Browsing by Author "Wanyama, Conrad Khisa"

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A Radiological Survey in Tailings: A Case Study of Rosterman Gold Mine, Western Kenya
(Open Access Library Journal, 2020-05-13) Wanyama, Conrad Khisa; Makokha, John Wanjala; Masinde, Fred Wekesa
Thirty samples of tailing waste weighing 200 g were randomly collected from both active and inactive tunnels at the Rosterman gold mine site in western Kenya. The average activity concentration of the radionuclides (40K, 232Th and 238U) analyzed by the gamma-ray spectrometry in the tailing samples was 260 ± 14.29 Bq/Kg for 40K, 118 ± 8.25 Bq/Kg for 232Th and 81 ± 3.63 Bq/Kg for 238U. The corresponding radiological parameters for all the collected thirty tailing waste samples were determined from the specific mean activity concentrations. The average dose rate for all the samples was 54 nGy/h. The average radium equivalent value was 262 ± 12.04 Bq/Kg with a range of 154 ± 6.42 Bq/Kg to 350 ± 10.24 Bq/Kg. The average values of external and internal indices were 0.6 ± 0.03 mSv/y and 0.7 ± 0.04 mSv/y respectively. The average indoor and outdoor annual effective dose rates that were determined for this study were 0.3 ± 0.02 and 0.2 ± 0.01 respectively. Therefore, the tailing samples recorded doses and radiological indices below the world average permissible values. This implies that the radiation exposure to the miners and general public due to tailing wastes at Rosterman gold mine poses no significant health risk.
Activity Concentration Levels of Natural Radionuclides in the Sediment Samples from Rosterman Gold Mine, Lurambi Sub – County, Kakamega County, Kenya
(International Journal of Research and Innovation in Applied Science, 2020-07-05) Wanyama, Conrad Khisa; Masinde, Fred Wekesa; Makokha, John Wanjala
Rosterman, located in Lurambi sub - county, Kakamega County, Western Kenya consists of gold mining that is done locally (artisanal gold mining). The activity concentration of 238U, 232Th and 40K in sediment samples from the wastes of gold mining were determined by gamma ray spectrometry using NaI (Tl) detector and decomposition of measured gammaspectra. As a measure of radiation hazard to the general population, gamma radiation dose rates were also evaluated. The average activity concentrations of 238U, 232Th and 40K were 85±2.24, 114±5.78and 260±12.18Bqkg-1, respectively. The mean absorbed dose rate in air was 52.5±4.2nGyh-1 while the annual average effective dose rate for indoor and outdoor were 0.4±0.02 and 0.3±0.01mSvy-1 respectively. The absorbed dose rate due to gamma radiation from naturally occurring radioactive materials was below the global average value of 60 nGyh-1. Hence, mining of gold at Rosterman has minimal hazardous health implicationto the general public.
Annual Effective Dose from Radon-222 Concentration Levels in Underground Water in Bungoma South Sub-County, Kenya
(Journal of Engineering and Technology for Industrial Applications, 2021-04-30) Butik, George Wangila; Makokha, John Wanjala; Masinde, Fred Wekesa; Wanyama, Conrad Khisa
This research measured the concentration levels of radon in groundwater and determined the ingestion and inhalation dose. The study used RAD7 detector with RAD7-H2O accessory from Durridge Company to determine the radon levels. Thirty water samples in granitic dominated regions were collected from various areas of Bungoma County: ten from boreholes (BH), ten from hand dug wells (WL) and ten from springs (SP). The water samples were collected in 250 ml bottles which were tightly covered with lid to avoid radon leakage. The highest value was 303±4.00 KBq/m3 recorded in Kanduyi well and the lowest was 126±11.4kBq/m3 from where most of the samples recorded a high radon concentration with a mean of 269±5.25 KBq/m3 in wells, 213±7.96 KBq/m3 in boreholes and 290±7.70 KBq/m3 in springs. The average ingestion dose was found to be 1.5±0.07mSv/yr, 1.9±0.09 mSv/yr and 2.1±0.1 mSv/yr. The average annual effective dose rate for the samples collected were 2±0.1 mSv/yr for boreholes, 2.6±0.13 mSv/yr for wells and 2.7±0.14 mSv/yr for springs. The samples reported an average.
Assessment of Natural Radioactivity Levels in Tailings From Lurambi Rosterman Gold Mine, Kakamega County Kenya.
(Global Scientific Journal, 2020-07-04) Wanyama, Conrad Khisa; Makokha, John Wanjala; Masinde, Fred Wekesa
Thirty samples were analyzed in the assessment of the activity concentration levels associated with naturally occurring radionuclides materials from Rosterman gold mine. Activity concentration with regard to gamma ray spectrometric analysis was 245±12.39 Bqkg-1; 110±5.15Bqkg-1 and84±4.23Bqkg-1 for 40K, 232Th and 238Urespectively. Averagely, the absorbed dose rate was53.65±6.2 nGy-1, the annual effective dose of 0.4±0.02𝑚𝑚𝑆𝑆𝑣𝑣𝑦𝑦−1 for indoor and 0.3±0.01𝑚𝑚𝑆𝑆𝑣𝑣𝑦𝑦−1 for outdoor were reported. The radiological parameters were averagely valued as 0.7±0.03 𝑚𝑚𝑆𝑆𝑣𝑣𝑦𝑦−1, 0.8±0.04 𝑚𝑚𝑆𝑆𝑣𝑣𝑦𝑦−1 and 278±13.08 Bq/Kg for internal hazard index, external hazard index and radium equivalent respectively. All the radiological parameters were within the recommended permissible values. This therefore points out that gold mining at Rosterman has no significant radiological health implication on the miners and population around.
Natural Radioactivity and External Dose Rates in Tailing Samples from Rosterman Gold Mine, Kakamega County, Kenya
(Journal of Engineering and Technology for Industrial Applications, 2020-12-11) Wanyama, Conrad Khisa; Makokha, John Wanjala; Masinde, Fred Wekesa; Waswa, Michael Nakitare
In this article, documented results of natural radionuclide concentrations in tailings at Rosterman gold mine, Kakamega county, Kenya were evaluated. Thirty tailing samples from Rosterman gold mine were collected as per standard sampling procedures and were analyzed for 238U, 232Th and 40K by NaI (TI) gamma-ray spectroscopy. The activities of 238U, 232Th and 40K was found to vary from 39 ± 1.63 Bq/Kg to 118 ± 4.43 Bq/Kg, 72 ± 2.24 Bq/Kg to 223 ± 8.36 Bq/Kg and 85 ± 3.6 Bq/Kg to 362 ± 10.65 Bq/Kg respectively. Radium equivalent activities were found below 370 Bq/Kg in all the collected samples. External gamma dose rates estimated from the levels of radionuclides in tailings had a range of 32 ±3.4 nGy/h to 68 ± 5.83 nGy/h. Hence, mining of gold at Rosterman has minimal significant health implications to the general population and the miners.
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, 2020-07-04) Wanyama, Conrad Khisa; Makokha, John Wanjala; Masinde, Fred Wekesa; Matsitsi, Stanley Muthama
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.