Computer-based structural investigation of the SY-103 waste storage tank which contains an out-of-tolerance bottom bump

A computer-based structural analysis was performed on the inner tank of SY-103 in the 241-SY tank farm on the Hanford reservation. The objectives of this study were to determine the general stress condition of the inner tank for selected water-fill, hydrotest heights, and, to investigate the magnitude of local stresses in the vicinity of an out-of-tolerance ''bump'' on the bottom of the inner tank under a loading equivalent to the anticipated waste storage condition. Results show that the stresses induced in flat-bottomed tank, due to hydrotest water-fill are quite low until fill heights in excess of 45 feet are encountered. Filling beyond this level, circumferential membrane compressive stresses in the upper knuckle become great enough to cause concern about the possibility of buckling. If the upper knuckle portion of the tank is effectively supported by the reinforced concrete roof when fill heights of approximately 43 feet are exceeded, the calculated stresses would not develop. Investigation of the measured bottom bump in SY-103 indicates that total flattening will not quite occur under the anticipated operating conditions. Results show that there will be no localized yielding of the tank inner surface when it is filled to normal height with terminal waste slurrymore » at Sp.Gr. = 2.0. The most severe tensile stress condition at the inner surface was slightly less than yield at expected service temperature; it occurred along the bump perimeter where service-filled, pressure flattening of the prior bump curvature caused high flexural stresses.« less