ADVANCED NUHOMSâ SYSTEM Solution For Spent Fuel Storage At High Seismic Activity ISFSI Sites

The standard NUHOMSâ System licensed under Certificate of Compliance (CoC) 72-1004, stores PWR and BWR spent fuel assemblies in sealed canisters within concrete horizontal storage modules (HSMs) at seven U. S. sites. The Advanced NUHOMSâ System consists of an advanced HSM (AHSM), NUHOMSâ 24PT transportable canister, and NUHOMSâ on-site transfer and off-site transport casks. This paper describes the design of the Advanced NUHOMSâ System. Sites with high seismic spectra and/or requirements for a significant reduction in site-boundary dose are well suited to the AHSM design. The Advanced NUHOMSâ System seismic criteria use the standard response spectrum shape in NRC Regulatory Guide 1.60 anchored at 1.50g ZPA for the horizontal direction. The vertical design spectra are set at two-thirds of the horizontal direction over the entire frequency range. At an Interim Spent Fuel Storage Installation (ISFSI), AHSMs are arranged in arrays to minimize space and maximize self-shielding. Keys and ties between adjacent AHSMs provide maximum resistance to extreme environmental conditions including high seismic loads. The NUHOMSâ 24PT canister is laterally and longitudinally restrained within the AHSM to prevent movement during seismic events. AHSM arrays are fully expandable to permit modular expansion of an ISFSI in support of an operating plant’s storage needs. The NUHOMSâ -24PT canister is a modification of the existing NUHOMSâ 24P transportable canister design with additional provisions for storage and transport of intact and damaged fuel assemblies along with control components in the same canister. The existing NUHOMSâ OS-197 transfer cask is used to transfer the 24PT canisters to the AHSMs. The Advanced NUHOMSâ System uses the existing NUHOMSâ MP187 or the new NUHOMSâ MP197 transport cask for transport of 24PT canisters off-site.