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

Trilochana, S; Somashekarappa, H.M.; Kumara, Karthik; Mayya, Y. S.; Karunakara, N.

doi:10.1007/s10967-019-06957-0

Cited by 7 publications

(2 citation statements)

References 22 publications

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“…To proceed further, we make an important assumption that the injected activity spreads rapidly in the chamber due to a mixing element such as fan, leading to spatially uniform 222 Rn concentration. Detailed studies conducted with a 22.7 m 3 calibration chamber at CARER 8 , 13 with a mixing fan of capacity 3,620 m 3 h −1 have shown that time required for attaining uniform concentration is < 10 min, which is much smaller than the pump OFF period ( T 2 ). With this experimental data we can convert the activities A n ’s to concentrations C n ’ as follows: …”

Section: Mathematical Formulation Of the Model And Solutionsmentioning

confidence: 99%

“…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%

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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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Section: Mathematical Formulation Of the Model And Solutionsmentioning

confidence: 99%