed at 130 mm thickness to better understand near-surface stresses. Weld and heat-affected zone microstructures and microconstituents were evaluated using a combination of hardness mapping, optical microscopy and electron microscopy. The as-welded residual stresses exhibit the characteristic M-shaped distribution for hardenable steels, reaching 500–600 MPa in tension in both steels at both thicknesses. However, the modest changes to the chemical composition and the change in plate thickness both significantly influenced microstructures, mechanical properties and residual stress distributions. These sensitivities underline the need for physically faithful models. This extensive characterisation study enables the development and validation of models that predict the development of microstructures and residual stresses in EB welds in low alloy pressure vessel steels.

The objective of the paper is study the effects of Soil-Foundation- Structure Interaction (SFSI) on seismic response of a deeply embedded Nuclear Island Building (NIB) using the finite element method. The interaction analysis of the NIB is carried out using flexible volume substructure method (FVSM). The SFSI model of the embedded NIB is subjected to a site-specific design ground motion. The computations required to study the seismic response of the NIB are accomplished using the program SASSI 2000. The present study is restricted to the evaluation of floor acceleration response spectrum and acceleration time-history at the selected locations along the heights of the eight buildings housed in the NIB. The floor response spectra (FRS) are useful for the earthquake resistant design of secondary systems located at different floor levels of the NIB. It is noted that the design of nuclear power plant structures should take into account the effect of embedment provided by the engineered backfill.