New looks at radionuclides in fly ash: Implications for disposal and utilization

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:549484

Zielinski, R A; Budahn, J R ^[1]

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1. Geological Survey, Denver, CO (United States). Denver Federal Center

The variety of uranium hosts and uranium distributions in fly ash particles was observed using fission-track radiography. The results complement measurements of uranium concentration in bulk samples and permit better prediction of the behavior of uranium during commercial utilization or long term disposal of fly ash. Spheres of clear or Fe-enriched brown glass (cenospheres) showed generally uniform distribution of U with higher U concentration in darker glass. Glass-rimmed spheres filled with a variety of smaller spheres (plerospheres) showed the expected heterogeneous distribution of U in the fill material but retained a uniform distribution of U in glassy rims. Spherical opaque grains of iron oxides can contain moderate amounts of uniformly distributed U. Composite grains of glass and iron oxides or other crystalline material had the expected complex distribution of U. Quartz grains and coal char particles had low uranium concentrations and a few rare spherical crystalline particles showed very high uranium concentrations. High concentrations of uranium on grain surfaces that could be attributed to secondary adsorption were not observed. The relative abundance of U-238 and its long-lived radioactive decay products Ra-226 and Pb-210 was measured in bulk samples of feed coal, fly ash and bottom ash using high precision gamma-ray spectrometry. Preliminary results indicate that U-238 and Ra-226 are not significantly fractionated (within 10%) and therefore the radium (and radon-generating capacity) of fly ash or bottom ash can be estimated from measurements of uranium concentration. In contrast, Pb-210 appears to be preferentially enriched in some samples of fly ash and depleted in bottom ash relative to U-238 and Ra-226. This may be related to the expected greater volatility of Pb during coal combustion.

• OSTI ID: 549484
• Report Number(s): CONF-960954--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
ASHES
DISTRIBUTION
FLY ASH
GAMMA SPECTROSCOPY
LEAD 210
NATURAL RADIOACTIVITY
RADIUM 226
URANIUM
WASTE DISPOSAL
WASTE PRODUCT UTILIZATION