Safety investigations of existing spent fuel storage structures for increased spent fuel storage capacity

Delays in the solution of disposal problems continue to create the need for additional onsite spent fuel storage capacity at commercial nuclear power generating facilities. Rod consolidation within existing storage pools is one interim solution which promises to be an economical and technically feasible means of acquiring the much needed additional capacity. Reanalysis of the pool structure becomes necessary, especially for elevated pools, to requalify for increased storage capacities. Reanalyses usually require some level of sophistication higher than what is normally used in design practice for these large highly redundant reinforced concrete structures in order to effectively handle accident thermal loads and large increases of dead and seismic loads. On the other hand, large scale iterative nonlinear finite element analyses are too costly and unnecessary. This paper presents some practical finite element analysis techniques coupled with reinforced concrete design programs and limit design methods which can be used to obtain safe and economical solutions