Applying multi-incremental sampling methodology to soils for radiological and environmental risks evaluation

Abstract

Multi-increment soil sampling is a methodology that allows evaluating environmental liability inside decision unit, providing a representative aliquot for laboratory analysis with associated uncertainties lower than conventional sampling. The literature has reported much works about environmental liabilities evaluation in soil using multi-increment sampling however, for nuclear facilities soils are practically nonexistent. Therefore, aim of this study was to determinate radionuclides concentration (by Gamma spectroscopy), major and minor constituents (by X-ray fluorescence spectrometry) and metals (by Inductively Coupled Plasma-Atomic Emission Spectrometry) in soils of nuclear material storage facilities in Nuclear and Energy Research Institute (IPEN/CNEN-SP) using multi-increment sampling. The natural radionuclides (210Pb, 226Ra, 228Ra, 238U), major and minor constituents (MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, and others) and metals (Cr, Fe, Co, Ni, Zn, As, Pb, and other) were determined in 120 soil samples, in-depth between 0 and 150 mm at 30 quadrants. The results showed specific activity of 57 ± 16 Bq kg-1 (210Pb), 51 ± 22 Bq kg-1 (226Ra), 81 ± 12 Bq kg-1 (228Ra) and 48 ± 14 Bq kg-1 (238U), corresponding uncontaminated soil, according reference values. With regarding metals concentration, results also were lower than values reference. The statistical tests showed that methodology is efficient for environmental impact studies and monitoring programs and adequate to attend established conditions in IPEN-CNEN / SP environmental licensing.