The heat capacities of Al2o3, Uo2 and PuO2 From 300 To 1100 °K

Engel, T.K.

doi:10.1016/0022-3115(69)90194-9

Cited by 28 publications

(7 citation statements)

References 3 publications

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“…This is caused by consol idation of particles into a more dense configuration. Engel reported a heat capacity for Pu02 increasing from 0.06 cal/g°K at 300°K to 0.07 cal/g°K to 1100°K, (Engel 1969). The oxide is physically stable up to a melting point of 2240°C (Chikalla et al 1964).…”

Section: Stability In Firementioning

confidence: 99%

Investigation into the feasibility of alternative plutonium shipping forms

Mishima¹,

Lindsey²

1983

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Section: Stability In Firementioning

confidence: 99%

Investigation into the feasibility of alternative plutonium shipping forms

Mishima¹,

Lindsey²

1983

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“…Models that can be divided into numerical [7,8] and semi-empirical [9][10][11][12] have been developed on the basis of measurements of the specifi c heat of uranium dioxide at constant pressure in the temperature range 5.7-1667 K [2][3][4][5][6]. The former are not suitable for theoretical evaluations of thermophysical quantities and the fuel temperature in asymptotic limits and the latter are incorrect.…”

mentioning

confidence: 99%

“…equals only hundredths of a per cent at room temperature and 1% at 1500 K. The computational error ~Δ 2 Experimental temperature dependence of the specific heat of uranium dioxide at constant pressure: -·-)[2]; b)[3]; a)[4]; c)[5]; A)[6]; --) computed specific heat at constant volume (4); ---) anharmonic correction to the specific heat(5).…”

mentioning

confidence: 99%

“…The model phonon density of states (3) satisfi es condition (2). The Einstein frequencies for the optical branches of the spectrum of normal vibrations, determined according to Fig.…”

mentioning

confidence: 99%

“…where k D = [6π 2 / Ω] 1/3 = 3.89 / a is the modulus of the Debye quasiwave vector and Ω ≡ a 3 is the volume of the elementary cell of uranium dioxide. Finally, the Debye temperature for uranium dioxide θ D = ˙ω D /k B = 168 K, where ˙ is Planck's constant, and k B is Boltzmann's constant.…”

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Model for the Specific Heat of Uranium Dioxide

et al. 2015

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The existing models of the specifi c heat of uranium dioxide are analyzed. A new physical model of the specifi c heat of uranium dioxide is developed on the basis of experimental phonon spectra by the methods of the theory of solids. The model proposed is applicable in a wide temperature interval and has no adjustable parameters.The temperature distribution in a uranium dioxide pellet is calculated using models with the thermal conductivity and specific heat as parameters. The thermal conductivity of a ceramic is usually measured by the laser flash method [1]. In this method, the thermal conductivity is calculated as the product of the measured thermal diffusivity by the specific heat capacity per unit volume. Thus, it is necessary to know the specific heat capacity of uranium dioxide not only to model the temperature distribution in a pellet of a fuel element but also to process measurements of other thermophysical parameters of this fuel.Models that can be divided into numerical [7,8] and semi-empirical [9-12] have been developed on the basis of measurements of the specifi c heat of uranium dioxide at constant pressure in the temperature range 5.7-1667 K [2-6]. The former are not suitable for theoretical evaluations of thermophysical quantities and the fuel temperature in asymptotic limits and the latter are incorrect.The aim of the present work is to develop a physically valid model for the specific heat of uranium dioxide. Uranium dioxide possesses a crystal lattice of the type found in fluorite CaF 2 ; the lattice parameter a = 547 pm at room temperature. Since the elementary cell contains three types of atoms, viz., one uranium atom and two oxygen atoms, there are nine branches in the spectrum of normal vibrations: three phonon branches are acoustic and six optical.All transverse phonon branches are doubly degenerate. For this reason, six of the nine possible modes are presented in Fig. 1 [13]. It is evident that the longitudinal optical modes not only depend weakly on the quasiwave vector of a phonon but they are also close. The first and second maxima of the phonon density of states correspond to the acoustic doubly degenerate transverse ν TA and longitudinal ν LA frequencies (Fig. 2). The third and fourth peaks correspond to two frequencies ν TO 2 > ν TO 1 of the doubly degenerate transverse optical branches. The frequencies ν LO 1 and ν LO 2 of the longitudinal optical vibrations are indistinguishable from one another.To construct a model of the specific heat C ν of uranium dioxide at constant volume, we shall take account of the contribution of the acoustic branches within the framework of the Debye model and the optical branches by means of Einstein's model [14][15][16].UO 2 Specific Heat at Constant Volume. We shall calculate the Debye frequency ω D of uranium dioxide. For this, we shall calculate the longitudinal and transverse velocity of sound. The isotropic elastic moduli of oxide nuclear fuel at room temperature 298 K as a function of the porosity P of the sample in the interval 0 < P < 0.1 can ...

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2.2.6 References for 2.2.2 - 2.2.5

Troć¹,

Kaczorowski²

Landolt-Börnstein - Group III Condensed Matter

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The heat capacities of Al2o3, Uo2 and PuO2 From 300 To 1100 °K

Cited by 28 publications

References 3 publications

Investigation into the feasibility of alternative plutonium shipping forms

Investigation into the feasibility of alternative plutonium shipping forms

Model for the Specific Heat of Uranium Dioxide

2.2.6 References for 2.2.2 - 2.2.5

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