Radioactive characteristics of the spent fuel of the Finnish nuclear power plants

The composition and radioactive characteristics of the spent fuel of the Finnish nuclear power plants have been estimated with the ORIGEN-S computer code of the SCALE-5 program package over a long range of cooling time. First the case- and burnup-dependent ORIGEN-S cross section libraries have been generated with the TRITON module, which includes a two-dimensional transport code NEWT allowing a quite precise definition of the geometry of the fuel bundles. Then the irradiation and subsequent cooling of the homogenized bundles have been calculated using ORIGEN-S as a stand-alone code. Radioactive characteristics of three different fuel types (VVER-440, BWR and EPR fuel bundles) have been calculated. For each fuel type the initial enrichment and the discharge burnup have been varied. The main results of the calculations are the composition, activity, alpha activity, decay heat production and radiation (photon and neutron) source terms of the spent fuel as a function of cooling time (at 51 time points). Only the most important data of the large ORIGEN output files have been given in the tables and figures of the report. (orig.)