Author(s)

Uwais Al Qarni Ahmed^1,2*, Adriaan Joubert¹

¹National Nuclear Regulator, Eco-Park Estate, Centurion, South Africa.
²CIMERA, Department of Geology, University of Johannesburg, Kingsway Campus, Auckland Park, Johannesburg, South Africa.

Coal-fired power plants (CFPP) provide approximately 40% of the world’s energy demand. Naturally occurring radioactive materials (NORM) contained in coal become enriched in coal combustion residues as a result of the elimination of carbon during combustion. The fly ash and bottom ash produced from CFPP may be significant sources of exposure to naturally occurring radionuclides for the population near the combustion plant or ash dumps. Despite this fact, very few studies have actually addressed the relationship of the NORM enrichment factors and the quality of coal used. This paper aims to relate the quality of coal to the enrichment factors for the radionuclides of interest (K⁴⁰, Ra²²⁶, Th²³² and Po²¹⁰) in coal combustion residues from three South African CFPP. The data from other CFPP was also taken into account to establish this correlation. The feedstock coal used in these CFPP is typically low quality, with ash content in the range of 25 - 45 wt%. The radionuclides investigated were determined by gamma spectrometry with the exception of Po²¹⁰, which was determined by alpha spectrometry. The enrichment factors for the radionuclides of K⁴⁰, Ra²²⁶, Th²³² and Po²¹⁰ in the fly ash and bottom ash (except Po²¹⁰) was found to be directly proportional to the quality of coal. That is when the ash percentage increased (coal quality decreased) the enrichment factor decreased. The Po²¹⁰ radionuclide in the bottom ash had an enrichment factor less than one. The relationship between coal quality and enrichment factors for the radionuclides of K⁴⁰, Ra²²⁶, Th²³² and Po²¹⁰ in both the fly ash and bottom ash (except Po²¹⁰ in the bottom ash) was demonstrated by the following mathematical equation: . This equation may be used as a good indication in obtaining an estimate in determining the enrichment of the mentioned radionuclides in coal combustion products such as fly ash and bottom ash.

Radionuclides, Coal, Enrichment Factor, Coal Quality

Ahmed, U. and Joubert, A. (2019) Establishing a Relationship between Coal Quality and the Enrichment of Radionuclides in Coal Combustion Residues. World Journal of Nuclear Science and Technology, 9, 113-126. doi: 10.4236/wjnst.2019.93008.