Verification of Sr-90 Determination in Water and Spruce Needles Samples Using IAEA-TEL-2016-04 ALMERA Proficiency Test Samples

Authors: S. Visetpotjanakit, N. Nakkaew

Abstract:

Determination of ⁹⁰Sr in environmental samples has been widely developed with several radioanlytical methods and radiation measurement techniques since ⁹⁰Sr is one of the most hazardous radionuclides produced from nuclear reactors. Liquid extraction technique using di-(2-ethylhexyl) phosphoric acid (HDEHP) to separate and purify ⁹⁰Y and Cherenkov counting using liquid scintillation counter to determine ⁹⁰Y in secular equilibrium to ⁹⁰Sr was developed and performed at our institute, the Office of Atoms for Peace. The approach is inexpensive, non-laborious, and fast to analyse ⁹⁰Sr in environmental samples. To validate our analytical performance for the accurate and precise criteria, determination of ⁹⁰Sr using the IAEA-TEL-2016-04 ALMERA proficiency test samples were performed for statistical evaluation. The experiment used two spiked tap water samples and one naturally contaminated spruce needles sample from Austria collected shortly after the Chernobyl accident. Results showed that all three analyses were successfully passed in terms of both accuracy and precision criteria, obtaining “Accepted” statuses. The two water samples obtained the measured results of 15.54 Bq/kg and 19.76 Bq/kg, which had relative bias 5.68% and -3.63% for the Maximum Acceptable Relative Bias (MARB) 15% and 20%, respectively. And the spruce needles sample obtained the measured results of 21.04 Bq/kg, which had relative bias 23.78% for the MARB 30%. These results confirm our analytical performance of ⁹⁰Sr determination in water and spruce needles samples using the same developed method.

Keywords: ALMERA proficiency test, Cherenkov counting, determination of 90Sr, environmental samples.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1340236

References:

[1] Korea Atomic Research Energy Institute, “Table of Nuclides,”http://atom.karei.re.kr, accessed 10 Dec. 2016.
[2] N. Vajda and C. Kim, “Determination of radiostrontium isotopes: A review of analytical methodology,” Appl. Radiat. Isot., vol. 68, pp. 2306-2326, May 2010.
[3] L. Salonen, Determination of Strontium-90 and Strontium-89 in Environmental Samples by Liquid Scintillation Counting, Liquid Scintillation Counting. London: Heyden&Son, 1977.
[4] J. Suomela, L. Wallberg, and J. Melin, Method for Determination of Strontium-90 in Food and Environmental Samples by Cherenkov Counting. Stockholm: Swedish Radiation Protection Institute, 1993.
[5] H.H. Ross, Theory an Application of Cherenkov Counting, Liquid Scintillation Science and Technology. New York: Academic Press Inc., 1976.
[6] A. Shakhashiro, U. Sansone, A. Trinkl, M. Makarewicz, C. Yonezawa, C. K. Kim, G. Kis-Benedek, T. Benesch, and R. Schorn, Report on the IAEA-CU-2006-04 ALMERA, Proficiency Test on the Determination of Gamma Emitting radionuclides IAEA/AL/170. Seibersdorf: International Atomic Energy Agency, 2007.
[7] A. Shakhashiro, A. Fajgelj and U. Sansone, Comparison of Different Approaches to Evaluate Proficiency Test Data, Cambridge: RSC Publishing, 2006.