Imitators of plutonium and americium in a mixed uranium- plutonium nitride fuel

Nikitin, S N; Shornikov, D. P.; Тарасов, B. A.; Баранов, В. Г.; Burlakova, M. A.

doi:10.1088/1757-899x/130/1/012036

Cited by 2 publications

(4 citation statements)

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“…The present study aims to systematically evaluate the phase transitions in the CaZrTi 2 O 7 –Dy 2 Ti 2 O 7 system with the progressive accommodation of Dy 3+ , acting as a surrogate for actinide species such as Pu 3+ , Am 3+ , Cm 3+ , and Np 3+ . These data are expected to complement existing data for closely related zirconolite solid solutions Ca 1– x Zr 1– x Gd 2 x Ti 2 O 7 , Ca 1– x Zr 1– x Y 2 x Ti 2 O 7 , Ca 1– x Zr 1– x Nd 2 x Ti 2 O 7 , Ca 1– x Zr 1– x Sm 2 x Ti 2 O 7 , and Ca 1– x Zr 1– x Ce 2 x Ti 2 O 7+δ . ,− While the incorporation of Dy 3+ within the zirconolite structure has not been previously reported, the Dy 2 Ti 2 O 7 pyrochlore end member has attracted notable interest given its applications as a spin-ice compound, due to prominent geometric frustration. , Furthermore, Dy has been previously used as a surrogate for Am for the fabrication of AmN and (Am-Pu)N compounds, on the basis of ionic radii constraints and expediency (Am 3+ = 1.09 Å; Dy 3+ = 1.03 Å in 8-fold coordination). , …”

Section: Introductionsupporting

confidence: 65%

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Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization

et al. 2022

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Zirconolite is considered to be a suitable wasteform material for the immobilization of Pu and other minor actinide species produced through advanced nuclear separations. Here, we present a comprehensive investigation of Dy 3+ incorporation within the self-charge balancing zirconolite Ca 1– x Zr 1– x Dy 2 x Ti 2 O 7 solid solution, with the view to simulate trivalent minor actinide immobilization. Compositions in the substitution range 0.10 ≤ x ≤ 1.00 (Δ x = 0.10) were fabricated by a conventional mixed oxide synthesis, with a two-step sintering regime at 1400 °C in air for 48 h. Three distinct coexisting phase fields were identified, with single-phase zirconolite-2M identified only for x = 0.10. A structural transformation from zirconolite-2M to zirconolite-4M occurred in the range 0.20 ≤ x ≤ 0.30, while a mixed-phase assemblage of zirconolite-4M and cubic pyrochlore was evident at Dy concentrations 0.40 ≤ x ≤ 0.50. Compositions for which x ≥ 0.60 were consistent with single-phase pyrochlore. The formation of zirconolite-4M and pyrochlore polytype phases, with increasing Dy content, was confirmed by high-resolution transmission electron microscopy, coupled with selected area electron diffraction. Analysis of the Dy L 3 -edge XANES region confirmed that Dy was present uniformly as Dy 3+ , remaining analogous to Am 3+ . Fitting of the EXAFS region was consistent with Dy 3+ cations distributed across both Ca 2+ and Zr 4+ sites in both zirconolite-2M and 4M, in agreement with the targeted self-compensating substitution scheme, whereas Dy 3+ was 8-fold coordinated in the pyrochlore structure. The observed phase fields were contextualized within the existing literature, demonstrating that phase transitions in CaZrTi 2 O 7 –REE 3+ Ti 2 O 7 binary solid solutions are fundamentally controlled by the ratio of ionic radius of REE 3+ cations.

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Section: Introductionsupporting

confidence: 65%

“…29,30 Furthermore, Dy has been previously used as a surrogate for Am for the fabrication of AmN and (Am-Pu)N compounds, on the basis of ionic radii constraints and expediency (Am 3+ = 1.09 Å; Dy 3+ = 1.03 Å in 8-fold coordination). 31,32 2. EXPERIMENTAL PROCEDURE 2.1.…”

Section: Introductionmentioning

confidence: 99%

Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization

et al. 2022

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“…Each has a face-centered cubic rock salt structure. [10][11][12] In this study, the thermal diffusivity, conductivity, coefficient of thermal expansion (CTE), and heat capacity were measured for MoW-HfN. Additionally, microstructural analysis was performed to draw structure-property correlations.…”

Section: Introductionmentioning

confidence: 99%

“…The two nitrides are chemically and structurally similar. Each has a face‐centered cubic rock salt structure 10–12 …”

Section: Introductionmentioning

confidence: 99%

Thermal properties of HfN‐MoW surrogate cermet fuel for nuclear thermal propulsion

et al. 2022

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The thermal properties of MoW-HfN, a surrogate cermet for MoW-UN nuclear thermal propulsion fuel, were characterized over a wide range of elevated temperatures. Thermal diffusivity, coefficient of thermal expansion (CTE), and heat capacity were measured. Optical and scanning electron microscopy were performed to characterize the microstructure and draw structure-property correlations. The thermal diffusivity was obtained using the laser flash method.Diffusivity values ranged from about 0.18 cm 2 /s at 200 • C to 0.15 cm 2 /s at 1800 • C. The CTE was measured using push-rod dilatometry up to 1600 • C, giving values between 6.0 and 9.0 μm/m. A scientific rationalization of the effective material properties is made using the rule-of-mixtures and other effective properties models.

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Imitators of plutonium and americium in a mixed uranium- plutonium nitride fuel

Cited by 2 publications

References 2 publications

Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization

Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization

Thermal properties of HfN‐MoW surrogate cermet fuel for nuclear thermal propulsion

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Imitators of plutonium and americium in a mixed uranium- plutonium nitride fuel

Cited by 2 publications

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Phase Evolution in the CaZrTi2O7–Dy2Ti2O7 System: A Potential Host Phase for Minor Actinide Immobilization

Phase Evolution in the CaZrTi2O7–Dy2Ti2O7 System: A Potential Host Phase for Minor Actinide Immobilization

Thermal properties of HfN‐MoW surrogate cermet fuel for nuclear thermal propulsion

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Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization

Phase Evolution in the CaZrTi₂O₇–Dy₂Ti₂O₇ System: A Potential Host Phase for Minor Actinide Immobilization