Modelling the release behaviour of cesium during severe fuel degradation

Lewis, Brian J.; André, Bernard; Morel, B.; Dehaudt, P.; Maro, D.; Purdy, Peter L.; Cox, D.S.; Iglesias, F.C.; Osborne, M.F.; Lorenz, R.A.

doi:10.1016/0022-3115(95)00130-1

Cited by 41 publications

(37 citation statements)

References 30 publications

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“…The conclusion was that irradiation had no effect on fuel oxidative volatilisation rate, but the uncertainties were rather large and the dependence of oxidative volatilisation rate on oxidation rate is not very strong. In another experiment [9], the fuel surface area increased 40 times, due to the presence of interconnected cracks; however, it did not lead to respective increase in fuel oxidation rate and only modest increase (by factors between 1.6 and 2.3) was observed. However, the presence of hydrogen in microcracks was noted that influences oxidation very significantly (for description, see also Figure 1 in Section 2).…”

Section: Introductionmentioning

confidence: 87%

“…In Figure 1, the commonly used [6,9] Blackburn (B) correlation [10] and the most accepted Lindemer and Besmann (LB) [11] correlation are compared against the correlation (Perron) used by…”

Section: Equilibrium Stoichiometry Deviationmentioning

confidence: 99%

“…To cover the whole range of stoichiometry, an empirical term (second term in Equation (2)) was added and this correlation (Equation (17a) in [10]) is used here (and elsewhere: e.g. [6,9]) for up to 0.25 x e value.…”

Section: Cox Et Al (The Original Model (Cp))mentioning

confidence: 99%

“…The model proposed by Cox et al for fuel oxidation in steam (Equation (1)) was generalised by Lewis et al [9] to high pressures using a modification of the correlation proposed by Abrefah et al [12]:…”

Section: Pressure Effectmentioning

confidence: 99%

“…Cox et al showed very good agreement between their model and the experimental data [1] for 1 atm pressure; however, in the work performed by Lewis et al (e.g. [6,9]) on oxidation of defected irradiated fuel at 100 atm pressure, an extra factor of 2-3 for the surface-tovolume ratio had to be introduced to get agreement with experimental fission-product releases. The need for this extra factor was interpreted as the effect of surface roughness and cracking of the fuel.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of the models of urania fuel oxidation in steam-rich atmosphere

Szpunar

2012

Journal of Nuclear Science and Technology

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The urania fuel oxidation model for a steam-rich atmosphere developed by Cox et al. using the extensive experimental database has been subsequently used widely but with some inconsistencies in implementations. They are listed and evaluated in this work to help improve the existing models as well as for future model development. The comparison of the equilibrium stoichiometry deviation, calculated using various models, is also given. Small differences between the equilibrium constants used for steam dissociation are found. In one application, the original model for steam dissociation was rewritten in terms of component partial pressures for simplification. It is shown that the modified model differs from the original model by a multiplicative factor (1 7 p O 2 /P tot ). A more complex equation that preserves total pressure is derived. However, the effect on the calculated fuel oxidation is much smaller than the effect of the uncertainty of the equilibrium stoichiometry deviation. The discrepancies in stoichiometry deviations and the estimate of the surface area of a pellet may lead to a double underprediction of fuel oxidation rate.

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Section: Introductionmentioning

confidence: 87%

“…In Figure 1, the commonly used [6,9] Blackburn (B) correlation [10] and the most accepted Lindemer and Besmann (LB) [11] correlation are compared against the correlation (Perron) used by…”

Section: Equilibrium Stoichiometry Deviationmentioning

confidence: 99%

Section: Cox Et Al (The Original Model (Cp))mentioning

confidence: 99%

Section: Pressure Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of the models of urania fuel oxidation in steam-rich atmosphere

Szpunar

2012

Journal of Nuclear Science and Technology

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Physico-Chemical Characterization of Particle Fallout from a Damaged Nuclear Reactor — Consequences for Remediation Procedures

Ronneau

Cara

Vanbegin

et al. 1997

Biotechnology for Waste Management and Site Restoration

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Modeling of the oxidation of uranium dioxide in a steam atmosphere

Dobrov¹,

Likhanskiǐ²,

Озрин³

et al. 1997

At Energy

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The properties of reactor materials determine both the normal operating regime of a reactor and the way in which thermophysical and physicochemical processes occur trader accident conditions. With an increase in temperature the interaction of the structural materials with each other and with the coolant can take place rapidly and result in serious accidents involving the destruction of the active zone of the reactor.One important practical problem is oxidation of the reactor fuel. Numerous investigations have shown that in the presence of a steam atmosphere oxidation of uranium dioxide takes place to a nonstoichiometric composition. The nonstoichiometric nature of the fuel depends on many parameters and can be quite extensive. An increase in the amount of oxygen in the uranium dioxide lattice changes the fuel properties. There are increases in the diffusion coefficient and electrical conductivity, changes in the thermal conductivity, etc. Other phases with a different specific density can appear, and this leads to a reduced strength and a change in the fuel structure. In particular, a consequence of nonstoichiometric fuel is a change in the diffusion coefficient of Oxygen and rare gases in the lattice which strongly influences the fission product yield.We present here the results of an analysis of experiments [I-3] and models on the oxidation of uranium dioxide in the temperature range 1200-2000 K. A new correlation oxidation model is formed which is developed in terms of the Langmuir adsorption theory with parameters optimized on the basis of experimental data. OXIDATION MODELIn previous work on the oxidation kinetics of solid fuel it was assumed that the rate of the process is mainly limited by the diffusion of oxygen in the UO2+ x lattice. However, it was later shown experimentally [4] that the reaction of the absorption of oxygen by the surface of a sample occurs relatively slowly, and in thin samples it is the gas-surface interaction and not the bulk diffusion which controls the rate of oxidation. This is explained by the fact that the coefficients of self-diffusion and chemical diffusion of oxygen in uranium dioxide in the temperature range T = 1200-2000 K are quite large (around 10 -7 to 10 -5 cm2/s) and for samples whose size is smaller than 1 cm the diffusion rate exceeds the rate of the processes occurring on the surface.The fundamental theoretical ideas are based on the following assumptions. The oxidation of a sample of uranium dioxide consists of two successive processes. Water vapor which is in contact with the solid uranium dioxide dissociates and the oxygen is absorbed on the surface of the sample:The rate of oxidation of the sample is determined by the difference between the current concentration of the oxygen in the UO2+ x and the equilibrium concentration. The latter depends on both the temperature and the composition of the gas mixture. Among the oxidation models, the correlation model introduced by Carter and Lay [4] and the mechanistic model based on the approach of Gala and Grabke [5] nee...

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Modelling the release behaviour of cesium during severe fuel degradation

Cited by 41 publications

References 30 publications

Assessment of the models of urania fuel oxidation in steam-rich atmosphere

Assessment of the models of urania fuel oxidation in steam-rich atmosphere

Physico-Chemical Characterization of Particle Fallout from a Damaged Nuclear Reactor — Consequences for Remediation Procedures

Modeling of the oxidation of uranium dioxide in a steam atmosphere

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