Ceramic Host Phases for Nuclear Waste Remediation

Lumpkin, Gregory R.

doi:10.1002/9781119115557.ch7

Cited by 10 publications

(16 citation statements)

References 118 publications

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“…Morphotropic transitions can also affect the resistance of matrices to irradiation; decreasing for REEPO 4 [ 62 ] when the structure of zircon (heavy REE phosphates) changed to monazite (light REE). Among REE titanates of (REE) 2 TiO 5 composition, cubic phases are more resistant to radiation than compounds with hexagonal and rhombic structures [ 25 ].…”

Section: Requirements (Selection Criteria) For High-level Waste Immob...mentioning

confidence: 99%

“…They may be obtained by all known methods—sintering at atmospheric or elevated pressures, melting and crystallization, high-speed pulsed electric current sintering, and self-propagating high-temperature synthesis [ 57 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ]. Zirconolite is stable in various natural conditions [ 22 , 24 , 25 , 75 ]; natural zirconolite is a rare mineral of terrestrial and lunar igneous rocks, and metasomatites. In nature, zirconolites from different localities have been found to contain UO 2 , ThO 2, or REE 2 O 3 reaching 24, 22, or 32 wt%, respectively [ 23 , 25 , 93 ].…”

Section: Zirconolite and Murataite As Matrices For The Immobilization...mentioning

confidence: 99%

“…Their ores are mined by underground leaching with the use of oxidizers, acidic, or alkaline solutions. The stability of U, Th, and REE minerals such as pyrochlore, perovskite, zircon, monazite, and britholite is even higher [ 22 , 23 , 24 , 25 ]. Zirconolite is highly stable in nature, with isotope systems that have been closed for hundreds of million years, making it possible to use zirconolite for age determination [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Zirconolite Polytypes and Murataite Polysomes in Matrices for the REE—Actinide Fraction of HLW

et al. 2022

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Electron backscatter diffraction (EBSD) has been used for more than 30 years for analyzing the structure of minerals and artificial substances. In recent times, EBSD has been widely applied for investigation of irradiated nuclear fuel and matrices for the immobilization of radioactive waste. The combination of EBSD and scanning electron microscopy (SEM/EDS) methods allows researchers to obtain simultaneously data on a specimen’s local composition and structure. The article discusses the abilities of SEM/EDS and EBSD techniques to identify zirconolite polytype modifications and members of the polysomatic murataite–pyrochlore series in polyphase ceramic matrices, with simulations of Pu (Th) and the REE-actinide fraction (Nd) of high-level radioactive waste.

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Section: Requirements (Selection Criteria) For High-level Waste Immob...mentioning

confidence: 99%

Section: Zirconolite and Murataite As Matrices For The Immobilization...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Zirconolite Polytypes and Murataite Polysomes in Matrices for the REE—Actinide Fraction of HLW

et al. 2022

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“…The generally increased susceptibility of radiation-damaged zircon to chemical alteration is of enormous importance, as these processes may negatively affect the ability of the mineral to retain radiogenic nuclei and therefore bias results of chemical and isotopic age determination applied in U-Pb geochronology [13][14][15]. Moreover, the investigation of gradually radiation damaged and metamict minerals, and their synthetic analogues, has increased appreciably over the past decades, stimulated by the potential use of mineral-like ceramics as waste forms for the immobilisation of reprocessed spent nuclear fuel and other radioactive waste [16,17]. Information obtained from studies on radiation-damage-assisted alteration in accessory minerals has important implications for the validation of the long-term performance of nuclear waste forms for the disposal in geological repositories, as radiation damage negatively affects the ability of analogue ceramics to immobilise incorporated radionuclides, e.g., Pu, Am, U and Th [18,19].…”

Section: Introductionmentioning

confidence: 99%

The In-Situ Quantification of Structural Radiation Damage in Zircon Using Laser-Induced Confocal Photoluminescence Spectroscopy

2020

Self Cite

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We present a new methodology for laser-induced steady-state photoluminescence (PL) spectroscopy of Dy3+ that aims at a direct quantification of the amorphous fraction fa present in zircon (ZrSiO4), which undergoes a transition from a crystalline to a metamict state due to cumulative self-irradiation damage caused by the radioactive decay of substituted U and Th. Using state-of-the-art confocal spectrometers attached to optical microscopes, measurements may be performed non-destructively on the micrometre length-scale with the option to visualize radiation-damage patterns as revealed by hyperspectral PL maps. Zircon from the Ratnapura district (Sri Lanka, ~520 Ma), was used as reference material to substantiate the applicability of the proposed method. The accumulation of radiation damage in this material was investigated in detail and obtained fa values correlate with calculated α-doses in accordance to the direct impact model reported variously in the literature. The impact of chemically-induced, heterogeneous broadening of Raman and Dy3+ emission spectral bands is discussed on two examples from Mt. Malosa district, Malawi. A mean weighted U-Pb isotope age of 111 ± 1 Ma (pegmatitic-type) and a discordia age of 112 ± 1.6 Ma (hydrothermal-type) as obtained by LA-ICP-MS confirm their close genetic and temporal relationship. Studied zircon examples demonstrate that the amount of radiation damage present may have a substantial effect on the precision of LA-ICP-MS ages, but cannot be considered an exclusive cause for bias of obtained isotope ages.

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“…In the last decade, the possibility of actinide containing fractions solidification into crystalline matrices of various structures was considered [3][4][5]. Crystalline matrices have many advantages: high corrosion resistance, incorporation of HLW without the formation of additional soluble phases, the presence of natural analogues as evidence of their longterm stability in the geological environment [6].…”

Section: Introductionmentioning

confidence: 99%

Titanate-Based Ceramic as a Matrix for Curium and Rare Earth Element Fraction of Radioactive Waste Immobilization

Danilov¹,

Frolova²,

Винокуров³

et al. 2020

RAD Conference Proceedings

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The effective isolation of radioactive waste (RW) from the environment is the main problem for the further development of nuclear power. The main phases in titanate-based ceramics are perovskite, rutile, zirconolite and murataite. Murataite grains have a zonal structure with high content of rare earth elements at the center of structure and low content of these at edges, that precludes their leaching in contact with a solution. Murataite-based ceramics containing simulated rare earth elements of high level waste (HLW) were produced via melting of oxide mixtures in a resistance furnace at 1500°C. All samples were composed of mainly murataite and minor perovskite, crichtonite, zirconolite, and pyrophanite/ilmenite phases. Thus, murataite is the dominant host phase for a sample containing zirconium oxide. All samples were analyzed by scanning electron microscopy with an energy dispersive X-ray spectroscopy. Elemental leaching rates from the ceramic with low perovskite content were lower by one order of magnitude then leaching rates for high perovskite content.

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Ceramic Host Phases for Nuclear Waste Remediation

Cited by 10 publications

References 118 publications

Zirconolite Polytypes and Murataite Polysomes in Matrices for the REE—Actinide Fraction of HLW

Zirconolite Polytypes and Murataite Polysomes in Matrices for the REE—Actinide Fraction of HLW

The In-Situ Quantification of Structural Radiation Damage in Zircon Using Laser-Induced Confocal Photoluminescence Spectroscopy

Titanate-Based Ceramic as a Matrix for Curium and Rare Earth Element Fraction of Radioactive Waste Immobilization

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