OPTIMIZED DESCRIPTION OF RADIOACTIVE CONTENTS OF PACKAGES FOR IRRADIATED FUEL ASSEMBLIES

For package approval the IAEA regulations require a detailed description of the proposed radioactive contents with reference to their physical and chemical states and the nature of the radiation emitted. Former approvals of casks for irradiated fuel assemblies in Germany were based on fixed combinations of max. enrichment, max. burnup and min. cooling time with respect to dose rate and temperature limitations. Recently, due to higher enrichment, higher burnup, and a great variety of burnup histories, these parameters in the approval led to strong and unnecessary restrictions for the use of the casks. In the present paper the physical parameters for performing the safety analysis with respect to maximum dose rate and temperatures are investigated to derive an optimal description of radioactive contents in package approvals. Presently, this set of parameters is already realised in some German package approvals for CASTOR casks.