A Study of the Rn-222 and Ra-226 Analysis in Aqueous Samples with a Low-Level Liquid Scintillation Counter and Pulse-Shape Analysis
Analytical Science and Technology / Analytical Science and Technology, (P)1225-0163; (E)2288-8985
1999, v.12 no.5, pp.428-435
Shin, Hyun-Sang
Lee, Chang-Woo
Lee, Myung-Ho
Cho, Yung-Hyun
Hong, Kwang-Hee
Choi, Geun-Sik
Shin,
H., Lee,
C., Lee,
M., Cho,
Y., Hong,
K., &
Choi,
G.
(1999). A Study of the Rn-222 and Ra-226 Analysis in Aqueous Samples with a Low-Level Liquid Scintillation Counter and Pulse-Shape Analysis. , 12(5), 428-435.
Abstract
A method for measuring Rn-222 and Ra-226 in aqueous sample using liquid scintillation counting technique has been studied. The Rn-222 was extracted easily from the water sample (10 mL) by 12 mL of xylene based organic scintillant. After radioactive equilibrium between Rn-222 and its alpha emitting decay products for three hours, the alpha activity from Rn-222 and its decay products were measured in a scintillation vial using the Wallae $1220^{TM}$ Quantulus liquid scintillation counter. Ra-226 concentration in aqueous sample was determined, after isolation of Ra-226 from the sample matrix, by extraction the ingrowth of the Rn-222 and its alpha emitting decay products with xylene based organic scintillant. The optimum pulse-shape analysis (PSA) value was evaluated by the figure of merit (FM) criterion. Minimum detectable activity (MDA) is about 0.14 Bq/L (3.78 pCi) for the region of Rn-222 and its alpha emitting decay products and 0.06 Bq/L (1.63 pCi) for the region of Po-214 respectively, with 200 min, counting time at PSA level 100 in the low-diffusion polyethylene vial and xylene based cocktail solution. Experiment on the optimum sample-cocktail volume ratio, the influence of agitation and the diffusion of radon from vial were carried out.
- keywords
-
Radon-222 and Radium-226,
liquid scintillation counter