Evaluación de la tasa de exhalación de gas radón del café y cacao ecuatorianos utilizando la técnica Electret Ion Chamber

Abstract

In this research the Electret Ion Chamber technique was used to determine the mass and surface exhalation rates of radon gas from samples of Coffee and Cocoa, grown in the province of Orellana. In addition, two methodological approaches were developed, depending on the Electret detection system - Ion Chamber. The first one was called Long Term Methodology (LTM) and the second one Short Term Methodology (STM). The study was carried out at the Nuclear Techniques Laboratory of ESPOCH. The samples of Robusta Coffee and Fine Cocoa were roasted and ground to granulometry of 1mm and 3mm. Additionally, two types of Minerva Coffee and Loja Coffee were analysed at 1mm granulometry. The average surface and mass exhalation rates of Robusta Coffee (1mm) and with MCP are compatible with 3mm particle size, while for Fine and Aroma Cocoa they are higher than with 3mm particle size. The results with MLP show that for Robusta Coffee and 1mm Fine and Aroma Cocoa they exhale more than the 3mm samples, so it can be deduced that the granulometry of the samples influences the exhalation of radon gas. For the evaluation study of average mass and surface exhalation rates, it is suggested that MCP is recommended to MLP, due to the measurement time to obtain accurate results. The comparison of the average rates of mass and surface exhalation of the three kinds of coffee studied (1mm) using MCP, shows that the Loja Coffee presents higher mass and surface exhalation (0.083 Bq/ kg h and 0.712 Bq/ m^2 h respectively), The Fine and Aroma Cocoa (1mm in MCP) in mass exhalation rate, (0.662 Bq/ m^2 h) is compatible within the experimental errors to the Loja Coffee.