NX Nastran Case Study

LARGE WASTE WATER TANKS

A series of large waste water tanks were seismically evaluated under rules developed by the ASCE 4-98 (Seismic Analysis of Safety-Related Nuclear Structures and Commentary) and BNL 52361 (Seismic Design and Evaluation Guidelines for the Department of Energy High-Level Waste Storage Tanks and Appurtenances). Finite element analysis was performed using the response-spectrum technique of eigenvalue excitation and summation was employed. Using a design basis earthquake (DBE) spectrum as the base excitation, the tanks were analyzed for structural integrity under ASME guidelines.

Modeling notes: due to the complexity of the numerical routine, care was exercised in the generation of the FEA models using a complex array of solid, plate, beam, rod, and rigid link elements. After several design revisions for each tank, the final tank models meet all ASME pressure vessel allowable stress guidelines.