Performance evaluation of the Laboratory for Neutron Activation Analysis, CDTN, in the application of the k₀ method to geological samples by the IAEA-WEPAL Proficiency Testing

The Members States have been supported by the IAEA related to increasing the application of neutron activation analysis (NAA) and, consequently the utilization of their research reactors. Neutron activation technique is well known for determining several elements in diversified matrixes. As an analytical technique NAA has the responsibility to produce accurate and reliable elemental data, Proficiency Test scheme is an important tool to evidence the quality of results produced by the laboratory. This participation is one of the requirements of the ISO/IEC 17025 in order to guarantee the quality of sample results. Between 2010 and 2017, the IAEA provided such interlaboratory comparison rounds in association with the Wageningen Evaluating Programs for Analytical Laboratories (WEPAL), The Netherlands. This institution, that is accredited by the Dutch Accreditation Council, RvA, since 2000 for the organization of inter-laboratory studies, was the provider of such schemes. The Laboratory for Neutron Activation Analysis, Nuclear Technology Development Centre (CDTN/CNEN) participated is these intercomparison rounds analysing biological and geological matrixes. This paper is about the high performance of the Laboratory for Neutron Activation Analysis on determining the elemental mass fractions in geological matrix applying the k₀-method in the rounds ISE 2013.4, 2015.1, 2015.2 and 2017.3 for soil samples. The good results from 2015 on, categorized as "excellent" basing on the criteria established by members of the IAEA, point out that the principles of QA/QC in the routine and in research analytical work of the LAN-CDTN, are producing reliable results. (author)