Hostname: page-component-84b7d79bbc-tsvsl Total loading time: 0 Render date: 2024-07-29T21:52:58.071Z Has data issue: false hasContentIssue false
  • English
  • Français

Actinide Microdistributions Within Monazite

Published online by Cambridge University Press:  26 February 2011

E. W. Jalajas ,
A. Kaufman  and
T.-L. Ku
E. W. Jalajas
Affiliation:
Department of Geological Sciences, University of Southern California, Los Angeles, California 90089-0741
A. Kaufman
Affiliation:
Department of Geological Sciences, University of Southern California, Los Angeles, California 90089-0741
T.-L. Ku
Affiliation:
Department of Geological Sciences, University of Southern California, Los Angeles, California 90089-0741
Get access

Abstract

The results of an induced fission track mapping study of uranium in 12 pegmatitic monazite samples indicate that as the U concentration in monazite surpasses ca. 300–400 ppm, the microdistribution becomes much less homogeneous resulting in localized areas of very high uranium concentration (hot spots) in a phase undetectable by XRD. Microprobe analysis of three additional pegmatitic monazites shows the occurrence of exsolution of the two other endmembers of the monazite solid-solution series, huttonite and cheralite, as indicated by a normative mineralogy computed from the probe data. The presence of each mineral is confirmed by XRD. Also supporting this exsolution hypothesis is a strong similarity between ratios of the structural elements of monazite (LREE, P) within the Th-rich hot spots as compared to these ratios in the surrounding monazite. Gradational contacts between banded monazite and a Th-rich phase can be observed microscopically as well as through microprobe scans for Th, indicating the close genetic relationship of the two phases. To prevent their enhanced leachabilities, actinide redistribution must be prevented in any single- or multi-phase nuclear waste form.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 44: Symposium N – Scientific Basis for Nuclear Waste Management VIII , 1984 , 693
Copyright
Copyright © Materials Research Society 1985

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Leonardos, O.H., 1974, Origin and provenance of fossil and recent monazite deposits in Brazil, Econ. Geo. 69:1126–1128.CrossRefGoogle Scholar
2. Overstreet, W.C., 1967, The geologic occurrence of monazite, USGS Prof. Paper 530.CrossRefGoogle Scholar
3. McCarthy, J.G., White, W.B., and Pfoertsch, D.E., 1978, Synthesis of nuclear waste monazites, ideal actinide hosts for geologic disposal, Mat. Res. Bull. 13:1239–45.CrossRefGoogle Scholar
4. Boatner, L.A., Beall, G.W., Abraham, M.M., Finch, C.B., Huray, P.G., and Rappaz, M., 1980, Monazite and other lanthanide orthophosphates as alternate actinide waste forms, in Scientific Basis for Nuclear Waste Management, Vol.2, pp. 289–296, Northrup, C.J.M., Ed., plenum Presss, New York.Google Scholar
5. Beall, G.W., Boatner, L.A., Mullica, D.F., and Milligan, W.O., 1981, The structure of cerium orthophosphate, a synthetic analog of monazite, J. Inorg. Nucl. Chem. 43:101–105.CrossRefGoogle Scholar
6. Floran, R.J., Abraham, M.M., Boatner, L.A., and Rappaz, M., 1981, Geologic stability of monazite and its bearing on the immobilization of actinide wastes, in Scientific Basis for Nuclear Waste Management, Vol.3, pp. 507–514, Moore, J.G., Ed., Plenum Press, New York.CrossRefGoogle Scholar
7. McCarthy, J.G., White, W.B., Smith, D.K., Lasaga, A.C., Ewing, R.C., Nicol, A.W., and Roy, R., 1982, Mineral models for crystalline hosts for radionuclides, in Radioactive Waste Disposal, Vol.1, pp. 184–232, Roy, R., Ed., Pergammon Press, New York, 232 pp.Google Scholar
8. Brookins, D.G., 1984, Geochemical Aspects of Radioactive Waste Disposal, Springer-Verlag, New York, 347 pp.CrossRefGoogle Scholar
9. Davis, D.D., Vance, E.R., and McCarthy, G.J., 1981, Crystal chemistry and phase relations in the synthetic minerals of ceramic waste forms. II. Studies of uranium-containing monazites, in Scientific Basis for Nuclear Waste Management, Vol.3, pp. 197–200, Moore, J.G., Ed., Plenum Press, NewYork.CrossRefGoogle Scholar
10. Shukolyukov, Yu.A., and Komarov, A.N., 1970, Tracks of fission fragments in monazite, Byull. Kom Opred. Absol. Vozrasta Geol. Form., Akad. Nauk SSSR 1970, No. 9, 20–26, (in Russian).Google Scholar
11. Green, P.F., 1981, A new look at statistics in fission-track dating, Nucl. Tracks 5(1–2):77–81.CrossRefGoogle Scholar
12. Gramaccioli, C.M., and Segalstad, T.V., 1978, A uranium- and thoriumrich monazite from a south-alpine pegmatite at Piona, Italy, Am. Mineral. 63:757–761.Google Scholar
13. Finney, J.J., and Rao, N.N., 1967, The crystal structure of cheralite, Am. Mineral. 52:13–19.Google Scholar
14. Ewing, R.C., and Haaker, R.F., 1980, The metamict state: Implications for radiation damage in crystalline waste forms, Nucl. and Chem. Waste Management 1:51–57.CrossRefGoogle Scholar
15. Bevington, P.R., 1969, Data Reduction and Error Analysis for the Physical Sciences (Ch. 8 ndApendi–Tx), McGraw-Hill, New York, 336pp.Google Scholar
16. Hikichi, Y., Hukuo, K.I., and Shiokawa, J., 1978, Solid solutions in systems monazite (CePO4), huttonite (ThSiO4) and monazite Ca0.5 Th0.5 PO4 , Nip. Kag. Kai. 1978(12):1635–1640, (in Japanese).CrossRefGoogle Scholar
17. Silver, L.T., Williams, I.S., and Woodhead, J.A., 1980, Uranium in Granites from the Southwestern United States: Actinide Parent-Daughter Systems, Sites andioTilization, First year report, DOE-GJBX-45(81), 380pp.CrossRefGoogle Scholar
18. Silver, L.T., Woodhead, J.A., Williams, I.S., and Chappell, B.W., 1984, Uranium in Granites from the Southwestern United States: Actinide Parent-Daughter Systems, Sites and Mobil ization, Second year report, DOE-GJBX-7(84), 431pp.Google Scholar
19. Amli, R., 1975, Mineralogy and rare-earth geochemistry of apatite and xenotime from the Gloserheia Granite Pegmatite, Froland, Southern Norway, Am. Mineral. 60:607–620.Google Scholar
20. Clark, A.M., 1984, Mineralogy of the rare earth elements, in Rare Earth Element Geochemistry, pp. 33–61, Henderson, P., Ed., Elsevier, Amsterdam, 510pp.CrossRefGoogle Scholar
21. Ueda, T., 1957, Studies of metamictization of radioactive minerals, Mem. of Coll. of Sci., Univ. Kyoto, Ser. B, 24(2):81–120; as cited in McCartFy, et al., 198U, Table P.15, p. 224.Google Scholar