Conceptual study of an intermediate spent fuel storage at the NPP Krsko site

Arguments for spent fuel dry storage at power station site for small nuclear systems in direct fuel cycle are presented. Assuming that such a storage consists of steel lined concrete cylinders containing 21 PWR spent fuel assemblies, additional dose rates at the site were calculated. Standard PWR (16x16) fuel assemblies of NPP Krsko with 33 GWd/MTU and 55 GWd/MTU burnup after 5 and 10 years of cooling time were supposed. Using functional module SAS2 of SCALE modular code, isotope inventory of spent fuel, neutron and gamma angular fluxes and dose rates at several points outside the concrete shield were calculated. Finally, using a simple geometrical model, additional dose rates at site boundaries from arrays of such concrete casks placed upright on a concrete pad were estimated and presented for various assumptions. (author)