REPRESENTATIVITY STUDY OF THE FRENCH HTC AND FP EXPERIMENTS FOR BURNUP CREDIT APPLICATION TO THE TN® 24 E TRANSPORT AND STORAGE CASK - Presentation

The criticality calculations for a transport and storage cask containing irradiated fuel assemblies associated with the burnup credit practice needs the validation of the criticality codes and the associated cross-section libraries. One of the requirements for the criticality code validation is to demonstrate the similarity between the selected set of critical experiments and the cask configuration. A set of “Haut Taux de Combustion” (HTC) and Fission Products (FP) experiments, co-funded by the AREVA Group and IRSN, was selected for the validation of the criticality code to be applied on the TN® 24 E cask loaded with 21 irradiated UO2 fuel assemblies (12 GWd/tHM). Similarity demonstrations require identifying the neutron-physical parameters of most influence for the cask and the selected critical experiments. The traditional method for assessing the similarity between experiments and an industrial application is to compare global parameters (EALF, H/X, Vm/Vf, etc.) or reaction rates for uranium, plutonium, and fission products. This approach is employed here, with the criticality safety code package CRISTAL V1.0, for the comparison between HTC and FP experiments, on the one hand, and the TN® 24 E cask configuration, on the other hand. It is highlighted that the TN® 24 E configuration is surrounded in terms of spectral parameters and reaction rates by the selected HTC and FP experiments. An alternative way to study the similarity is to use sensitivity/uncertainty (S/U) analysis methods. As a further assessment for the TN® 24 E cask application, its similarity with the selected set of HTC and FP experiments is analysed using the TSUNAMI tools of the SCALE 5.1 package. The TN® 24 E cask sensitivity profiles obtained with the TSUNAMI-3D module are compared to the selected FP and HTC profiles. It is shown that the profiles of the experiments match well those of TN® 24 E cask configuration in terms of magnitude and shape. Computation of the correlation coefficients (ck) with the TSUNAMI-IP module further demonstrate a close similarity between the selected set of HTC and FP experiments and the TN® 24 E cask configuration with irradiated UO2 fuel assemblies.