Assessment of supported radon in ground water from highland area using portable continuous radon monitor

Abstract

ABSTRACT

Ground water contain natural radioactivity associated with uranium and thorium that present naturally in rocks and soils. Humans may be exposed to the emission of energetic alpha particle from supported radon decaying process in this water when it is inhaled or ingested. Assessment of supported radon in ground water was carried out using fourteen ground water samples from Cameron Highlands. The measurement was accomplished by degassing the water samples using pump and then allowing the gas to flow into specially constructed 0.0191 m³ metal chamber. The activity concentration of supported radon in water sample was measured using continuous radon monitor inside the radon chamber. Measurement was carried out at one hour interval for twenty four hours. The hourly supported radon concentration was found to stabilize after about 8 hours.  The stabilized concentration was used to determine supported radon activity concentration in the water samples. Results of the study show that depending on the sampling location, the activity concentrations of supported radon are in the range from 0.09 – 0.48 Bq/L which is lower than the activity concentration of radon in drinking water as proposed by USEPA (11 Bq/L).

ABSTRAK

Air tanih mengandungi radioaktiviti tabii termasuk uranium dan torium yang hadir secara tabii dalam batuan dan tanih. Manusia mungkin terdedah kepada pancaran zarah alfa bertenaga tinggi dari proses penyepaian ‘supported radon’ dalam air ini apabila dihidu atau diminum. Pengukuran ‘supported radon’ dalam air tanih dijalankan menggunakan empat belas sampel air tanih dari Cameron Highlands. Pengukuran telah dilakukan dengan menyalurkan udara kepada sampel air menggunakan pam dan membenarkan gas memasuki kebuk logam bersaiz 0.0191 m³ yang telah diubahsuai. Kepekatan aktiviti ‘supported radon’ dalam sampel air telah diukur menggunakan alat pengesan radon di dalam kebuk radon. Pengukuran telah dijalankan pada setiap satu jam bagi tempoh 24 jam dan kepekatan ‘supported radon’ mencapai kestabilan dijumpai selepas 8 jam. Kepekatan yang stabil itu digunakan untuk mengira kepekatan aktiviti ‘supported radon’ dalam sampel air. Keputusan daripada kajian menunjukkan bahawa bergantung kepada lokasi sampel, kepekatan aktiviti ‘supported radon’ dalam lingkungan dari 0.09 – 0.48 Bq/L di mana lebih rendah daripada kepekatan aktiviti radon dalam air minuman yang dianjurkan oleh USEPA (11 Bq/L).