Long-term behavior of R7T7-type nuclear glass: Current state of knowledge and outlook

Gin, Stéṕhane; Godon, N.; Ribet, I.; Jollivet, Patrick; Minet, Y.; Frugier, Pierre; Vernaz, E.; Cavedon, J.M.; Bonin, Bernard; Quang, R. Do

doi:10.1557/proc-824-cc5.7

Cited by 28 publications

(16 citation statements)

References 14 publications

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“…The results of the investigations agree with the existing data on the meaning of embryos of the surface layer and the intermediate gel-like layer, which, possessing sorption properties, impede further leaching of the radionuclides out of the glass blocks [3,4,[6][7][8][9]17].…”

supporting

confidence: 87%

Change of structure and properties of vitrified radioactive wastes during long-time storage in an experimental repository

Barinov¹,

Varlakova²,

Stefanovskii³

et al. 2008

At Energy

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Scanning electron microscopy, x-ray phase analysis, and infrared spectroscopy are used to study samples selected from a near-surface zone of glass blocks of vitrified radioactive wastes from nuclear power plants after they have been in storage in an experimental repository for 17 years. It is shown that only a thin surface layer of the glass blocks undergoes any changes due to environmental factors, and quartz-like and alumosilicate embryos are found on this layer.The world regards the vitrification of high-and medium-level wastes as one of the most promising methods of isolating such wastes from the biosphere, but this method has only limited application at the present time [1,2]. This is due to the problems associated with the operation of high-temperature melters (corrosion resistance of structural materials and electrodes, volatilization of the components of the wastes), and the uncertainty in the behavior of vitrified wastes during long-term storage in different geological media for periods up to several thousands of years. The main methods for evaluating the stability of the vitrified wastes are:• leaching samples under conditions simulating the medium in the repository or under more stringent conditionsin corrosive media at high temperature and pressure, which make it possible to predict the change of the structure and the properties over long periods of time; • tests in underground laboratories or at sites approximating real conditions of long-time storage; • study of the natural analogs and archeological data. Accelerated methods of determining the corrosion resistance of solidified forms of radioactive wastes, including vitrified wastes, make it possible to achieve changes of their structure and properties over relatively short times and make comparative estimates as a function of the composition and synthesis parameters. As a rule, the conditions under which testing (temperature and radiation fields, leaching medium) is performed, differ substantially from the real conditions in a repository and, correspondingly, the data obtained on the corrosion resistance of solidified wastes can be too high or too low. The known natural analogs (obsidian, tektites, basaltic glasses) and archeological artifacts have very different chemical compositions from real vitrified wastes, so that the data on the changes occurring in these materials can be transferred to vitrified wastes only with great care.The best method for evaluating and predicting the behavior of vitrified wastes under the conditions of long-time storage is experimental storage under test area conditions (underground laboratories and near-surface or deep repositories) with Britain. periodic sampling of the material being tested. In the case of vitrified high-level wastes, the interaction of the products of radiolysis of water with the surface of the glass has a large effect on the glass matrix, while this effect is negligible for vitrified medium-level wastes.The glasses were placed in an experimental repository in Canada, Sweden, France, USA, Belgium, ...

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supporting

confidence: 87%

Change of structure and properties of vitrified radioactive wastes during long-time storage in an experimental repository

Barinov¹,

Varlakova²,

Stefanovskii³

et al. 2008

At Energy

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“…According to the most documented theory on glass corrosion, two coupled mechanisms control the residual alteration rate of nuclear glass: (1) interdiffusion, involving water transport from solution to the pristine glass and diffusion through the alteration film of species arising from glass dissolution; (2) precipitation of silicate phases, generally crystalline (Abrajano et al, 1990;Gin and Mestre, 2001;Gin et al, 2004Gin et al, , 2011Gin et al, , 2012Curti et al, 2006;Frugier et al, 2006Frugier et al, , 2008Valle et al, 2010). Recent studies have shown that the transport of aqueous species within the alteration film can be affected by pore closure in the gel Cailleteau et al, 2008), and/or by silica saturation of the pore solution in the interdiffusion zone (Maeda et al, 2012;Gin et al, 2013b,c).…”

Section: Discussionmentioning

confidence: 99%

Long-term alteration of basaltic glass: Mechanisms and rates

Parruzot

Jollivet

Rébiscoul

et al. 2015

Geochimica et Cosmochimica Acta

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“…Cation interdiffusion is often considered as a short duration tertiary process in the general process of glass corrosion [52,66]. However since the first experimental studies it has been clear that the time of change from the first (diffusion-controlled) mechanism to the second (hydrolysis) depends upon the temperature and composition of glass [16,17].…”

Section: Discussionmentioning

confidence: 99%