Dry-ADU process for UO2 production

Ching-Tsven, Huang

doi:10.1016/0022-3115(92)90440-v

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…The surface morphology and fluorine impurity concentrations have long been studied for deconversion materials, particularly UO 2 fuel properties. Since high densities of UO 2 fuel pellets are desired for optimal reactor efficiency, past research has investigated the effects of chemical and thermal processes on powder particle sizes and the resulting sintered UO 2 pellet densities. − Fluorine’s high reactivity can damage reactor fuel cladding and compromise the reactor’s integrity. As such, standards for allowable fluorine concentrations in fuels have been set, and methods for its removal have been devised. ,− In particular, steam during the reduction reaction is advantageous for removing fluorine. ,, …”

Section: Introductionmentioning

confidence: 99%

“…Since high densities of UO 2 fuel pellets are desired for optimal reactor efficiency, past research has investigated the effects of chemical and thermal processes on powder particle sizes and the resulting sintered UO 2 pellet densities. 16 − 19 Fluorine’s high reactivity can damage reactor fuel cladding and compromise the reactor’s integrity. As such, standards for allowable fluorine concentrations in fuels have been set, and methods for its removal have been devised.…”

Section: Introductionmentioning

confidence: 99%

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Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors

et al. 2023

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The surface morphology characteristics of postenrichment deconversion products in the nuclear fuel cycle are important for producing nuclear fuel pellets. They also provide the first opportunity for a microstructural signature after conversion to gaseous uranium hexafluoride (UF 6 ). This work synthesizes uranium oxides from uranyl fluoride (UO 2 F 2 ) starting solutions by the wet ammonium diuranate route and a modification of the dry route. Products are reduced under a nitrogen/hydrogen atmosphere, with and without water vapor in the reducing environment. The crystal structures of the starting materials and resulting uranium oxides are characterized by powder X-ray diffraction. Scanning electron microscopy (SEM) and focused ion beam SEM with energy-dispersive X-ray spectroscopy (EDX) are used to investigate microstructural properties and quantify fluorine impurity concentrations. Heterogeneous distributions of fluorine with unique morphology characteristics were identified by backscatter electron imaging and EDX; these regions had elevated concentrations of fluorine impurities relating to the incomplete reduction of UO 2 F 2 to UO 2 and may provide a novel nuclear forensics morphology signature for nuclear fuel and U metal precursors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors

et al. 2023

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“…The mass production of oxide fuel pellets for nuclear reactors currently involves four main steps: (a) fabrication of hyperstoichiometic uranium dioxide powder (wet and dry ADU [1], AUC [2] or ID [3] processes); (b) attrition [4] and/or mixing with a plasticizing binder [5]; (c) cold pressing (usually done at a compressive stress σ = 200-400 MPa [4]) to obtain 'green' pellets with a density ρ = 50 -55 % [4,6]; and (d) sintering at T = 1400-1600 °C [5,7,8] in a reducing atmosphere (e.g., Ar-8% H 2 [5]). Although some work is on-going to modify and improve various technological parameters at the sintering stage [5], the latter process is currently regarded as a relatively cheap and effective way to obtain fully dense large-grained pellets.…”

Section: Introductionmentioning

confidence: 99%

On Morphological and Microstructural Changes in Uranium Dioxide Powder during Binder-Free Hot Pressing

Lunev

Zazolin

Pchelyakov

et al. 2017

DDF

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Plasticity of oxide fuel based on uranium dioxide is one of the less-covered topics in nuclear materials science. A useful tool to study the deformation mechanisms in this material at elevated temperatures is hot pressing. In this work, UO$_{2.06}$ powder prepared via~ADU route was uniaxially compacted at temperatures within the~$250$--$600$~{\textdegree}C range under a compressive axial stress from~$95$ to~$220$~MPa applied for a time interval between~$10$ and~$60$~min. Examinations performed with scanning electron microscopy~(SEM) and density measurements revealed a temperature effect on densification when increasing the compaction temperature from~$400$ to~$600$~\textdegree{C} with other conditions being equal. By varying the loading duration for hot pressing at~$600$~{\textdegree}C under constant compressive stress~$95$~MPa, different stages of compactions were analyzed. In addition,~XRD measurements revealed a texture developing in the material during compaction and a possible increase in dislocation density. It is argumented that dislocation-mediated plasticity contributes to densification at elevated temperatures.

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Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

Kumar

Ananthasivan

Krishnan

et al. 2016

Journal of Nuclear Materials

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Dry-ADU process for UO2 production

Cited by 5 publications

References 4 publications

Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors

Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors

On Morphological and Microstructural Changes in Uranium Dioxide Powder during Binder-Free Hot Pressing

Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

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