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Determination of air-loop volume and radon partition coefficient for measuring radon in water sample.

Lee KY, Burnett WC - J Radioanal Nucl Chem (2013)

Bottom Line: In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation.The results were within 5 % variance throughout the temperature range.The results have shown good agreement between this method and the standard methods.

View Article: PubMed Central - PubMed

Affiliation: Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon, 305-350 Korea.

ABSTRACT

A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0-75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the system designed in this work. WB, 2.5 L glass water bottle; DU, drying unit; RAD7, radon in air detector; A-loop, RAD7 and connection tubing set (blue line); B-loop, water bottle and connection tubing set (red line); V1 and V2, volume of A-loop and B-loop; Vt, volume of bypass tubing (dotted line); C1 and C2, radon activity concentration in A-loop and A + B-loops; , 2-way valves. (Color figure online)
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Fig1: Schematic diagram of the system designed in this work. WB, 2.5 L glass water bottle; DU, drying unit; RAD7, radon in air detector; A-loop, RAD7 and connection tubing set (blue line); B-loop, water bottle and connection tubing set (red line); V1 and V2, volume of A-loop and B-loop; Vt, volume of bypass tubing (dotted line); C1 and C2, radon activity concentration in A-loop and A + B-loops; , 2-way valves. (Color figure online)

Mentions: The designed system consists of two closed air loops (A and B) as shown in Fig. 1. The closed air loop A (A-loop) includes a RAD7, a laboratory drying column (Drierite) and connection tubing up to the cutoff that separates the A-loop from the rest of the system (Vt). The closed air loop B (B-loop) has a glass water bottle, and connection tubing with an aerator at the end. The radon source is a manganese dioxide impregnated acrylic fiber (Mn-fiber), charged with 226Ra in a flow through column (Ra-column), with bypass valves so it can be separated from the closed air loops. The RAD7 has an approximately 0.9 L hemisphere internal sample cell, coated on the inside with an electrical conductor. A solid-state, ion-implanted, planar, silicon alpha detector is at the center of the hemisphere. The high voltage power circuit charges the inside conductor to a potential of 2000 to 2500 V, relative to the detector, creating an electric field throughout the volume of the cell [7]. The electric field propels positively charged particles onto the detector. A 222Rn nucleus that decays within the dome leaves its transformed nucleus, 218Po (t1/2 = 3.10 min; alpha energy = 6.00 MeV) as positively charged ions. The electric field attracts these positively charged ions to the detector, where they are measured. Energy discrimination allows one to select either or both the 218Po or 214Po windows for 222Rn assessment. For faster analyses, the 218Po is preferred, as it will reach radioactive equilibrium with 222Rn in only about 15 min. The 214Po lags behind because of the intermediate beta emitting daughters, 214Pb (t1/2 = 27 m) and 214Bi (t1/2 = 19.9 m) resulting in an equilibration time of approximately 3 h.Fig. 1


Determination of air-loop volume and radon partition coefficient for measuring radon in water sample.

Lee KY, Burnett WC - J Radioanal Nucl Chem (2013)

Schematic diagram of the system designed in this work. WB, 2.5 L glass water bottle; DU, drying unit; RAD7, radon in air detector; A-loop, RAD7 and connection tubing set (blue line); B-loop, water bottle and connection tubing set (red line); V1 and V2, volume of A-loop and B-loop; Vt, volume of bypass tubing (dotted line); C1 and C2, radon activity concentration in A-loop and A + B-loops; , 2-way valves. (Color figure online)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4514466&req=5

Fig1: Schematic diagram of the system designed in this work. WB, 2.5 L glass water bottle; DU, drying unit; RAD7, radon in air detector; A-loop, RAD7 and connection tubing set (blue line); B-loop, water bottle and connection tubing set (red line); V1 and V2, volume of A-loop and B-loop; Vt, volume of bypass tubing (dotted line); C1 and C2, radon activity concentration in A-loop and A + B-loops; , 2-way valves. (Color figure online)
Mentions: The designed system consists of two closed air loops (A and B) as shown in Fig. 1. The closed air loop A (A-loop) includes a RAD7, a laboratory drying column (Drierite) and connection tubing up to the cutoff that separates the A-loop from the rest of the system (Vt). The closed air loop B (B-loop) has a glass water bottle, and connection tubing with an aerator at the end. The radon source is a manganese dioxide impregnated acrylic fiber (Mn-fiber), charged with 226Ra in a flow through column (Ra-column), with bypass valves so it can be separated from the closed air loops. The RAD7 has an approximately 0.9 L hemisphere internal sample cell, coated on the inside with an electrical conductor. A solid-state, ion-implanted, planar, silicon alpha detector is at the center of the hemisphere. The high voltage power circuit charges the inside conductor to a potential of 2000 to 2500 V, relative to the detector, creating an electric field throughout the volume of the cell [7]. The electric field propels positively charged particles onto the detector. A 222Rn nucleus that decays within the dome leaves its transformed nucleus, 218Po (t1/2 = 3.10 min; alpha energy = 6.00 MeV) as positively charged ions. The electric field attracts these positively charged ions to the detector, where they are measured. Energy discrimination allows one to select either or both the 218Po or 214Po windows for 222Rn assessment. For faster analyses, the 218Po is preferred, as it will reach radioactive equilibrium with 222Rn in only about 15 min. The 214Po lags behind because of the intermediate beta emitting daughters, 214Pb (t1/2 = 27 m) and 214Bi (t1/2 = 19.9 m) resulting in an equilibration time of approximately 3 h.Fig. 1

Bottom Line: In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation.The results were within 5 % variance throughout the temperature range.The results have shown good agreement between this method and the standard methods.

View Article: PubMed Central - PubMed

Affiliation: Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon, 305-350 Korea.

ABSTRACT

A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0-75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.

No MeSH data available.


Related in: MedlinePlus