Determination of traces of uranium and thorium in environmental matrices by neutron activation analysis

Radioactive elements like Th-232 and U-238 along with their daughter produc ts, form part of all environmental matrices and are getting transferred to living beings by different pathways, leading to a continuos radiation expos ure and need to be monitored. This paper presents an analytical methodology , highlighting the need to separate interfering beta- and gamma-emitters fr om the analytes, when neutron activation analysis is employed fur the deter mination of traces of uranium and thorium in soil and plant materials. The method has been applied to the soil and plant materials from selected regio ns of India, along with standard reference materials to verify the validity of the proposed separation scheme. The overall reproducibility of the proc edure was 2-10%. The concentration values of uranium and thorium so obtaine d, have been used to calculate transfer factors from soil to various parts of wheat plant.