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

This work presents the re-characterization of pneumatic station irradiation position of IEA-R1 reactor for use in k0-INAA method. The thermal-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 – 95Zr.  To evaluate its reproducibility, the temporal variation of these parameters was analyzed, with validation carried out through irradiation of reference materials of geological origin G-S-N (granite) and biological INCT-MPH-2 (mix of herbs). The results obtained for f  and α show that such values ​​are reproducible and compatible with each other, according to the normal Gaussian distribution for up to 1 standard deviation of confidence. The results obtained for the elements detected in the samples agree with the recommended values, with relative errors (bias) less than 10%, except in the case of Mn in G-S-N (16.3%). These results indicate that it is possible to routinely use this method for LAN-IPEN researchers to analyze geological and biological samples.