A 25-year laboratory experiment on French SON68 nuclear glass leached in a granitic environment – First investigations

Guittonneau, Claire; Gin, Stéṕhane; Godon, N.; Mestre, J.P.; Dugne, O.; Allegri, P.

doi:10.1016/j.jnucmat.2010.10.075

Cited by 47 publications

(32 citation statements)

References 54 publications

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“…The properties of this layer depend on both glass composition and leaching conditions, resulting in different protective effects [51,53]. Some researchers [55] argue that a passive layer develops almost immediately, i.e. the layer exists during the forward rate regime, but with weak passivating property.…”

Section: Rate Drop and Residual Ratementioning

confidence: 99%

A mechanistic model for long-term nuclear waste glass dissolution integrating chemical affinity and interfacial diffusion barrier

Jivkov

et al. 2017

Journal of Nuclear Materials

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Abstract:Understanding the alteration of nuclear waste glass in geological repository conditions is critical element of the analysis of repository retention function. Experimental observations of glass alterations provide a general agreement on the following regimes: inter-diffusion, hydrolysis process, rate drop, residual rate and, under very particular conditions, resumption of alteration. Of these, the mechanisms controlling the rate drop and the residual rate remain a subject of dispute. This paper offers a critical review of the two most competitive models related to these regimes: affinity-limited dissolution and diffusion barrier. The limitations of these models are highlighted by comparison of their predictions with available experimental evidence. Based on the comprehensive discussion of the existing models, a new mechanistic model is proposed as a combination of the chemical affinity and diffusion barrier concepts. It is demonstrated how the model can explain experimental phenomena and data, for which the existing models are shown to be not fully adequate.Key words: nuclear waste glasses, long-term dissolution, mechanisms, modelling IntroductionRadioactivity wastes are generated at all stages of the nuclear fuel cycle, including the decommissioning of nuclear facilities, as well as from military applications. Of particular concern for the storage/disposal of radioactivity wastes are those containing long-lived radionuclides [1].The current plan ( countries such as Belgium, Finland , Sweden , France etc.)for long-term management of such wastes is to store them in deep, stable and lowpermeable geological formations [2].The storage design is based on the so-called multi-barrier concept, where several barriers prevent for a period of time, or slow down the release and migration of radionuclides through the geosphere [3,4].Within this concept, hazardous nuclides are immobilized into solidified bodies. The wasteform selection is difficult, since durability is not the sole criterion [5]. Currently, vitrification is regarded as the best solution for immobilizing radionuclides. This technology has been progressively developed over the last half-century, has matured and has become industrially robust.Data collected to date suggest that glass waste forms offer the advantages that they can accommodate a wide range of waste streams, are resistant to radiation damage, and are relatively inert to both chemical and thermal perturbations [6].The use of natural and archeological analogues supported further the durability argument of glass as waste forms [7][8][9][10][11]. Except for the alumino-phosphate glass used in Russia, the borosilicate glass has been universally selected by all other nations [12].In order to make scientifically-underpinned safety cases, the long-term behaviour of glassy wasteforms requires further understanding and assessment. Half-lives of some radionuclides extend to millions of years, requiring isolation for geological periods, while the period of investigation possible in the field and the la...

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Section: Rate Drop and Residual Ratementioning

confidence: 99%

A mechanistic model for long-term nuclear waste glass dissolution integrating chemical affinity and interfacial diffusion barrier

Jivkov

et al. 2017

Journal of Nuclear Materials

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“…While the Guittonneau et al (2011) study presented important information on the bulk leaching rate of the nuclear glass specimen over 25 years, the ground-breaking study by Gin et al (2013) on the SON68 glass specimen presented extremely high spatial resolution post-mortem chemical profiles using atom probe tomography (APT) and Energy-Filtered Transmission Electron Microscopy (EFTEM). The APT technique allows the 3D reconstruction of the elemental distribution at the reactive interphase with subnanometer precision.…”

Section: Summary Of 25 Year French Glass Son68 Leaching Experimentsmentioning

confidence: 99%

“…At the other end of the 1D system, we assume a no-flux condition, which is reasonable as long as the corrosion front does not fully penetrate the glass specimen. Within the first 25 nanometers of the reaction, the system is characterized by a porosity of 0.41 (as in the experimental system reported by Guittonneau et al, 2011) and a mixture of quartz sand and granite. A diffusivity of 10 -11 m 2 /s for all ions was assumed for the sand-granite mixture.…”

Section: Model Setup For 25 Year French Glass Experimentsmentioning

confidence: 99%

“…A linear dependence on time would call into question the model of a Passive Reactive Interface (PRI) presented by Cailleteau et al (2008), although it does not entirely preclude such a model if the interface maintains a constant width over time (forming at the leading edge next to the pristine glass and dissolving at the trailing edge). The leachate concentration measurements collected every 56 days over 25 years by Guittonneau et al (2011) provide data to constrain the long term corrosion rate and its time dependence.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, it allows us to include full multicomponent chemistry (including precipitation and dissolution), something which is not possible with molecular modeling approaches (Bourg and Steefel, 2012). Guittonneau et al (2011) report on a 25.75-year leaching experiment designed to improve our understanding of the mechanisms controlling glass dissolution in geological disposal conditions. A SON68 glass block was leached in slowly renewed synthetic groundwater (at 90ºC, 100 bars) in contact with sand, granite and Ni-Cr-Mo alloy specimens.…”

Section: Introductionmentioning

confidence: 99%

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