Estimation of radiation hazard indices from syenite building rocks in the South-western region of Cameroon

• Published in: Radioprotection Vol. 52; no. 4; pp. 277 - 280
• Main Authors: Beyala Ateba, J.F., Owono Ateba, P., Simo, A., Ben-Bolie, G.H., Ekobena, H.F., Abega, C.R., Mvondo, S.
• Format: Journal Article
• Language: English
• Published: EDP Sciences 01.10.2017
• Subjects: absorbed dose; effective dose; external hazard index; radium equivalent; syenite building rock
• ISSN: 0033-8451; 1769-700X
• DOI: 10.1051/radiopro/2017023

Radium equivalent (Raeq) and external hazard index (Hex) were estimated based on 226Ra, 232Th and 40K measurements in syenite building rocks collected from various sampling sites of Lolodorf area, South-western region of Cameroon to assess the radiation hazards due to the use of these rocks in dwellings construction. The analysis has been carried out by γ-ray spectrometry using a high purity germanium (HPGe) detector. Raeq varied from 186 ± 4 to 2564 ± 24 Bq · kg−1, while Hex varied from 0.5 ± 0.01 to 6.93 ± 0.06. The corresponding mean values are 1463 ± 930 Bq · kg−1 and 3.95 ± 2.51 in Awanda subdivision while in Madong subdivision, these values are 683 ± 553 Bq · kg−1 and 1.84 ± 1.49, respectively. Absorbed dose rate ranged from 98 ± 2 to 1171 ± 11 nGy · h−1 while annual effective dose ranged from 0.60 to 7.18 mSv · year−1. The average absorbed dose rates are 670 ± 420 nGy · h−1 and 313 ± 245 nGy · h−1 in Awanda and Madong, respectively. These average values give rise to a mean annual effective dose of 4.11 mSv · year−1 and 1.92 mSv · year−1. All syenite building rocks have shown Raeq activity concentrations higher than the limit set in the Organization for Economic Cooperation and Development (370 Bq · kg−1), equivalent to external gamma dose of 1.5 mSv · year−1. The obtained values of the annual external effective dose in Awanda and Madong are higher (nine-fold and four-fold, respectively) than the worldwide mean annual effective dose (0.48 mSv · year−1). The syenite rocks in the corresponding localities can be considered as high radiation's material not recommended for dwellings construction.