Study on background interference in the process of determination of the ultra-low concentration of 226 Ra in water by manganese fiber enrichment-scintillation cell radon measurement method

The determination of the ultra-low concentration of 226 Ra in water samples (< 0.2 Bq/m 3 ) is carried out by using the 226 Ra concentration determination method widely used in oceanography. Various background sources in the determination process were tested and measures to reduce the background were explored. the sum of the residual blank background was reduced to less than 12 mBq after various measures were taken. The requirement of measuring the ultra-low concentration radium solution with concentration < 0.2 Bq/m 3 was met. In this paper, the possibility of further reducing the background is suggested.