Solubility study of Ti,Zr-based ceramics designed to immobilize long-lived radionuclides

Leturcq, Gilles; Advocat, T.; Hart, K.P.; Berger, G.; Lacombe, J.; Bonnetier, A.

doi:10.2138/am-2001-0710

Cited by 38 publications

(30 citation statements)

References 18 publications

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“…However, recent work has shown that they can also be produced from a melt process analogous to GCM processing. For example, demonstrations have been completed using the Cold Crucible Induction Melter (CCIM) technology to produce several crystalline ceramic waste forms, including murataite-rich ceramics, [13,14] zirconolite/pyrochlore ceramics, [15] Synroc-C (zirconolite, hollandite, perovskite), [16,17] aluminotitanate ceramics, and zirconia [18]. This production route is advantageous since melters are already in use for commercial and defense high level waste (HLW) vitrification in several countries, and melter technology greatly reduces the potential for airborne contamination as compared to processes involving extensive powder handling operations.…”

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confidence: 99%

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Brinkman

Fox

Marra

et al. 2013

Journal of Alloys and Compounds

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Crystalline and glass composite materials are currently being investigated for the immobilization of combined High Level Waste (HLW) streams resulting from potential commercial fuel reprocessing scenarios. Several of these potential waste streams contain elevated levels of transition metal elements such as molybdenum (Mo). Molybdenum has limited solubility in typical silicate glasses used for nuclear waste immobilization.Under certain chemical and controlled cooling conditions, a powellite (Ba,Ca)MoO 4 crystalline structure can be formed by reaction with alkaline earth elements. In this study, single phase BaMoO 4 and CaMoO 4 were formed from carbonate and oxide precursors demonstrating the viability of Mo incorporation into glass, crystalline or glass composite materials by a melt and crystallization process. X-ray diffraction, photoluminescence, and Raman spectroscopy indicated a long range ordered crystalline structure. In-situ electron irradiation studies indicated that both CaMoO 4 and BaMoO 4 powellite phases exhibit radiation stability up to 1000 years at anticipated doses with a crystalline to *Manuscript Click here to view linked References amorphous transition observed after 1 X 10 13 Gy. Aqueous durability determined from product consistency tests (PCT) showed low normalized release rates for Ba, Ca, and Mo (<0.05 g/m 2 ).

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confidence: 99%

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Brinkman

Fox

Marra

et al. 2013

Journal of Alloys and Compounds

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“…Zirconolite was identified as anion deficient superstructure derived from eight fluorite subcells with a monoclinic distortion. Zirconolites of the type CaZr x Ti 3−x O 7 are monoclinic with two-layer repeat sequence [10][11][12][13]. These are referred to as 2M type zirconolites.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Crystal Structure Refinement of Lanthanum and Yttrium Substituted Polycrystalline 2M Type Zirconolite Phases: Ca_1-xM_xZrTi₂O₇(M = Y, La andx= 0.2)

Bohre

Avasthi

Shrivastava

2014

Journal of Powder Technology

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Solid phases of zirconolite-2M with composition Ca 0.8 M 0.2 ZrTi 2 O 7 (M = La, Y) have been synthesized through ceramic route and their structures refined to a satisfactory convergence using Rietveld analysis. Zirconolites crystallize in space group C2/c with Z = 8. The powder diffraction data of Ca 0.8 Y 0.2 ZrTi 2 O 7 (CZTY) and Ca 0.8 La 0.2 ZrTi 2 O 7 (CZTLa) have been subjected to General Structural Analysis System software to arrive at a satisfactory structure fit with Rp = 0.1128 and Rwp = 0.1805 for CZTY and Rp = 0.1178 and Rwp = 0.1874 for CZTLa, respectively. The unit cell parameters are a = 10.1708 (6) >, b = 6.2711 (4), and c = 11.2779 (6) > for CZTY and a = 11.2548 (6) >, b = 6.2601 (4), and c=11.2606 (7) > for CZTLa. Calculated interatomic distances and bond angles are in good agreement with their standard values. Particle size along prominent reflecting planes calculated by Scherrer's formula ranges between 67 and 107 nm. The polyhedral (CaO 8 , ZrO 7 , and TiO 6 /TiO 5 ) distortions and valence calculation based on bond strength analysis have been reported. The compositions of the zirconolites were determined using energy dispersive X-ray (EDAX) analysis. Cation site occupancies were determined by applied compositional constraints which were found consistent with the expected zirconolite-2M cation site occupancies.

