National intercomparison programme for radionuclide analysis in environmental samples: Aramar radioecological laboratory performance

The radioecological laboratory is concerned with the measurements of background radiation (mainly uranium and thorium natural series) and present effluents in the Aramar Experimental Centre, as well as in its surroundings. The laboratory is directly subordinated to the Navy Technological Centre in Sao Paulo (CTMSP - Sao Paulo - Brazil), a military research organization whose goal is to develop nuclear and energy systems for the Brazilian naval ship propulsion. The measurements were performed in addition to the Environmental Monitoring Programme carried out in the same region. For this endeavour, the laboratory has attended to the National Intercomparison Programme conducted by the Institute for Radioprotection and Dosimetry (IRD) by analyzing several kinds of solid and liquid samples containing specific radionuclides through gamma spectrometry, liquid scintillation, alpha-beta total counting and fluorimetry techniques, since December 1995. In the last 15 years, our results were compared to another 19 laboratories and rated as 'very good' and 'acceptable' in at least 90% of the results. (author)