Stable control of thoron progeny concentration in a thoron chamber for calibration of active sampling monitors

He, Zhengzhong; Xiao, Detao; Lv, Lidan; Zhou, Qingxiang; Wu, Xijun; Jian, Shan

doi:10.1016/j.radmeas.2017.02.013

Cited by 8 publications

(1 citation statement)

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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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