Radiological Assessment of the Activity concentrations of 40K, 232Th, 238U and Exposure Levels in the Rosterman Gold Mine of Lurambi Area, Western, Kenya

International Journal of Research and Scientific Innovation (IJRSI) | Volume VII, Issue VII, July 2020 | ISSN 2321–2705

Radiological Assessment of the Activity concentrations of ⁴⁰K, ²³²Th, ²³⁸U and Exposure Levels in the Rosterman Gold Mine of Lurambi Area, Western, Kenya

Conrad Khisa Wanyama¹, John Wanjala Makokha², Fred Wekesa Masinde³, Stanley Muthama Matsitsi^4
1,2Department of Science, Technology and Engineering, Kibabii University, P.O BOX1699-50200 Bungoma, Kenya
³Department of Physical Sciences, University of Kabianga, P.O BOX 2030-20200 Kericho, Kenya
⁴Department of Physical Sciences, South Eastern Kenya University, and P.O BOX 170-90200 Kitui, Kenya

Abstract: Lurambi – Rosterman gold mine consist of miners who engage in daily small-scale artisanal gold mining activities. The gold mine wastes may contain naturally occurring radioactive materials (NORM) which may pose a potential health risk to this population. In this survey, thirty samples were collected from sediments in the tunnels for radioactivity measurements using the NaI(Tl) gamma ray spectrometer. The activity concentrations of ⁴⁰K, ²³²Th and ²³⁸U were 262 ± 11.48, 114 ± 5.78 and 84 ± 2.64 Bqkg^-1, respectively. The mean radium equivalent for all the collected samples was 274 ± 12.90 Bqkg^-1 which is less than the recommended limit of 370 Bqkg^-1. The mean outdoor and indoor annual effective dose rates were 0.4 ± 0.02 and 0.3 ± 0.01 mSvy^-1 respectively. Since the radium equivalent was less than the recommended criterion value, mining of gold at Rosterman poses no radiological hazardous health risk to the miners and the general public.

Key Words:  Annual Effective Dose Rate, Gamma Ray Spectrometric Measurements, Secular Equilibrium

Subject Area: Nuclear Physics and Radiations

I. INTRODUCTION

Ionizing radiations may expose human beings to radiation doses from atomic species like Uranium-238, Thorium-232, Potassium-40, and their decay products which widely spread in the earth’s environment. Naturally Occurring Radioactive materials (NORM) including Uranium and Thorium are found in traces in almost all types of rocks, soil, sands and Waters (1), with specific mean elemental activity concentration for uranium in rock and soil being around 30 Bq/kg (2). Previous studies show that the activity levels of ²³⁸U, ²³²Th, ⁴⁰K and their decay products in sediments depend on local geological composition (3), geographical conditions during rock formation and distributions in the earth crust as well as the geochemical features (2). Other scholarly work shows that natural radiation sources deliver the highest radiation dose to which human beings are exposed to (4).

Read More