Processing of magnesia–pyrochlore composites for inert matrix materials

Yates, Samantha J.; Xu, Peng; Wang, J.; Tulenko, J.S.; Nino, Juan C.

doi:10.1016/j.jnucmat.2007.01.171

Cited by 25 publications

(26 citation statements)

References 14 publications

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“…Ceramics with pyrochlore structure have been identified as potential waste form materials for the immobilization of actinides present in radioactive waste and as inert matrix materials for actinide transmutation. [5][6][7] As nuclear waste forms materials, structures based on titanate, stannate and zirconate pyrochlore have been investigated extensively. [8][9][10][11][12][13][14] In contrast to titanate pyrochlore which are susceptible to radiation induced amorphization, the zirconate ceramics show remarkable resistance to amorphization under ion beam irradiation.…”

Section: Introductionmentioning

confidence: 99%

Nd and Ce simultaneous substitution driven structure modifications in Gd2−xNdxZr2−yCeyO7

Sijin

Ding

Shu

et al. 2015

Journal of the European Ceramic Society

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Section: Introductionmentioning

confidence: 99%

Nd and Ce simultaneous substitution driven structure modifications in Gd2−xNdxZr2−yCeyO7

Sijin

Ding

Shu

et al. 2015

Journal of the European Ceramic Society

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“…47 As described in our previous work, the composites made by ball milling have a relatively more homogeneous microstructure than the composites made by mortar and pestle mixing and water magnetic bar stirring, which contain agglomerates of Nd 2 Zr 2 O 7 and MgO. 7 As expected, the hydrothermal corrosion resistance is strongly microstructure dependant. The inhomogeneous composites made by the mortar and pestle mixing and water magnetic bar mixing first fractured and then completely dissolved in less than 1 hour after exposure to 300 °C deionized water regardless MgO volume fraction from 40 vol% to 70 vol%, showing similar low corrosion resistance as pure MgO.…”

Section: Preliminary Resultsmentioning

confidence: 51%

“…Neutronic property simulations indicate that the MgO volume fraction should be at least 70% for the composite to provide enough reactivity at the end of life (EOL). 7 Nevertheless, the current status shows that the composite with 70 vol% MgO failed because the microstructure had high contiguity of MgO and was less homogeneous even though it was produced by the ball milling process. Therefore, the desired microstructure has to be made for the composite with 70 vol% MgO so as to achieve adequate hydration resistance.…”

Section: Hydrothermal Corrosion Of the Compositesmentioning

confidence: 98%

“…The thermal conductivity of the composites is calculated by multiplying the thermal diffusivity by the specific heat capacity and density according to   C P (7) where  is the thermal diffusivity,  is the density and C P is the specific heat capacity.…”

Section: Thermal Conductivitymentioning

confidence: 99%

“…6 In search for an alternative composite strategy, Nd 2 Zr 2 O 7 , an oxide compound with pyrochlore structure, has been proposed recently as a corrosion resistant phase, and MgO-Nd 2 Zr 2 O 7 composites have been investigated as potential IM materials. 7 An adequate thermal conductivity of 6 W·m at 1000 °C for the MgO-Nd 2 Zr 2 O 7 composite with 90 vol% MgO was recently calculated and reported. 8,9 Other simulations proposed that the MgO-pyrochlore composites could exhibit higher radiation stability than previously reported.…”

Section: Introductionmentioning

confidence: 98%

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Neri Final Technical Report, De-Fc07-O5id14647, Optimization of Oxide Compounds for Advanced Inert Matrix Materials

Nino¹

2009

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The following is a technical report summarizing all the procedures, experiments, simulations and technical findings of this NERI project. For additional information, details or technical questions regarding this project, please contact jnino@mse.ufl.edu MgO and NDZ......................................................................69 8.4. Grain Size Dependence of MgO and NDZ Polycrystal Thermal Conductivity75 8.5 2009 Composite Processing and Characterization IntroductionIn order to reduce the current excesses of plutonium (both weapon grade and reactor grade) and other transuranium elements, a concept of inert matrix fuel (IMF) has been proposed for an uranium free transmutation of fissile actinides which excludes continuous uranium-plutonium conversion in thermal reactors and advanced systems. 1,2 Magnesium oxide (MgO) is a promising candidate for inert matrix (IM) materials due to its high melting point (2827 °C) 2 , high thermal conductivity (13 W/K·m at 1000 °C) 2 , good neutronic properties, and irradiation stability 3,4 However, MgO reacts with water and hydrates easily, which prevents it from being used in light water reactors (LWRs) as an IM. To improve the hydration resistance of MgO-based inert matrix materials, Medvedev 5 and coworkers have recently investigated the introduction of a secondary phase that acts as a hydration barrier. An MgO-ZrO 2 composite was specifically studied and the results showed that the composite exhibited improved hydration resistance than pure MgO. However, ZrO 2 is insoluble in most acids except HF, which is undesirable for fuel reprocessing. Moreover, the thermal conductivity of ZrO 2 is low and typically less than 3 W·m at 1000 °C. 6 In search for an alternative composite strategy, Nd 2 Zr 2 O 7 , an oxide compound with pyrochlore structure, has been proposed recently as a corrosion resistant phase, and MgO-Nd 2 Zr 2 O 7 composites have been investigated as potential IM materials. at 1000 °C for the MgO-Nd 2 Zr 2 O 7 composite with 90 vol% MgO was recently calculated and reported. 8,9 Other simulations proposed that the MgO-pyrochlore composites could exhibit higher radiation stability than previously reported. 10 Final optimization of the composite microstructure was performed on the 70 vol% MgONd 2 Zr 2 O 7 composite that burnup calculations had shown to have the closest profile to that of MOX fuel. Theoretical calculations also indicated that a homogeneous 70 vol% MgO composite could achieve the desired microstructure that would result in satisfying the dual requirements of good thermal properties. Experimental Procedures Composite Synthesis Solid State Synthesis of Nd 2 Zr 2 O 7Stoichiometric ratios of Nd 2 O 3 (Alfa Aesar 99.9%) and ZrO 2 (99.7%) were added to spherical 3 mm and 10 mm yttria stabilized zirconia (YSZ) milling media in a PTFE (polytetrafluoroethylene) ball mill jar with 100 ml of deionized water and 3 ml of ammonium polyacrylate dispersant (20 vol% Darvan 821A in deionized water). The slurry was milled for 24 hours on the ball mill at 85 rpm ...

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Fabrication, characterization, and acid solubility of MgO-Nd2Zr2O7 composite ceramics for inert matrix fuel

Zhang

Wang

et al. 2019

J Aust Ceram Soc

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Processing of magnesia–pyrochlore composites for inert matrix materials

Cited by 25 publications

References 14 publications

Nd and Ce simultaneous substitution driven structure modifications in Gd2−xNdxZr2−yCeyO7

Nd and Ce simultaneous substitution driven structure modifications in Gd2−xNdxZr2−yCeyO7

Neri Final Technical Report, De-Fc07-O5id14647, Optimization of Oxide Compounds for Advanced Inert Matrix Materials

Fabrication, characterization, and acid solubility of MgO-Nd2Zr2O7 composite ceramics for inert matrix fuel

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