RADIUM ISOTOPES DETERMINATION IN ROCK SAMPLES USING ALPHA SPECTROMETRY

ABSTRACT. In the present paper different methods for radium isotopes determination in the environmental samples are discussed. In the framework of IAEA Contract No 11298 the new procedure is adapted and applied for more precise determination of the Radium isotopes concentration in soil and rock materials. The radiochemical procedure is based on fusion technique for rapid determination of Ra-226 described by R.Bojanowwski at all, 2002. The isotope of Ba-133 was used for determination of the chemical yield. The main steps in the procedure described and discussed in this study are: 1) total sample decomposition by fusion with Lithium Metaborate; 2) dissolution in Na2SO4 and citric acid solution; 3) separation of Barium and Radium by co-precipitation as sulfate; 4) source preparation on 0.1 µm pore size filter by filtration of the fine Ba/Ra-sulfate precipitation; 5) alpha spectrometry of the source for 223Ra, 224Ra and 226Ra isotopes determination immediately after source preparation to avoid Radium daughters growth 6) 133Ba yield determination by gamma spectrometry. The procedure was tested successfully on IAEA-reference materials. Large number analyses for Radium isotopes content in samples of the newly developed reference material from the region of the village of Eleshniza were performed. The proposed material had been previously tested for uranium isotopes content and has shown acceptable homogeneity. The results from radium isotopes determination show homogeneity in Ra concentration and dis-equilibrium with parent uraniu