Residual Waste from Hanford Tanks 241-C-203 and 241-C-204. 1. Solids Characterization
详细信息 查看全文
- 作者：Kenneth M. Krupka ; Herbert T. Schaef ; Bruce W. Arey ; Steve M. Heald ; William J. Deutsch ; Michael J. Lindberg ; and Kirk J. Cantrell
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：June 15, 2006
- 年：2006
- 卷：40
- 期：12
- 页码：3749 - 3754
- 全文大小：567K
- 年卷期：v.40,no.12(June 15, 2006)
- ISSN：1520-5851
文摘
Bulk X-ray diffraction (XRD), synchrotron X-ray microdiffraction (
XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) wereused to characterize solids in residual sludge from single-shell underground waste tanks C-203 and C-204 at theU.S. Department of Energy's Hanford Site in southeasternWashington state. 
ejkaite [Na4(UO2)(CO3)3] was thedominant crystalline phase in the C-203 and C-204 sludges.This is one of the few occurrences of 
ejkaite reportedin the literature and may be the first documented occurrenceof this phase in radioactive wastes from DOE sites.Characterization of residual solids from water leach andselective extraction tests indicates that ejkaite has a highsolubility and a rapid rate of dissolution in water atambient temperature and that these sludges may alsocontain poorly crystalline Na2U2O7 [or clarkeiteNa[(UO2)O(OH)](H2O)0-1] as well as nitratine (soda niter,NaNO3), goethite [
-FeO(OH)], and maghemite (
-Fe2O3).Results of the SEM/EDS analyses indicate that the C-204sludge also contains a solid that lacks crystalline form andis composed of Na, Al, P, O, and possibly C. Otheridentified solids include Fe oxides that often also containCr and Ni and occur as individual particles, coatingson particles, and botryoidal aggregates; a porous-lookingmaterial (or an aggregate of submicrometer particles) thattypically contain Al, Cr, Fe, Na, Ni, Si, U, P, O, and C; Sioxide (probably quartz); and Na-Al silicate(s). The latter twosolids probably represent minerals from the Hanfordsediment, which were introduced into the tank duringprior sampling campaigns or other tank operation activities.The surfaces of some Fe-oxide particles in residualsolids from the water leach and selective extraction testsappear to have preferential dissolution cavities. If theseFe oxides contain contaminants of concern, then the releaseof these contaminants into infiltrating water would belimited by the dissolution rates of these Fe oxides, whichin general have low to very low solubilities and slow dissolutionrates at near neutral to basic pH values under oxicconditions.
XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) wereused to characterize solids in residual sludge from single-shell underground waste tanks C-203 and C-204 at theU.S. Department of Energy's Hanford Site in southeasternWashington state. ejkaite [Na4(UO2)(CO3)3] was thedominant crystalline phase in the C-203 and C-204 sludges.This is one of the few occurrences of ejkaite reportedin the literature and may be the first documented occurrenceof this phase in radioactive wastes from DOE sites.Characterization of residual solids from water leach andselective extraction tests indicates that ejkaite has a highsolubility and a rapid rate of dissolution in water atambient temperature and that these sludges may alsocontain poorly crystalline Na2U2O7 [or clarkeiteNa[(UO2)O(OH)](H2O)0-1] as well as nitratine (soda niter,NaNO3), goethite [-FeO(OH)], and maghemite (-Fe2O3).Results of the SEM/EDS analyses indicate that the C-204sludge also contains a solid that lacks crystalline form andis composed of Na, Al, P, O, and possibly C. Otheridentified solids include Fe oxides that often also containCr and Ni and occur as individual particles, coatingson particles, and botryoidal aggregates; a porous-lookingmaterial (or an aggregate of submicrometer particles) thattypically contain Al, Cr, Fe, Na, Ni, Si, U, P, O, and C; Sioxide (probably quartz); and Na-Al silicate(s). The latter twosolids probably represent minerals from the Hanfordsediment, which were introduced into the tank duringprior sampling campaigns or other tank operation activities.The surfaces of some Fe-oxide particles in residualsolids from the water leach and selective extraction testsappear to have preferential dissolution cavities. If theseFe oxides contain contaminants of concern, then the releaseof these contaminants into infiltrating water would belimited by the dissolution rates of these Fe oxides, whichin general have low to very low solubilities and slow dissolutionrates at near neutral to basic pH values under oxicconditions.