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Alpha-Decay Damage and Annealing Effects in Natural Pyrochlores: Analogues for Long-Term Radiation Damage Effects in Actinide, Pyrochlore, Structure Types

Published online by Cambridge University Press:  26 February 2011

G. R. Lumpkin  and
R. C. Ewing
G. R. Lumpkin
Affiliation:
Dept. of Geology, Un. of New Mexico, Albuquerque, NM 87131, USA
R. C. Ewing
Affiliation:
Dept. of Geology, Un. of New Mexico, Albuquerque, NM 87131, USA
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Abstract

Cubic pyrochlore structure types, A2-mB2O6(O, OH, F) i-n*pH2O, and their derivatives (e.g., monoclinic zirconolite) are important actinide-bearing phases in polyphase, ceramic waste forms (e.g., SYNROC). These waste form phases may typically accumulate alpha-decay doses of 1025 alpha-events/m3 in 1, 000 years or 1026alpha-events/m3 in one million years (i.e., for SYNROC with 20 wt. % HLW). Natural pyrochlores have calculated doses ranging from 1024 to 1027 alpha-events/m3 (= 0.02 to 50 dpa) which have accumulated over ten to a thousand million years. Actinide doping experiments typically reach doses of 1025 alpha-events/m3over periods of several years. Detailed x-ray diffraction analysis of natural samples reveals that the alpha-decay dose at which there is an initial loss of crystallinity (i.e., transition from crystalline to the aperiodic, metamict state as a result of alpha-decay damage) increases as a function of the geologic age of the sample. The increase in the calculated alpha-decay dose which is associated with a specific degree of damage (e.g., loss of x-ray diffraction intensity) is attributed to annealing of isolated alpha-recoil tracks back to the original, crystalline structure. Based on a model of gradual track fading, the alpha-recoil tracks in natural pyrochlores have mean lives on the order of 108 years. In contrast, minerals which remain crystalline (e.g., uraninite, UO2) despite doses of over 1027 alpha-events/m3 have mean alpha-recoil track lives of approximately 104 years. This demonstrates that the microstructure of alpha-decay damaged materials depends not only on the total alpha-event dose, but also on the annealing kinetics of alpha-recoil track fading. Therefore, the prediction of the long-term performance and final state of crystalline phases in ceramic nuclear waste forms requires the determination of alpha-recoil damage annealing as a function of time and temperature.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 127: Symposium BERLIN – Scientific Basis for Nuclear Waste Management XII , 1988 , 253
Copyright
Copyright © Materials Research Society 1989

