Many pressurized water reactor (PWR) plants have used weld overlays to mitigate the pressurizer dissimilar metal welds that are susceptible to primary water stress corrosion cracking (PWSCC). These configurations typically consist of SA-508 Class 2 low alloy steel welded to a stainless steel safe end by Alloy 82/182 weld metal. The overlay weld metal is typically Alloy 52M. In a few cases, solidification cracking (hot cracking) has been observed on the stainless steel portion of the configuration when the first weld overlay layer is deposited. To overcome this problem, a process consisting of deposition of ER308L or ER309L stainless steel buffer layer for the first layer in conjunction with a low Power Ratio welding procedure has been developed and applied successfully. The Alloy 52M weld overlay is then deposited after the buffer layer. This paper discusses the causes of the hot cracking and test programs to develop the parameters for the welding of the buffer layer and subsequent weld overlay layers. In addition the results of analysis performed to determine the impact of the buffer layer on the post weld overlay residual stresses are also discussed.

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Weld overlays have been used to repair or mitigate stress corrosion cracking (SCC) in both boiling water reactor (BWR) and pressurized water reactor (PWR) nozzle-to-pipe dissimilar metal welds (DMW). One of the contributing factors to SCC is the high tensile residual stresses produced during the fabrication of the original butt weld, especially when local weld repairs were present during the welding process. In analytical simulations to determine the post weld overlay residual stresses, complete simulation of the original butt weld, weld repair and the overlay is desired. However, to reduce the computational effort, it is commonly assumed that the weld repair stresses overwhelm the original butt weld residual stresses such that the original butt weld need not be simulated and only the weld repair is simulated before the application of the overlay. Questions have also been raised as to why the butt weld and/or the weld repair need to be simulated since it is assumed that both of these fabrication processes would be overcome by the weld overlay process. This paper investigates three fabrication sequences in order to determine their effect on the post weld overlay residual stresses: (1) the butt weld is simulated followed by a weld repair and then the weld overlay is applied; (2) the butt weld is simulated followed by the weld overlay with no consideration of a weld repair; (3) the butt weld is not simulated but a weld repair is assumed and the weld overlay is applied. Five different nozzle-to-pipe size configurations were used in the study to determine the effect of pipe size on the three fabrication sequences described above. The investigation indicates that the post weld overlay residual stresses for Cases 1 and 3 are similar and hence simulation of the weld repair alone (without the butt weld simulation) prior to simulating the weld overlay is a reasonable assumption. However, not simulating the weld repair (corresponding to Case 2) may provide different residual stress distribution.

This paper uses textual data contained in certified (q-graded) coffee reviews to predict corresponding scores on a scale from 0-100. By transforming this highly specialized and standardized textual data in a predictor space, we construct regression models which accurately capture the patterns in corresponding coffee bean scores.