REVIEW OF BURN-UP CALCULATION VALIDATION FOR SPENT PWR URANIUM OXIDE FUEL INCLUDING ACTINIDES AND FISSION PRODUCTS

With the increasing amount of spent fuel assemblies with high initial 235U enrichment stored at nuclear facilities the need to account for the burn-up of the fuel in criticality safety assessments for transport and storage casks becomes more important. In the past, this burn-up credit was mostly limited to considering the changes in the concentration of the main actinides only, as those isotopes have been investigated thoroughly as concerns burn-up credit. But recently a method for applying burn-up credit based on nine actinides and six fission products to a package for spent PWR uranium oxide fuel (TN 24 E) by TN International has been approved for the first time by the German competent authority BfS. The paper focuses on the review of the validation of the spent fuel nuclide inventory calculation. In order to enable the use of burn-up credit for fission products, experimental data from French post-irradiation examination experiments have been provided by the applicant and reviewed by the German competent authority BfS. The review additionally included post-irradiation examination results from other international sources and calculations with the TRITON module of the modeling and simulation code system for nuclear safety analysis SCALE. Procedures and limitations for the validation of nuclide inventory calculations are discussed. The results also emphasize the need for evaluated high quality PIE data applicable to actinides and fission products.