Assessment of the impact of radionuclides in coal ash

An assessment of the potential environmental and health impacts of radionuclides in the coal fuel cycle is being conducted at Mound. This paper describes studies evaluating the potential for migration of radionuclides from ash disposal sites. Studies at a power plant burning western-US coal dealt with an assessment of potential radiation doses from coal ash ponds and leachate discharges of radionuclides from the ponds. Emanation of 222Rn from the ash is relatively low. The emanation of 222Rn from the ash pond (226Ra at 4.5pCi.g-1) is predicted to be about six times less than from soil (226Ra at 1pCi.g-1). Ash with 226Ra at 25pCi.g-1 would approximate emanation of 222Rn from soil. At 1000m from the centre of the ash pond area, 222Rn from the ash pond is predicted to be 1000 to 6000 times less than background (0.1 to 0.5pCi.ltr-1). Pathways exist for transport of radionuclides leached from ash into the aquifer beneath the holding ponds, but concentrations of radionuclides in water leaving the ponds are lower than concentrations in groundwater which is upgradient of the ponds. Leachability of the ash is quite low, on the order of 0.002% in one month, and flow of ash-sluicing water (3% of the volume of the ponds each day) has actually diluted normal background concentrations of radionuclides in the aquifer between the ponds and the adjacent river. (author)