Validation of Monte Carlo activation calculation for V1 NPP reactor concrete shaft

This work is aimed at developing an advanced model of the Slovak VVER-440/V-230, reactor in the MCNP code, to calculate induced activity in ex-vessel structural components and to validate obtained results to achieve an effective calculation tool for decommissioning purposes. A survey of the V1 NPP operating his-tory revealed that after 12 fuel cycles the shielding assemblies were placed at the core boundary positions thereby reducing the core and decreasing the neutron flux on reactor pressure vessel as well as in adja-cent ex-vessel components. Representative fuel cycles were selected for given periods. Model of the V1 reactor at the core level was developed, covering in-vessel and ex-vessel components. The activation cal-culation of the reactor concrete shaft at the sample volume location was performed using the MCNP5 code with the ENDF/B-VII cross-section library. Activities of selected radionuclides were determined and verified by measurements of samples at the Slovak University of Technology. (c) 2021 Elsevier Ltd. All rights reserved.