The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
DETERMINATION OF Sr-90 IN MILK
N. ASLAN. Ü. YÜCEL
Sarayköy Nuclear Research and Training Center (SANAEM), Radioactivity Measurement and Analysis Unit, 06983, Saray, Kazan- ANKARA
e-mail: nazife. aslan(a>,taek. eov. tr
Commission Recommendation (8 June 2000) on the protection of the public against exposure to strontium-90 in milk supplies (2000/473/Euratom) gives reporting levels. Turkish Atomic Energy Authority (TAEA) is responsible for carrying out the national environmental radiological survey. For this reason, a monitoring program was planned to provide relevant information on radioactivity levels in different components such as spinach, milk, meat, soil and grass. The measurement o f Sr-90 is also necessary for radiation protection purposes. Because Sr-90 has long physical and biological half-lives and could be in taken by man through food chain transfer and accumulates in bones. Strontium has been widely measured in milk samples by using various classical methods. In this study, the procedure we used is based on the separation of Y-90 by HDEHP extraction and counting the Cerenkov radiation by liquid scintillation spectrometer, Quantulus 1220. Prior to analyses, spiked milk samples were dried and prepared as milk powder. Microwave ashing programme was optimized and recovery of the radiochemical separation steps was tested for spiked milk powder samples before routine analysis. This method is found to be applicable for the routine analysis of Sr-90 in milk samples after validation o f the method by measuring IRMM milk powder sample, too. The lower limit of detection about 0.013 Bq/L was obtained for samples in the case of 84-99 % Y chemical yield, 1.45 cpm reagent blank, 3 x 60 minutes counting time and about 73.7 % counting efficiency.
