Reactor channel characterization is commonly performed by irradiating bare and cadmium-covered “fluence rate monitors”, avoiding
as much as possible the use of irradiation vials and spacers to position the monitors inside the channel. However, in routine
k0-Neutron Activation Analysis often samples are packed in small polyethylene vials prior to irradiation. This work aims at
studying the impact of typical NAA polyethylene vials (~1 mm wall thickness) on the determination of the f and α channel-specific parameters through the “Bare”, “Cadmium-Covered” and “Cadmium-Ratio” methods. The impact of these vials
on each method was studied for 3 irradiation channels of the Belgian Reactor 1 at SCK·CEN (Mol, Belgium) with low to high f and α-values. The net impact was 1% on each parameter. Inconsistencies between the different methods were found when the impact
of the polyethylene was neglected, implying that all determination methods must be pooled and thin monitors should be used
for an accurate channel characterization.