Development and characterization of a large thermal neutron beam for neutron radiography at Isfahan MNSR

Abstract

The feasibility study of performing neutron radiography (NR) at the Isfahan Miniature Neutron Source Reactor (MNSR) was carried out in the previous work that was including calculations and experiments in support of the implementation of a prototype NR beam tube. Results were shown the obtained neutron beam from that prototype beam tube had appropriate conditions for NR and it is possible to obtain a large NR beam at this low power research reactor. The main disadvantage of the prototype beam tube was the small size of the beam port with diameter of 5 cm. In this study, a large diameter beam tube is designed and installed at the reactor. This beam tube has a telescopic divergent shape and is installed in the west side of the reactor pool. The neutron beam parameters and image quality of the obtained beam from this beam tube are measured based on ASTM-E545. Results showed that this neutron beam has good quality for NR experiments over a beam diameter of about 25 cm. Also, a simple and practical system, for fill and drain water to the beam tube, is designed and incorporated as a beam shutter in order to maintain the radiation safety.