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“…For example, demonstrations have been completed using the Cold Crucible Induction Melter (CCIM) technology to produce several crystalline ceramic waste forms, including murataite-rich ceramics, 7 zirconolite/pyrochlore ceramics, 8 Synroc-C (zirconolite, hollandite, perovskite), 9 aluminotitanate ceramics, and zirconia. 10 This production route is advantageous since melters are already in use for defense high level waste (HLW) vitrification in several countries, and melter technology greatly reduces the potential for airborne contamination as compared to powder handling operations.…”

Section: Introductionmentioning

confidence: 99%

“…Electron irradiation studies on the single phase CaMoO 4 (a component of the multiphase waste form) suggested that this material exhibits stability to 1000 years at anticipated self-irradiation doses (2×10 10 -2×10 11 Gy), but that its stability may be rate dependent, therefore limiting the activity of the waste for which it can be employed. Overall, these preliminary results indicate good radiation damage tolerance for the crystalline ceramic materials.…”

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Development of Crystalline Ceramics for Immobilization of Advanced Fuel Cycle Reprocessing Wastes

Fox¹,

Brinkman²

2011

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SUMMARYThe Savannah River National Laboratory (SRNL) is developing crystalline ceramic waste forms to incorporate CS/LN/TM high Mo waste streams consisting of perovskite, hollandite, pyrochlore, zirconolite, and powellite phase assemblages. Simple raw materials, including Al 2 O 3 , CaO, and TiO 2 were combined with simulated waste components to produce multiphase crystalline ceramics. Fiscal Year 2011 (FY11) activities included i) expanding the compositional range by varying waste loading and fabrication of compositions rich in TiO 2 , ii) exploring the processing parameters of ceramics produced by the melt and crystallize process, iii) synthesis and characterization of select individual phases of powellite and hollandite that are the target hosts for radionuclides of Mo, Cs, and Rb, and iv) evaluating the durability and radiation stability of single and multi-phase ceramic waste forms.Two fabrication methods, including melting and crystallizing, and pressing and sintering, were used with the intent of studying phase evolution under various sintering conditions. An analysis of the XRD and SEM/EDS results indicates that the targeted crystalline phases of the FY11 compositions consisting of pyrochlore, perovskite, hollandite, zirconolite, and powellite were formed by both press and sinter and melt and crystallize processing methods. An evaluation of crystalline phase formation versus melt processing conditions revealed that hollandite, perovskite, zirconolite, and residual TiO 2 phases formed regardless of cooling rate, demonstrating the robust nature of this process for crystalline phase development.The multiphase ceramic composition CSLNTM-06 demonstrated good resistance to proton beam irradiation. Electron irradiation studies on the single phase CaMoO 4 (a component of the multiphase waste form) suggested that this material exhibits stability to 1000 years at anticipated self-irradiation doses (2×10 10 -2×10 11 Gy), but that its stability may be rate dependent, therefore limiting the activity of the waste for which it can be employed. Overall, these preliminary results indicate good radiation damage tolerance for the crystalline ceramic materials.The PCT results showed that, for all of the waste forms tested, the normalized release values for most of the elements measured, including all of the lanthanides and noble metals, were either very small or below the instrument detection limits. Elevated normalized release values were measured only for Cs, Mo, and Rb. It is difficult to draw further conclusions from these data until a benchmark material is developed for the PCT with this type of waste form. Calcined, simulated CS/LN/TM High Mo waste without additives had relatively low normalized release values for Cs, Mo, and Rb. A review of the chemical composition data for this sample showed that these elements were well retained after the calcination. Therefore, it will be useful to further characterize the calcined material to determine what form these elements are in after calcining. This, along with single phase...

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Solubility study of Ti,Zr-based ceramics designed to immobilize long-lived radionuclides

Cited by 38 publications

References 18 publications

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Synthesis, Characterization, and Crystal Structure Refinement of Lanthanum and Yttrium Substituted Polycrystalline 2M Type Zirconolite Phases: Ca_1-xM_xZrTi₂O₇(M = Y, La andx= 0.2)

Development of Crystalline Ceramics for Immobilization of Advanced Fuel Cycle Reprocessing Wastes

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Solubility study of Ti,Zr-based ceramics designed to immobilize long-lived radionuclides

Cited by 38 publications

References 18 publications

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

Synthesis, Characterization, and Crystal Structure Refinement of Lanthanum and Yttrium Substituted Polycrystalline 2M Type Zirconolite Phases: Ca1-xMxZrTi2O7(M = Y, La andx= 0.2)

Development of Crystalline Ceramics for Immobilization of Advanced Fuel Cycle Reprocessing Wastes

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Synthesis, Characterization, and Crystal Structure Refinement of Lanthanum and Yttrium Substituted Polycrystalline 2M Type Zirconolite Phases: Ca_1-xM_xZrTi₂O₇(M = Y, La andx= 0.2)