Assessment of Neutron Flux Gradients in Irradiation Channels at the TRIGA Reactor by Au-Cr-Mo Monitor Set Based on k0-INAA

A gradient of neutron flux distribution in an irradiation channel in research reactor is considered to have effect on the k0-instrumental neutron activation analysis (k0-INAA) measurement. A study has been carried out to determine: (1) the variation of the thermal to epithermal neutron flux ratio (f); (2) the epithermal neutron flux shape factor (!), and; (3) the neutron flux in an irradiation container at four selected irradiation channels, use being made of an Au-Cr-Mo monitor set. In this work, f was found to range from 15.5 – 16.3, while! was found to range from 1.52 × 10-2 – 5.58 × 10-2. Additionally, within the selected irradiation channels the variation in calculated thermal neutron flux within one irradiation container was found to vary from 11.8 %- 26.7%. The results of analysis have provided a determination of variation in the neutron parameters, f and!, and neutron flux between the irradiation channels and within the irradiation container