Characteristic and performance of a simple thoron chamber

Zhao, Chao; Zhuo, Weihai; Chen, B.; Zhang, H.

doi:10.1093/rpd/ncq250

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…The present study also provides insights into calibration and intercomparison processes for diffusion-type thoron detectors. Thoron detectors are calibrated in the atmosphere with a known thoron concentration, which is produced, for example, in thoron calibration chambers (e.g., [33,[41][42][43][44]). Intercomparison exercises are also important for quality assurance and quality control of thoron detectors (e.g., [44][45][46][47]).…”

Section: Discussionmentioning

confidence: 99%

Impact of Wind Speed on Response of Diffusion-Type Radon-Thoron Detectors to Thoron

Omori

Tamakuma

Nugraha

et al. 2020

IJERPH

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Air exchange through a porous medium depends partly on a pressure gradient induced in it, i.e., air-flow conditions of the outer air. Consequently, response of diffusion-type detectors to radon and thoron may vary with air-flow conditions surrounding the detectors. This effect may be significant for thoron measurement because thoron has a shorter half-life than radon. The present study examined response of diffusion-type detectors (RADUETs and one AlphaGUARD) to thoron with respect to wind speed using a thoron calibration chamber. Response of RADUETs to thoron increased with wind speed. Response of the AlphaGUARD increased with wind speed, but it became constant at a high wind speed. Different response trends to thoron between the RADUETs and the AlphaGUARD could be qualitatively explained by flow states induced by the pressure gradient in the filter or the sponge of these detectors. For RADUETs, laminar (Darcy) flow was induced in the sponge in the examined wind speed range, which meant that thoron entry into the detector increased with wind speed. For the AlphaGUARD, laminar flow was induced in the filter in the low wind speed range, whereas flow was changed to turbulent (non-Darcy) flow at a high wind speed for which thoron entry into the detector did not depend on wind speed.

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Section: Discussionmentioning

confidence: 99%

Impact of Wind Speed on Response of Diffusion-Type Radon-Thoron Detectors to Thoron

Omori

Tamakuma

Nugraha

et al. 2020

IJERPH

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show abstract

“…Subsequently, the scintillation cell was purged and filled with nitrogen, following a calibration trial to determine the intrinsic background. Finally, the scintillation cell was connected to a homemade thoron chamber with fixed thoron concentration [35], following another calibration trial to determine the response factor for thoron gas η0 and the accumulation effect coefficient K.…”

Section: Calibration Proceduresmentioning

confidence: 99%

“…To verify the feasibility and accuracy of the measurement method proposed in this study, laboratory experiments were conducted in the thoron chamber at the Shanghai Institute of Measurement and Testing Technology (SIMT) [35]. The proposed method was applied using a self-developed scintillation cell [36], and the thoron concentration was simultaneously measured using a PIPS detector-based device (referred to as "PIPS device" throughout the latter part of this article) for comparison purposes.…”

Section: Laboratory Validation and Testmentioning

confidence: 99%

“…The thoron chamber used in the study has an inner size of 60×90×55 cm 3 and a total volume of about 300 L [35]. It contains four sets of replaceable ion-exchanged solid thoron sources [37], allowing for rapid switching of the activity concentration of thoron gas in the range of 1,000 Bq m -3 to 50,000 Bq m -3 by changing thoron sources.…”

Section: Laboratory Validation and Testmentioning

confidence: 99%

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Thoron gas measurement using an airflow-through scintillation cell with consideration for progeny deposition

Zhao¹,

Liu²,

Chen³

et al. 2023

Preprint

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Accurate measurement of low-level thoron gas and high-accuracy calibration of thoron measurement devices are essential for assessing and preventing thoron radiological risks. This study aimed to develop a thoron gas measurement technique using an airflow-through scintillation cell for both low-level measurement and high-accuracy calibration. To achieve this, a compartment model was developed to estimate the influence of progeny deposition and accumulation on the wall of the scintillation cell to prevent overestimation of thoron. A self-developed scintillation cell was utilized to implement and validate this technique. The lower detection limit and measurement uncertainty were then evaluated to assess the feasibility of the technique for low-level measurement and high-accuracy calibration. The results showed that the compartment model effectively addressed the influence of the progeny deposition. The measurement technique achieved a lower detection limit below 100 Bq m-3 even with the coexistence of 100 Bq m-3 of radon and attained a measurement uncertainty (k = 2) below 10% when the concentration of thoron exceeded 1,000 Bq m-3. In summary, this study developed a reliable and practical thoron gas measurement technique using an airflow-through scintillation cell with consideration for progeny deposition, and is expected to contribute to the assessment and prevention of thoron radiological risk.

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“…Thoron chamber, providing a reference atmosphere for complete and standard testing and calibration of thoron monitors with active or passive sampling, is one of essential equipment in metrology system for thoron [19]. Unlike sound metrological system for radon with the ability of calibration of radon activity concentration below 20 Bq m −3 [20], only a few thoron chambers were established in the world, such as the Canadian CANMET's thoron chamber [21], the German PTB's thoron chamber [22], Japanese NIRS's thoron chamber [23] as well as the thoron chambers in China [24][25][26] and in other regions [27,28]. Most established thoron chambers fundamentally consist of a thoron source and a container of reference atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Development of a thoron chamber for calibration of thoron monitors under natural wind speed conditions

Lv¹,

He²,

Xiao³

et al. 2022

Meas. Sci. Technol.

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To examine the response of diffusion-type detectors for thoron under wind speeds similar to natural air ventilation, a special design thoron chamber was developed with a dynamic circulating air-flow field forced by fans. Wind speeds of 0–0.52 m·s-1 were adjusted by control of the fan rotation rate according to a linear model, with higher wind speeds contributing to more homogenous air flow status. Thoron concentrations, ranging between 3.2×103 and 3.7×104 Bq·m-3, were easily available through different injection conditions and 220Rn gas sources with high and stable emanation coefficient. The stability and homogeneity of thoron concentrations was controlled within 5.0% and the concentrations in the direction of wind speed had minimal differences compared with the other direction. Higher wind speeds also improved the stability and homogeneity of thoron concentrations. The design and construction of the thoron chamber functioned well in controlling thoron concentration. The response of an AlphaGUARD monitor to thoron was examined in the thoron chamber under different wind speeds. The study revealed a monitor response to thoron (rates of thoron infiltration into the detection chamber of the monitor) respectively was from 0.044 to 0.065 under winds speeds from 0.05 to 0.51 m.s-1. Reproducible and controlled expourse conditions can be provided for testing thoron monitors.

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Characteristic and performance of a simple thoron chamber

Cited by 11 publications

References 13 publications

Impact of Wind Speed on Response of Diffusion-Type Radon-Thoron Detectors to Thoron

Impact of Wind Speed on Response of Diffusion-Type Radon-Thoron Detectors to Thoron

Thoron gas measurement using an airflow-through scintillation cell with consideration for progeny deposition

Development of a thoron chamber for calibration of thoron monitors under natural wind speed conditions

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