On the oxidation of (U,Pu)C fuel: Experimental and kinetic aspects, practical issues

Mazaudier, Fabrice; Tamani, C.; Galerie, A.; Marc, Yves

doi:10.1016/j.jnucmat.2010.07.041

Cited by 14 publications

(12 citation statements)

References 15 publications

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“…The model differs from the only other model of this reaction that is available in the open literature in that the oxide product is not adherent, as is suggested by Mazuadier [11] and by Mukerjee [10] when higher O 2 partial pressures are applied ( 20kPa). The model is therefore significant to the field by virtue of being valid at different conditions to Scott's model [15], and also by comprehensively generating a stable and convergent numerical solution of the system.…”

Section: Discussionmentioning

confidence: 95%

“…It is unclear in the literature whether or not this is the case. Some reports suggest it adheres to the pellet [10], which slows the reaction due to diffusion across the oxide layer, whilst Mazaudier et al [11] observe that no product layer adheres: perhaps due to the marked decrease in density from UC (13.6 / ) to UO 2 (11.0 / ), which causes a significant volume expansion of approximately 33%. This assumption, of an instantaneously spalling oxide product layer, allows the oxidation kinetics to be simply represented by Eq.…”

Section: ( ) + ( ) ( )mentioning

confidence: 99%

“…It is observed by Berthinier et al [12,13] that further oxidation of the UO 2 occurs under most conditions, producing higher oxides such as U 3 O 8 and U 3 O 7 . However, since the UO 2 produced in the initial surface reaction is assumed to spall off, as suggested by Mazaudier et al [11], and hence not be present in this model, these further oxidations are not considered.…”

Section: ( ) + ( ) ( )mentioning

confidence: 99%

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Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Shepherd

Fairweather

Heggs

et al. 2015

Computers & Chemical Engineering

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Uranium carbide is a candidate fuel for future nuclear reactors. However, for it to be implemented in a closed fuel cycle, an outline for its reprocessing is necessary. One proposed method is to oxidise the uranium carbide into uranium oxide which can then be reprocessed using current infrastructure. A mathematical model describing the heat and mass transfer processes involved in such an oxidation has been constructed. The available literature was consulted for reaction coefficients and information on reaction products. A stable and convergent numerical solution has been developed using a combination of finitedifference approximations of the differential equations. Completion times of approximately 3-30 hours are predicted given a spherical pellet with a radius of 9.35 under varying initial conditions. The transient temperature distribution throughout the system is predicted, with a maximum temperature of 1458° observed from an initial temperature of 500° at an oxygen concentration of 3.15 .

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Section: Discussionmentioning

confidence: 95%

Section: ( ) + ( ) ( )mentioning

confidence: 99%

Section: ( ) + ( ) ( )mentioning

confidence: 99%

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Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Shepherd

Fairweather

Heggs

et al. 2015

Computers & Chemical Engineering

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“…Uranium monocarbide (UC) is under consideration for use in Generation IV reactors due to its higher conductivity and metal atom density making it easier to control in a reactor [12,11,3,19]. An important consideration when implementing a novel fuel type into the nuclear fuel cycle is that it must be able to be efficiently reprocessed.…”

Section: Introductionmentioning

confidence: 99%

Mathematical model of the oxidation of a uranium carbide fuel pellet including an adherent product layer

Shepherd

Fairweather

Hanson

et al. 2017

Applied Mathematical Modelling

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Highlights• Model of the oxidation of UC including an adherent U 3 O 8 product layer is presented.• Highly non-linear numerical solution to a double moving boundary problem.• Transient heat and mass transfer in expanding oxide and shrinking carbide phases• Temperature and oxygen concentration sensitivities tested and recommendations made. AbstractUranium carbide is a candidate fuel for Generation IV nuclear reactors. However, like any candidate fuel, a reprocessing route should be established before implementation. One proposed method involves a preoxidation step, where the carbide fuel is oxidised to an oxide and then reprocessed as normal. A mathematical model has been developed to simulate such an oxidation using finite difference approximations of the heat and mass transfer processes occurring. Available literature was consulted to provide coefficients for the reaction rates and importantly the diffusion of oxygen through the adherent oxide layer that forms on the carbide: the rate limiting step. The transient temperature, oxygen and carbon monoxide distributions through the system are modelled in order to predict oxidation completion times and the temperatures reached. It was found that for a spherical pellet of radius 0.935 cm, the oxidation can take between 1 h to 19 h depending on the oxidation conditions and reach temperatures of up to 1556 • C. A robust model results that offers increased understanding of a process crucial to the sustainable use of carbide fuels in energy generation.

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“…However, these reactions are not considered due to the assumption that the UO 2 product layer produced by the reaction instantaneously spalls off and hence is not present in the system being modelled, as has been suggested by Mazaudier et al [3], although this effect was in fact observed on a porous pellet.…”

Section: Introductionmentioning

confidence: 99%

A two-dimensional, finite-difference model of the oxidation of a uranium carbide fuel pellet

Shepherd¹,

Fairweather²,

Hanson³

et al. 2015

AIP Conference Proceedings

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Abstract. The oxidation of spent uranium carbide fuel, a candidate fuel for Generation IV nuclear reactors, is an important process in its potential reprocessing cycle. However, the oxidation of uranium carbide in air is highly exothermic. A model has therefore been developed to predict the temperature rise, as well as other useful information such as reaction completion times, under different reaction conditions in order to help in deriving safe oxidation conditions. Finite difference-methods are used to model the heat and mass transfer processes occurring during the reaction in two dimensions and are coupled to kinetics found in the literature.

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On the oxidation of (U,Pu)C fuel: Experimental and kinetic aspects, practical issues

Cited by 14 publications

References 15 publications

Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Mathematical model of the oxidation of a uranium carbide fuel pellet including an adherent product layer

A two-dimensional, finite-difference model of the oxidation of a uranium carbide fuel pellet

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