Assessment of the Radiological Impact of Coal Utilization. II. Radionuclides in Western Coal Ash

摘要

A project has been initiated at Mound Facility specifically to evaluate the potential radiological impact of coal utilization. Phase I of the project included a survey of western US coal mines and an assessment of emissions from a power plant burning Western coal. Concentrations of uranium in coal from operating Western mines were slightly below the national average and roughly comparable to Eastern coal. Environmental deposition of radionuclides from stack emissions over a 20-year accumulation at a power plant burning Western coal was estimated to be 0.1 to 1.0% of measured background. Phase II of the project, the subject of the present report, has involved an interlaboratory comparison of results of radioanalytical procedures, determining partitioning coefficients for radionuclides in bottom ash and fly ash, and an assessment of the potential for migration of radionuclides from ash disposal sites. Results from the various laboratories for uranium-238, uranium-234, thorium-230, radium-226, polonium-210, thorium-232, thorium-228, and uranium-235 were generally in very good agreement. However, values for lead-210 in coal varied widely. Essentially all the nonvolatile radionuclides (uranium, radium, and thorium) from feed coal were accounted for in fly ash and bottom ash. However, 20 to 50% of the volatile radionuclides (lead and polonium) from subbituminous and lignitic coals could not be accounted for in ash, and it is assumed that this fraction exits via the stack. At the power plant burning bituminous coal, essentially all the lead and most of the polonium remained with the ash. (ERA citation 06:015633)