Comparative study on U, Th and K concentrations in sediments at the Mae Moh mine and Lam Phra Phloeng Dam.

The concentration of uranium, thorium and potassium in sediment matrices, collected from the Mae Moh mine in Lampang Province, Northern Thailand and from the Lam Phra Phloeng Dam on Nakhon Ratchasima Province, Northeastern Thailand were determined using gamma spectrometry together with a neutron activation analysis technique (NAA). A high purity germanium (HPGe) welltype detector and digital spectrometer were calibrated by reference standard sources to obtain high efficiency for the quantitative evaluation. The concentration of uranium, thorium, and potassium of the Mae Moh mine samples achieved by these techniques was in the range 0.08 to 1.40 ppm, 4.60 to 6.70 ppm, and 0.80 to 1.50%, respectively and significantly lower than the samples collected from the Lam Phra Phloeng Dam which were in the range 2.28 to 2.96 ppm, 8.43 to 16.01 ppm, and 2.04 to 3.30%, respectively. It was shown that the concentration of naturally occurring radioactive materials (NORM) depended on the type and formation age of the sediment.