Monazite and Other Lanthanide Orthophosphates as Alternate Actinide Waste Forms

Boatner, L. A.; Beall, Gary W.; Abraham, M. M.; Finch, C. B.; Huray, Paul G.; Rappaz, M.

doi:10.1007/978-1-4684-3839-0_35

Cited by 91 publications

(52 citation statements)

References 6 publications

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“…Other reported products of alteration include: unspecified phases or amorphous material (e.g., Morin 1977), cerianite, CeO 2 (Meintzer & Mitchell 1988), epidote (Carcangiu et al 1997), lanthanite, (La,Ce) 2 (CO 3 ) 3 •8H 2 O (Saebø 1961), and monazite, (Ce,La)PO 4 (see Discussion for references). The formation of monazite is of particular interest because it generally has been considered to be very stable under natural geological conditions over long periods of time and has been considered as an alternative to borosilicate glass for actinide containment in the disposal of high-level nuclear waste (Boatner et al 1980).…”

Section: Introductionmentioning

confidence: 99%

ALLANITE-(Ce) FROM THE EOCENE CASTO GRANITE, IDAHO: RESPONSE TO HYDROTHERMAL ALTERATION

Wood¹,

Ricketts²

2000

The Canadian Mineralogist

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The response of allanite-(Ce) in the Eocene Casto granite of Idaho to hydrothermal activity has been investigated. Unaltered, igneous allanite from the Casto pluton is characterized by a narrow range of compositional variation, with little or no zoning. A representative empirical formula, based on the composition of the least-altered grain, is: (REE 0.83 . Slightly altered crystals exhibit a rim in which Th is enriched, and La and Ce are depleted. Increasing alteration lead to extensive corrosion and replacement of allanite by fluorite, a REE-, Th-and P-rich phase (probably monazite), and a Th-rich phase (probably thorianite). In spite of attack by fluoride-rich hydrothermal solutions, the REE and Th originally in allanite were not transported significant distances, but were redeposited locally as secondary phases. The lack of significant REE and Th transport is due to the availability of phosphorus, which allowed the REE to be fixed in a secondary phosphate phase, and the removal of fluoride as fluorite. This work has implications for the behavior of radioactive waste in deeply buried geological repositories upon interaction with heated groundwaters.Keywords: allanite-(Ce), monazite-(Ce), hydrothermal alteration, radioactive waste analogue, rare-earth elements, thorium, Casto granite, Idaho. . Les cristaux faiblement altérés font preuve d'un liseré dans lequel le Th est enrichi, et le La et le Ce sont appauvris. A mesure que le degré d'altération augmente, il y a corrosion importante et remplacement de l'allanite par la fluorite, un phosphate de TR, Th et P (probablement monazite), et un minéral riche en Th (probablement thorianite). Malgré l'attaque par des solutions riches en fluorures, les terres rares et le thorium originellement dans l'allanite n'ont pas été transportés très loin, mais plutôt redéposés localement sous forme de phases secondaires. Le transfert très limité des terres rares et du thorium serait attribuable à la disponibilité du phosphore, ce qui a permis aux terres rares d'être fixées dans un phosphate secondaire, avec l'élimination des fluorures sous forme de fluorite. Ce travail aurait des implications dans l'étude du comportement des éléments radioactifs lors de l'interaction de déchets radioactifs enfouis avec l'eau souterraine chauffée. SOMMAIRE(Traduit par la Rédaction)

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Section: Introductionmentioning

confidence: 99%

ALLANITE-(Ce) FROM THE EOCENE CASTO GRANITE, IDAHO: RESPONSE TO HYDROTHERMAL ALTERATION

Wood¹,

Ricketts²

2000

The Canadian Mineralogist

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“…They also find applications in the nuclear cycle, either as host matrices for actinide radwastes or, more recently, as products of the reaction of the spent nuclear fuel with tributyl phosphate during the reprocessing [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: M'mentioning

confidence: 99%

Structural study of polymorphism and thermal behavior of CaZr(PO4)2

Brégiroux

Wallez

Popa

2015

Solid State Sciences

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The crystal structure of CaZr(PO 4 ) 2 has been revised by ab initio Rietveld analysis of X-ray powder diffraction data. At room temperature, CaZr(PO 4 ) 2 crystallizes in the orthorhombic space group Pna2 1 (Z = 4). Differential thermal analysis suggests a reversible second order transition at 1000°C confirmed by high temperature XRD analysis that brings out the existence of a high temperature form, very similar to the room temperature one, but more symmetrical (Pnma, Z = 4). Analysis of the crystal parameters evolution during heating reveals that CaZr(PO 4 ) 2 exhibits a quite low thermal expansion coefficient of 6.11 10 -6 K -1 .This value stems from a combination of several mechanisms, including Coulombic repulsion and bridging oxygen rocking motion.Keywords: Crystal structure; thermal expansion; calcium zirconium phosphate Highlights:Room temperature structure CaZr(PO 4 ) 2 was revised A high temperature form of CaZr(PO 4 ) 2 was described for the first time Thermal expansion of CaZr(PO 4 ) 2 was studied on the basis of the evolution of the crystal parameters evolution during heating M

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“…Ceramic or mineral waste forms, including phosphates and apatites, have been proposed for some time, dating before the 1970s [McCarthy, 1973;Roy, 1977;Komarneni and Roy, 1986;Boatner, et al, 1980]. Over the past decade, several patents have been issued for phosphate treatment of waste [Pal and Yost, 1993;Chesner, 1996;Webster, 1999;Amer, 2001;Bhat, 2001;Forrester, 2001].…”

Section: Phosphate Precipitation and Sorptionmentioning

confidence: 99%

State of the Art Report on High-Level Waste Tank Closure

Langton¹

2002

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Monazite and Other Lanthanide Orthophosphates as Alternate Actinide Waste Forms

Cited by 91 publications

References 6 publications

ALLANITE-(Ce) FROM THE EOCENE CASTO GRANITE, IDAHO: RESPONSE TO HYDROTHERMAL ALTERATION

ALLANITE-(Ce) FROM THE EOCENE CASTO GRANITE, IDAHO: RESPONSE TO HYDROTHERMAL ALTERATION

Structural study of polymorphism and thermal behavior of CaZr(PO4)2

State of the Art Report on High-Level Waste Tank Closure

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