Mapping of Radon (²²⁰Rn and ²²²Rn) Concentration Distribution in a Microclimate Condition Cellar Using Nuclear Track Methodology

Abstract

This work presents the results of the Radon ( 220 Rn and 222 Rn) measurements made with 486 chips of CR-39 (Allyl Dyglicol Poly Carbonate) MASL ? bared detectors, in a reticular mode distribution, inside of a cellar with average indoor radon concentration 862 ± 49 Bq/m 3 . The exposure time was 3 months, in microclimate condition of constant temperature, humidity, barometric pressure and no airflow. After these 3 months, all the detectors were chemically etched in KOH 6.25 M solution at 60°C ± 1°C for 18 hours, following a very well established protocol for indoor radon survey by the Dosimetry Applications Laboratory of the Physics Institute of the National Autonomous University of Mexico, and later read automatically by CADIS (Counting Automatically Digital Image System). The results show that each one of the nine measured planes is not homogeneous presenting important differences of indoor radon concentration values. Specifically, the Radon ( 220 Rn and 222 Rn) concentration levels vary for each measured point within the cellar. It is a very important observation to consider for the calculation of dose and radiological risk.