Rapid Determination of Gross Alpha/Beta Activity in Water Based on Reverse Osmosis Membrane Enrichment Pretreatment

Table 3

Measurement uncertainty of total β in each region.

Sites	Reverse osmosis membrane method			Thick source method
	urel(Cβ) (%)	u(Cβ) (Bq·L^−1)	U(Cβ) (k = 2) (Bq·L^−1)	urel(Cβ) (%)	u(Cβ) (Bq·L^−1)	U(Cβ) (k = 2) (Bq·L^−1)
1	8.8	0.008	0.092 ± 0.016	7.8	0.007	0.087 ± 0.014
2	9.1	0.011	0.116 ± 0.021	12.8	0.014	0.106 ± 0.027
3	8.2	0.008	0.103 ± 0.017	9	0.009	0.095 ± 0.017
4	14.1	0.012	0.087 ± 0.025	14.3	0.011	0.08 ± 0.023
5	12.9	0.010	0.078 ± 0.020	13.4	0.010	0.073 ± 0.020
Average value	10.6			11.5

u_rel(C_β) is the relative uncertainty when measuring the concentration of β activity; u(C_β) is the combined uncertainty when measuring the concentration of β activity; U(C_β) is the expanded uncertainty when measuring the concentration of β activity (coverage factor k = 2).