New reference materials (RMs), zirconium silicate, bauxite and phosphogypsum, were produced and characterized according to an ISO guide. The homogeneity of the three RMs was evaluated using X-ray fluorescence (XRF), and characterizations of the three candidate materials were performed through a collaborative study with nine expert radioanalytical laboratories. The assigned radionuclides are 230Th, 232Th, 234U, 235U, and 238U for zirconium silicate; 230Th, 232Th, 234U, and 238U for bauxite; and 226Ra, 230Th, 234U, and 238U for phosphogypsum.
Keywords: Naturally occurring radioactive materials; Reference materials; Thorium; Uranium.
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