The maiden voyage of the TN 52 L dual purpose cask

The Leibstadt NPP (KKL) spent fuel management strategy consists cooling of the spent fuel assemblies (SFA) at the reactor site prior to reprocessing a limited amount of SFA and storing the remaining SFA in casks at ZWILAG. ZWILAG is a centralised off-site interim storage facility built by the Swiss NPP operators. At some late stage, these SFA could be sent for reprocessing or disposed off. In order to implement this strategy in a cost-effective manner, EGL (on behalf of KKL), having identified the needs and requirements and after a thorough evaluation, contracted transnucleaire to design a dual-purpose high capacity transport cask that could also be used for interim storage. This resulted in the TN 52L design which belongs to the TN 24 family cask. The TN 52L cask can hold up to 52 BWR assemblies, with burnups that can reach 55 GWd/tHM and short 30 month cooling period, for an initial enrichment up to 4,95% in weight. Its heat load is about 53 kW, reduced to about 40 kW due to specific transport constraints. (orig.)