O’Donnell Consulting performed a third party engineering review of the Babcock & Wilcox (B&W) analyses of the head/divider plate/tubesheet/shell complex for the replacement steam generators that were being manufactured for Baltimore Gas & Electric.
The review was performed, addressing the calculation of effective elastic and plastic material properties to be used in representing the perforated tubesheet as an equivalent of solid material, material instability strain computations for SB-18, a plastic collapse analysis of the head/divider plate/tubesheet/shell complex, predictions of the maximum divider plate strain under hydrotest conditions, an estimate of the maximum elastic stress intensity range for cyclic loading, and shakedown analysis.
In addition to the third party review of the B&W analysis, OCE performed efficient Primary Stress analyses of the BG&E steam generators for design and hydrostatic test conditions using elastic-plastic analyses. An independent finite element model was used to perform these analyses, which had more detail and a finer mesh density than the B&W models.
The results showed that the design met the Primary Stress Allowables of the ASME Code, Section III, Subsection NB.