Re-characterization of pneumatic station position for short irradiations of the IEA-R1 reactor for use in the k0 method

Abstract

This work presents the re-characterization of the pneumatic station irradiation position of the IEA-R1 reactor for use in the k0-INAA method. The thermal-to-epithermal neutron flux ratio (f) and the epithermal neutron flux distribution factor (α) of the IPEN IEA-R1 reactor were determined at the pneumatic irradiation station. To obtain these values, the “bare triple monitor” method was used with 198Au, 97Zr, and 95Zr. To evaluate reproducibility, the temporal variation of these parameters was analyzed, with validation carried out through irradiation of the reference materials G-S-N (granite) and INCT-MPH-2 (mix of herbs), of geological and biological origin, respectively. The results obtained for f and α showed that these values are reproducible and mutually compatible, according to a normal Gaussian distribution within one standard deviation. The results obtained for the elements detected in the samples agreed with the recommended values, with relative errors (bias) below 10%, except for Mn in G-S-N (16.3%). These results indicate that the method can be routinely used by LAN-IPEN researchers for the analysis of geological and biological samples.