The severe damage to the Fukushima nuclear plant occurred as a result of a beyond design basis event. This has prompted a systematic review of safety critical systems at US nuclear power plants to evaluate the existing safety margin based on beyond design basis loads.
At one US nuclear power plant it was found that the Refueling Water Storage Tank (RWST) did not have sufficient margin to withstand the defined beyond design basis seismic event. An analysis indicated that the RWST would fail in an elephant foot buckling mode. This paper describes the design and analysis of a Carbon Fiber Reinforced Polymer (CFRP) repair system used to strengthen the RWST to increase the critical buckling stress for the elephant foot buckling mode.