Comparative analysis of radon, thoron and thoron progeny concentration measurements

Abstract

This study examined correlations between radon, thoron and thoron progeny concentrations based on surveys conducted in several different countries. For this purpose, passive detectors developed or modified by the National Institute of Radiological Sciences (NIRS) were used. Radon and thoron concentrations were measured using passive discriminative radon-thoron detectors. Thoron progeny measurements were conducted using the NIRS-modified detector, originally developed by Zhuo and Iida. Weak correlations were found between radon and thoron as well as between thoron and thoron progeny. The statistical evaluation showed that attention should be paid to the thoron equilibrium factor for calculation of thoron progeny concentrations based on thoron measurements. In addition, this evaluation indicated that radon, thoron and thoron progeny were independent parameters, so it would be difficult to estimate the concentration of one from those of the others.

Long-term measurements of residential radon, thoron, and thoron progeny concentrations around the Chhatrapur placer deposit, a high background radiation area in Odisha, India

“…The thickness of the films was adjusted to absorb the energy of alpha particles from radon, thoron and their progenies except for 212 Po (8.78 MeV). Since the Raduet and thoron progeny deposition detector are inexpensive and easy to use, they are often used in a large-scale survey (e.g., Chen et al, 2012;Janik et al, 2013;Kudo et al, 2015;McLaughlin et al, 2011;Ramola et al, 2010Ramola et al, , 2012.…”

“…On the other hand, the conversion factor for the thoron progeny deposition detector was determined based on results of a field survey (Zhuo and Iida, 2000) and the chemical etching condition, and it was 6.9 Â 10 À2 tracks cm À2 (Bq m À3 h) À1 . In these measurement techniques, when measurement time is set to 90 days, detection limits of radon and thoron concentrations are 5 Bq m À3 and 7 Bq m À3 in the presence of thoron and radon at 15 Bq m À3 for each, while detection limit of thoron progeny concentration is 0.005 Bq m À3 (Janik et al, 2013). Together with radon, thoron and thoron progeny concentrations, ambient gamma dose rates were measured at 1 m above the floor at the center of a room and 1 m above the ground in front of the dwelling entrance.…”

A pilot study for dose evaluation in high-level natural radiation areas of Yangjiang, China

“…On the basis of a linear relationship between them, for a radon-thoron discriminative monitor using CR-39 as an SSNTD [21], we concluded that one measurement period should be approximately 3 months. For measurement of thoron progeny, this period is long enough to measure low concentrations, but not too long to measure high concentrations [22]. Because there is seasonal variation of the weather condition which affects ventilation in dwellings and, as a result concentrations of radon, thoron and thoron progeny, the long-term measurements should be repeated several times to obtain annual average concentrations of them.…”

“…Owing to recent advances in measurement methods, the passive-type monitors with solid-state nuclear track detectors (SSNTD) were developed for the long-term measurements of radon, thoron and thoron progeny concentrations [11,21,22]. However, before using them, optimization of measurement conditions such as deployment position and period is desirable.…”

Impact from indoor air mixing on the thoron progeny concentration and attachment fraction

“…On the experimental side studies on thoron and thoron progeny concentrations in climate chambers and dwellings have been performed (Li et al, 2012;Sorimachi et al, 2015;Janik et al, 2013), using various kinds of measurements techniques. Despite this, little studies have focussed on mitigation strategies to reduce exposure to thoron and its progeny (Vanmarcke, 1996;Wang et al, 2012).…”