Thermal and epithermal neutron fluence rates in the irradiation facilities of the TRIGA IPR-R1 nuclear reactor

the triga ipr-r1 nuclear reactor at the centro de desenvolvimento da tecnologia nuclear cdtn/cnen, belo horizonte, brazil, has three irradiation facilities: a rotary specimen rack outside the reactor core with 40 irradiation channels which provide large scale isotope irradiation; the central tube placed at the center of the reactor core which permits sample irradiation with maximum neutron flux, as well as neutron beam extraction; a pneumatic transfer tube which makes possible the analysis of short half-life radioisotopes. the aim of this work is to evaluate the thermal and epithermal neutron fluence rates in the three irradiation facilities of the ipr-r1. al-0.1%au reference materials were irradiated bare and cd-covered, at 100 kw thermal power, and gamma spectrometry was applied with an hpge detector. for the rotary specimen rack, the values obtained for thermal and epithermal neutron fluence rates are (8.2 ± 0.2) × 1011n.cm-2.s-1 and (3.5 ± 0.1) × 1010n.cm-2.s-1, respectively. for the pneumatic transfer tube and the central tube, epithermal neutron fluence rate values are respectively (3.3 ± 0.2) ×109n.cm-2.s-1 and (2.6 ± 0.1) x 1011n.cm-2.s-1. for these facilities, thermal neutron fluence rate values are (2.5 ± 0.2) × 1011n.cm-2.s-1 and (2.8 ± 0.1) × 1012n.cm-2.s-1, respectively. knowledge of these parameters will be fundamental in the planning of sample irradiation for analysis or radioisotope production in a more accurate way.