Fast Neutron-Flux Monitoring Instrumentation for Lead Fast Reactors: A Preliminary Study on Fission Chamber Performances

Although Sodium Fast Reactors (SFRs) are the most investigated solutions for the future fast-flux facilities so far, Lead Fast Reactors (LFRs) promise to be a very competitive alternative thanks to their peculiarity concerning coolant-safety, fuel cycle and waste management. Nevertheless, the development of LFRs presents today some drawbacks still to be solved. Due to the harder neutron flux, the current instrumentation developed for SFRs is likely to be extended to LFRs as a first attempt. Otherwise, new monitoring instrumentation could be developed in order to assure more tailored results. Different measurement technologies can be considered for fast flux monitoring and flux absolute measurements in order to provide a reliable and quick calibration of the overall reactor neutron instrumentation. The goal of this paper is to study the validity of typical fast reactor fission chamber designs (e.g. SuperPhénix fission chambers), indicating which are the limitations when used in a LFR environment. Afterwards, alternative detector solutions with enhanced sensitivity and response will be proposed.