The chemical compositions of Babcock & Wilcox Nuclear 177 fuel assembly (B&W 177 FA) reactor vessel beltline welds were characterized. Emphasis was placed on copper concentration and variability due to the effect of copper on the fracture and impact toughness properties of irradiated weld metals. Fourteen full section and surveillance program welds were examined. These welds (unique filler wire heats and flux lots) were made with 8 of the 13 heats of filler wire and a majority of the flux lots used in the B&W 177 FA reactor vessel beltline welds. The concentrations of 21 elements were measured using emission spectrographic analysis. A total of 290 through-weld-thickness analyses were performed on these welds that provided a measure of copper concentration and variation. The mean copper concentration of the 14 welds ranged from 0.18 to 0.42% by weight with standard deviation ranging from 0.005 to 0.07% by weight. The mean copper concentration of the 290 analyses was 0.29% by weight. Variability of the other 20 elements was found to be small within each weld.

Electron microprobe analysis was used to assess the micro-variations in copper concentration in a typical reactor vessel weldment. The measured degree of segregation was low.

Additional analyses were performed to determine the quantity of copper available on the weld filler wire that was transferred to the weld deposit during the weld process. The results of these analyses indicate copper concentration equivalence between the filler wire and the weld deposit.