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Phase and Chemical Stability of Murataite Containing Uranium, Plutonium and Rare Earths

Published online by Cambridge University Press:  21 March 2011

S.V. Yudintsev ,
S.V. Stefanovsky ,
B.S. Nikonov  and
B.I. Omelianenko
S.V. Yudintsev
Affiliation:
Institute of Geology of Ore Deposits, Staromonetny 35, Moscow 109017, Russia
S.V. Stefanovsky
Affiliation:
SIA "Radon", 7-th Rostovskii per., 2/14, Moscow 119121, Russia
B.S. Nikonov
Affiliation:
Institute of Geology of Ore Deposits, Staromonetny 35, Moscow 109017, Russia
B.I. Omelianenko
Affiliation:
Institute of Geology of Ore Deposits, Staromonetny 35, Moscow 109017, Russia
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Abstract

Murataite –a complex actinide (An)- and rare earth element (REE)-bearing oxide with a cubic fluorite-related lattice – is one of the promising host-phases for immobilization of Pu-containing waste. The murataite phase composition corresponds to the empirical formula:A4B2C7O22-x, where the A-sites are occupied by Ca, Mn, REE, and An (U); B sites – by Mn, Ti,Zr, and An (U); and C sites – by Ti, Al, and Fe. The total amount of the actinides (U) and REE (Ce, Gd) in the murataite may exceed 20 wt%. In contrast to the other prospective hosts for actinide waste immobilization (cubic zirconia and pyrochlore), murataite accommodates higher amounts of corrosion products(Al, Fe) along with the actinides. The authors compared murataite-based ceramics having similar compositions and produced by melting in a high-temperature resistance furnace or via inductive melting in a cold crucible. Eight samples of the murataite-based ceramics were produced and investigated in detail. Murataite was found to be the major phase in four of the samples – with a basic composition, in wt%, of: 5.0 Al2O3, 10.0 CaO, 55.0 TiO2, 10.0 MnO, 5.0 Fe2O3, 5.0 ZrO2, and 10.0 UO2. These samples were produced by melting in a resistive furnace and in the cold crucible and included Gd-bearing samples and one Pu-bearing sample. The extra phases were other titanates: (from more to less typical) rutile, pyrochlore, zirconolite, crichtonite, pseudobrookite, and perovskite (in the Pu-doped samples only). Three varieties of the murataite, with 3-, 5-, and 8-fold fluorite-type lattices, were observed. Addition of uranium and rare earth oxides stabilizes pyrochlore as the major phase, whereas addition of zirconia yields zirconolite. Plutonium stabilizes the perovskite-type phase, probably due to the formation of Pu3+. The maximum waste oxide content in the murataite for the elements studied was found to be 10% ZrO2, 12% CeO2, 13% Gd2O3, and 14% UO2. Waste element partitioning among the murataite and all the other phases with similar fluorite-related structure (pyrochlore and zirconolite) was analyzed. The uranium leach rate for the sample with maximum murataite content was measured using a procedure similar to MCC-3. This leach rate was close to10-5 g/(m2*day) in a½-day test and decreased by more than one order of magnitude in 28-day tests. Investigation of the stability of the murataite structure after irradiation byheavy ions is in progress.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 357
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

1. Vance, E.R., Begg, B.D., Day, R.A. and Ball, C.J., Mat. Res. Soc. Symp. Proc. 353 (1995) 767.Google Scholar
2. Ebbinghaus, B.E., VanKonynenburg, R.A., and Ryerson, F.J., in: Waste Management '98. CD-Rom version.Google Scholar
3. Stefanovsky, S.V., Yudintsev, S.V., Nikonov, B.S., et al., Mat. Res. Soc. Symp. Proc. 556 (1999) 121.Google Scholar
4. Morgan, P.E.D. and Ryerson, F.J., J. Mater. Sci. Lett. 1 (1982) 351.Google Scholar
5. Sobolev, I.A., Stefanovsky, S.V., Yudintsev, S.V., et al., Mat. Res. Soc. Symp. Proc. 465 (1997) 363.Google Scholar
6. Morgan, P.E.D., Harker, A.B., Flintoff, J.F., et al., Adv. in Ceram. 8 (1984) 234.Google Scholar
7. Ryerson, F.J., J. Amer. Ceram. Soc. 66 (1983) 629; 67 (1984) 75.Google Scholar
8. Knyazev, O.A., Nikonov, B.S., Omelianenko, B.I., et. al.,in SPECTRUM '96. Proc.Int. Conf. 2 (1996) 2130.Google Scholar
9. Lumpkin, G.R., Smith, K.L., Blackford, M.G., Mat. Res. Soc. Symp. Proc. 353 (1995) 855.Google Scholar
10. Smith, K.L., Blackford, M.G., Lumpkin, G.R., et al., Mat. Res. Soc. Symp. Proc. 412 (1996) 313.Google Scholar
11. Jostsons, A., Vance, E.R., Mercer, D.J., and Oversby, V.M.,Mat. Res. Soc. Symp. Proc. 353 (1995) 775.Google Scholar
12. Jardine, L.J., Borisov, G.B., and Mansurov, O.A., in ICEM '99. Proc. Int. Conf., (1999) CD-Rom version.Google Scholar