Estimation of neutron fluence distribution within German PWR components for decommissioning studies.

On 15 April 2023, the last German NPPs were shut down. The final shutdown is followed by a post-operational phase in which measures can be carried out to prepare for the NPPs dismantling and decommissioning. One of the tasks in preparation for the dismantling is to acquire accurate knowledge of the activation distribution within the reactor components. The activation levels depend on the neutron fluence within the reactor. Therefore, to achieve this task, a 3D detailed Monte Carlo model of a German PWR has been developed to calculate the neutron fluence characteristics (spectrum and distribution) within the components of such nuclear reactors type. The reliability of the calculations was validated via metal foil-activation measurements carried out in two active PWRs. This paper presents the Monte Carlo model and describes the calculations and measurement procedures. [ABSTRACT FROM AUTHOR]