The melting behaviour of plutonium dioxide: A laser-heating study

Bruycker, F. De; Boboridis, K.; Pöml, P.; Eloirdi, R.; Konings, R.J.M.; Manara, D.

doi:10.1016/j.jnucmat.2010.11.030

Cited by 34 publications

(32 citation statements)

References 18 publications

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“…However, the general trend of the entire actinide dioxide series, reported in Figure 8, 3,5,7,[28][29][30][31] changes considerably when new values for NpO 2 and PuO 2 are taken into account instead of old ones. Figure 8 also shows that the difference between old and new melting temperatures of actinide dioxides increases with the atomic number of the actinide.…”

Section: Discussionmentioning

confidence: 99%

“…14) and PuO 2 . 5 The best estimate for the greybody-NSE was then used to convert the measured radiance temperature to true temperatures. Since all measurements were taken on liquid or resolidified material, the surface was considered to be sufficiently smooth, as supported by the good repeatability of the measured radiance temperatures upon freezing.…”

Section: B High Temperature Measurementsmentioning

confidence: 99%

“…Comparison between old (induction furnace heating in a tungsten crucible) 3,[29][30][31] and new (quasi-containerless laser heating) 5,7,28 data points for the melting/solidification temperatures of dioxides of the actinide series. Data for the dioxides of protactinium and trans-plutonium actinides are missing or considered as unreliable.…”

Section: Figmentioning

confidence: 99%

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Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements

Böhler

Welland

Bruycker

et al. 2012

Journal of Applied Physics

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This work revisits the melting behaviour of neptunium dioxide, an actinide compound which can be produced in the nuclear fuel during operation, and which has an important impact on the nuclear fuel and waste radioactivity especially on the very long term. The present experimental approach employs remote laser heating under controlled atmosphere and fast pyrometry. This technique circumvents problems encountered by more traditional heating techniques, in particular, the reaction between sample and containment at temperatures beyond 2500 K. In addition, only a small amount of sample material is required, which is an advantage with respect to the radioactivity and limited availability of neptunium. The NpO 2 melting/freezing temperature has been measured to be 3070 K 6 62 K, much higher than previous values (around 2830 K) obtained by more traditional thermal analysis methods. The large amount of experimental data collected allowed a consistent statistical analysis. It seems likely, although not fully evident from the present results, that the high oxygen potential at temperatures around melting leads to a slightly hypo-stoichiometric congruent melting composition, as already observed in other actinide (ThO 2 , PuO 2 ) and lanthanide oxides (e.g., CeO 2 ). Finally, a recently developed phase-field model was used for the simulation of the observed thermograms, allowing a deeper insight in material properties that are difficult to directly measure. For example, a polaron contribution to the high-temperature thermal conductivity, well accepted for the commonly studied actinide oxide UO 2 , is shown here to likely be present in NpO 2 .

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Section: Discussionmentioning

confidence: 99%

Section: B High Temperature Measurementsmentioning

confidence: 99%

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Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements

Böhler

Welland

Bruycker

et al. 2012

Journal of Applied Physics

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“…Figure 6 shows two ideal solidus-liquidus curves, generated by taking into account two different melting points of PuO2 as reported by Bakker et al [46] and Bruycker et al [20]. In this definition it is assumed that the heat capacity is same for solid and liquid phases in the vicinity of melting and only configurational entropy is contributing to the Gibbs free energy.…”

Section: Melting Temperatures Of (Thpu)o2 Moxmentioning

confidence: 97%

“…For ThO2, these thermodynamic quantities for the solid phase are available only over a limited temperature range [21][22][23][24]26] and no data is available for the liquid phase. Recently, Böhler et al [18] and Bruycker et al [20] determined melting temperatures of PuO2 using a laser heating method and pyrometry. Valu et al [34] determined enthalpy increments of Th1-xPuxO2 (for x = 0, 0.03, 0.08, 0.30, 0.54, 0.85 and 1) using drop calorimetry in the temperature range 476 K to 1790 K. Still, high temperature enthalpy and density values of solid PuO2, (Th,Pu)O2 and(Th,U)O2 MOX as well as their respective liquid phases are not available.…”

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confidence: 99%

Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

Ghosh

Kuganathan

Galvin

et al. 2016

Journal of Nuclear Materials

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The melting behaviors of pure ThO2, UO2 and PuO2 as well as (Th,U)O2 and (Th,Pu)O2 mixed oxides (MOX) have been studied using molecular dynamics (MD) simulations. The MD calculated melting temperatures (MT) of ThO2, UO2 and PuO2 using two-phase simulations, lie between 3650-3675 K, 3050-3075 K and 2800-2825 K, respectively, which match well with experiments. Variation of enthalpy increments and density with temperature, for solid and liquid phases of ThO2, PuO2 as well as the ThO2 rich part of (Th,U)O2 and (Th,Pu)O2 MOX are also reported. The MD calculated MT of (Th,U)O2 and (Th,Pu)O2 MOX show good agreement with the ideal solidus line in the high thoria section of the phase diagram, and evidence for a minima is identified around 5 atom% of ThO2 in the phase diagram of (Th,Pu)O2 MOX.

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Behaviour and Properties of Nuclear Fuels

Konings

Bertolus

2018

Experimental and Theoretical Approaches to Actinide Chemistry

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The melting behaviour of plutonium dioxide: A laser-heating study

Cited by 34 publications

References 18 publications

Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements

Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements

Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

Behaviour and Properties of Nuclear Fuels

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