Direct determination of radionuclides in building materials with self-absorption correction for the 63 and 186 keV γ-energy lines

• Proposed procedure allows to determine 238U from the 234Th line (63 keV) and 226Ra after subtraction of 235U interference in the 186 keV.
• It is important in the case of low uranium concentration and weak intensity of 235U 143 keV γ energy line, when activity of this radionuclide can be apprised on the natural constant 238U/235U ratio, only.
• Therefore, by this method a direct and fast determination of the 226Ra, without one month waiting period for 226Ra-222Rn daughter equilibrium, is possible.

The use of 911 keV and 129 keV γ-line intensity ratio has been applied for self-absorption correction of the 63 keV 234Th (238U) and 186 keV(226Ra and 235U) lines in typical building materials and soil samples. Proposed procedure allows to determine 238U from the 234Th line (63 keV) and 226Ra after subtraction of 235U interference in the 186 keV. It is important in the case of low uranium concentration and weak intensity of 235U 143 keV γ energy line, when activity of this radionuclide can be apprised on the natural constant 238U/235U ratio, only (excluding accidental anthropogenic depleted uranium deposition in the soil samples). Therefore, by this method a direct and fast determination of the 226Ra and other important radionuclides, without one month waiting period for 226Ra–222Rn daughter equilibrium, is possible. The accuracy of the method has been confirmed (relative relation deviation <10%) for typical buildings materials such as: tales, bricks, concrete blocks and various type of ceramic materials.