RADIOACTIVITY LEVELS AROUND THE JOS TIN MINES AND MILLS

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Date
1995-10
Authors
RABIU, NASIRU
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Abstract
Cassiterite, the most common tin bearing mineral is associated with a number of mineral impurities such as monazites, zircon, thorite and xenotime which contain radioactive U and Th that may constitute radiological hazard. The interest of this work is therefore to determine the level of radiological hazards associated with the activities of tin mining and milling. To this end, 55 samples of soil, minerals, plants and water collected around the Jos tin mines and mills were analysed for gross radioactivity using G-M tube and liquid scintillation counter in the case of water samples. The gross activity of the soils and plant range from 0.1 - 6.0 Bq/g and that of the water sample range from 0.1 - 0.3 cps. The highest activity was recorded in the monazite waste (95.9 Bq/g) and zircon (77.4 Bq/q) samples. Nine of the soils and minerals samples that were found to have appreciable activity were subsequently analysed using 3" x 3" Nal(Tl) detector coupled to a computer and the U and Th concentrations were determined. The U and Th concentrations range from 61 - 2042 ppm and 104 ppm to 2.7% respectively. The dose contribution from the U and Th were then calculated. The doses obtained were found to be within the maximum permissible dose of 5 rem/yr (50 mSv/yr) for radiation workers except in two cases where doses of 37 rem/yr (370 mSv/yr) and 79 rem/yr (790 mSv/yr) were obtained. But, all were found to be higher than the maximum permissible dose of 0.5 rem/yr (5 mSv/yr) for the general population. This makes monitoring around the tin mines and mills mandatory. However, this will only be possible when the necessary laws on radiation protection are made by the Government.
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Thesis submitted to the Postgraduate School, Ahmadu Bello University, Zaria, in partial fulfillment of the award for the degree of Master of Science in Physics. Department of Physics Ahmadu Bello University Zaria October, 1993
Keywords
RADIOACTIVITY,, JOS TIN MINES,, MILLS
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