A simple radon chamber for use with soil gas for calibration of radon measuring devices and instruments

Al-Azmi, Darwish; Karunakara, N.

doi:10.1504/ijlr.2011.047183

Cited by 5 publications

(8 citation statements)

References 9 publications

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“…The soil gas as a rich source of 222 Rn and 220 Rn and its use for calibration experiments have been demonstrated earlier by 14,15 for small dimension chambers of volume 0.22 m 3 and 0.13 m 3 respectively. Soil gas was also used as a source of high 222 Rn and 220 Rn concentrations in studies aimed at developing techniques for mitigation of these gases in workplaces [16][17][18] .…”

mentioning

confidence: 84%

“…The extraction was performed using a hand-driven soil gas probe (STITZ, Germany) inserted inside the ground to a depth of about 1 m, as shown in Fig. 2 a, b 14 , 16 . The extraction was carried out at flow rates ranging from 10 to 80 L min −1 , depending upon the experimental requirements.…”

Section: Methodsmentioning

confidence: 99%

“…It was also observed that irrespective of the mode of chamber operation, the concentration stabilization could be achieved very quickly using soil gas. In the majority of the calibration facilities static mode of operation was adopted 5,14,21 . However, this results in a short time exposure of the detectors due to the continuous decay of initially injected 222 Rn with no scope for maintaining temporal stability.…”

Section: Comparison With Other Calibration Chambers Of the Worldmentioning

confidence: 99%

“…The 222 Rn concentration in soil gas of typical background radiation region, with 226 Ra activity of 30 Bq kg −1 (worldwide average value), is expected to vary from 20 to 100 kBq m −3 depending upon the emanation factor, porosity and grain density 22 . In earlier publications, the use of soil gas as a steady source of 222 Rn for small chamber experiments for a sufficiently long duration of up to 9 days was successfully demonstrated 14 . However, its applicability in large chambers and for a long period needs to be examined carefully.…”

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confidence: 99%

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An innovative technique of harvesting soil gas as a highly efficient source of 222Rn for calibration applications in a walk-in type chamber: part-1

Karunakara

Shetty

Sahoo

et al. 2020

Sci Rep

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The paper describes a novel technique to harvest 222Rn laden air from soil gas of natural origin as a highly efficient source of 222Rn for calibration applications in a walk-in type 222Rn calibration chamber. The technique makes use of a soil probe of about 1 m to draw soil gas, through a dehumidifier and a delay volume, using an air pump to fill the calibration chamber. 222Rn concentration in the range of a few hundred Bq m−3 to a few tens of kBq m−3 was easily attained in the chamber of volume 22.7 m3 within a short pumping duration of 1 h. A new technique referred to as “semi-dynamic mode of operation” in which soil gas is injected into the calibration chamber at regular intervals to compensate for the loss of 222Rn due to decay and leak is discussed. Harvesting soil gas has many important advantages over the traditional methods of 222Rn generation for calibration experiments using finite sources such as solid flow-through, powdered emanation, and liquid sources. They are: (1) soil gas serves as an instantaneous natural source of 222Rn, very convenient to use unlike the high strength 226Ra sources used in the calibration laboratories, and has no radiation safety issues, (2) does not require licensing from the regulatory authority, and (3) it can be used continuously as a non-depleting reservoir of 222Rn, unlike other finite sources. The newly developed technique would eliminate the need for expensive radioactive sources and thereby offers immense application in a variety of day to day experiments—both in students and research laboratories.

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mentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Comparison With Other Calibration Chambers Of the Worldmentioning

confidence: 99%

mentioning

confidence: 99%

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An innovative technique of harvesting soil gas as a highly efficient source of 222Rn for calibration applications in a walk-in type chamber: part-1

Karunakara

Shetty

Sahoo

et al. 2020

Sci Rep

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“…In our previous publications, we demonstrated the harvesting of soil gas as a highly efficient secondary source of 222 Rn for calibration experiments 13 – 16 as well as a substitute for 226 Ra source in research studies 17 , 18 . Advantages of soil gas 222 Rn over the conventional sources are instantaneous natural availability, zero regeneration time required, zero cost, and excellent source stability.…”

Section: Introductionmentioning

confidence: 99%

A periodic pumping technique of soil gas for 222Rn stabilization in large calibration chambers: part 2—theoretical formulation and experimental validation

Shetty¹,

Mayya²,

Kumara³

et al. 2020

Sci Rep

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In an adjoining publication, we demonstrated the novel technique to harvest soil gas of natural origin as a highly efficient source of 222Rn for calibration applications in a large volume 222Rn calibration chamber. Its advantages over the use of conventional high strength 226Ra sources, such as the capability to serve as a non-depleting reservoir of 222Rn and achieve the desired concentration inside the calibration chamber within a very short time, devoid of radiation safety issues in source handling and licensing requirements from the regulatory authority, were discussed in detail. It was also demonstrated that stability in the 222Rn concentration in large calibration chambers could be achieved within ± 20% deviation from the desired value through a semi-dynamic mode of injection in which 222Rn laden air was periodically pumped to compensate for its loss due to leak and decay. The necessity of developing a theory for determining the appropriate periodicity of pumping was realized to get good temporal stability with a universally acceptable deviation of ≤ ± 10% in the 222Rn concentration. In this paper, we present a mathematical formulation to determine the injection periods (injection pump ON and OFF durations) for the semi-dynamic operation to achieve long term temporal stability in the 222Rn concentration in the chamber. These computed pumping parameters were then used to efficiently direct the injection of soil gas into the chamber. We present the mathematical formulation, and its experimental validations in a large volume calibration chamber (22 m3). With this, the temporal stability of 222Rn concentration in the chamber was achieved with a deviation of ~ 3% from the desired value.

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CFD-based simulation and experimental verification of 222Rn distribution in a walk-in type calibration chamber

Trilochana

Somashekarappa

Kumara

et al. 2019

J Radioanal Nucl Chem

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A simple radon chamber for use with soil gas for calibration of radon measuring devices and instruments

Cited by 5 publications

References 9 publications

An innovative technique of harvesting soil gas as a highly efficient source of 222Rn for calibration applications in a walk-in type chamber: part-1

An innovative technique of harvesting soil gas as a highly efficient source of 222Rn for calibration applications in a walk-in type chamber: part-1

A periodic pumping technique of soil gas for 222Rn stabilization in large calibration chambers: part 2—theoretical formulation and experimental validation

CFD-based simulation and experimental verification of 222Rn distribution in a walk-in type calibration chamber

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