STRUCTURAL EVALUATION OF SPENT FUEL TRANSFER WITH A CRANE

Transfer of spent fuel from the spent fuel pool to concrete casks for long term storage can be accomplished by a variety of designs. In the design under consideration, the fuel is loaded into a welded stainless steel canister in a shielded transfer cask and is then moved to the location having the concrete casks. A gantry crane is used to transfer the shielded transfer cask with the canister from the conveyance to the concrete cask. In this paper, a series of evaluations are presented to confirm the safety of the crane and system. The accelerations from the seismic event are determined from an extensive soil structure evaluation to account for the soil variation as well as the mass distribution due to the partially loaded casks on the pad. Evaluations for the crane use transient analyses in which the results are compared to the allowables defined in the ASME NOG and ASME Section III, Subsection NF Codes. While the peak accelerations are in excess of 0.85g’s the actual bounding loading condition was an obligation to factor the vertical accelerations to enforce parity between the vertical and lateral accelerations applied to the base of the crane. To mitigate the member loading due to crane excitation, the design included the use of viscous dampers. The use of viscous dampers was observed to significantly reduce the system response. Sensitivity studies are performed to ensure that the range of crane motion is captured due to tolerances in the viscous dampers. To capture the bounding conditions due to local crane base and pad compliance, additional studies are presented to examine the effect of local pad stiffness. These analyses employ a detailed model of the crane, cabling and transfer cask for all transient evaluations. Results for the crane evaluations confirm that the crane integrity and canister confinement are maintained during design basis seismic conditions.