Terrestrial Gamma Radiation in Phuket Island, Thailand

The aim of this study was to evaluate the level of terrestrial radioactivity on Phuket Island, which used to be the richest tin province in Thailand. We measured 124 survey points of terrestrial gamma dose rate at one meter above the surface of local soil along roads in the environs of Phuket Island. Another 31 survey points were examined inside an old ore-dressing plant. The terrestrial gamma dose rate of the Island (excluding the abandoned area of the old dressing plant) ranges from 20 to 900 nGy h-1, while the geometric mean Island value was 190 nGy h-1. Soil samples were also collected from selected areas having high gamma dose rates to analyze for activity concentrations of 226Ra, 232Th and 40K. Based on these soil activities, the calculated terrestrial gamma dose rate found to range between 25 and 520 nGy h-1. The corresponding annual effective doses varied between 0.03 and 0.6 mSv y-1. The results of the terrestrial gamma dose rate obtained from direct measurement in the old tin dressing plant ranged from 110-17,170 nGy h-1 with a mean value of 1410 nGy h-1. The terrestrial gamma dose rate calculated from soil samples in the dressing plant ranged from 590 to 206,080 nGy h-1 which corresponding to annual effective dose of 0.7-250 mSv y-1. Thus, the dose rates on much of Phuket Island are within typical background values while the dose rates within the old tin dressing plant are elevated by as much as 16 times background

Development and evaluation of an impactor sampler for radioactive aerosol particles.

IRPA1

Upgrade of the NIRS radon chamber - generation of aerosol-attached radon progeny -

第3回欧州放射線防護会

Performance of passive thoron progeny monitor

International workshop on radiation biology and radiation protectio

A Simple Technique for Determining the Equiliburium Equivalent Toron Concentration Using a CR-39 Detector

International Conference on Radioecology & Environmental Radioactivit

Territorial Gamma Radiation Dose Rate in Phuket island: Thailand

7th International Conference on High Levels of Natural Radiation and Radon Areas(7HLRRA

An Improved Passive CR-39-Based Direct 222Rn/220Rn

An improved passive CR-39-based direct 222Rn/220Rn progeny detector with 3 detection channels was designed and tested in this study to measure and calculate equilibrium equivalent concentration (EEC) of both 222Rn and 220Rn without the equilibrium factor. A theoretical model was established to calculate the EEC with optimization. Subsequently, an exposure experiment was carried out to test the performance of this detector, and we compared the chamber experiment and the theoretical model by estimating and measuring various parameters. The deposition flux of progeny derived from the prediction agreed well with the value measured in the exposure chamber. The energy-weighted net track density (NTD) measured by this detector is much more reliable to reflect the linear relation between NTD and time-integrated EEC. Since the detector is sensitive to the exposure environmental condition, it is recommended to apply the detector to measure the EEC after its calibration in a typical indoor environment