Abstract
A model to predict the dissolution of UO{sub 2} fuel under both oxidizing and non-oxidizing conditions is presented and compared with other available models for fuel dissolution. Dissolution rates under oxidizing conditions are predicted by extrapolating steady-state electrochemical currents for the anodic dissolution of UO{sub 2} to the corrosion potentials measured in solutions containing various oxidants, including dissolved oxygen, hydrogen peroxide, and the products of the gamma or alpha radiolysis of water. For non-oxidizing conditions, the dissolution rate of UO{sub 2} is not well known. Attempts to measure this rate are fraught with difficulties, and the published values are difficult to rationalize within the framework of our model. Consequently, we briefly reviewed the literature on the dissolution of similar p-type semiconducting oxides and chose to estimate the chemical dissolution rate of UO{sub 2} by analogy to the well-studied oxide NiO. In this manner we have managed to establish a threshold rate below which the rate of oxidative dissolution becomes negligible in comparison with the rate of chemical dissolution. This threshold agrees quite well with that established electrochemically. Using these extrapolated rates we predict that the rate for oxidative dissolution of CANDU (CANada Deuterium Uranium) fuel due to gamma radiolysis will
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Citation Formats
Shoesmith, D W, and Sunder, S.
An electrochemistry-based model for the dissolution of UO{sub 2}.
Canada: N. p.,
1991.
Web.
Shoesmith, D W, & Sunder, S.
An electrochemistry-based model for the dissolution of UO{sub 2}.
Canada.
Shoesmith, D W, and Sunder, S.
1991.
"An electrochemistry-based model for the dissolution of UO{sub 2}."
Canada.
@misc{etde_10157050,
title = {An electrochemistry-based model for the dissolution of UO{sub 2}}
author = {Shoesmith, D W, and Sunder, S}
abstractNote = {A model to predict the dissolution of UO{sub 2} fuel under both oxidizing and non-oxidizing conditions is presented and compared with other available models for fuel dissolution. Dissolution rates under oxidizing conditions are predicted by extrapolating steady-state electrochemical currents for the anodic dissolution of UO{sub 2} to the corrosion potentials measured in solutions containing various oxidants, including dissolved oxygen, hydrogen peroxide, and the products of the gamma or alpha radiolysis of water. For non-oxidizing conditions, the dissolution rate of UO{sub 2} is not well known. Attempts to measure this rate are fraught with difficulties, and the published values are difficult to rationalize within the framework of our model. Consequently, we briefly reviewed the literature on the dissolution of similar p-type semiconducting oxides and chose to estimate the chemical dissolution rate of UO{sub 2} by analogy to the well-studied oxide NiO. In this manner we have managed to establish a threshold rate below which the rate of oxidative dissolution becomes negligible in comparison with the rate of chemical dissolution. This threshold agrees quite well with that established electrochemically. Using these extrapolated rates we predict that the rate for oxidative dissolution of CANDU (CANada Deuterium Uranium) fuel due to gamma radiolysis will fall below this threshold after {approx} 200 a, a time period that is short in comparison with the anticipated lifetimes of titanium waste containers, which are expected to last for a period greater than {approx} 1200 a. For dissolution due to alpha radiolysis, oxidative rates are uncertain, but could be above this threshold for a period of 500 to 10 000 a for CANDU fuel, and 500 to 30 000 a for pressurized water reactor (PWR) fuel. The uncertainty in these ranges reflects the poor quality and limited number of corrosion potential measurements in the presence of alpha radiolysis.}
place = {Canada}
year = {1991}
month = {Nov}
}
title = {An electrochemistry-based model for the dissolution of UO{sub 2}}
author = {Shoesmith, D W, and Sunder, S}
abstractNote = {A model to predict the dissolution of UO{sub 2} fuel under both oxidizing and non-oxidizing conditions is presented and compared with other available models for fuel dissolution. Dissolution rates under oxidizing conditions are predicted by extrapolating steady-state electrochemical currents for the anodic dissolution of UO{sub 2} to the corrosion potentials measured in solutions containing various oxidants, including dissolved oxygen, hydrogen peroxide, and the products of the gamma or alpha radiolysis of water. For non-oxidizing conditions, the dissolution rate of UO{sub 2} is not well known. Attempts to measure this rate are fraught with difficulties, and the published values are difficult to rationalize within the framework of our model. Consequently, we briefly reviewed the literature on the dissolution of similar p-type semiconducting oxides and chose to estimate the chemical dissolution rate of UO{sub 2} by analogy to the well-studied oxide NiO. In this manner we have managed to establish a threshold rate below which the rate of oxidative dissolution becomes negligible in comparison with the rate of chemical dissolution. This threshold agrees quite well with that established electrochemically. Using these extrapolated rates we predict that the rate for oxidative dissolution of CANDU (CANada Deuterium Uranium) fuel due to gamma radiolysis will fall below this threshold after {approx} 200 a, a time period that is short in comparison with the anticipated lifetimes of titanium waste containers, which are expected to last for a period greater than {approx} 1200 a. For dissolution due to alpha radiolysis, oxidative rates are uncertain, but could be above this threshold for a period of 500 to 10 000 a for CANDU fuel, and 500 to 30 000 a for pressurized water reactor (PWR) fuel. The uncertainty in these ranges reflects the poor quality and limited number of corrosion potential measurements in the presence of alpha radiolysis.}
place = {Canada}
year = {1991}
month = {Nov}
}