Absolute neutron and photon flux characterization in the CNESTEN’s TRIGA Mark II research reactor

Abstract

The National Center for Nuclear Energy, Sciences and Technology (CNESTEN) located in Rabat, Morocco, operates a 2 MW TRIGA Mark II research reactor. This type of reactor is specially designed to effectively implement the various fields of nuclear research such as neutron activation analysis, neutron radiography, detectors testing, radioisotopes production as well as education and training. In the last few years, a collaboration between the French Atomic Energy and Alternative Energies Commission (CEA) and the CNESTEN was established to expand the utilization of the TRIGA computational model by carrying out new in-situ measurements in order to characterize neutron and photon fields within and beyond the TRIGA reactor core. These new measurements will consolidate the knowledge of neutron and photon fluxes in different irradiation and instrumentation channels. The results of these experiments will also be used to extend the experimental validation of the new developed TRIPOLI-4® computational model of the reactor and to quantify the uncertainties and biases. This paper focuses on the neutron and photon flux characterization of two irradiation channels inside the TRIGA reactor core. Neutron measurements are ensured by activation dosimetry whereas photon measurements are ensured by thermo-luminescent detectors (TLD400 – CaF2: Mn). Based on these techniques, the experiments were carried out during an experimental campaign conducted in June 2022. Preceding the implementation of these measurements, two experimental devices were specifically designed and manufactured to ensure a reproducible positioning of the detectors in the selected irradiation channels. This paper presents the experimental results analysis and the associated uncertainty quantification. These results will be then compared to the calculation ones obtained by the computational models of the TRIGA reactor.

Keywords

• in-core measurements
• triga reactor
• activation detectors
• tld detectors
• ionization chamber