Calibration of the short irradiation facility for K0 − NAA implementation at the IEA-R1 Reactor

The short irradiation facility of the IEA-R1 nuclear research reactor at IPEN, Sao  Paulo,  Brazil , has been used for short irradiation of samples for the purpose of determining the concentration of elements of these samples through the use of the instrumental neutron activation analysis technique. With the aim of implementing the k 0 -NAA method at the Neutron Activation Analysis Laboratory (LAN), the reactor parameters a  and f were obtained using the bare triple method. In this method, a set of three neutron flux monitors were irradiated  without Cd-cover. The efficiency curve of the gamma-ray spectrometer used  was  determined by measuring calibrated radioactive sources at the  commonly used  counting geometries. The results for the parameters  a  and f were respectively 0.0384 ± 0.0016 and 35.67 ± 0.26.  This  value of f shows that the neutrons in the irradiation position are well  thermalized . The  variation of these parameters was studied with time and the reproducibility was verified.