Abstract
Currently, in the EU, activities related to storage of spent fuel are constantly increasing. This is particularly true in Finland and Sweden, where final geological repository sites are planned to be operational in 2023 and 2026 respectively, but also in several other countries where fuel is moved from wet ponds to dry storage (Germany, Belgium, Spain, Czech Republic, Bulgaria). The required verification activities present a considerable challenge to the EURATOM Safeguards authority. Both EURATOM and IAEA safeguards need to know the contents of the storage casks and keep continuity of knowledge of the spent fuel. A frequently-used tool for the verification of the nuclear material during loading is the Fork detector for gross gamma and neutron counting. The data acquisition applications RADAR (Remote Acquisition of Data and Review) and CRISP (Central RADAR Inspection Support Package), developed by EURATOM, are used to acquire safeguards measurement data and to analyse them in order to verify the declarations of the nuclear plant operators. Under the framework of the U.S. DOE-EURATOM agreement on nuclear safeguards and security, a module for automated analysis of spent fuel measurement data using the ORIGEN (Oak Ridge Isotope GENeration) code, part of the SCALE nuclear systems modelling and simulation package, has been integrated into CRISP. Measurement data are collected in an unattended mode by RADAR and then processed by CRISP, which outputs, for each fuel assembly, the measured gamma and neutron count rates. In parallel, ORIGEN performs burn-up calculations based on operator declarations previously entered into CRISP and calculates the expected neutron and gamma count rates for each assembly. These calculations use detector response functions, developed using Monte Carlo modelling, to account for the detection probabilities of both neutron and photon particles that originate in each fuel pin. Finally, CRISP correlates and compares the expected (calculated) gamma and neutron signals with the measured values. The comparison is presented to the inspector to help draw safeguards conclusions. This paper will show initial case studies of in-field applications of the CRISP-ORIGEN approach for safeguards inspection activities during the loading of a spent fuel cask.