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References

REFERENCES

[1] Lumpkin, G. R. and Ewing, R. C., in Scientific Basis for Nuclear Waste Management VIII, edited by Jantzen, C.M., Stone, J. A. and Ewing, R. C. (Mater. Res. Soc. Proc. 44, Pittsburgh, PA, 1985) pp. 647–654.Google Scholar
[2] Kesson, S. E. and Ringwood, A. E., in Scientific Basis for Nuclear Waste Management VIII, edited by McVay, G. (Elsevier Science Publishing, New York, 1984) pp. 507–512.Google Scholar
[3] Harker, A. B. and Flintoff, J. F., in Scientific Basis for Nuclear Waste Management VII, edited by McVay, G. (Elsevier Science Publishing, New York, 1984) pp. 513–520.Google Scholar
[4] Morgan, P.E.D., Harker, A.B., Flintoff, J.F., Shaw, T.M., Clarke, D.R., in Advances in Ceramics 8. edited by Wicks, G.G. and Ross, W.A. (American Ceramic Society, Columbus, OH, 1984) pp. 234–246.Google Scholar
[5] Morgan, P.E.D., Shaw, T.M., Pugar, E.A., in Advances in Ceramics 8. edited by Wicks, G.G. and Ross, W.A. (American Ceramic Society, Columbus, OH, 1984) pp. 209–221.Google Scholar
[6] Lumpkin, G. R. and Ewing, R. C., Physics and Chemistry of Minerals, in press.Google Scholar
[7] Pyatenko, Yu. A., Sov. Phys-Crystallogr. 4, 184 (1960).Google Scholar
[8] Subramanian, M.A., Aravamudan, G., and Subba Rao, G.V., Prog. Solid State Chem. 15, 55 (1983).Google Scholar
[9] Chakoumakos, B.C., J. Sol. State Chem. 53, 120 (1984).Google Scholar
[10] Chakoumakos, B.C., in McGraw-Hill Yearbook of Science and Technology, edited by Parker, S.P. (McGraw-Hill, New York, 1986) pp. 393–395.Google Scholar
[11] Chakoumakos, B.C. and Ewing, R. C., in Scientific Basis for Nuclear Waste Management VIII, edited by Jantzen, C.M., Stone, J.A. and Ewing, R.C. (Mater. Res. Soc. Proc. 44. Pittsburgh, PA 1985) pp. 641–646.Google Scholar
[12] Lumpkin, G.R. and Ewing, R. C., in Scientific Basis for Nuclear Waste Management VIII, edited by Jantzen, C.M., Stone, J.A. and Ewing, R.C. (Mater. Res. Soc. Proc. 44. Pittsburgh, PA 1985) pp. 647–654.Google Scholar
[13] Holland, H.D. and Gottfried, D., Acta Crystal. 8, 291 (1955).Google Scholar
[14] Matzke, Hj., Radiat. Eff. 64, 3 (1982).Google Scholar
[15] Weber, W.J., Turcotte, R.P. and Roberts, F.P., Rad. Waste Manage. 2, 295 (1982).Google Scholar
[16] Lumpkin, G.R., Chakoumakos, B.C. and Ewing, R. C., Am. Mineral. 21, 569 (1986).Google Scholar
[17] Lumpkin, G.R., Ewing, R. C., Chakoumakos, B.C., Greegor, R.B., Lytle, F.W., Foltyn, E.M., Clinard, F. W. Jr, Boatner, L. A., Abraham, M.M., J. Mater. Res. 1, 564 (1986).Google Scholar
[18] Eyal, Y. and Fleischer, R.L., Geochim. Cosmochim. Acta 49 1155 (1985).Google Scholar
[19] Wald, J.W. and Offermann, P., in Scientific Basis for Nuclear Waste Management V, edited by Lutze, W. (Elsevier Science Publishing, New York, 1982) pp. 369–378.Google Scholar
[20] Clinard, F. W. Jr, Peterson, D.E., Rohr, D.L. and Hobbs, L.W., J. Nucl. Mater. 126, 245 (1984).Google Scholar
[21] Clinard, F. W. Jr, Rohr, D.L. and Roof, R.B., Nucl. Instr. Meth. Phys. Res. B1, 581 (1984).Google Scholar
[22] Foltyn, E.M., Clinard, F.W. Jr, Rankin, J. and Peterson, D.E., J. Nucl. Mater. 136, 97 (1985).Google Scholar
[23] Weber, W.J., Wald, J. W. and Matzke, Hj., in Scientific Basis for Nuclear Waste Management VIII, edited by Jantzen, C.M., Stone, J.A. and Ewing, R. C. (Mater. Res. Soc. Proc. 44, Pittsburgh, PA 1985) pp. 679–686.Google Scholar
[24] Weber, W. J. and Matzke, Hj., Radiat. Eff. 98, 93 (1986).Google Scholar
[25] Clinard, F. W. Jr, Ceram. Bull. 65, 1181 (1986).Google Scholar
[26] Sinclair, W. and Ringwood, A.E., Geochem. J. 15, 229 (1981).Google Scholar
[27] Ewing, R.C., Haaker, R.F., Headley, T.J. and Hlava, P.F., in Scientific Basis for Nuclear Waste Management V, edited by Topp, S.V. (Elsevier Science Publishing, New York, 1982) pp. 249–256.Google Scholar
[28] Ewing, R.C. and Headley, T.J., J. Nucl. Mater. 111, 102 (1983).Google Scholar
[29] Busche, F.D., Prinz, M., Keil, K. and Kurat, G., Earth Planet. Sci. Lett. 11, 313 (1972).Google Scholar
[30] Hurley, P.M. and Fairbairn, H.W., Geol. Soc. Am. Bull. 64, 659 (1953).Google Scholar
[31] Lipova, L.M., Kuznetsova, G.A. and Makarov, Ze.S., Geochem. Int. 2, 513 (1965).Google Scholar
[32] Tornroos, R., Bull. Geol. Soc. Finland 57, 181 (1985).Google Scholar
[33] Murakami, T., Chakoumakos, B.C. and Ewing, R.C., 14th Gen. Meeting Inter. Mineral. Assoc, Abstracts with Program, p. 179 (1986).Google Scholar
[34] Van Konynenburg, R.A. and Guinan, M.W., Nucl. Technol. 60, 206 (1983).Google Scholar
[35] Exarhos, G. J., Nucl. Instr. Meth. Phys. Res. B1, 538 (1984).Google Scholar