Determination of uranium fission products interference factors in neutron activation analysis

Neutron activation analysis is a method used in the determination of several elements in different kinds of matrices. However, when the sample contains high U levels the problem of 235U fission interference occurs. A way to solve this problem is to perform the correction using the interference factor due to U fission for the radionuclides used on elemental analysis. In this study was determined the interference factor due to U fission for the radioisotopes 141Ce, 143Ce, 140La, 99Mo, 147Nd, 153Sm and 95Zr in the research nuclear reactor IEA-R1 on IPEN-CNEN/SP. These interference factors were determined experimentally, by irradiation of synthetic standards for 8 hours in a selected position in the reactor, and theoretically, determining the epithermal to neutron fluxes ratio in the same position where synthetic standards were irradiated and using reported nuclear parameters on the literature. The obtained interference factors were compared with values reported by other works. To evaluate the reliability of these factors they were applied in the analysis of studied elements in the certified reference materials NIST 8704 Buffalo River Sediment, IRMM BCR- 667 Estuarine Sediment e IAEA-SL-1 Lake Sediment. (author)