Upgrade of 400,000 gallon water storage tank at Argonne National Laboratory - West to UCR-15910 high hazard seismic requirements

As part of the Integral Fast Reactor (IFR) Project at Argonne National Laboratory - West (ANL-W), it was necessary to strengthen an existing 400,000 gallon flat-bottom water storage tank to meet UCRL-15910 (currently formulated as DOE Standard DOE-STD0-1020-92, Draft) high hazard natural phenomena requirements. The tank was constructed in 1988 and preliminary calculations indicated that the existing base anchorage was insufficient to prevent buckling and potential failure during a high hazard seismic event. General design criteria, including ground motion input, load combinations, etc., were based upon the requirements of UCRL-15910 for high hazard facilities. The analysis and capacity assessment criteria were based on the Generic Implementation Procedure developed by the Seismic Qualification Utilities Group (SQUG). Upgrade modifications, consisting of increasing the size of the foundation and installing additional anchor bolts and chairs, were necessary to increase the capacity of the tank anchorage/support system. The construction of the upgrades took place in 1992 while the tank remained in service to allow continued operation of the EBR-II reactor. The major phases of construction included the installation and testing of 144 1-1/4 inches x 15 inches, and 366 1 inches x 16 inches epoxied concrete anchors, placement of 220 cubic yards of concrete heavily reinforced, and installation of 24 1-1/2 inches x 60 inches tank anchor bolts and chairs. A follow-up inspection of the tank interior by a diver was conducted to determine if the interior tank coating had been damaged by the chair welding. The project was completed on schedule and within budget