Analysis of Combustion of Graphite-Uranium Fuels in a Fixed Bed or Moving Bed

Scott, C.D.

doi:10.1021/i260019a004

Cited by 6 publications

(7 citation statements)

References 3 publications

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“…The reaction kinetics for the oxidation described in Eq. 1 taking place at the surface of the carbide pellet are provided by Scott [18] and given in Eq. 6: [14], R g the ideal gas constant, A U C is the surface area of the carbide and T | r1 and C O2 | r1 are the temperature and O 2 concentration at the carbide surface, respectively.…”

Section: Mathematical Representationmentioning

confidence: 99%

“…This allows a calculation of the reaction rate provided by Scott [18] in Eq. 6 giving the rate of O 2 consumed.…”

Section: Calculating the Changing Pellet Sizementioning

confidence: 99%

“…The existing literature does include some kinetic parameters presented by Scott [18] in a model describing the burning of graphite uranium fuel in oxygen that are of use, including an Arrhenius expression for the reaction rate. Mukerjee et al [13] added more detail by studying the initiation temperatures and temperature evolution under different oxygen partial pressures during the oxidation of UC microspheres.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Mathematical Representationmentioning

confidence: 99%

“…This allows a calculation of the reaction rate provided by Scott [18] in Eq. 6 giving the rate of O 2 consumed.…”

Section: Calculating the Changing Pellet Sizementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…(1), are taken from work published by Scott [4] and are presented below in Eq. (3): (3) where is the rate of oxygen consumed by the surface reaction, is a constant, the activation energy, the gas constant, the surface area of the sphere and and are the temperature and oxygen concentration at the surface of the pellet.…”

Section: Mathematical Representationmentioning

confidence: 99%

“…(4): (4) where is the temperature of the bulk gas and represents the concentration of the relevant species in the bulk gas.…”

Section: Mathematical Representationmentioning

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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Reprocessing of Spent Nuclear Fuels

Walton

Merz

1981

U Uranium

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Analysis of Combustion of Graphite-Uranium Fuels in a Fixed Bed or Moving Bed

Cited by 6 publications

References 3 publications

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

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

Reprocessing of Spent Nuclear Fuels

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