Determination of uncertainties of PWR spent fuel radionuclide inventory based on real operational history data

Abstract

An important requirement for the official approval of the safe final disposal of SNF is a comprehensive specification and declaration of the nuclear inventory in SNF by the waste supplier. In the verification process both the radionuclide (RN) activities and the associated uncertainties are required. Burn-up (BU) calculations based on typical and generic reactor operational parameters do not encompass any possible uncertainties observed in real reactor operations. At the same time, details of irradiation history are often missing, what complicates the assessment of declared RN inventories. Here, we present a set of burn-up calculations, in which the real operational histories of 339 published or anonymized PWR fuel assemblies (FA) are taken into account. These histories provide information about ranges of values of the associated secondary reactor parameters (SRP), which are useful for the SRP analysis. Hence, we can calculate realistic variations in the spectrum of RN inventories. SCALE 6.1 has been employed for the burn-up calculations. The results have been validated using experimental measurements from the online database SFCOMPO.