γ Spectrometry Analysis Method for ²²⁸Ra in Water Based on Fe(OH)₃-CaCO₃ Carrier

The γ spectrometry analysis method for ²²⁸Ra in water based on Fe(OH)₃-CaCO₃ carrier was developed, which is suitable for the analysis of 228Ra in environmental water. The enrichment method of ²²⁸Ra in water was carried out by Fe(OH)₃-CaCO₃ co-precipitation method. The enriched 228Ra was further loaded by Ba(Ra)SO₄ co-precipitation method, and ²²⁸Ra was determined by ¹³³Ba tracer method. The full recovery rate was measured using high-purity Ge γ spectrometer to measure the characteristic γ energy of the decaying daughter ²²⁸Ac, which reached the radioactive equilibrium with ²²⁸Ra, thereby obtaining the analysis result of 228Ra. Through the calibration of 5 L water sample, it is known that the recovery rate of 228Ra is in the range of 81.8%-87.5%. The relative deviation of the water sample measurement is 1.7%-5.3%, and the detection limit of this method is 57.2 mBq/L.