Determination of the linear behavior of FC detectors in Isfahan MNSR using ex-core offline and online experiments

Abstract

The linear behavior of fission chamber (FC) neutron detectors in Isfahan miniature neutron source reactor (MNSR) was investigated experimentally. FC neutron detectors are installed near the reactor core to measure the produced neutron flux in the core. The linearity of the response of these detectors is important because the measured neutron flux by them is one of the important methods in determining and controlling the reactor power and therefore affects the safety of the reactor. For this purpose, the measured neutron fluxes by these detectors at different reactor powers were compared with the measured neutron flux at the output of the external beam tubes by different methods. In this study, two online and offline neutron flux detection methods were used to analysis the linear behavior of MNSR neutron detectors. The BF3 detector and solid-state nuclear track detector (SSNTD) were used to determine the neutron flux in the online and offline methods, respectively. The results of two diverse methods showed that the response of MNSR FC detectors for measuring the reactor power is linear with acceptable accuracy in the neutron flux range between 5×107 to 1012n.cm−2. s−1, which is equivalent to reactor power of 1.5 W to 30 kW.