Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

Butt, Drryl P.; Jaques, Brian J.

doi:10.2172/953344

Cited by 2 publications

(3 citation statements)

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“…A variety of sintering methods have been used to make actinide and lanthanide nitride fuel pellets, including tungsten refractory metal furnaces, tube furnaces, hot extrusion, hot pressing, hot isostatic pressing (HIP), and spark plasma sintering (SPS) [1,[3][4][5][6][7][8]. Using a tungsten refractory metal furnace or tube furnace, UN pellets achieved 95% or higher of theoretical density (TD) with a sintering profile of 2500 • C for 2 to 6 h [3], and (U, Nd)N pellets achieved ~95%TD with a sintering profile of 1800 • C for 4 h [9].…”

Section: Introductionmentioning

confidence: 99%

“…Using a tungsten refractory metal furnace or tube furnace, UN pellets achieved 95% or higher of theoretical density (TD) with a sintering profile of 2500 • C for 2 to 6 h [3], and (U, Nd)N pellets achieved ~95%TD with a sintering profile of 1800 • C for 4 h [9]. However, most studies in the open literature reported that such sintering methods cannot achieve enough densification if the temperature was lower-at sintering temperatures of 1700 • C or lower, the density of UN or (U, Dy)N pellet was less than 85%TD [5,7,9]. What's more, the process generally requires a long sintering time, which results in heavy oxidation due to the difficulties in retaining an inert atmosphere for many hours.…”

Section: Introductionmentioning

confidence: 99%

“…The hot extrusion of UN pellets resulted in heavy cracking but showed promising densification at 2200 • C [3]. A study of a surrogate material, (Dy, Zr)N, found that hot pressing at 2000 • C and 26 MPa would lead to 99%TD [7]. However, there is room for improvement as the pressure-assisted sintering method lacks production efficiency, both in throughput and energy requirements, as a result of the technique's operation.…”

Section: Introductionmentioning

confidence: 99%

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A Rapid Sintering Method for Cerium Nitride Pellet: A Uranium Mononitride Surrogate

Joyce

2022

Ceramics

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Uranium mononitride (UN) is a candidate fuel material for light water reactors with higher uranium (U) loading and thermal conductivity than uranium dioxide (UO2). However, the sintering of UN pellets is challenging as the UN powder particles oxidize rapidly at high temperatures unless the oxygen concentration is extremely low. Oxidation during sintering either reduces the relative density of the sintered UN pellet or disintegrates the sintered UN pellet to powder. To address this problem, the present work developed a rapid sintering method for producing highly densified UN surrogate pellets with minimal oxidation. Cerium nitride (CeN) is used as a surrogate for UN to reduce radiation hazards. With the custom-developed fast-heating system, the sintering process was completed within 150 s. The sintering atmosphere was flowing nitrogen (N2). The sintered CeN pellet density was 95% of the theoretical density (TD) or higher. The microstructure was uniform with a 10–25 µm grain size as demonstrated by scanning electron microscopy (SEM) and contained trivial levels of oxides as demonstrated by X-ray diffraction (XRD). The resultant pellets indicate that the rapid sintering method is a promising method to make UN fuel pellets with equivalent or higher density to pellets made by conventional sintering methods, while also being more efficient in time and costs.

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