“…Neutrons are emitted from SNF discharged from the reactor core through spontaneous fissions, (α, n) reactions, etc., and radioactive activation products are to be produced by interactions of neutrons with surrounding structures or components through neutron activation reactions such as (n, γ) and (n, p). Accordingly, a few studies have been reported on the activation of not only reactor pressure vessels (RPVs) housing the reactor core and internals, but also out-of-core structures, systems, and components (SSCs) including components in the SFP [4][5][6]. A study on neutron activation of metallic storage racks of an SFP in which SF has been stored for 40 years reported that the SFP racks are to be activated to form radionuclides 51 Cr, 54 Mn, 55 Fe, 58 Co, and 60 Co showing activity concentrations of 4.64, 0.64, 3.20, 1.31, and 3.19 Bq/g, respectively, which implies that during the decommissioning of NPPs, the SFP racks could be generated as a radioactive waste subject to land disposal [6].…”