Fission chambers characterization outside ALFRED reactor vessel

This thesis presents the characterization of fission chambers for neutron monitoring in the external region of the ALFRED reactor vessel, a European demonstrator for Lead-cooled Fast Reactor (LFR) technology. The study is based on a dedicated Monte Carlo simulation framework aimed at evaluating neutron and photon fluxes under realistic operating conditions. A simplified yet representative model of the reactor geometry was developed to estimate the radiation environment outside the vessel. Several commercially available fission chambers were analyzed in terms of their sensitivity across thermal, epithermal, and fast neutron spectra. The results provide quantitative insight into detector response, operational constraints, and optimal deployment strategies, supporting the development of reliable neutron instrumentation for Generation IV fast reactors.