Radiological Evaluation of Quarry Products from Oban Massif, Southeastern Nigeria

A gamma spectrometry analysis using a Thallium-Doped Sodium-Iodide detector has been conducted on rock samples collected from parts of Oban Massif to ascertain the concentration of radionuclide elements: U-(238), Th-(232), and K-(40). The specific objective of this study was to estimate the potential radiological risk associated with the use of rocks from the study area in construction. The estimated radiological hazard indicators showed that the Alpha index ranged from 0.01 to 2.72 Bq/Kg (mean: 0.81 Bq/Kg), and the Gamma index ranged from 0.27 to 5.54 Bq/Kg (mean: 2.35). Internal and external hazard index varied between 0.20 to 5.30 Bq/Kg (mean: 2.20) and 0.19 to 3.82 Bq/Kg (mean: 1.76) respectively, Radium Equivalent ranged from 72.05 to 1406 Bq/Kg (mean: 650 Bq/Kg), Representative Level Index varies from 0.55 to 11.08 Bq/Kg (mean: 4.70 Bq/Kg) and Annual Gonadal Equivalent Dose varied from 248.9 to 5173 (mean: 2070 ). The results showed that, of the 18 surveyed locations, only 3 have quarry products suitable for use as building materials. Others showed results that are above permissible limits. Hence, may pose radiological risks when used as building materials It is worth noting that most quarries in the zone are situated in the Akamkpa, an area observed to have radiologically unsafe rocks, and rocks from this region (Akamkpa) are mostly mined for all sorts of construction purposes, which further implies that those buildings and other constructions made from these materials are radiologically unsafe for humans. Further studies are necessary to assess the potential for mitigating these radiations naturally, since it may be impossible to avoid building in those areas due to urban expansion and population growth.

Keywords: Radiological effect; Quarry products; Radionuclides, Radioelements