The Malaysian Journal of Analytical Sciences Vol 12 No 1 (2008): 179 – 186

 

 

VALIDATION OF Ra-226 AND K-40 MEASUREMENT IN ENVIRONMENTAL SAMPLES USING GAMMA

SPECTROMETRY SYSTEM

 

Yii Mei Wo and Zaharudin Ahmad

 

Industrial Technology Division,  Agensi Nuklear Malaysia

Bangi, 43000 Kajang, Malaysia

 

 

 

Abstract

Mineral and natural resources usually contains long half-life natural radionuclides (such as U-238, Th-232 and K-40) and had been greatly exploited for different utilizations.   When these materials are processed, their  concentration become higher  in the wastes.   Since all these radionuclides have a very long half-life, when concerning about  the safety of members of public, it became a requirement by regulation under the Atomic Energy Licensing Act (Act 304) to control the limits of discharge.  Both U-232 and Th-228 are less soluble and less mobile compared to their decay daughter products (such as Ra-226 for U-238 and Ra-228 for Th-232).  Therefore the determination of these soluble radionuclides, i.e. Ra-226, Ra-228 and K-40 in the environmental samples becomes more important due to their high mobility and solubility. Gamma Spectrometry System was used in the measurement of radium isotopes and K-40, because it is one of the easiest methods to be performed.  This measuring method must be validated for several parameters include specificity, precision (repeatability), bias (accuracy), linearity, range, detection limit, robustness and ruggedness in order to ensure it fits for the purpose.   This work summarizes how these  parameters were fulfilled for this analytical method using several types of certified reference materials.   The same validation method would be considered workable on Ra-228 as well, since both Ra-226 and Ra-228 are isotopic, thus have similar physical and chemical properties.

 

Keywords: Ra-226, K-40, Method Validation, Gamma Spectrometry System

 

References

1.         Povinec P. P., 1994. Sources of Radioactivity in the Marine Environment and their Relative Contributions to Overall Dose Assessment from Marine Radioactivity. IAEA-MEL-R2/94.

2.         Instituto de Pesquisas Energeticas e Nucleares, 1998-1999. Progress Report. Brazil. 87.

3.         Malaysian Institute for Nuclear Technology Research, 2002. Radiation Safety, Second Edition.  Malaysia.  341.

4.         Lawrence Berkeley National Laboratory, 1999.   Source from “The Lund/LBNL Nuclear Data Search  Version 2.0, February 1999” website  http://nucleardata.nuclear.lu.se/nucleardata /toi/.. Accessed on 21 March 2005.

5.         Department of Standards Malaysia, 1999.  ISO/IEC 17025: General Requirements for The Competence of Testing and Calibration Laboratories.  Malaysia.  16.

6.         Ellison,  S.L.R.,  Rosslein,  M.  and  Williams,  A.,  2000.            EURACHEM,  Quantifying  Uncertainty  in   Analytical Measurement, Second Edition. UK.

7.         National Association of Testing Authorities, 1997. Format and Content of Test Methods and Procedures for Validation and Verification of Chemical Test Methods., Technical note. ISBN 0947289151. Australia.

8.         Peter, V., 2003. Method Validation, 4th     Regional Training Course on QA/QC of Nuclear Analytical Techniques.  20-24 October 2003. KAERI, Taejon, Korea.

9.         Yii, M. W., Zaharudin, A., and Kamarozaman, I., 2003.  The Effect Of Surrounding Conditions On The Radioactivities Measurement Using Gamma Spectrometry System. In MTC Proceeding. 22-24 July 2003. MINT, Malaysia.

10.     Omar, M., Ibrahim, M. Y., Hassan, A., Lau, H.M., and Ahmad, Z., 1990.  Enhanced Radium Level in Tin Mining Areas in Malaysia.  In: Proceedings of an International Conference on High Levels of Natural Radiation.  M. Sohrabi, J.U. Ahmad and S. A. Durrani (editors). 3-7 Nov 1990. Ramsar, Islamic Republic of Iran. 191-195.

11.     Debertin, K. and Helmer, R. G., 1988.   Gamma and X-Ray Spectrometry with Semiconductor  Detectors.  Elservier Science. The Netherlands.  399.

12.     Dovlete, C. and Povinec, P.P., 2002.  Quantification of Uncertainty in Gamma Spectrometric Analysis of Environmental samples.   2nd    Regional Training Course on QA/QC of Nuclear Analytical Techniques.   12-16 August 2002. Kuala Lumpur.

13.     LGC Limited, 2001. Method Validation Training Course. 3-5 December 2001. SCK•CEN, Mol, Belgium.