Abstract

Radon is a naturally radioactive gas , but it causes lung cancer to humans. The risk of lung cancer due to radiation depends on the amount of radon inhalation and radon exposure time. In Vietnam, radon concentrations are usually determined by RAD7, however RAD7 just showed the immediate values of radon, and have to regularly calibrate it. The construction process to determine the accumulates indoor radon concentration by detector CR- 39 in order to be widely used in the study of environmental pollution, especially the study of health risks of radon for humans and mapping radon pollution.

Detector CR - 39 is placed in a 7 cm - plastic holder, and in exposure time, the holders were covered with glass fiber filter paper ∅ 47mm on the bottom of the detector to avoid the exposure of dust. Then it is hung in the indoor location as Vietnam Standard 7889:2008. After 3 months, holders are returned to a laboratory, and CR - 39 will be soaked in 6M NaOH at 700C. Indoor radon concentrations will be proportional to the density traces obtained on CR-39.

The study uses an radium 226 source of the NIST (National Institute for Standards and Technology) with the released radon coefficient : f = 0.891 ± 0.015. Results show the calibration factor K is 4.533 ± 0.218 [(Bq.m-3. day)]/(tracks / CR-39)]. Using K factor, we can determine the cumulative indoor radon concentration.