Natural radioactivity concentration in raw materials used for manufacturing refractory products

¹ Nuclear Science and Technology Research Institute, PO Box, 11365-3486 Tehran, Iran
² National Radiation Protection Department, PO Box, 14155-4494 Tehran, Iran

Abstract

The natural radioactivity due to presence of ²³⁸U, ²³²Th and ⁴⁰K in zirconium minerals used in the Iranian ceramic industry, tiles and waste sludges has been measured. The measurements were made by gamma spectrometry system with a high pure germanium (HPGe) detector connected to multichannel analyzer (MCA). The average concentrations of ²³⁸U and ²³²Th determined in the mineral samples (3000, 500 Bq kg^-1 respectively) are much higher than concentrations found in the earth's crust. The specific activity of ²³⁸U and ²³²Th in tiles (62,54 Bq kg^-1 respectively) are not higher than in other building materials.

The ²³⁸U concentration of sludges (150 Bq kg^-1) is higher than the mean value for the earth's crust. The results are examined on the basis of the existing national limit.