Modelling aqueous corrosion of nuclear waste phosphate glass

Abstract

A model is presented on nuclear sodium alumina phosphate (NAP) glass aqueous corrosion accounting for dissolution of radioactive glass and formation of corrosion products surface layer on the glass contacting ground water of a disposal environment. Modelling is used to process available experimental data demonstrating the generic inhibiting role of corrosion products on the NAP glass surface.

Surface Alteration of Borosilicate and Phosphate Nuclear Waste Glasses by Hydration and Irradiation

“…The composition of synthesized borosilicate glass was based on data published by S. Peuget et al [12]. Published data on composition of glasses utilized at the Russian HLW vitrification plant "Mayak" were used for the synthesis of aluminophosphate glass [3,13,17,18]. The compositions of non-radioactive and Pu-doped glass samples obtained in this study are presented in Table 1 in comparison with the real vitrified LILW containing decaying 134,137 Cs [15].…”

“…The Na-Al-P_238 sample demonstrates lower Pu mass loss than B-Si_238 in the same conditions, at least during the first month of the experiment. According to published data [3,13,21], alkalialuminophosphate glass is less chemically durable than the borosilicate one. Reference [3] also provides acceptance data for normalized leaching rates of vitrified radioactive waste, for which Pu should be below 10 −7 g × cm −2 × day −1 at room temperature.…”

“…It was suggested that behavior of glass samples similar to the alteration renewal could be explained by formation of small cracks on the surface and the involvement of new pristine glass areas in contact with water [22]. One should also account for Formation of silica-based gel as a result of contact of the borosilicate glass with water is a well-known effect, which is described in the literature [3,[5][6][7][8][9][10][11][12][13][14]. Surprisingly, examination of this particular gel by SEM and Raman spectroscopy showed a mainly aluminohydroxide structure of this phase [19].…”

“…Nevertheless, some nuclear waste streams, such as legacy LILW accumulated during the completion of various nuclear development programs, are better suited to immobilization using specially designed silicate or phosphate systems due to their composition [3,4]. Although there are numerous publications dedicated to the chemical durability of vitreous (glass) wasteforms in contact with water and under radiation damage (see, e.g., [5][6][7][8][9][10][11][12][13][14]), it is important to note that most of the results obtained are related to the study of non-radioactive simulants apart from a small number of works with real vitrified nuclear waste [15,16]. This is apparently caused by essential difficulties in carrying out experiments using real radioactive materials and the high cost of such experiments.…”

The effect of mixed La-Y doping on water resistance of phosphate glass

“…For example, the therapeutic effect of phosphate bioglass is achieved by controlling the degradation rate of glass as well as the specie and rate of ion release during the degradation process [9]; Phosphate laser glass will be eroded by water molecules during processing, transportation and service stages. The corrosion of glass surface by water molecules not only leads to subcritical crack growth, the OHproduced in the process of corrosion will also reduce the luminous performance of phosphate laser glass [10][11][12]; The extremely high water resistance is required for phosphate glass used to nuclear waste immobilization, which ensures that the solidified body's unexpected contact with groundwater will not lead to a large number of radioactive elements release [13]. It is not difficult to find that the chemical durability of phosphate glass directly affects the application effect and service life of the material in different fields.…”